International Journal of Occupational Safety and Ergonomics
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Measuring limitations in activities of daily living (LADL): A population based validation of a short questionnaire Achim Elfering, Sonja Cronenberg, Simone Grebner, Oezguer Tamcan & Urs Müller To cite this article: Achim Elfering, Sonja Cronenberg, Simone Grebner, Oezguer Tamcan & Urs Müller (2017): Measuring limitations in activities of daily living (LADL): A population based validation of a short questionnaire, International Journal of Occupational Safety and Ergonomics, DOI: 10.1080/10803548.2017.1388621 To link to this article: http://dx.doi.org/10.1080/10803548.2017.1388621
Accepted author version posted online: 10 Oct 2017.
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Date: 11 October 2017, At: 06:27
Publisher: Taylor & Francis & Central Institute for Labour Protection – National Research Institute (CIOP-PIB) Journal: International Journal of Occupational Safety and Ergnomics DOI: 10.1080/10803548.2017.1388621
Measuring limitations in activities of daily living (LADL): A population
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based validation of a short questionnaire Achim Elfering1,2, Sonja Cronenberg3,4, Simone Grebner1, Oezguer Tamcan3 & Urs Müller3 1
University of Bern, Department of Work and Organizational Psychology, Fabrikstrasse 8,
CH-3012 Bern, Switzerland 2
National Centre of Competence in Research, Affective Sciences, University of Geneva, CISA,
Chemin des Mines 9, CH-1202 Geneva, Switzerland 3
University of Bern, Institute for Evaluative Research in Orthopedic Surgery,
Stauffacherstrasse 78, CH-3014 Bern, Switzerland 4
University of Basel, University Hospital, Spitalstrasse 21, CH-4031 Basel, Switzerland
Contact Details: AE - corresponding author: phone +41 631 3639, [email protected] ORCiD: 0000-0003-4274-0261 SC: phone +41 61 556 51 98, [email protected] SG: phone +41 76 4544113, [email protected] OT: phone +49 76 571 91 71, [email protected] UM: phone +49 44 384 80 00, [email protected]
AE: phone +41 31 631 3639, [email protected] Address Correspondence (after acceptance) and reprints to: Achim Elfering, Tel: 0041-31-
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6313639, email: [email protected]
Measuring limitations in activities of daily living (LADL): A population based validation of a short questionnaire Achim Elfering1,2, Sonja Cronenberg3,4, Simone Grebner1, Oezguer Tamcan3 & Urs Müller3 1
University of Bern, Department of Work and Organizational Psychology, Fabrikstrasse 8,
CH-3012 Bern, Switzerland
Downloaded by [Gothenburg University Library] at 06:27 11 October 2017
2
National Centre of Competence in Research, Affective Sciences, University of Geneva, CISA,
Chemin des Mines 9, CH-1202 Geneva, Switzerland 3
University of Bern, Institute for Evaluative Research in Orthopedic Surgery,
Stauffacherstrasse 78, CH-3014 Bern, Switzerland 4
University of Basel, University Hospital, Spitalstrasse 21, CH-4031 Basel, Switzerland
Contact Details: AE - corresponding author: phone +41 631 3639, [email protected] ORCiD: 0000-0003-4274-0261 SC: phone +41 61 556 51 98, [email protected] SG: phone +41 76 4544113, [email protected] OT: phone +49 76 571 91 71, [email protected] UM: phone +49 44 384 80 00, [email protected]
AE: phone +41 31 631 3639, [email protected] Address Correspondence (after acceptance) and reprints to: Achim Elfering, Tel: 0041-316313639, email: [email protected]
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Measuring limitations in activities of daily living (LADL): A population based validation of a short questionnaire Purpose A newly developed questionnaire assessing limitations in activity of daily living (LADL–Q) that should improve assessment of LADL is tested in a large populationbased validation study. Methods This was a paper based survey. Overall, 16634 individuals that were representative for Downloaded by [Gothenburg University Library] at 06:27 11 October 2017
the working population in German speaking part of Switzerland participated in the study. Item analysis was used the final version of the LADL–Q to four items per subscale that correspond to potential problems in three body regions (back and neck, upper extremities, lower extremities). Analysis included tests for reliability, internal consistency, dimensionality and convergent validity. Results Test–retest reliability coefficients after two weeks ranged from .82 to .99 (Mdn = .87), with no item having a coefficient below .60. The median item-total coefficients ranged between moderate and good. Correlation coefficients between LADL–Q–subscales and three validated clinical instruments (WOMAC, SPADI, Oswestry) ranged from .63 to .81. In structural equation modeling the three subscales were significantly related with two important outcomes in occupational rehabilitation: self-reported general health and daily task performance. Conclusion The new LADL–Q is a brief, reliable and valid tool for assessment of LADL in studies on musculoskeletal health. Keywords: Short questionnaire, occupational rehabilitation, loco-motor system, musculoskeletal pain
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1. INTRODUCTION The World Health Organization (WHO) definition of disability refers to the International Classification of functioning, disability and health (ICF) and characterizes disability as problems in human functioning in three areas: Impairments (i.e. problems in body functions or alterations in body structure), activity limitations (i.e. difficulties in executing tasks or
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actions), and participation restrictions (i.e. problems in involvement in any area of life) [1]. Limitations in activities of daily living (LADL) are more common than participation restrictions and impairments [2]. For instance, in nonclinical samples musculoskeletal impairments and participation restrictions are often rare or absent while LADL are more frequent [2]. Thus, specific measurement of LADL is needed. Measurement of LADL should also be sensitive to adequately reflect benefits of nonclinical interventions to reduce musculoskeletal disability [3]. Nevertheless available LADL instruments do not specifically address LADL but sum up items that address LADL, impairment, and participation restrictions [4]. Unique interest in LADL is also grounded in Activity Theory, which focuses on the analysis of basic activities in daily life [5,6]. Vernon and Lawson point out that “it is in activities that a person's disability with a health condition is best evaluated“ (p. 103 [4]). LADL in musculoskeletal complaints have prognostic value in predicting mortality in rheumatoid patients and the normal population [7]. Thereby, LADL that are sensibly related to musculoskeletal complaints differentiate between diseases (e.g., rheumatoid arthritis (RA) from non-inflammatory diffuse musculoskeletal pain [8]. However, the heterogeneity of most LADL questionnaires contributes to inconclusive results. Therefore, improved LADL assessment is an important aim [9]. A new adequate instrument should have sufficient gradations – and no common yes/no format [4]. Questions 5
should include an adequate time frame (e.g., the last four weeks) to capture also episodic LADL [4,10,11]. Moreover items should be specific (e.g., “stand for half an hour at work“ instead of “work activities“) and representative for the body region and body structures, i.e. when addressing the most prevalent musculoskeletal complaints. Such specific questions are useful when function-specific LADL is in focus, e.g., in estimating the burden of occupational back pain [12].
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We aimed at deriving three region-specific independent subscales of LADL for back and neck, upper extremities and lower extremities. Specificity should be unbiased from individual attributions that might be triggered by complaint-specific instructions (“because of my neck and back problems…“). Therefore, we made no reference to regions of musculoskeletal complaints in the instruction.
2. METHODS 2.1. Development of the new LADL–Questionnaire We selected 12 questionnaires widely used for LADL assessment in studies of the musculoskeletal system: the Western Ontario and McMaster Universities osteoarthritis index (WOMAC, Harris hip score, American knee society score, Merle d’Aubigné score, Roland Morris disability questionnaire, Oswestry low back pain disability questionnaire, North American spine society (NASS) outcome assessment, low back outcome scale, disability of the arm-shoulder-hand (DASH) questionnaire, shoulder pain disability index (SPADI), constant score, and the University of California at Los Angeles rating system (UCLA score) [13-24]. Experts (one rheumatologist, two orthopedic surgeons and one clinical epidemiologist) chose out of the above listed questionnaires 125 items related to limitations in activities of
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daily living (from a total of 221) which did not ask for narrow disease- or treatment-specific ability. The experts discussed all 125 items, regarding their importance to daily functioning and potential content overlap. 61 items were excluded because they were endorsed by less than half of the experts. The remaining 64 items were translated into German and rephrased, if necessary, to achieve a standardised format. All items were scored on a seven-point scale ranging from 0 (no problems) to 6 (not possible).
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2.2. Participants in a Pilot Study For the pilot study, 1100 individuals from 17 institutions were contacted and 637 individuals agreed to participate (175 participants of an advanced training course from three sports schools (n = 125 [72%] participated), 254 employees from 4 commercial companies (n = 171 [67%] participated), 130 residents of three homes for the elderly (n = 69 [53%] participated), 370 patients from a tertiary care emergency department (n = 161 [44%] participated) and 171 patients from six orthopedic or rheumatology tertiary care centers (n = 111 [64%] participated). Fifty-three percent were women (mean age = 47.2 years, SD = 20.0; mean body mass index = 23.8 kg/m2, SD = 4.0). Musculoskeletal complaints were reported by 56%, while 9% were dependent on help for daily living. The first 48 respondents took part in a structured interview to identify ambiguities in wording (45 [94%] participated). The wording of 32 items was altered. 249 randomly chosen individuals participated in a test–retest study with repeated response within seven to 14 days. The study was planned and conducted in accordance with the code of ethics of the World Medical Association (Declaration of Helsinki) and was in accordance to the supervisors of the hospitals. Local ethics committee approved the study. 2.3. Participants the Validation Study 32440 private households in the German speaking part of Switzerland were selected from the telephone directory by computer based randomisation. 8677 were excluded because of invalid 7
phone numbers, inability to understand German, death or age below 18 years (Figure 1), leaving 23763 eligible for a telephone interview. 21377 of these households (90%) were contacted by phone between November 2002 and June 2003 and informed about the study. 2368 of 23763 households (10%), which could not be reached by phone after a maximum of 12 attempts, were contacted by mail using an extended covering letter. The last birthday technique was used in households where more than one person was 18 years or older [25]. If
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willing to participate, they were sent a postal questionnaire. Overall, 17341 of 21377 individuals (81%) gave consent to participate and were sent a covering letter with additional information about the study, the questionnaire and a prepaid return envelope. After a maximum of 12 attempts still 10% (2386 of 23763 households) could not be reached. These were contacted by mail using an extended covering letter. Those who still did not reply were sent a reminder after three and six weeks. 2.4. Questionnaire 2.4.1. Pain. Pain was assessed using the pain standard evaluation questionnaire (SEQ) assessing the intensity of pain in various regions of the back: “In the last four weeks, how much pain did you experience in the following body regions?” The regions included: (1) left shoulder, arm, hand; (2) right shoulder, arm, hand; (3) neck and upper back; and (4) lower back, (5) left hip, leg, foot, (6) right hip, leg, foot. There were seven response options (0 = no pain to 6 = unbearable pain) [26]. Single items addressed self-reported general health (“How would you rate your general state of health?” with seven response options (1 = very poor to 7 = very good) and performance in daily tasks (“How often do you feel you do not meet daily task demands?” with seven response options (1 = never to 7 = very often) [26].
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2.5. Statistical Analysis Our aims were (a) to develop a reliable short instrument that (b) covers the range of important LADL. These aims are somewhat conflicting because short scales are often constructed solely based on item-total correlations. However, item-total correlations are often highest when items ask for similar or same content, i.e. they are redundant. Consequently, primary reliance upon item-total correlations might lead to narrowed item content and consequential low
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validity [27,28]. Hence, we followed Stanton, Sinar, Balzer, and Smith’s recommendations to focus on external (e.g., relations of items or a scale to other scales or its items) and judgmental item qualities (i.e. subjective judgment) [29]. Items should show good item-total correlations but should not be redundant and items should demonstrate good judgmental item quality attributed by experts. External item qualities should be good (i.e. specific relation to main musculoskeletal pain locations). A pre-specified stepwise approach was used [30,31]. Unless indicated otherwise, all steps were performed in the overall sample, with a subsequent sensitivity analysis restricted to individuals reporting pain in any of the six items of the SEQ pain rating scale [26]. 2.5.1. Test–retest reliability. By sending out a second questionnaire after seven to 14 days to the first 170 responders the test–retest reliability was assessed employing intraclass correlation coefficient (ICC) and κ. When κ and ICC were larger than .60, they were considered to indicate good reliability [30,32]. Items related to pain during activities of daily living were discarded if the estimated ICCs were below .60 [33]. 2.5.2. Floor and ceiling effects. We calculated the proportion of lowest (no problem) and highest score (not possible) for each item in four age strata (less than 35, from 34 to 55, from 54 to 75, older than 74). Items with
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90% or higher proportion in all four age strata were excluded to avoid age-related floor or ceiling effects. 2.5.3 Associations of LADL subscales with pain in different body regions. As a measure of overall pain in upper and lower extremities the maximum of the ratings reported separately for the left and right side of the body was used [26]. Product-moment correlations between regional pain ratings and items of LADL were calculated. Items with
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coefficients below .25 for all body regions were discarded. Items with correlations with more than one body region over .25 were also excluded. 2.5.4. Inter-item correlations. To identify redundancy the correlation between items was assessed. If product-moment correlations between any two items were larger than .70 we discarded the item that showed less specific correspondence to pain in a specific body region. 12 items resulted that assigned LADL rather specifically to three body regions. 2.5.5. Principal components factor analysis Principal components factor analysis with subsequent varimax rotation was used to derive factors, which potentially corresponded to the subscales for the three body regions. Items were retained if they had a factor loading of at least .40 and correlation coefficients for the corresponding body region of at least .25. 2.5.6. Internal consistency. Item-total correlations were determined by calculating product moment correlations between an item of the sub score and the total sub score for each of the three final subscales. Items with coefficients below .20 were discarded [30]. As a measure of the overall consistency Cronbach's α was determined for each subscale.
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2.5.7. Convergent validity. Convergent validity was examined based on product moment correlations of summary scores on upper extremity, lower extremity and back and neck subscales with relevant sub scores of SPADI, WOMAC (ADL Part) and Oswestry indexes, respectively. 2.5.8. Criterion validity. In structural equation models, separately for men and women, with use of AMOS 22.0 the Downloaded by [Gothenburg University Library] at 06:27 11 October 2017
LADL–Q subscales on upper- and lower extremities and back and neck were modeled as a latent variable that predicts self-reported general health and task performance in daily demands that are important outcome variables in research on occupational musculoskeletal pain [34,35]. Age and body mass index (BMI) were controlled. Acceptability of fit was calculated using standardised root mean square residuals (SRMR < .05 = good fit, < .08 = acceptable fit) [36]. Estimation of path coefficients was based on an asymptomatically distribution-free estimation because LADL–Q back and neck items and items on general health and task performance were not normally distributed.
3. RESULTS Figure 1 shows a flowchart of the study samples. Table 1 presents the characteristics of the participants. 3.1. Item Selection Sixty-nine per cent of the 170 participants included in the test–retest study completed the retest questionnaire. The median ICC between baseline and retest ratings was .84 (range from .01 to .99). Seven of 64 items were discarded because of correlations below .60 (Figure 2). Because of floor and ceiling effects, lack of clear association with musculoskeletal pain in
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body regions, and inter-item correlations the number of items was finally reduced to 12 (Figure 2). 3.2. Principal Components Factor Analysis Three factors were retained, with key items allowing the unequivocal assignment of the factors to either of the three body regions of interest (Table 2). Because no item showed factor
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loadings ≥ .50 for more than one factor all 12 items were retained. 3.3. Internal Consistency Item-total correlations for the three subscales ranged from .84 to .86 for the lower extremity, from .63 to .85 for the upper extremity and from .70 to .79 for the back and neck (Table 3). Cronbach's α were moderate to high for each of the subscales: .84, .72 and .73. 3.4. Discriminant Validity Based on 10610 individuals, the correlation was r = .66 between the lower and upper extremity subscale, 95% CI [.65, .67], r = .54 between lower extremity and back/neck subscale, 95% CI [.53, .55] and r = .51 between back/neck and upper extremity subscale, 95% CI [.50, .52]. 3.5. Convergent Validity Correlations between scores in LADL–Q subscales and relevant SPADI, WOMAC and Oswestry scales were substantial to high: r = .73 for scores in the LADL–Q upper extremity scale and the SPADI shoulder pain index, 95% CI [.66, .79]; r = .82 for scores in the LADL– Q lower extremity scale and the WOMAC pain score, 95% CI [.77, .86] and r = .66 for scores in the LADL–Q back-neck scale and the Oswestry score, 95% CI [.57, .73]. 3.6. Criterion Validity Figure 3 shows the structural equation model for back and neck pain related LADL subscale. For both men and women – with control of age and BMI – LADL–Q subscale back and neck 12
predicted self-reported health and problems in meeting daily task demands. Standardised path coefficients were all significant and moderate to large [37]. The model fit was good (SRMR = .03). The explained variation in general state of health was 24 % for men and 28 % in women. The explained variation in meeting daily task demands was lower with 7 % for men and 8 % in women. The LADL–Q subscale for upper extremities showed good model fit (SRMR = .05) and criterion validity (general state of health: R2 = .26 in men, R2 = .28 in women; daily
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task demands: R2 = .07 in men, R2 = .06 in women). Finally, the LADL–Q subscale for lower extremities showed lower but acceptable model fit (SRMR = .09) and slightly lower criterion validity (general state of health: R2 = .20 in men, R2 = .19 in women; daily task demands: R2 = .04 in men, R2 = .04 in women). 4. DISCUSSION Limitations in activities of daily living (LADL) gained importance as predictors and outcomes in occupational health research [2,35]. Because most occupational musculoskeletal problems do not relate to a specific impairment, we developed a short questionnaire (LADL–Q) that asks not for the function of specific joints as many other (clinical) questionnaires (e.g., hip) but is related to function in body regions (Figure 4). The short LADL–Q has the same factorial structure when individuals with or without pain were addressed (measurement equivalence). Subscales can be used separately (e.g., LADL–Q back and neck in studies on occupational low back pain) [38,39]. The definition of standards and norm values will be subject in future research and hopefully facilitate the identification of individuals at risk for developing disabling musculoskeletal complaints. Moreover, musculoskeletal complaints are often rather complex and the LADL–Q could help to differentiate (e.g., people with fibromyalgia or chronic pain conditions from people with rheumatoid arthritis [40]. Finally, in accordance with the WHO definition of disability the LADL–Q allows to assess LADL separately from impairments and participation restrictions. 13
4.1. Practical Implications The LADL–Q can assist efforts to reduce work-related musculoskeletal disease and related costs [12]. As a reliable and valid short outcome instrument the LADL–Q should be included in screening questionnaires and evaluation of ergonomic interventions [35]. 4.2. Limitations Demographic characteristics differed slightly from the average Swiss population as no data
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from the French- and Italian-speaking part of Switzerland were collected. As in other studies women and individuals with higher education were overrepresented [41]. Another common limitation in research using self-reports is less pronounced in this study. Compared to other studies the response rate was high [42,43]. 5. CONCLUSIONS The LADL–Q is a short, reliable and valid tool for LADL assessment in population-based studies on musculoskeletal health. It is suitable for electronic or postal surveys of the general population. Disclosure Statement All authors state no conflict of interest. REFERENCES 1. World Health Organization [WHO]. International Classification of Functioning, Disability and Health. Geneva (Switzerland): WHO; 2011. 2. Elfering A, Mannion AF. Epidemiology and risk factors of spinal disorders. In: Boos N and Aebi M, editors. Spinal disorders – Fundamentals of diagnosis and treatment. Berlin (Germany): Springer; 2008. p. 153-173.
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41. Angus VC, Entwistle VA, Emslie MJ, Walker KA, Andrew JE. The requirement for prior consent to participate on survey response rates: A population-based survey in Grampian. BMC Health Serv Res. 2003;3:21. 42. Asch DA, Jedrziewski MK, Christakis NA. Response rates to mail surveys published in medical journals J Clin Epidemiol. 1997;50:1129-1136. 43. Nakash RA, Hutton JL, Jorstad-Stein EC, Gates S, Lamb SE. Maximising response to
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TABLE 1 Caption: Characteristics of Participants Legend: Note: A = individuals who reported pain in at least one of the six pain questions. B = village of less than 10,000 inhabitants. C = list of complaints (yes/no) adapted from Eurostat
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Yearbook [44].
TABLE 2 Caption: Results from Principal Components Factor Analysis, with Loadings of Items for the three Varimax-rotated Factors corresponding to the Lower Extremity, Upper Extremity and Back and Neck (12 items retained) Legend: Note.
TABLE 3 Caption: The final three LADL–Q-subscales with the Correlation of each Item with the corresponding Scale and Cronbach’s α for each Scale (12 items retained) Legend: Note.
Figure 1 Caption: Flowchart of the study samples
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Note: LADL = limitations in activity of daily living; Oswestry = Oswestry low back pain disability questionnaire [18]; SPADI = shoulder pain disability index [22]; WOMAC = Western Ontario and McMaster Universities osteoarthritis index [13].
Figure 2
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Caption: Flow of item selection
Figure 3 Caption: LADL back and neck predicting self-reported health and task performance (standardised path coefficients shown for men [upper value] and women [lower value]) Note: LADL = limitations in activity of daily living. *** = p < .001
Figure 4 Caption: The final LADL–Q (this is an English translation of the German LADL–Q, which is not validated)
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TABLE 1. Characteristics of Participants Participants
Characteristic
All participants
included in analyses
Participants
(N = 16634 [%])
(n = 16191 [%])
reporting paina (n = 10610 [%])
Females (n [%])
9459 (57)
9256 (58)
6316 (60)
18–34
3580 (22)
3554 (23)
2194 (21)
35–44
3721 (23)
3691 (23)
2393 (23)
45–54
2842 (18)
2797 (18)
1901 (18)
55–64
2574 (16)
2522 (16)
1782 (17)
65–74
2020 (13)
1957 (12)
1306 (13)
75–84
1183 (7)
1136 (7)
718 (7)
≥85
229 (1)
220 (1)
127 (1)
ISSN: 1080-3548 (Print) 2376-9130 (Online) Journal homepage: http://www.tandfonline.com/loi/tose20
Measuring limitations in activities of daily living (LADL): A population based validation of a short questionnaire Achim Elfering, Sonja Cronenberg, Simone Grebner, Oezguer Tamcan & Urs Müller To cite this article: Achim Elfering, Sonja Cronenberg, Simone Grebner, Oezguer Tamcan & Urs Müller (2017): Measuring limitations in activities of daily living (LADL): A population based validation of a short questionnaire, International Journal of Occupational Safety and Ergonomics, DOI: 10.1080/10803548.2017.1388621 To link to this article: http://dx.doi.org/10.1080/10803548.2017.1388621
Accepted author version posted online: 10 Oct 2017.
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Date: 11 October 2017, At: 06:27
Publisher: Taylor & Francis & Central Institute for Labour Protection – National Research Institute (CIOP-PIB) Journal: International Journal of Occupational Safety and Ergnomics DOI: 10.1080/10803548.2017.1388621
Measuring limitations in activities of daily living (LADL): A population
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based validation of a short questionnaire Achim Elfering1,2, Sonja Cronenberg3,4, Simone Grebner1, Oezguer Tamcan3 & Urs Müller3 1
University of Bern, Department of Work and Organizational Psychology, Fabrikstrasse 8,
CH-3012 Bern, Switzerland 2
National Centre of Competence in Research, Affective Sciences, University of Geneva, CISA,
Chemin des Mines 9, CH-1202 Geneva, Switzerland 3
University of Bern, Institute for Evaluative Research in Orthopedic Surgery,
Stauffacherstrasse 78, CH-3014 Bern, Switzerland 4
University of Basel, University Hospital, Spitalstrasse 21, CH-4031 Basel, Switzerland
Contact Details: AE - corresponding author: phone +41 631 3639, [email protected] ORCiD: 0000-0003-4274-0261 SC: phone +41 61 556 51 98, [email protected] SG: phone +41 76 4544113, [email protected] OT: phone +49 76 571 91 71, [email protected] UM: phone +49 44 384 80 00, [email protected]
AE: phone +41 31 631 3639, [email protected] Address Correspondence (after acceptance) and reprints to: Achim Elfering, Tel: 0041-31-
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6313639, email: [email protected]
Measuring limitations in activities of daily living (LADL): A population based validation of a short questionnaire Achim Elfering1,2, Sonja Cronenberg3,4, Simone Grebner1, Oezguer Tamcan3 & Urs Müller3 1
University of Bern, Department of Work and Organizational Psychology, Fabrikstrasse 8,
CH-3012 Bern, Switzerland
Downloaded by [Gothenburg University Library] at 06:27 11 October 2017
2
National Centre of Competence in Research, Affective Sciences, University of Geneva, CISA,
Chemin des Mines 9, CH-1202 Geneva, Switzerland 3
University of Bern, Institute for Evaluative Research in Orthopedic Surgery,
Stauffacherstrasse 78, CH-3014 Bern, Switzerland 4
University of Basel, University Hospital, Spitalstrasse 21, CH-4031 Basel, Switzerland
Contact Details: AE - corresponding author: phone +41 631 3639, [email protected] ORCiD: 0000-0003-4274-0261 SC: phone +41 61 556 51 98, [email protected] SG: phone +41 76 4544113, [email protected] OT: phone +49 76 571 91 71, [email protected] UM: phone +49 44 384 80 00, [email protected]
AE: phone +41 31 631 3639, [email protected] Address Correspondence (after acceptance) and reprints to: Achim Elfering, Tel: 0041-316313639, email: [email protected]
3
Measuring limitations in activities of daily living (LADL): A population based validation of a short questionnaire Purpose A newly developed questionnaire assessing limitations in activity of daily living (LADL–Q) that should improve assessment of LADL is tested in a large populationbased validation study. Methods This was a paper based survey. Overall, 16634 individuals that were representative for Downloaded by [Gothenburg University Library] at 06:27 11 October 2017
the working population in German speaking part of Switzerland participated in the study. Item analysis was used the final version of the LADL–Q to four items per subscale that correspond to potential problems in three body regions (back and neck, upper extremities, lower extremities). Analysis included tests for reliability, internal consistency, dimensionality and convergent validity. Results Test–retest reliability coefficients after two weeks ranged from .82 to .99 (Mdn = .87), with no item having a coefficient below .60. The median item-total coefficients ranged between moderate and good. Correlation coefficients between LADL–Q–subscales and three validated clinical instruments (WOMAC, SPADI, Oswestry) ranged from .63 to .81. In structural equation modeling the three subscales were significantly related with two important outcomes in occupational rehabilitation: self-reported general health and daily task performance. Conclusion The new LADL–Q is a brief, reliable and valid tool for assessment of LADL in studies on musculoskeletal health. Keywords: Short questionnaire, occupational rehabilitation, loco-motor system, musculoskeletal pain
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1. INTRODUCTION The World Health Organization (WHO) definition of disability refers to the International Classification of functioning, disability and health (ICF) and characterizes disability as problems in human functioning in three areas: Impairments (i.e. problems in body functions or alterations in body structure), activity limitations (i.e. difficulties in executing tasks or
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actions), and participation restrictions (i.e. problems in involvement in any area of life) [1]. Limitations in activities of daily living (LADL) are more common than participation restrictions and impairments [2]. For instance, in nonclinical samples musculoskeletal impairments and participation restrictions are often rare or absent while LADL are more frequent [2]. Thus, specific measurement of LADL is needed. Measurement of LADL should also be sensitive to adequately reflect benefits of nonclinical interventions to reduce musculoskeletal disability [3]. Nevertheless available LADL instruments do not specifically address LADL but sum up items that address LADL, impairment, and participation restrictions [4]. Unique interest in LADL is also grounded in Activity Theory, which focuses on the analysis of basic activities in daily life [5,6]. Vernon and Lawson point out that “it is in activities that a person's disability with a health condition is best evaluated“ (p. 103 [4]). LADL in musculoskeletal complaints have prognostic value in predicting mortality in rheumatoid patients and the normal population [7]. Thereby, LADL that are sensibly related to musculoskeletal complaints differentiate between diseases (e.g., rheumatoid arthritis (RA) from non-inflammatory diffuse musculoskeletal pain [8]. However, the heterogeneity of most LADL questionnaires contributes to inconclusive results. Therefore, improved LADL assessment is an important aim [9]. A new adequate instrument should have sufficient gradations – and no common yes/no format [4]. Questions 5
should include an adequate time frame (e.g., the last four weeks) to capture also episodic LADL [4,10,11]. Moreover items should be specific (e.g., “stand for half an hour at work“ instead of “work activities“) and representative for the body region and body structures, i.e. when addressing the most prevalent musculoskeletal complaints. Such specific questions are useful when function-specific LADL is in focus, e.g., in estimating the burden of occupational back pain [12].
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We aimed at deriving three region-specific independent subscales of LADL for back and neck, upper extremities and lower extremities. Specificity should be unbiased from individual attributions that might be triggered by complaint-specific instructions (“because of my neck and back problems…“). Therefore, we made no reference to regions of musculoskeletal complaints in the instruction.
2. METHODS 2.1. Development of the new LADL–Questionnaire We selected 12 questionnaires widely used for LADL assessment in studies of the musculoskeletal system: the Western Ontario and McMaster Universities osteoarthritis index (WOMAC, Harris hip score, American knee society score, Merle d’Aubigné score, Roland Morris disability questionnaire, Oswestry low back pain disability questionnaire, North American spine society (NASS) outcome assessment, low back outcome scale, disability of the arm-shoulder-hand (DASH) questionnaire, shoulder pain disability index (SPADI), constant score, and the University of California at Los Angeles rating system (UCLA score) [13-24]. Experts (one rheumatologist, two orthopedic surgeons and one clinical epidemiologist) chose out of the above listed questionnaires 125 items related to limitations in activities of
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daily living (from a total of 221) which did not ask for narrow disease- or treatment-specific ability. The experts discussed all 125 items, regarding their importance to daily functioning and potential content overlap. 61 items were excluded because they were endorsed by less than half of the experts. The remaining 64 items were translated into German and rephrased, if necessary, to achieve a standardised format. All items were scored on a seven-point scale ranging from 0 (no problems) to 6 (not possible).
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2.2. Participants in a Pilot Study For the pilot study, 1100 individuals from 17 institutions were contacted and 637 individuals agreed to participate (175 participants of an advanced training course from three sports schools (n = 125 [72%] participated), 254 employees from 4 commercial companies (n = 171 [67%] participated), 130 residents of three homes for the elderly (n = 69 [53%] participated), 370 patients from a tertiary care emergency department (n = 161 [44%] participated) and 171 patients from six orthopedic or rheumatology tertiary care centers (n = 111 [64%] participated). Fifty-three percent were women (mean age = 47.2 years, SD = 20.0; mean body mass index = 23.8 kg/m2, SD = 4.0). Musculoskeletal complaints were reported by 56%, while 9% were dependent on help for daily living. The first 48 respondents took part in a structured interview to identify ambiguities in wording (45 [94%] participated). The wording of 32 items was altered. 249 randomly chosen individuals participated in a test–retest study with repeated response within seven to 14 days. The study was planned and conducted in accordance with the code of ethics of the World Medical Association (Declaration of Helsinki) and was in accordance to the supervisors of the hospitals. Local ethics committee approved the study. 2.3. Participants the Validation Study 32440 private households in the German speaking part of Switzerland were selected from the telephone directory by computer based randomisation. 8677 were excluded because of invalid 7
phone numbers, inability to understand German, death or age below 18 years (Figure 1), leaving 23763 eligible for a telephone interview. 21377 of these households (90%) were contacted by phone between November 2002 and June 2003 and informed about the study. 2368 of 23763 households (10%), which could not be reached by phone after a maximum of 12 attempts, were contacted by mail using an extended covering letter. The last birthday technique was used in households where more than one person was 18 years or older [25]. If
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willing to participate, they were sent a postal questionnaire. Overall, 17341 of 21377 individuals (81%) gave consent to participate and were sent a covering letter with additional information about the study, the questionnaire and a prepaid return envelope. After a maximum of 12 attempts still 10% (2386 of 23763 households) could not be reached. These were contacted by mail using an extended covering letter. Those who still did not reply were sent a reminder after three and six weeks. 2.4. Questionnaire 2.4.1. Pain. Pain was assessed using the pain standard evaluation questionnaire (SEQ) assessing the intensity of pain in various regions of the back: “In the last four weeks, how much pain did you experience in the following body regions?” The regions included: (1) left shoulder, arm, hand; (2) right shoulder, arm, hand; (3) neck and upper back; and (4) lower back, (5) left hip, leg, foot, (6) right hip, leg, foot. There were seven response options (0 = no pain to 6 = unbearable pain) [26]. Single items addressed self-reported general health (“How would you rate your general state of health?” with seven response options (1 = very poor to 7 = very good) and performance in daily tasks (“How often do you feel you do not meet daily task demands?” with seven response options (1 = never to 7 = very often) [26].
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2.5. Statistical Analysis Our aims were (a) to develop a reliable short instrument that (b) covers the range of important LADL. These aims are somewhat conflicting because short scales are often constructed solely based on item-total correlations. However, item-total correlations are often highest when items ask for similar or same content, i.e. they are redundant. Consequently, primary reliance upon item-total correlations might lead to narrowed item content and consequential low
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validity [27,28]. Hence, we followed Stanton, Sinar, Balzer, and Smith’s recommendations to focus on external (e.g., relations of items or a scale to other scales or its items) and judgmental item qualities (i.e. subjective judgment) [29]. Items should show good item-total correlations but should not be redundant and items should demonstrate good judgmental item quality attributed by experts. External item qualities should be good (i.e. specific relation to main musculoskeletal pain locations). A pre-specified stepwise approach was used [30,31]. Unless indicated otherwise, all steps were performed in the overall sample, with a subsequent sensitivity analysis restricted to individuals reporting pain in any of the six items of the SEQ pain rating scale [26]. 2.5.1. Test–retest reliability. By sending out a second questionnaire after seven to 14 days to the first 170 responders the test–retest reliability was assessed employing intraclass correlation coefficient (ICC) and κ. When κ and ICC were larger than .60, they were considered to indicate good reliability [30,32]. Items related to pain during activities of daily living were discarded if the estimated ICCs were below .60 [33]. 2.5.2. Floor and ceiling effects. We calculated the proportion of lowest (no problem) and highest score (not possible) for each item in four age strata (less than 35, from 34 to 55, from 54 to 75, older than 74). Items with
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90% or higher proportion in all four age strata were excluded to avoid age-related floor or ceiling effects. 2.5.3 Associations of LADL subscales with pain in different body regions. As a measure of overall pain in upper and lower extremities the maximum of the ratings reported separately for the left and right side of the body was used [26]. Product-moment correlations between regional pain ratings and items of LADL were calculated. Items with
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coefficients below .25 for all body regions were discarded. Items with correlations with more than one body region over .25 were also excluded. 2.5.4. Inter-item correlations. To identify redundancy the correlation between items was assessed. If product-moment correlations between any two items were larger than .70 we discarded the item that showed less specific correspondence to pain in a specific body region. 12 items resulted that assigned LADL rather specifically to three body regions. 2.5.5. Principal components factor analysis Principal components factor analysis with subsequent varimax rotation was used to derive factors, which potentially corresponded to the subscales for the three body regions. Items were retained if they had a factor loading of at least .40 and correlation coefficients for the corresponding body region of at least .25. 2.5.6. Internal consistency. Item-total correlations were determined by calculating product moment correlations between an item of the sub score and the total sub score for each of the three final subscales. Items with coefficients below .20 were discarded [30]. As a measure of the overall consistency Cronbach's α was determined for each subscale.
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2.5.7. Convergent validity. Convergent validity was examined based on product moment correlations of summary scores on upper extremity, lower extremity and back and neck subscales with relevant sub scores of SPADI, WOMAC (ADL Part) and Oswestry indexes, respectively. 2.5.8. Criterion validity. In structural equation models, separately for men and women, with use of AMOS 22.0 the Downloaded by [Gothenburg University Library] at 06:27 11 October 2017
LADL–Q subscales on upper- and lower extremities and back and neck were modeled as a latent variable that predicts self-reported general health and task performance in daily demands that are important outcome variables in research on occupational musculoskeletal pain [34,35]. Age and body mass index (BMI) were controlled. Acceptability of fit was calculated using standardised root mean square residuals (SRMR < .05 = good fit, < .08 = acceptable fit) [36]. Estimation of path coefficients was based on an asymptomatically distribution-free estimation because LADL–Q back and neck items and items on general health and task performance were not normally distributed.
3. RESULTS Figure 1 shows a flowchart of the study samples. Table 1 presents the characteristics of the participants. 3.1. Item Selection Sixty-nine per cent of the 170 participants included in the test–retest study completed the retest questionnaire. The median ICC between baseline and retest ratings was .84 (range from .01 to .99). Seven of 64 items were discarded because of correlations below .60 (Figure 2). Because of floor and ceiling effects, lack of clear association with musculoskeletal pain in
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body regions, and inter-item correlations the number of items was finally reduced to 12 (Figure 2). 3.2. Principal Components Factor Analysis Three factors were retained, with key items allowing the unequivocal assignment of the factors to either of the three body regions of interest (Table 2). Because no item showed factor
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loadings ≥ .50 for more than one factor all 12 items were retained. 3.3. Internal Consistency Item-total correlations for the three subscales ranged from .84 to .86 for the lower extremity, from .63 to .85 for the upper extremity and from .70 to .79 for the back and neck (Table 3). Cronbach's α were moderate to high for each of the subscales: .84, .72 and .73. 3.4. Discriminant Validity Based on 10610 individuals, the correlation was r = .66 between the lower and upper extremity subscale, 95% CI [.65, .67], r = .54 between lower extremity and back/neck subscale, 95% CI [.53, .55] and r = .51 between back/neck and upper extremity subscale, 95% CI [.50, .52]. 3.5. Convergent Validity Correlations between scores in LADL–Q subscales and relevant SPADI, WOMAC and Oswestry scales were substantial to high: r = .73 for scores in the LADL–Q upper extremity scale and the SPADI shoulder pain index, 95% CI [.66, .79]; r = .82 for scores in the LADL– Q lower extremity scale and the WOMAC pain score, 95% CI [.77, .86] and r = .66 for scores in the LADL–Q back-neck scale and the Oswestry score, 95% CI [.57, .73]. 3.6. Criterion Validity Figure 3 shows the structural equation model for back and neck pain related LADL subscale. For both men and women – with control of age and BMI – LADL–Q subscale back and neck 12
predicted self-reported health and problems in meeting daily task demands. Standardised path coefficients were all significant and moderate to large [37]. The model fit was good (SRMR = .03). The explained variation in general state of health was 24 % for men and 28 % in women. The explained variation in meeting daily task demands was lower with 7 % for men and 8 % in women. The LADL–Q subscale for upper extremities showed good model fit (SRMR = .05) and criterion validity (general state of health: R2 = .26 in men, R2 = .28 in women; daily
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task demands: R2 = .07 in men, R2 = .06 in women). Finally, the LADL–Q subscale for lower extremities showed lower but acceptable model fit (SRMR = .09) and slightly lower criterion validity (general state of health: R2 = .20 in men, R2 = .19 in women; daily task demands: R2 = .04 in men, R2 = .04 in women). 4. DISCUSSION Limitations in activities of daily living (LADL) gained importance as predictors and outcomes in occupational health research [2,35]. Because most occupational musculoskeletal problems do not relate to a specific impairment, we developed a short questionnaire (LADL–Q) that asks not for the function of specific joints as many other (clinical) questionnaires (e.g., hip) but is related to function in body regions (Figure 4). The short LADL–Q has the same factorial structure when individuals with or without pain were addressed (measurement equivalence). Subscales can be used separately (e.g., LADL–Q back and neck in studies on occupational low back pain) [38,39]. The definition of standards and norm values will be subject in future research and hopefully facilitate the identification of individuals at risk for developing disabling musculoskeletal complaints. Moreover, musculoskeletal complaints are often rather complex and the LADL–Q could help to differentiate (e.g., people with fibromyalgia or chronic pain conditions from people with rheumatoid arthritis [40]. Finally, in accordance with the WHO definition of disability the LADL–Q allows to assess LADL separately from impairments and participation restrictions. 13
4.1. Practical Implications The LADL–Q can assist efforts to reduce work-related musculoskeletal disease and related costs [12]. As a reliable and valid short outcome instrument the LADL–Q should be included in screening questionnaires and evaluation of ergonomic interventions [35]. 4.2. Limitations Demographic characteristics differed slightly from the average Swiss population as no data
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from the French- and Italian-speaking part of Switzerland were collected. As in other studies women and individuals with higher education were overrepresented [41]. Another common limitation in research using self-reports is less pronounced in this study. Compared to other studies the response rate was high [42,43]. 5. CONCLUSIONS The LADL–Q is a short, reliable and valid tool for LADL assessment in population-based studies on musculoskeletal health. It is suitable for electronic or postal surveys of the general population. Disclosure Statement All authors state no conflict of interest. REFERENCES 1. World Health Organization [WHO]. International Classification of Functioning, Disability and Health. Geneva (Switzerland): WHO; 2011. 2. Elfering A, Mannion AF. Epidemiology and risk factors of spinal disorders. In: Boos N and Aebi M, editors. Spinal disorders – Fundamentals of diagnosis and treatment. Berlin (Germany): Springer; 2008. p. 153-173.
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TABLE 1 Caption: Characteristics of Participants Legend: Note: A = individuals who reported pain in at least one of the six pain questions. B = village of less than 10,000 inhabitants. C = list of complaints (yes/no) adapted from Eurostat
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Yearbook [44].
TABLE 2 Caption: Results from Principal Components Factor Analysis, with Loadings of Items for the three Varimax-rotated Factors corresponding to the Lower Extremity, Upper Extremity and Back and Neck (12 items retained) Legend: Note.
TABLE 3 Caption: The final three LADL–Q-subscales with the Correlation of each Item with the corresponding Scale and Cronbach’s α for each Scale (12 items retained) Legend: Note.
Figure 1 Caption: Flowchart of the study samples
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Note: LADL = limitations in activity of daily living; Oswestry = Oswestry low back pain disability questionnaire [18]; SPADI = shoulder pain disability index [22]; WOMAC = Western Ontario and McMaster Universities osteoarthritis index [13].
Figure 2
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Caption: Flow of item selection
Figure 3 Caption: LADL back and neck predicting self-reported health and task performance (standardised path coefficients shown for men [upper value] and women [lower value]) Note: LADL = limitations in activity of daily living. *** = p < .001
Figure 4 Caption: The final LADL–Q (this is an English translation of the German LADL–Q, which is not validated)
21
TABLE 1. Characteristics of Participants Participants
Characteristic
All participants
included in analyses
Participants
(N = 16634 [%])
(n = 16191 [%])
reporting paina (n = 10610 [%])
Females (n [%])
9459 (57)
9256 (58)
6316 (60)
18–34
3580 (22)
3554 (23)
2194 (21)
35–44
3721 (23)
3691 (23)
2393 (23)
45–54
2842 (18)
2797 (18)
1901 (18)
55–64
2574 (16)
2522 (16)
1782 (17)
65–74
2020 (13)
1957 (12)
1306 (13)
75–84
1183 (7)
1136 (7)
718 (7)
≥85
229 (1)
220 (1)
127 (1)
