J Clim Epidembl Vol.45, No. II, pp. 1315-1326, 1992 Printed in Great Britain. All rights reserved
089S-i356/92 SS.00 + 0.00 Copyright 0 1992 Pergamon Press Ltd
FUNCTIONAL ABILITY OF COMMUNITY DWELLING ELDERLY. CRITERION-RELATED VALIDITY OF A NEW MEASURE OF FUNCTIONAL ABILITY KIRSTEN SCHULTZ-LARSEN,‘*‘*KIRSTEN AVLUNLI~ and SVENDKREINER~ ‘Institute of Social Medicine, University of Copenhagen, Blegdamsvej 3, DK 2200 Copenhagen N, 2Section of Prospective Medicine, Medical Department C, Copenhagen County Hospital in Glostrup, DK 2600 Glostrup and 3Daaish Institute for Educational Research, Hermodsgade 28, DK-2200 Copenhagen N, Denmark (Received in revised form 10 May 1992)
AbstractKriterion-related validity of a new measure of functional ability was conducted according to a causal model based on conceptual models employed in the area of rehabilitative and geriatric medicine. The criteria variables included concurrent diagnosed diseases, global self-rated health, drug consumption and general practitioner (GP) consultations. The measure of functional ability was developed with the intention of achieving a high degree of discrimination among a group of community dwelling elderly. Data were derived from a sample survey of 70-year-old men and women conducted in 1984 in the county of Copenhagen (Denmark). Altogether 366 men and 368 women participated in each of the two phases of the study-a comprehensive medical examination at the county hospital at Glostrup followed by a home visit conducted by an occupational therapist l-2 weeks later. The analysis included four different unidimensional index scales of functional ability divided into two types, with reduced speed and tiredness as subdimensions. The two scale types were mobility function and lower limb function. Early losses of ability together with global self-rated health were treated as outcome measures of diagnosed chronic diseases. At the same time these outcome measures together with diagnosed diseases were considered to predict drug consumption and GP consultations. It was shown that functional ability as measured by the new index scales were strongly influenced by diagnosed diseases: arteriostenosis and osteoarthrosis in lower extremities, obesity, shoulder impairments and bronchitis among women, and glucose intolerance, arteriostenosis in lower extremities and shoulder impairments among men. Global
self-rated health was strongly associated with the new functional ability rating system. Early losses of ability but not self-rated health was a strong predictor for drug consumption and frequent contacts with GP. It is concluded that the new measure of functional ability is suitable for health studies of community dwelling elderly, in particular as a summary statement of the individual’s health status. Functional ability Behavior
Activities of daily living
Chronic disease
INTRODUCTION
There is a general consensus that, particularly where the elderly are concerned, assessments of *Author for correspondence.
Self-rated health
Illness
health should not only be multidimensional but should also be in terms of functional status. Self-care ability generally called “activities of daily living” is considered probably the most important dimension of elderly individuals’ personal functioning [la]. Not only is the
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KIMTEN SCHULTZ-LARSEN et al.
functional ability in daily life related to both mental and physical health, it may also influence social wellbeing. The elderly tend to suffer from multiple chronic conditions. Interactions between manifestations of senescence and chronic diseases lead to patterns of different complications and combinations of diseases in different stages of severity. Consequently, diagnosis does not adequately identify elderly people with similar functional ability and need for care. There is, however, a major question of how to provide suitable information about the types of physical impairments and chronic conditions, which contribute to the functional status in individuals and populations. The number of “activities of daily living” assessment measures, which are specifically designed to assess functional status in populations of handicapped and very old individuals, and which meet acceptable standards of validity and reliability is high [5,6]. Most of these assessment instruments do not however provide relevant information about early losses of ability among community dwelling elderly. The proportion of impairments defined by commonly used levels of competence in basic bodily maintenance (ADL) is low, when the focus is on general population surveys of older people. Therefore, in some research investigations attention has been paid to disabilityscales based on activities basic to independent community residence (Instrumental ADL), which seem to be relevant to a broader proportion of elderly [7-121. The functional ability scales described in this paper should be viewed as instruments intended for general population level assessments. In order to achieve a high degree of discrimination, we included a higher than normal number of traditional activities related to functional ability and used two newly developed classification levels--difficulty in terms of tiredness and reduced speed. The rationale for using the categories of tiredness and reduced speed when measuring functional ability has been developed earlier [ 131.The feeling of tiredness and reduced speed in relation to tasks of daily life is a frequent experience among elderly men and women and is in accordance with theories of biological aging. Construct validity of the new measure of functional ability was tested by the Rasch model for item analysis. The Rasch model is a latent trait analysis among several item response models. It is a statistical pro-
cedure, developed for construct validation addressing specifically the internal validity by assessing the homogeneity of items under different conditions. It postulates that the response patterns, defined by answers to different questions or items, are homogeneous across items and individuals [14]. In this way it investigates whether the separate questions belong to the same dimension or not. The item analysis showed in the present study that the proposed measure of functional ability did not form a unidimensional structure. At least 6 dimensions divided into 3 types with reduced speed and tiredness as subdimensions were found. The 3 types were: mobility function, lower limb function and upper limb function. The detailed aspects of reliability and construct validity of the new functional ability scales have been discussed elsewhere [ 131. In this paper our concern is criterion-related validity [15] of the mobility function scales and the lower limb function scales-the scales which according to the construct validation analysis were the most consistent ones. The criteria included diagnosed variables concurrent diseases, global self-rated health, drug consumption and general practitioner (GP) consultations. The analysis is conducted according to a causal model based on conceptual models employed in the area of rehabilitative and geriatric medicine, where the consequences of disease are investigated [16]. Early losses of ability together with global self-rated health are treated as outcome measures of diagnosed diseases among 70-year-old men and women born in 1914. At the same time these outwith diagnosed come measures together diseases are considered to predict drug consumption and GP consultants as indicators of illness behavior. METHOD
Sample
Since 1964 age-cohorts have been followed in the Glostrup study with regular investigations every 5-10 years of social situational, biological and psychological, behavioral and chronic disease variables. A detailed description of the surveys is available elsewhere [ 17, 181. International, standardized measures and procedures have been used whenever possible to try to ensure the reliability and comparability of the health data. With few exceptions all assessments in each investigation have been carried
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Functional Ability of Community Dwelling Elderly
out by the same person to avoid inter-observer variation. Data presented in this paper are derived from a sample survey of 1119 70-year-old, former or present Glostrup residents, which was conducted in 1984 [18]. The investigation took place in the period from 1 April 1984 to 31 March 1985. 16 persons died before the investigation. 72% of the total sample participated in a comprehensive medical survey at the Copenhagen County Hospital in Glostrup. The health examination followed a fixed routine and included fasting ur&e and blood sampling, interview by questionnaire, medical examination and glucose tolerance test. During a home visit conducted by an occupational therapist l-2 weeks later, the medical survey participants were interviewed on self-reported functional abilities [ 181.Altogether 366 men and 368 women (66% of the total sample) participated in all phases of the study. These individuals constitute the sample studied. The non-participants did not in essence significantly differ from those who participated with regard to social and demographic characteristics or to days spent in hospital for all causes and for five different diseases (stroke, cancer, diabetes mellitus, bronchitis and ischemic heart diseases). Study variables Assessment of functional ability was based on the 70-year-olds’ ability to perform physical activities of daily living according to an interview. Four different one-dimensional index scales divided into two types, with reduced speed and tiredness as sub-dimensions, were specially developed and validated for the pur-
Mobility
function-reduced
speed
pose of describing health in a group of community dwelling elderly people [ 131. The two scale types were: mobility function, and lower limb function (Fig. 1). Global self-rated health was measured by the respondents’ answer to the question: “How would you rate your health during the last year: Excellent, good, fair or poor?’ [19]. Diagnosed chronic diseases were defined according to three different diagnostic principles. (1) Impairments based on objectively evaluated criteria (e.g. arterial blood pressure, systolic ankle blood pressure and hyperglycemia); (2) diseases defined by international standardized patient reports of characteristic types of symptoms (e.g. intermittent claudication and bronchitis); and (3) diseases classified according to common clinical judgement (e.g. osteoarthrosis, myocardial infarction and pulse findings). Subjects were defined as hypertensive, according to the WHO definition, when blood pressure 2 160/95 mmHg [20,21]. In the analysis the hypertension variable was categorized according to four levels: participants with normal blood pressure (< 140/90 mmHg); participants with borderline blood pressure; participants with elevated blood pressure z 160/95 mmHg); participants diagnosed and treated with drugs. The classification of diabetes mellitus and other categories of glucose intolerance was made according to international standardized principles [22]. Participants categorized as suffering from diabetes mellitus included those already diagnosed and treated with drugs and those with fasting blood value > 125 mg% and/or Zhour value > 170 mg%.
Mobility
function-tiredness
Get outdoors Transfer
Transfer
Walk
indoors
Walk
indoors
Walk
out
of
doors
in
nice
weather
Walk
out
of
doors
in
nice
weather
Walk
out
of
doors
in
poor
weather
Walk
out
of
doors
in
poor
weather
Manage Lower
Get
Manage
stairs limb
outdoors
function-reduced
speed
Go to the toilet Wash the lower half of the body Dress the lower half of the body Put/take shoes/stockings Cut toenails
on/off
Lower
stairs limb
function-tiredness
Go to the toilet Wash the lower half of the body. Dress the lower half of the body Put/take shoes/stockings on/off Cut toenails
Fig. 1. The four dimensionswithin functionalability. The order of activitiesfrom least to most difficult is listed with the easiesttask first.
KIRS~ENSCHULTZ-LARSEN et al.
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Bodyweight was expressed as body mass index (BMI = weight/height2, kg/m2). For analysis of the relationship between overweight and other health indicators the continuous variable was categorized in the following 4 groups: (O-19.9), (20-24.9), (2529.9), (30+). A Danish translation of the British Medical Research Council (BMRC) questionnaire on respiratory symptoms was used [23]. Persons were designated to have chronic bronchitis if they had both cough and sputum production on most days for at least 3 months during the previous 2 years. The medical evaluation conducted by the project physician included pulse palpitation and registration of joint impairments in respect of lower limbs. Restricted range of motion (ROM), palpable enlargements and crepitation of joints were registered (osteoarthrosis in lower limbs). Arcs of passive motion of the shoulders were measured by an ordinary goniometer with subjects seated. The absolute values obtained at the registration of shoulder joint ROM were directly transformed into two categories, normal and restricted (inward/outward rotation less than 60” and/or neutral abduction less than 1200). Arteriostenosis in lower limbs was diagnosed on three criteria: symptoms of intermittent claudication according to a WHO standardized questionnaire [24], pulselessness as found by pulse palpitation at clinical examination,
and an ankle/arm index below 90% as calculated from the systolic ankle blood pressure measurement [25]. Myocardiul infarction (ICD No. 410) was defined as non-fatal cases verified by hospital records, where two of three criteria, viz. pain, serial ECG or enzyme changes pointed towards the diagnosis. The procedure followed international standardized principles [26]. Drug consumption was measured as the number of specific prescribed and non-prescribed drugs consumed at least twice a week. Medication habits (amount, frequency and duration) were determined from two independent investigations. The first was an interview carried out by the project physician at the hospital, and the second during a home visit where the occupational therapist examined the pill bottles to identify drugs and prescription date. General practitioner consultations were reported during the medical examination at the hospital, as the number of GP visits from 70 year olds during the last year. The validity and precision of the questionnaire have been discussed elsewhere [27]. Analytical model
The statistical model used in the analysis is a subclass of log-linear models for multidimensional tables defined in terms of so-called independence graphs of which Figs 2 and 3 are examples. We refer to Wermuth and Lauritzen [28] and Whittaker [29] for an overview and
Women
Fig. 2. Independence graph after model search by recursive graphical models. Variables associated with the graph: A, GP consultations last year; B, numbers of medication; D, global self-rated; E, lower limb function-reduced speed; F, lower limb function-tiredness; G, mobility function-reduced speed; H, mobility function-tiredness; J, arteriostenosis in lower limbs; K, myocardial infarction; L, shoulder impairments; M, bronchitis; N, hypertension; 0, osteoarthrosis in lower limbs; P, glucose intolerance; Q, BMI.
Functional Ability of Community Dwelling Elderly
Men
Fig. 3. Independence graph after model search by recursive graphical models. Variables associated with the graph: A, GP consultations last year; B, numbers of medication; D, global self-rated, E, lower limb function-reduced speed; F, lower limb function-tiredness; G, mobility function-reduced speed; H, mobility function-tiredness; J, arteriostenosis in lower limbs; K, myocardial infarction; L, shoulder impairments; M, bronchitis; N, hypertension; 0, osteoarthrosis in lower limbs; P, glucose intolerance; Q, BMI.
additional references on these “block recursive graphical models” [30]. Causal order in the models is assumed according to the rules spelled out in Davis’ book [31]. The causal influences studied in this paper are diagnosed chronic diseases or illness conditions based on relatively objectively evaluated criteria and physician ratings among 70-year-old men and women. In selecting our casual structure for statistical analyses of the data, a number of specific disease entities were examined as independent variables in the recursive structure of our analytical model. Functional ability measurements and global self-rated health are intermediate variables that may a&t illness behavior, which in this study are indicated by drug consumption and contacts with a GP. The models are pictured in Figs 2 and 3, men and women separately. The independence graphs, Figs 2 and 3, identify all direct and indirect relationships. These graphs serve two purposes. They are used to display the results of the analysis in order to support the interpretation of the results. They are also used, however, during statistical analysis, guiding the analysis towards appropriate and coherent statistical procedures. The statistical analysis relies heavily not only on standard chi-squared statistics from the theory of log-linear models, but also on partial gamma coefficients for ordinal categorial data [32]. Most statistical tests were performed as exact conditional tests [33]. The variables included in the
analysis were all defined as ordinal categorial variables. In diagnosed disease variables, level 1 corresponds to healthy participants, in the functional ability scales, to participants with poorer function.
RESULTS
The distribution of health indicators in the population of 70 year olds is presented in Table 1. It is seen that 70-year-old men and women differed significantly with respect to a number of diagnosed chronic diseases. Bronchitis, myocardial infarction, arteriostenosis in lower limbs and glucose intolerance were more frequent among men, while hypertension was more frequent among women. There were no significant lower limb osteoarthrosis differences based on clinical judgement between men and women, but among men there was a relatively higher degree of restricted range of motion in the shoulders. The 70-year-old women rated their global health more pessimistically and they consumed more drugs than did the 70-year-old men. At the same time no differences were seen between 70-year-old men and women with respect to functional ability in daily life and the number of visits to a GP. In the multivariate analysis the four functional ability index-scales and global self-rated health were found to be closely interrelated and strongly influenced by diagnosed chronic disease. Likewise, there was a complex net of
KIR~TENSCHULTZ-LARSEN et al.
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Table 1. The distribution of health indicators in the population of 70-year-old women and men Diagnosed diseases
% Men
% Women
Hypertension
27.5
35.3
*
Bronchitis
15.3
7.9
**
Osteoarthrosis in lower limbs
38.2
37.9
Shoulder-impairments
(ROM)
19.6
9.7
Body mass index (BMI kg/mz) O-19.9 2C24.9 25 29.9 30-
4.9
41.0 42.7 11.4
7.7 40.9 33.5
Arteriostenosis in lower limbs 0 symptoms
***
17.9
10.1
67.7 20.5 8.5 3.3
***
9.2
4.2
**+
12.0 15.3
23.2
*
20.6 64.3 12.2 2.9
15.8 62.2 20.2 1.8
??
Mobility function reduced speed level 1 24.4 level 2 28.9 level 3 14.6 level 4 32.1
24.8 31.1 18.0 26.1
Mobility function tiredness level 1 level 2 level 3
33.5 21.3 45.2
59.1
I symptoms
21.2
2 symptoms 3 symptoms Myocardial infarction
9.6
Glucose inrolerance
Diabetes mellitus Other categories
9.1
Self-reported health Global self-rated health
Excellent Good Fair Poor
*
Functional Ability scales
33.2 17.9 48.9
Lower limb function reduced speed level 1 25.2 level 2 11.7 level 3 63.1
61.3
Lower limb function tiredness level 1 level 2
22.0 78.0
24.6 75.4
53.0
19.2
19.5
Illness behavior Numbers of medication 0
1
21.9
2 3 and more
11.2
41.6 23.7 15.1
13.9
19.6
GP consultations last year 0 1 2 3-4 5 and more
19.8
23.3
30.7 18.5 21.0
18.9 17.9 25.4
10.0
14.5
***
Categories in functional ability scales were: poorest function-level 1, best function-level 4, 3 or 2. ***p < 0.001; “p < 0.01; ‘p < 0.05.
correlations with specific chronic diseases in both men and women (Figs 2 and 3). Drug consumption was independently affected by the presence of hypertension in both sexes, but also indirectly affected by chronic disease influences on functional abilities in daily life. This means that the drug consumption found in the population of 70 year olds was observed independently of functional ability and global self-rated health status. At the same time the relative increase in early losses of ability among chronically sick 70 year olds, also contributed to the drug consumption seen in the population. The number of contacts between 70 year olds and their GP was only influenced indirectly by diagnosed diseases through functional ability in daily life (women) and drug consumption (men). Global self-rated health was also affected both indirectly and directly by specific chronic diseases, but only in men. In addition to the general health problems for males suffering from early losses of ability (as a consequence of diabetes and arteriostenosis in lower limbs) obese men had an independent significant deterioration in their experience of global health. In contrast, deterioration in global self-rated health appeared to hold for all women suffering from early losses of ability irrespective of type of diagnosed disease. In an attempt to understand the meaning of the statistical relationships between determinants and outcome variables, it is necessary to explore more deeply the extent to which the effects of the diagnosed chronic diseases are found in different subgroups of the conditioning variables. In Tables 2 and 3, those relationships where the specific disease influence is found in all subgroups of the conditioning variables are shown by a G (“global” relationships), whereas L indicates specific disease influences observed in only specific subgroups of the conditioning variables (“local” relationships). GM indicates that the global influence is modified by other determinants. The differences between men and women with regard to influences of diagnosed chronic diseases on functional ability are presented in Table 2. Among the number of diagnosed chronic conditions analyzed in this study, glucose intolerance especially but also arteriostenosis in lower limbs and restricted range of motion in shoulder joint, were associated directly with functional ability in daily life among men. In women, osteoarthrosis in lower limbs, and obes-
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Functional Ability of Community Dwelling Elderly
ity in addition to arteriostenosis in lower limbs, were all strong, global determinants of early losses of ability. Shoulder impairments together with bronchitis were only local determinants in specific subgroups of bodyweight and osteoarthrosis among women. It was among women suffering from bronchitis that we found the strongest association between obesity and functional ability. Hypertension and myocardial infarction, together with glucose intolerance in women and osteoarthrosis, bronchitis and obesity in men were only indirectly (through other chronic disease variables) related to functional ability in daily life. It can be seen from Table 3 that the influence of functional ability in daily life on visits to the GP among women, holds in all categories of the conditioning variables. Likewise, the correlation between drug consumption and measurements of early losses of
ability was also global for both men and women. On the other hand, there was a strong global iniluence of hypertension on drug consumption among men, but only a local influence among women, who were in regular personal contact with their GP. For global self-rated health (not in tables) the influence of obesity in men was seen in all subgroups of the conditioning variables. Moreover, a strong, global correlation was found between global self-rated health and abilities of daily living in both sexes.
DISCUSSION
It has long been recognized that assessments of health among the elderly should not only be multidimensional but also in terms of functional status [I]. A great number of valid and reliably functional ability assessment measurements
Table 2. Associations between diagnosed diseases and functional ability in the population of ‘IO-year-old women and men Dimensions of functional ability
Determinants
Control variables
Tvne of relationshin
Arteriostenosis Il.*
G7 = -0.43 p = 0.0000
Osteoarthrosis 1.1.
Functional ability Shoulder impairments Bronchitis BMI Osteoarthrosis 1.1. Functional ability Arteriostenosis 1.1. Shoulder impairments Bronchitis Osteoarthrosis 1.1. Functional ability Arteriostenosis 1.1. Shoulder impairments BMI Gsteoarthrosis 1.1. Functional ability Bronchitis Arteriostenosis 1.1. BMI Osteoarthrosis 1.1. Functional ability
Gsteoarthrosis 1.1.
Function ability
Gy = -0.31 p = 0.0067
Arteriostenosis 1.1.
Self-rated health Functional ability Shoulder impairments BMI Self-rated health Functional ability Arteriostenosis 1.1. Shoulder impairments BMI Functional ability Glucose intolerance Shoulder impairments Functional ability
Ly = -0.67 p = 0.0033
women Mobility function reduced speed
Obesity
Bronchitis
Shoulder impairments
Lower limb function tiredness Lower limb function reduced speed Men Mobility function tiredness Mobility function reduced speed
Glucose intolerance
Arteriostenosis 1.1. Lower limb function tiredness Y.1.. lower limbs.
Shoulder impairments
GM1 = -0.26 to -0.79 p=o.OoOO Modified by occurrence of bronchitis Ly = -0.87 p = 0.0000 Local relation for women with BMI > 20
Lr = -0.76 p = 0.0049 Local relation for women without osteoarthrosis 1.1.
@ = -0.40 p = 0.0167
Gy = -0.44 p = 0.0002
G1, = -0.35 p = 0.0033 Gy = -0.48 p = 0.0043
KIRSTEN SCHULTZ-LARSEN et al.
have been developed during the last 30-40 years [5,6,34]. Most of these traditional scales however are not sensitive enough to detect early losses of ability in community dwelling elderly individuals. The purpose of this paper is to examine the criterion-related validity [15] of a new measure of functional ability in daily life, developed with the intention of achieving a high degree of discrimination among a group of comparatively young and healthy elderly men and women. As shown before [13], this new measure opens up this possibility by using a scoring that defines difficulty in terms of both tiredness and reduced speed. The analysis of construct validity tested by the Rasch model for item response analysis discovered 6 different dimensions of functional ability, divided into 3 types with reduced speed and tiredness as subdimensions. One of the 3 types (upper limb function) was omitted in the actual study, because the items in this scale were problematical from a methodological point of view. In addition, the upper limb function scale did not discriminate very well among 70-yearold men and women. The hypothesis underlying the presentation of data is that occurrence of physical dysfunction is an important determinant of self-rated health. Therefore, in selecting our causal structure for statistical analysis of the concurrent validity of the functional ability scales, diagnosed diseases were examined as independent variables in the recursive structure of our analytical model. Functional ability and global self-rated health were treated as outcome measures, which together with concurrent diagnosed diseases were considered to predict illness behaviour-in this study defined by traditional indicators such as drug consumption and GP consultations [35]. Lack of knowledge of the natural history of many chronic diseases makes definition and measurement difficult. Interactions between physical impairments and manifestations of senescence, together with multiple pathology, result in different combinations of diseases, different patterns of complications and combinations of diseases in different stages of severity. Our analysis of specific conditions or impairments was limited to hypertension, bronchitis, diabetes, myocardial infarction, arteriostenosis in lower limbs, obesity and osteoarthrosis due to the cardiovascular main purpose of the Glostrup-study. Some important conditions were missing, such as cancer, Alzheimer’s disease, stroke and congestive heart failure.
Functional Ability of Community Dwelling Elderly
Compared with the diagnosed diseases included in the study, these four illness conditions have lower prevalence rates in populations of community dwelling young elderly. Six percent of the sample survey had been in hospital because of cancer during the previous 5 years, 5% because of stroke (non-published register data). Paralysis as found by clinical examination was present in 1.6%. The overall European prevalences of dementia for the 5-year age groups from 65 to 75 years were 1.4 and 4.1%, respectively [36]. The specific conditions included in this study all have public health importance due to their known high prevalence in general populations of elderly. The results show firstly that functional ability as measured by the new index scales was strongly influenced by specific chronic conditions, especially in women. Morbidity, due to broad locomotor disorders such as arteriostenosis in lower limbs, osteoarthrosis and shoulder impairments, as well as obesity (in women) and glucose intolerance (in men) were independently related to assessments of functional abilities in daily life. Secondly, the relationship between global selfrelated health and the functional ability scales was high, and in the direction hypothesized. Thirdly drug consumption and GP consultations were mainly indirectly affected by diagnosed chronic disease influences on early losses of ability detected by the new index scales. However, there is a possibility of bias in our results. Other factors, such as sociodemographic and lifestyle factors besides illness conditions not covered in the study, are likely to predict functional ability as well as drug consumption and GP consultations. Furthermore, there is a net of correlations between heart failure, arteriostenosis in lower limbs, stroke and blood pressure levels. One example of the most serious problems in the study is the relationship found between arteriostenosis in lower limbs and functional ability. Because a stroke may be related to arteriostenosis in lower limbs, there is a minor possibility that stroke and not arteriostenosis in lower limbs is the true determinant of functional ability. Sociodemographic and lifestyle factors are not, however, considered to be potential confounders in the actual study. Recent results from the Glostrup study (not yet published) suggest that illness conditions are intervening variables between social situational and lifestyle variables, and functional ability variables. The findings of this investigation are consistent with previous studies which have been con-
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cemed with validity and reliability of self-ratings of health as a component of health status in elderly individuals. Thus, self and physician ratings of health have been found to be predominantly congruous [19,37,38] in addition to the fact that correlations of self-rated health with the number of illness symptoms have been noted repeatedly among both older and younger groups [39-41]. The number of diseases reported in interviews [41-43], medical care utilization based on hospitalization and visits to physicians [43], and medication [42,43], have also been linked to self-rated health status. Among those living at home, but not for those in institutions, Fillenbaum [42] found that self-assessment of health was related to measures of physical health including various capabilities in daily functions (Multidimensional Functional Assessment: the OARS Methodology). Similar correlations between declining capabilities with respect to daily function and poor self-rated health have also been demonstrated in other community based studies [43-46]. Furthermore, it is in agreement with other studies [43,47,48] that the presence of osteoarthrosis, especially in women, has great influence on assessments of functional ability in daily life and global self-rated health. In the Framingham Disability Study [49], for those not diagnosed as having cardiovascular disease, diabetes was a predictor of disability in women but not in men. However, on the other hand, our findings indicated certain perceived health effects of glucose intolerance indirectly through obesity and arteriostenosis in women, while for men the influence of diabetes on functional ability was direct as in the longitudinal study by Lammi et al. [50]. Previous studies [49-521 have also reported that persons labelled as hypertensive have poorer health perceptions and more disability problems than normative. The demonstration of conditional independence between hypertensive disease and perceived health status in the present investigation of comparatively healthy elderly people suggests pathways of influence through other problems e.g. obesity and diabetes. Additionally, the present results are in agreement with experiences from clinical practice. The interactions seen in this study between obesity, hypertension and osteoarthrosis have also been reported in other studies [53-551. Shared risk factors and biological aspects of gender have been mentioned as possible explanations, but causal chains are not strictly understood.
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KIR~TENSCHULTZ-LARSEN et al.
It is also clear from previous investigations [48-50,52,54] that there is a large variability in the self-assessed functional ability of men and women depending on the illness conditions or symptoms involved. In our study the impact of low-risk chronic conditions on functional ability assessments were mainly present in women but not in men. In Manton’s study [48] the major causes of female disability were arthritis and diabetes as opposed to male disability causes, which were cancer and heart diseases, conditions which in our population of 70 year olds hardly were defined. Sex differences in the causes of loss of functional ability may be partly explained by age and disease related decrements in muscular strength and physical fitness [56,57]. The 70-year-old women were, according to previous studies, more likely to be taking some medicine and were consuming a higher number of them, compared to 70-year-old men [58]. This difference was mainly attributable to greater use of non-prescribed medicine in women, which was also found in other studies [58]. The strong impact of low-risk illness conditions on elderly women’s functional ability may be one of several causes of women’s relatively high selfmedication rate. From the standpoint of health promotion and disease prevention, understanding the influential interactions shaping health and function in old age is more important than ever, since there has been a striking increase in the proportion of elderly people during the last century, and since this trend seems likely to continue into the next century. It is concluded that the new measure of functional ability in daily life is suitable for health studies of community dwelling elderly, and particularly as a summary statement of the individual’s health status. Acknowledgements-This study has been supported by The Danish Medical Research Council (SLF 12-6409), The Medical Research Foundation of the Hospitals in the Counties of Bomholm, Frederiksborg, Roskilde, Storstrom and Vestsjmlland, The Velux foundation of 1981 and The Danish Health Insurance Foundation. The authors are grateful to Gavin Mooney for his helpful comments. REFERENCES 1. Fillenbaum GG. The wellbeing of the elderly. Approaches to Moltidhnensional Assessment. Geneva: World Health Organization; 1984. 2. Brorsson B. ADL-index: Sammanfattande mitt @ individens firm&ga att klsrs det dagligs livets aktiviterter. Metodoversikt. Stokholm: Medicinska forskn-
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Kane RA, Kane RL. Amessing the Elderly. A Practical Guide to Measurement. Toronto: Lexington Books; 1981. Applegate WB, Blass JP, Williams TF. Instruments for the functional assessment of older patients. N Engl J Med 1990; 322: 1207-1214. Katz S, Ford AB, Moskowitz RW, Jackson BA, Jaffe MW. Studies of illness in aned. JAMA 1963: 12: 914-919. Katz S, Akpom CA. A measure of primary sociobiological functions. Int J Health Sew 1976; 6: 493-597. Lawton MP, Brody EM. Assessment of older people: Self-maintaining and Instrumental Activities of Daily Living. Geront&gist 1969; 9: 179-186. Branch LG. Katz S. Knienmann K. Pansidero JA. A prospective study of ‘functional s&s among community elders. Am J Public Health 1984; 74: 266-268. Koyano W, Shibata H, Haga H, Suyama Y. Prevalence and outcome of low ADL and incontinence among the elderly: Five years follow-up in a Japanese urban community. Arch Gerontol Ceriatr 1986; 5: 197-206. Spector WD, Katz S, Murphy JB, Fulton JP. The heirarchical relationship between Activities of Daily Living and Instrumental Activities of Daily Living. J Chron Dis 1987: 40: 481489. Asberg KH, Sonn U. The cumulative structure of Personal and Instrumental ADL. A study of elderly people in a health service district. Scand J Rehabil Mtxl 1988; 21: 171-177. Fillenbaum GG. Screening the elderly. A brief instrumental Activities of Daily Living measure. Am Geriatr Sot 1985; 33: 698-706. Avlund K, Kreiner S, Schultz-Larsen K. Construct Validation and the Rasch Model: Functional capability of healthy elderly people. Scand J Sot Med Submitted. Andrich D. Rasch Models for Measurement. Sage University Paper. Series on Quantitative Applications in The Social Sciences, series No. 07-001. Beverly Hills: Sage; 1988. Rosenbaum PR. Criterion-related construct validity. Psychometrika 1989; 54: 625633. World Health Organization. International Class& cation of Impairments, Disabilities, and Handicaps: Manual of Classification Relating to the Consequences of Disease. Geneva: WHO; 1980.
17. Schroll M. A ten-year prospective study, 1964-1974, of cardiovascular risk factors in men and women from the Glostrup Population born in 1914. Thesis. Copenhagen: Laegeforeningens Forlag; 1982. _ 18. Avlund K. Schultz-Larsen K. What do 70-vear-old men and women do? And what are they able to do? From the Glostrup Survey in 1984. Aging. Clin Exp Res 1991; 3: 3949. 19. Maddox GL, Douglass EB. Self-assessment of health: A longitudinal study of elderly subjects. J Health Sot Behav 1973; 14: 87-93. 20. Arterial Hypertension. Geneva: World Health Organization; 1978: Tech Rep Ser 628. 21. Schroll M. Blood pressure as a cardiovascular risk factor in a IO-year prospective study of men and women born in 1914 and examined in 1964 and 1974 in Glostrup. Dao Med Boil 1981; 28: 154163. 22. National Diabetes Data Group, National Institute of Health. Classification of diabetes mellitus and other categories of glucose intolerance. Diabetes 1979; 28: 1039-1057. 23. Fletcher CM, Tinker CM. Chronic bronchitis: A further study of simple diagnostic methods in a working population. Br Med J 1961; 2: 1491-1498.
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25.
26. 27.
28.
29. 30. 31. 32. 33. 34. 35.
36.
Rose GA, Blackburn H. CardIovasa~Iar Survey Methods. Geneva: World Health Organization; 1968; Monograph Ser 56. Schroll M, Munck 0. Estimation of peripheral arteriosclerotic disease by ankle blood pressure measurements in a population study of 60-year-old men and women. J Chren Dis 1981; 34: 261-269. World Health Organization. Monica Manual. Geneva: WHO; 1990. Hollnagel H, Kamper-Jorgensen F. Utilization of health services by 40-year-old men and women in the Glostrup area, Denmark. Dan Med BuU 1980; 27: 130-139. Wermuth N, Lauritzen SL. On substantive research hypothesis, conditional independence graphs and graphical chain models. J Stat Sot Scr B 1990; 52: 21-50. Whittaker J. GraphieaI Models in Applied Multivariate St&&s. New York: Wiley; 1990. Kreiner S. User Guide to Diagram: A Program for Discrete Graphical Modeliog. University of Copenhagen: Statistical Research Unit; 1989. Davis JA. The I&c of Caosal Order. Sage University Paper series on Quantitative Applications in the Social Sciences, ser. No. 07-055. Beverly Hills: Sage; 1988. Agresti A. AnaIysis of Ordhml Categorical Data. New York: Wiley; 1984. Kreiner S. Analysis of multidimensional contingency tables by exact conditional tests: Techniques and strategies. ScamI J Stat 1987; 14: 97-112. Mahoney FI, Barthel DW. Functional evaluation: The Barthel Index. Md State Med J 1965: 14: 61-65. Mechanic D. The epidemiology of illness behaviour and its relationship to physical and psychological distress. In Mechanic D, Ed. Symptoms, BIness Behaviour and Help See&g. New York: Prodist; 1982. Hofman A, Rocca WA, Brayne C. et al. The prevalence of dementia in Europe: A collaborative study of 1980-1990 findings. Int J Epidemiol 1991; 20:
Fillenbaum GG. Social context and self-assessments of health among the elderly. J He&h Sne Behav 1979; 20: 45-51. 43. Linn BS, Linn MW. Objective and self-assessed health in the old and very old. Sot Sci Med 1980; 14A: 311-315. 44. Shanas E, Townsend P, Wedderburn D, Friis H, Miu P, Stehouwer J. OId People in Three IadusMaIIzed &&ties. London: Atherton Press; 1968. 45. Tissue T. Another look at self-rated health among the elderly. J Cereatol 1972; 27: 91-94. 46. Wan ‘lTH. Predicting self-assessed health status: A multivariate approach. He&b Sew Rea 1976; 11I: 464-477. 47. Verbrugge LM. Longer life but worsening health? Trends in health and mortality of middle aged and older persons. MIIbank Mem Fond Q 1984; 62:
42.
48.
Friedsam HJ, Martin HW. A comparison of self and physicians’ health ratings in an -older population. J He&h Human Bebav 1963: 4: 17s183. 38. LaRue A, Bank L, Jarvik L, Hetland M. Health in old age: How do physicians’ ratings and self-ratings compare? J Gcrontol 1979; 34: 687-691. 39. Murray J, Dunn G, Tarnopolsky A. Self-assessment of health: An exploration of the effects of physical and psychological symptoms. Psycho1 Med 1982; 12: 371-378. 40. Cockerham WC, Sharp K, Wilcox JA. Aging and perceived health status. J Gerontol 1983; 38: 349-355. 41. Jylhl M, Leskinen E, Alanen E, Leskinen AL, Heikkinen E. Self-rated health and associated factors among men of different ages. J Gerontol 1986; 41: 71&717.
475619. Manton
KG. A longitudinal study of functional change and mortality in the United States. J Cerwtol 1988; 43: Sl53-161. 49. Pinsky JL, Branch LG, Jette AM et al. Framingham disability study: Relationship of disability to cardiovascular risk factors among persons free of diagnosed cardiovascular disease. Am J F@demiol 1985; 122 644656. 50. Lammi UK, Kivelii SL, Nissinen A, Punsar S, Puska P, Karvonen M. Predictors of disability in elderly Finnish men-a longitudinal study. J Clh~ Epidemiol 1989; 42: 12t5-1225.
51. 52.
53.
736-748.
37.
1325
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Bloom JR, Monterossa S. Hypertension labelling and sense of well-being. Am J F+obtk He&b 1981; 71: 1228-1232. Stewart AL, Greenfield S, Hays RD ef al. Functional status and well-being of patients with chronic conditions. Results from the medical outcomes study. JAMA 1989; 262: 907-913. Bergstr6m G, Bjelle A, Sundh V, Svanborg A. Joint disorders at ages 70,75 and 79 years-a cross-sectional comparison. Br J Rheunutol 1986; 25: 333-341. Verbrugge LM, Lepkowski JM, Imanaka Y. Comorbidity and its impact on disability. MiIbank Mem Fund Q 1990; 67: 450-484. Verbrugge LM, Gates DM, Ike RW. Risk factors for disability among U.S. adults with arthritis. J cull Epidomiol 1991; 44: 167-182. Posner JD, Gorman KM, Klein HS, Woldow A. Exercise capacity in the elderly. Am J CardIoll986; 57: 52C-58C. Grimby G, Saltin B. The ageing muscle. Mini-review. CBn PhysIoi 1983; 3: 208-218. Dunnell K, Cartwright A. Medicioe Takers, Prescribers nod Hoarders. London: Routledge & Kegan Paul; 1972.
(Appendix overleaf)
1326
KIRSTENSCHULTZ-LARSEN et al. APPENDIX Questionnaire of Functional Ability
Mobility function: 1. Are you able to walk indoors? If yes: Do you get tired? Does it take more time than earlier? 2. Are you able to walk out of doors in nice weather? If yes: Do you get tired? Does it take more time than earlier? 3. Are you able 10 walk out of doors in poor weather? If yes: Do you get tired? Does it take more time than earlier? 4. Are you able to manage stairs? If yes: Do you get tired? Does it take more time than earlier? 5. Are you able to gei outdoors? If yes: Do you get tired? Does it take more time than earlier? 6. Are you able to get up from a chair/bed?
If yes: Do you get tired? Does it take more time than earlier? Lower limb function: 7. Are you able to wash the lower part of the body? If yes: Do you get tired? Does it take more time than earlier?
I. yes Yes
2. no
no
1
2 2
1. yes ves
2. no
i
2 2
I I. yes Yes
no
2. no
no
1 1
2 2
1. yes yes 1 1
2. no
1. yes yes
no 2 2 2. no
no
I I
2 2
I. yes
2. no
yes 1 1
I. yes Yes 1 1
no 2 2
2. no
no 2 2
8. Are you able to cut toenails? If yes: Do you get tired? Does it take more time than earlier?
1. yes
2. no
yes
no
9. Are you able to go to the toilet yourself? If yes: Do you get tired? Does it take more time than earlier?
yes
10. Are you able to dress the lower part of the body? If yes: Do you get tired? Does it take more time than earlier?
1I. Are you able to take shoes/stockings on /oj? If yes: Do you get tired? Does it take more time than earlier?
1
2 2
1. yes
2. no
1
I
1 I. yes yes 1 I
no 2 2 2. no
no 2 2
I. yes
2. no
yes
no
I
1
2 2
089S-i356/92 SS.00 + 0.00 Copyright 0 1992 Pergamon Press Ltd
FUNCTIONAL ABILITY OF COMMUNITY DWELLING ELDERLY. CRITERION-RELATED VALIDITY OF A NEW MEASURE OF FUNCTIONAL ABILITY KIRSTEN SCHULTZ-LARSEN,‘*‘*KIRSTEN AVLUNLI~ and SVENDKREINER~ ‘Institute of Social Medicine, University of Copenhagen, Blegdamsvej 3, DK 2200 Copenhagen N, 2Section of Prospective Medicine, Medical Department C, Copenhagen County Hospital in Glostrup, DK 2600 Glostrup and 3Daaish Institute for Educational Research, Hermodsgade 28, DK-2200 Copenhagen N, Denmark (Received in revised form 10 May 1992)
AbstractKriterion-related validity of a new measure of functional ability was conducted according to a causal model based on conceptual models employed in the area of rehabilitative and geriatric medicine. The criteria variables included concurrent diagnosed diseases, global self-rated health, drug consumption and general practitioner (GP) consultations. The measure of functional ability was developed with the intention of achieving a high degree of discrimination among a group of community dwelling elderly. Data were derived from a sample survey of 70-year-old men and women conducted in 1984 in the county of Copenhagen (Denmark). Altogether 366 men and 368 women participated in each of the two phases of the study-a comprehensive medical examination at the county hospital at Glostrup followed by a home visit conducted by an occupational therapist l-2 weeks later. The analysis included four different unidimensional index scales of functional ability divided into two types, with reduced speed and tiredness as subdimensions. The two scale types were mobility function and lower limb function. Early losses of ability together with global self-rated health were treated as outcome measures of diagnosed chronic diseases. At the same time these outcome measures together with diagnosed diseases were considered to predict drug consumption and GP consultations. It was shown that functional ability as measured by the new index scales were strongly influenced by diagnosed diseases: arteriostenosis and osteoarthrosis in lower extremities, obesity, shoulder impairments and bronchitis among women, and glucose intolerance, arteriostenosis in lower extremities and shoulder impairments among men. Global
self-rated health was strongly associated with the new functional ability rating system. Early losses of ability but not self-rated health was a strong predictor for drug consumption and frequent contacts with GP. It is concluded that the new measure of functional ability is suitable for health studies of community dwelling elderly, in particular as a summary statement of the individual’s health status. Functional ability Behavior
Activities of daily living
Chronic disease
INTRODUCTION
There is a general consensus that, particularly where the elderly are concerned, assessments of *Author for correspondence.
Self-rated health
Illness
health should not only be multidimensional but should also be in terms of functional status. Self-care ability generally called “activities of daily living” is considered probably the most important dimension of elderly individuals’ personal functioning [la]. Not only is the
1315
1316
KIMTEN SCHULTZ-LARSEN et al.
functional ability in daily life related to both mental and physical health, it may also influence social wellbeing. The elderly tend to suffer from multiple chronic conditions. Interactions between manifestations of senescence and chronic diseases lead to patterns of different complications and combinations of diseases in different stages of severity. Consequently, diagnosis does not adequately identify elderly people with similar functional ability and need for care. There is, however, a major question of how to provide suitable information about the types of physical impairments and chronic conditions, which contribute to the functional status in individuals and populations. The number of “activities of daily living” assessment measures, which are specifically designed to assess functional status in populations of handicapped and very old individuals, and which meet acceptable standards of validity and reliability is high [5,6]. Most of these assessment instruments do not however provide relevant information about early losses of ability among community dwelling elderly. The proportion of impairments defined by commonly used levels of competence in basic bodily maintenance (ADL) is low, when the focus is on general population surveys of older people. Therefore, in some research investigations attention has been paid to disabilityscales based on activities basic to independent community residence (Instrumental ADL), which seem to be relevant to a broader proportion of elderly [7-121. The functional ability scales described in this paper should be viewed as instruments intended for general population level assessments. In order to achieve a high degree of discrimination, we included a higher than normal number of traditional activities related to functional ability and used two newly developed classification levels--difficulty in terms of tiredness and reduced speed. The rationale for using the categories of tiredness and reduced speed when measuring functional ability has been developed earlier [ 131.The feeling of tiredness and reduced speed in relation to tasks of daily life is a frequent experience among elderly men and women and is in accordance with theories of biological aging. Construct validity of the new measure of functional ability was tested by the Rasch model for item analysis. The Rasch model is a latent trait analysis among several item response models. It is a statistical pro-
cedure, developed for construct validation addressing specifically the internal validity by assessing the homogeneity of items under different conditions. It postulates that the response patterns, defined by answers to different questions or items, are homogeneous across items and individuals [14]. In this way it investigates whether the separate questions belong to the same dimension or not. The item analysis showed in the present study that the proposed measure of functional ability did not form a unidimensional structure. At least 6 dimensions divided into 3 types with reduced speed and tiredness as subdimensions were found. The 3 types were: mobility function, lower limb function and upper limb function. The detailed aspects of reliability and construct validity of the new functional ability scales have been discussed elsewhere [ 131. In this paper our concern is criterion-related validity [15] of the mobility function scales and the lower limb function scales-the scales which according to the construct validation analysis were the most consistent ones. The criteria included diagnosed variables concurrent diseases, global self-rated health, drug consumption and general practitioner (GP) consultations. The analysis is conducted according to a causal model based on conceptual models employed in the area of rehabilitative and geriatric medicine, where the consequences of disease are investigated [16]. Early losses of ability together with global self-rated health are treated as outcome measures of diagnosed diseases among 70-year-old men and women born in 1914. At the same time these outwith diagnosed come measures together diseases are considered to predict drug consumption and GP consultants as indicators of illness behavior. METHOD
Sample
Since 1964 age-cohorts have been followed in the Glostrup study with regular investigations every 5-10 years of social situational, biological and psychological, behavioral and chronic disease variables. A detailed description of the surveys is available elsewhere [ 17, 181. International, standardized measures and procedures have been used whenever possible to try to ensure the reliability and comparability of the health data. With few exceptions all assessments in each investigation have been carried
1317
Functional Ability of Community Dwelling Elderly
out by the same person to avoid inter-observer variation. Data presented in this paper are derived from a sample survey of 1119 70-year-old, former or present Glostrup residents, which was conducted in 1984 [18]. The investigation took place in the period from 1 April 1984 to 31 March 1985. 16 persons died before the investigation. 72% of the total sample participated in a comprehensive medical survey at the Copenhagen County Hospital in Glostrup. The health examination followed a fixed routine and included fasting ur&e and blood sampling, interview by questionnaire, medical examination and glucose tolerance test. During a home visit conducted by an occupational therapist l-2 weeks later, the medical survey participants were interviewed on self-reported functional abilities [ 181.Altogether 366 men and 368 women (66% of the total sample) participated in all phases of the study. These individuals constitute the sample studied. The non-participants did not in essence significantly differ from those who participated with regard to social and demographic characteristics or to days spent in hospital for all causes and for five different diseases (stroke, cancer, diabetes mellitus, bronchitis and ischemic heart diseases). Study variables Assessment of functional ability was based on the 70-year-olds’ ability to perform physical activities of daily living according to an interview. Four different one-dimensional index scales divided into two types, with reduced speed and tiredness as sub-dimensions, were specially developed and validated for the pur-
Mobility
function-reduced
speed
pose of describing health in a group of community dwelling elderly people [ 131. The two scale types were: mobility function, and lower limb function (Fig. 1). Global self-rated health was measured by the respondents’ answer to the question: “How would you rate your health during the last year: Excellent, good, fair or poor?’ [19]. Diagnosed chronic diseases were defined according to three different diagnostic principles. (1) Impairments based on objectively evaluated criteria (e.g. arterial blood pressure, systolic ankle blood pressure and hyperglycemia); (2) diseases defined by international standardized patient reports of characteristic types of symptoms (e.g. intermittent claudication and bronchitis); and (3) diseases classified according to common clinical judgement (e.g. osteoarthrosis, myocardial infarction and pulse findings). Subjects were defined as hypertensive, according to the WHO definition, when blood pressure 2 160/95 mmHg [20,21]. In the analysis the hypertension variable was categorized according to four levels: participants with normal blood pressure (< 140/90 mmHg); participants with borderline blood pressure; participants with elevated blood pressure z 160/95 mmHg); participants diagnosed and treated with drugs. The classification of diabetes mellitus and other categories of glucose intolerance was made according to international standardized principles [22]. Participants categorized as suffering from diabetes mellitus included those already diagnosed and treated with drugs and those with fasting blood value > 125 mg% and/or Zhour value > 170 mg%.
Mobility
function-tiredness
Get outdoors Transfer
Transfer
Walk
indoors
Walk
indoors
Walk
out
of
doors
in
nice
weather
Walk
out
of
doors
in
nice
weather
Walk
out
of
doors
in
poor
weather
Walk
out
of
doors
in
poor
weather
Manage Lower
Get
Manage
stairs limb
outdoors
function-reduced
speed
Go to the toilet Wash the lower half of the body Dress the lower half of the body Put/take shoes/stockings Cut toenails
on/off
Lower
stairs limb
function-tiredness
Go to the toilet Wash the lower half of the body. Dress the lower half of the body Put/take shoes/stockings on/off Cut toenails
Fig. 1. The four dimensionswithin functionalability. The order of activitiesfrom least to most difficult is listed with the easiesttask first.
KIRS~ENSCHULTZ-LARSEN et al.
1318
Bodyweight was expressed as body mass index (BMI = weight/height2, kg/m2). For analysis of the relationship between overweight and other health indicators the continuous variable was categorized in the following 4 groups: (O-19.9), (20-24.9), (2529.9), (30+). A Danish translation of the British Medical Research Council (BMRC) questionnaire on respiratory symptoms was used [23]. Persons were designated to have chronic bronchitis if they had both cough and sputum production on most days for at least 3 months during the previous 2 years. The medical evaluation conducted by the project physician included pulse palpitation and registration of joint impairments in respect of lower limbs. Restricted range of motion (ROM), palpable enlargements and crepitation of joints were registered (osteoarthrosis in lower limbs). Arcs of passive motion of the shoulders were measured by an ordinary goniometer with subjects seated. The absolute values obtained at the registration of shoulder joint ROM were directly transformed into two categories, normal and restricted (inward/outward rotation less than 60” and/or neutral abduction less than 1200). Arteriostenosis in lower limbs was diagnosed on three criteria: symptoms of intermittent claudication according to a WHO standardized questionnaire [24], pulselessness as found by pulse palpitation at clinical examination,
and an ankle/arm index below 90% as calculated from the systolic ankle blood pressure measurement [25]. Myocardiul infarction (ICD No. 410) was defined as non-fatal cases verified by hospital records, where two of three criteria, viz. pain, serial ECG or enzyme changes pointed towards the diagnosis. The procedure followed international standardized principles [26]. Drug consumption was measured as the number of specific prescribed and non-prescribed drugs consumed at least twice a week. Medication habits (amount, frequency and duration) were determined from two independent investigations. The first was an interview carried out by the project physician at the hospital, and the second during a home visit where the occupational therapist examined the pill bottles to identify drugs and prescription date. General practitioner consultations were reported during the medical examination at the hospital, as the number of GP visits from 70 year olds during the last year. The validity and precision of the questionnaire have been discussed elsewhere [27]. Analytical model
The statistical model used in the analysis is a subclass of log-linear models for multidimensional tables defined in terms of so-called independence graphs of which Figs 2 and 3 are examples. We refer to Wermuth and Lauritzen [28] and Whittaker [29] for an overview and
Women
Fig. 2. Independence graph after model search by recursive graphical models. Variables associated with the graph: A, GP consultations last year; B, numbers of medication; D, global self-rated; E, lower limb function-reduced speed; F, lower limb function-tiredness; G, mobility function-reduced speed; H, mobility function-tiredness; J, arteriostenosis in lower limbs; K, myocardial infarction; L, shoulder impairments; M, bronchitis; N, hypertension; 0, osteoarthrosis in lower limbs; P, glucose intolerance; Q, BMI.
Functional Ability of Community Dwelling Elderly
Men
Fig. 3. Independence graph after model search by recursive graphical models. Variables associated with the graph: A, GP consultations last year; B, numbers of medication; D, global self-rated, E, lower limb function-reduced speed; F, lower limb function-tiredness; G, mobility function-reduced speed; H, mobility function-tiredness; J, arteriostenosis in lower limbs; K, myocardial infarction; L, shoulder impairments; M, bronchitis; N, hypertension; 0, osteoarthrosis in lower limbs; P, glucose intolerance; Q, BMI.
additional references on these “block recursive graphical models” [30]. Causal order in the models is assumed according to the rules spelled out in Davis’ book [31]. The causal influences studied in this paper are diagnosed chronic diseases or illness conditions based on relatively objectively evaluated criteria and physician ratings among 70-year-old men and women. In selecting our casual structure for statistical analyses of the data, a number of specific disease entities were examined as independent variables in the recursive structure of our analytical model. Functional ability measurements and global self-rated health are intermediate variables that may a&t illness behavior, which in this study are indicated by drug consumption and contacts with a GP. The models are pictured in Figs 2 and 3, men and women separately. The independence graphs, Figs 2 and 3, identify all direct and indirect relationships. These graphs serve two purposes. They are used to display the results of the analysis in order to support the interpretation of the results. They are also used, however, during statistical analysis, guiding the analysis towards appropriate and coherent statistical procedures. The statistical analysis relies heavily not only on standard chi-squared statistics from the theory of log-linear models, but also on partial gamma coefficients for ordinal categorial data [32]. Most statistical tests were performed as exact conditional tests [33]. The variables included in the
analysis were all defined as ordinal categorial variables. In diagnosed disease variables, level 1 corresponds to healthy participants, in the functional ability scales, to participants with poorer function.
RESULTS
The distribution of health indicators in the population of 70 year olds is presented in Table 1. It is seen that 70-year-old men and women differed significantly with respect to a number of diagnosed chronic diseases. Bronchitis, myocardial infarction, arteriostenosis in lower limbs and glucose intolerance were more frequent among men, while hypertension was more frequent among women. There were no significant lower limb osteoarthrosis differences based on clinical judgement between men and women, but among men there was a relatively higher degree of restricted range of motion in the shoulders. The 70-year-old women rated their global health more pessimistically and they consumed more drugs than did the 70-year-old men. At the same time no differences were seen between 70-year-old men and women with respect to functional ability in daily life and the number of visits to a GP. In the multivariate analysis the four functional ability index-scales and global self-rated health were found to be closely interrelated and strongly influenced by diagnosed chronic disease. Likewise, there was a complex net of
KIR~TENSCHULTZ-LARSEN et al.
1320
Table 1. The distribution of health indicators in the population of 70-year-old women and men Diagnosed diseases
% Men
% Women
Hypertension
27.5
35.3
*
Bronchitis
15.3
7.9
**
Osteoarthrosis in lower limbs
38.2
37.9
Shoulder-impairments
(ROM)
19.6
9.7
Body mass index (BMI kg/mz) O-19.9 2C24.9 25 29.9 30-
4.9
41.0 42.7 11.4
7.7 40.9 33.5
Arteriostenosis in lower limbs 0 symptoms
***
17.9
10.1
67.7 20.5 8.5 3.3
***
9.2
4.2
**+
12.0 15.3
23.2
*
20.6 64.3 12.2 2.9
15.8 62.2 20.2 1.8
??
Mobility function reduced speed level 1 24.4 level 2 28.9 level 3 14.6 level 4 32.1
24.8 31.1 18.0 26.1
Mobility function tiredness level 1 level 2 level 3
33.5 21.3 45.2
59.1
I symptoms
21.2
2 symptoms 3 symptoms Myocardial infarction
9.6
Glucose inrolerance
Diabetes mellitus Other categories
9.1
Self-reported health Global self-rated health
Excellent Good Fair Poor
*
Functional Ability scales
33.2 17.9 48.9
Lower limb function reduced speed level 1 25.2 level 2 11.7 level 3 63.1
61.3
Lower limb function tiredness level 1 level 2
22.0 78.0
24.6 75.4
53.0
19.2
19.5
Illness behavior Numbers of medication 0
1
21.9
2 3 and more
11.2
41.6 23.7 15.1
13.9
19.6
GP consultations last year 0 1 2 3-4 5 and more
19.8
23.3
30.7 18.5 21.0
18.9 17.9 25.4
10.0
14.5
***
Categories in functional ability scales were: poorest function-level 1, best function-level 4, 3 or 2. ***p < 0.001; “p < 0.01; ‘p < 0.05.
correlations with specific chronic diseases in both men and women (Figs 2 and 3). Drug consumption was independently affected by the presence of hypertension in both sexes, but also indirectly affected by chronic disease influences on functional abilities in daily life. This means that the drug consumption found in the population of 70 year olds was observed independently of functional ability and global self-rated health status. At the same time the relative increase in early losses of ability among chronically sick 70 year olds, also contributed to the drug consumption seen in the population. The number of contacts between 70 year olds and their GP was only influenced indirectly by diagnosed diseases through functional ability in daily life (women) and drug consumption (men). Global self-rated health was also affected both indirectly and directly by specific chronic diseases, but only in men. In addition to the general health problems for males suffering from early losses of ability (as a consequence of diabetes and arteriostenosis in lower limbs) obese men had an independent significant deterioration in their experience of global health. In contrast, deterioration in global self-rated health appeared to hold for all women suffering from early losses of ability irrespective of type of diagnosed disease. In an attempt to understand the meaning of the statistical relationships between determinants and outcome variables, it is necessary to explore more deeply the extent to which the effects of the diagnosed chronic diseases are found in different subgroups of the conditioning variables. In Tables 2 and 3, those relationships where the specific disease influence is found in all subgroups of the conditioning variables are shown by a G (“global” relationships), whereas L indicates specific disease influences observed in only specific subgroups of the conditioning variables (“local” relationships). GM indicates that the global influence is modified by other determinants. The differences between men and women with regard to influences of diagnosed chronic diseases on functional ability are presented in Table 2. Among the number of diagnosed chronic conditions analyzed in this study, glucose intolerance especially but also arteriostenosis in lower limbs and restricted range of motion in shoulder joint, were associated directly with functional ability in daily life among men. In women, osteoarthrosis in lower limbs, and obes-
1321
Functional Ability of Community Dwelling Elderly
ity in addition to arteriostenosis in lower limbs, were all strong, global determinants of early losses of ability. Shoulder impairments together with bronchitis were only local determinants in specific subgroups of bodyweight and osteoarthrosis among women. It was among women suffering from bronchitis that we found the strongest association between obesity and functional ability. Hypertension and myocardial infarction, together with glucose intolerance in women and osteoarthrosis, bronchitis and obesity in men were only indirectly (through other chronic disease variables) related to functional ability in daily life. It can be seen from Table 3 that the influence of functional ability in daily life on visits to the GP among women, holds in all categories of the conditioning variables. Likewise, the correlation between drug consumption and measurements of early losses of
ability was also global for both men and women. On the other hand, there was a strong global iniluence of hypertension on drug consumption among men, but only a local influence among women, who were in regular personal contact with their GP. For global self-rated health (not in tables) the influence of obesity in men was seen in all subgroups of the conditioning variables. Moreover, a strong, global correlation was found between global self-rated health and abilities of daily living in both sexes.
DISCUSSION
It has long been recognized that assessments of health among the elderly should not only be multidimensional but also in terms of functional status [I]. A great number of valid and reliably functional ability assessment measurements
Table 2. Associations between diagnosed diseases and functional ability in the population of ‘IO-year-old women and men Dimensions of functional ability
Determinants
Control variables
Tvne of relationshin
Arteriostenosis Il.*
G7 = -0.43 p = 0.0000
Osteoarthrosis 1.1.
Functional ability Shoulder impairments Bronchitis BMI Osteoarthrosis 1.1. Functional ability Arteriostenosis 1.1. Shoulder impairments Bronchitis Osteoarthrosis 1.1. Functional ability Arteriostenosis 1.1. Shoulder impairments BMI Gsteoarthrosis 1.1. Functional ability Bronchitis Arteriostenosis 1.1. BMI Osteoarthrosis 1.1. Functional ability
Gsteoarthrosis 1.1.
Function ability
Gy = -0.31 p = 0.0067
Arteriostenosis 1.1.
Self-rated health Functional ability Shoulder impairments BMI Self-rated health Functional ability Arteriostenosis 1.1. Shoulder impairments BMI Functional ability Glucose intolerance Shoulder impairments Functional ability
Ly = -0.67 p = 0.0033
women Mobility function reduced speed
Obesity
Bronchitis
Shoulder impairments
Lower limb function tiredness Lower limb function reduced speed Men Mobility function tiredness Mobility function reduced speed
Glucose intolerance
Arteriostenosis 1.1. Lower limb function tiredness Y.1.. lower limbs.
Shoulder impairments
GM1 = -0.26 to -0.79 p=o.OoOO Modified by occurrence of bronchitis Ly = -0.87 p = 0.0000 Local relation for women with BMI > 20
Lr = -0.76 p = 0.0049 Local relation for women without osteoarthrosis 1.1.
@ = -0.40 p = 0.0167
Gy = -0.44 p = 0.0002
G1, = -0.35 p = 0.0033 Gy = -0.48 p = 0.0043
KIRSTEN SCHULTZ-LARSEN et al.
have been developed during the last 30-40 years [5,6,34]. Most of these traditional scales however are not sensitive enough to detect early losses of ability in community dwelling elderly individuals. The purpose of this paper is to examine the criterion-related validity [15] of a new measure of functional ability in daily life, developed with the intention of achieving a high degree of discrimination among a group of comparatively young and healthy elderly men and women. As shown before [13], this new measure opens up this possibility by using a scoring that defines difficulty in terms of both tiredness and reduced speed. The analysis of construct validity tested by the Rasch model for item response analysis discovered 6 different dimensions of functional ability, divided into 3 types with reduced speed and tiredness as subdimensions. One of the 3 types (upper limb function) was omitted in the actual study, because the items in this scale were problematical from a methodological point of view. In addition, the upper limb function scale did not discriminate very well among 70-yearold men and women. The hypothesis underlying the presentation of data is that occurrence of physical dysfunction is an important determinant of self-rated health. Therefore, in selecting our causal structure for statistical analysis of the concurrent validity of the functional ability scales, diagnosed diseases were examined as independent variables in the recursive structure of our analytical model. Functional ability and global self-rated health were treated as outcome measures, which together with concurrent diagnosed diseases were considered to predict illness behaviour-in this study defined by traditional indicators such as drug consumption and GP consultations [35]. Lack of knowledge of the natural history of many chronic diseases makes definition and measurement difficult. Interactions between physical impairments and manifestations of senescence, together with multiple pathology, result in different combinations of diseases, different patterns of complications and combinations of diseases in different stages of severity. Our analysis of specific conditions or impairments was limited to hypertension, bronchitis, diabetes, myocardial infarction, arteriostenosis in lower limbs, obesity and osteoarthrosis due to the cardiovascular main purpose of the Glostrup-study. Some important conditions were missing, such as cancer, Alzheimer’s disease, stroke and congestive heart failure.
Functional Ability of Community Dwelling Elderly
Compared with the diagnosed diseases included in the study, these four illness conditions have lower prevalence rates in populations of community dwelling young elderly. Six percent of the sample survey had been in hospital because of cancer during the previous 5 years, 5% because of stroke (non-published register data). Paralysis as found by clinical examination was present in 1.6%. The overall European prevalences of dementia for the 5-year age groups from 65 to 75 years were 1.4 and 4.1%, respectively [36]. The specific conditions included in this study all have public health importance due to their known high prevalence in general populations of elderly. The results show firstly that functional ability as measured by the new index scales was strongly influenced by specific chronic conditions, especially in women. Morbidity, due to broad locomotor disorders such as arteriostenosis in lower limbs, osteoarthrosis and shoulder impairments, as well as obesity (in women) and glucose intolerance (in men) were independently related to assessments of functional abilities in daily life. Secondly, the relationship between global selfrelated health and the functional ability scales was high, and in the direction hypothesized. Thirdly drug consumption and GP consultations were mainly indirectly affected by diagnosed chronic disease influences on early losses of ability detected by the new index scales. However, there is a possibility of bias in our results. Other factors, such as sociodemographic and lifestyle factors besides illness conditions not covered in the study, are likely to predict functional ability as well as drug consumption and GP consultations. Furthermore, there is a net of correlations between heart failure, arteriostenosis in lower limbs, stroke and blood pressure levels. One example of the most serious problems in the study is the relationship found between arteriostenosis in lower limbs and functional ability. Because a stroke may be related to arteriostenosis in lower limbs, there is a minor possibility that stroke and not arteriostenosis in lower limbs is the true determinant of functional ability. Sociodemographic and lifestyle factors are not, however, considered to be potential confounders in the actual study. Recent results from the Glostrup study (not yet published) suggest that illness conditions are intervening variables between social situational and lifestyle variables, and functional ability variables. The findings of this investigation are consistent with previous studies which have been con-
1323
cemed with validity and reliability of self-ratings of health as a component of health status in elderly individuals. Thus, self and physician ratings of health have been found to be predominantly congruous [19,37,38] in addition to the fact that correlations of self-rated health with the number of illness symptoms have been noted repeatedly among both older and younger groups [39-41]. The number of diseases reported in interviews [41-43], medical care utilization based on hospitalization and visits to physicians [43], and medication [42,43], have also been linked to self-rated health status. Among those living at home, but not for those in institutions, Fillenbaum [42] found that self-assessment of health was related to measures of physical health including various capabilities in daily functions (Multidimensional Functional Assessment: the OARS Methodology). Similar correlations between declining capabilities with respect to daily function and poor self-rated health have also been demonstrated in other community based studies [43-46]. Furthermore, it is in agreement with other studies [43,47,48] that the presence of osteoarthrosis, especially in women, has great influence on assessments of functional ability in daily life and global self-rated health. In the Framingham Disability Study [49], for those not diagnosed as having cardiovascular disease, diabetes was a predictor of disability in women but not in men. However, on the other hand, our findings indicated certain perceived health effects of glucose intolerance indirectly through obesity and arteriostenosis in women, while for men the influence of diabetes on functional ability was direct as in the longitudinal study by Lammi et al. [50]. Previous studies [49-521 have also reported that persons labelled as hypertensive have poorer health perceptions and more disability problems than normative. The demonstration of conditional independence between hypertensive disease and perceived health status in the present investigation of comparatively healthy elderly people suggests pathways of influence through other problems e.g. obesity and diabetes. Additionally, the present results are in agreement with experiences from clinical practice. The interactions seen in this study between obesity, hypertension and osteoarthrosis have also been reported in other studies [53-551. Shared risk factors and biological aspects of gender have been mentioned as possible explanations, but causal chains are not strictly understood.
1324
KIR~TENSCHULTZ-LARSEN et al.
It is also clear from previous investigations [48-50,52,54] that there is a large variability in the self-assessed functional ability of men and women depending on the illness conditions or symptoms involved. In our study the impact of low-risk chronic conditions on functional ability assessments were mainly present in women but not in men. In Manton’s study [48] the major causes of female disability were arthritis and diabetes as opposed to male disability causes, which were cancer and heart diseases, conditions which in our population of 70 year olds hardly were defined. Sex differences in the causes of loss of functional ability may be partly explained by age and disease related decrements in muscular strength and physical fitness [56,57]. The 70-year-old women were, according to previous studies, more likely to be taking some medicine and were consuming a higher number of them, compared to 70-year-old men [58]. This difference was mainly attributable to greater use of non-prescribed medicine in women, which was also found in other studies [58]. The strong impact of low-risk illness conditions on elderly women’s functional ability may be one of several causes of women’s relatively high selfmedication rate. From the standpoint of health promotion and disease prevention, understanding the influential interactions shaping health and function in old age is more important than ever, since there has been a striking increase in the proportion of elderly people during the last century, and since this trend seems likely to continue into the next century. It is concluded that the new measure of functional ability in daily life is suitable for health studies of community dwelling elderly, and particularly as a summary statement of the individual’s health status. Acknowledgements-This study has been supported by The Danish Medical Research Council (SLF 12-6409), The Medical Research Foundation of the Hospitals in the Counties of Bomholm, Frederiksborg, Roskilde, Storstrom and Vestsjmlland, The Velux foundation of 1981 and The Danish Health Insurance Foundation. The authors are grateful to Gavin Mooney for his helpful comments. REFERENCES 1. Fillenbaum GG. The wellbeing of the elderly. Approaches to Moltidhnensional Assessment. Geneva: World Health Organization; 1984. 2. Brorsson B. ADL-index: Sammanfattande mitt @ individens firm&ga att klsrs det dagligs livets aktiviterter. Metodoversikt. Stokholm: Medicinska forskn-
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17. Schroll M. A ten-year prospective study, 1964-1974, of cardiovascular risk factors in men and women from the Glostrup Population born in 1914. Thesis. Copenhagen: Laegeforeningens Forlag; 1982. _ 18. Avlund K. Schultz-Larsen K. What do 70-vear-old men and women do? And what are they able to do? From the Glostrup Survey in 1984. Aging. Clin Exp Res 1991; 3: 3949. 19. Maddox GL, Douglass EB. Self-assessment of health: A longitudinal study of elderly subjects. J Health Sot Behav 1973; 14: 87-93. 20. Arterial Hypertension. Geneva: World Health Organization; 1978: Tech Rep Ser 628. 21. Schroll M. Blood pressure as a cardiovascular risk factor in a IO-year prospective study of men and women born in 1914 and examined in 1964 and 1974 in Glostrup. Dao Med Boil 1981; 28: 154163. 22. National Diabetes Data Group, National Institute of Health. Classification of diabetes mellitus and other categories of glucose intolerance. Diabetes 1979; 28: 1039-1057. 23. Fletcher CM, Tinker CM. Chronic bronchitis: A further study of simple diagnostic methods in a working population. Br Med J 1961; 2: 1491-1498.
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Fillenbaum GG. Social context and self-assessments of health among the elderly. J He&h Sne Behav 1979; 20: 45-51. 43. Linn BS, Linn MW. Objective and self-assessed health in the old and very old. Sot Sci Med 1980; 14A: 311-315. 44. Shanas E, Townsend P, Wedderburn D, Friis H, Miu P, Stehouwer J. OId People in Three IadusMaIIzed &&ties. London: Atherton Press; 1968. 45. Tissue T. Another look at self-rated health among the elderly. J Cereatol 1972; 27: 91-94. 46. Wan ‘lTH. Predicting self-assessed health status: A multivariate approach. He&b Sew Rea 1976; 11I: 464-477. 47. Verbrugge LM. Longer life but worsening health? Trends in health and mortality of middle aged and older persons. MIIbank Mem Fond Q 1984; 62:
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(Appendix overleaf)
1326
KIRSTENSCHULTZ-LARSEN et al. APPENDIX Questionnaire of Functional Ability
Mobility function: 1. Are you able to walk indoors? If yes: Do you get tired? Does it take more time than earlier? 2. Are you able to walk out of doors in nice weather? If yes: Do you get tired? Does it take more time than earlier? 3. Are you able 10 walk out of doors in poor weather? If yes: Do you get tired? Does it take more time than earlier? 4. Are you able to manage stairs? If yes: Do you get tired? Does it take more time than earlier? 5. Are you able to gei outdoors? If yes: Do you get tired? Does it take more time than earlier? 6. Are you able to get up from a chair/bed?
If yes: Do you get tired? Does it take more time than earlier? Lower limb function: 7. Are you able to wash the lower part of the body? If yes: Do you get tired? Does it take more time than earlier?
I. yes Yes
2. no
no
1
2 2
1. yes ves
2. no
i
2 2
I I. yes Yes
no
2. no
no
1 1
2 2
1. yes yes 1 1
2. no
1. yes yes
no 2 2 2. no
no
I I
2 2
I. yes
2. no
yes 1 1
I. yes Yes 1 1
no 2 2
2. no
no 2 2
8. Are you able to cut toenails? If yes: Do you get tired? Does it take more time than earlier?
1. yes
2. no
yes
no
9. Are you able to go to the toilet yourself? If yes: Do you get tired? Does it take more time than earlier?
yes
10. Are you able to dress the lower part of the body? If yes: Do you get tired? Does it take more time than earlier?
1I. Are you able to take shoes/stockings on /oj? If yes: Do you get tired? Does it take more time than earlier?
1
2 2
1. yes
2. no
1
I
1 I. yes yes 1 I
no 2 2 2. no
no 2 2
I. yes
2. no
yes
no
I
1
2 2
