The Role of Ambulatory Medical Care In Hypertension Screening BEULAH K. CYPRESS, PHD
Abstract: Data from the 1975-1976 National Ambulatory Medical Care Survey conducted by the National Center for Health Statistics were examined retrospectively to determine the extent to which blood pressure was measured during visits to office-based physicians in the conterminous United States. Blood pressure was more often measured for females (especially black) than for males although males (especially black) in certain age groups had a higher prevalence of hypertension and comprised the higher proportion of undiagnosed hypertensives. Blood pressure measurement increased with age, but was rarely measured for those under 15 years of age. Blood pressure was measured about 79 per cent of the time when hypertension was present but only 30 per cent of the time when hypertension was absent. When diseases shown to be frequently concomitant with hypertension were diag-
nosed in the absence of hypertension, blood pressure checks ranged from 24 per cent of visits diagnosed neuroses to 66 per cent diagnosed obesity. Blood pressure was measured during about 12 per cent of visits for diseases of the nervous system and sense organs as well as diseases of the skin and subcutaneous tissue; 24 per cent of visits for infective and parasitic diseases, diseases of the respiratory system, and mental disorders. Blood pressure was measured most often when diagnoses were in the categories of diseases of the circulatory system and endocrine, nutritional, and metabolic diseases. Opportunities for blood pressure measurement during routine visits did not appear to be fully utilized, nor did some specialists take frequent blood pressure measurements. (Am. J. Public Health 69:19-24, 1979.)
Introduction
cost. Indeed, many problems other than cost operate against the long range success of mass screening programs. The poor reliability associated with one-time or casual measurement was documented by Armitage and Rose.3 Rosner offered a screening procedure designed to reduce measurement variability but implementation was dependent on sequential patient visits.4 Public screening programs, however, have been unsuccessful with follow-up visits. For example, Berkson, et al., had difficulty persuading patients to return for second determinations although their initial diastolic blood pressure was 2 90 mm Hg.5 However, the success of hypertension case finding during office visits requires that all patients visiting a physician for whatever reason have their blood pressure measured. Analysis of National Ambulatory Medical Care Survey (NAMCS) data for the years 1975 and 1976 revealed that an estimated 1 billion, 155 million visits were made to officebased physicians in the United States. Essential benign hypertension was the leading morbidity-related problem, accounting for an estimated 46.1 million visits. During the same two-year period an additional 29 million visits occurred in which hypertension was the diagnosis listed second or third, in order of importance at that encounter, making a total of about 75 million visits in which hypertension was a recognized and diagnosed condition. About 79 per cent of these hypertension-related visits included blood pressure checks. However, blood pressure was measured in only about 30 per cent of the remaining 1 billion, 80 million visits for other reasons.6 This figure was only slightly improved (to about 37 per cent) when visits by children under 6 years of age were not included. These data indicated that the physician's office may be an underutilized resource for hyper-
In its 1977 report, the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure (JNC) recommended that all health care professionals routinely take a patient's blood pressure regardless of the patient's reason for visit.' The private office of the practicing physician often has health care personnel available who are trained to measure blood pressure, record findings, and provide patient counseling under clinical conditions. When elevated blood pressure is detected during an office visit, immediate arrangements for follow-up can be made, thus increasing the likelihood of early patient therapy. Furthermore, hypertensive status can be more accurately gauged if the patient is available for sequential measurements. Blood pressure measurement is probably one of the least costly diagnostic tools in the physician's armamentarium in terms of professional time and services. Routine blood pressure measurement during office visits also offers a significant means of reducing the need for expensive mass screening since, according to a national survey, about 76 per cent of the population in the United States saw a physician at least once during 1976 for some reason.2 It is doubtful that so high a proportion of the population could be reached in a reasonable time by a public screening program for the same Address reprint requests to Beulah K. Cypress, PhD, Ambulatory Care Statistics Branch, Division of Health Resources Utilization Statistics, National Center for Health Statistics, DHEW, 3700 East-West Highway, Hyattsville, MD 20782. This paper, submitted to the Journal April 24, 1978, was revised and accepted for publication July 21, 1978.
AJPH January 1979, Vol. 69, No. 1
19
CYPRESS
-~ ~emal=34%
tension screening. In order to explore further the extent to which blood pressure was measured in physicians' offices, additional analyses of physician data obtained during the 1975-76 NAMCS were undertaken.
Source of the Data NAMCS is a sample survey conducted annually in the conterminous United States by the Division of Health Resources Utilization Statistics in the National Center for Health Statistics (NCHS). Samples of approximately 3,500 physicians in 1975 and 3,000 physicians in 1976 were selected from master files maintained by the American Medical Association and the American Osteopathic Association. Sampled physicians, randomly assigned to one of the 52 weeks in the survey year, were requested to complete brief encounter forms (Patient Records) for a systematic random sample of office visits taking place within their practice during the assigned reporting period. Additional data concerning physician practice characteristics, such as primary specialty, were obtained during an induction interview. The response rate was about 80 per cent for both 1975 and 1976. Detailed information regarding survey design and methodology, instruments, definitions, and estimates of sampling variability has been published by NCHS.7
Methodology In addition to demographic and other data, the Patient Record used in the 1975-1976 surveys included: the patient's principal complaint or other reason for visit as nearly as possible in the patient's own words, the physician's principal diagnosis, other significant diagnoses known to exist for the patient at the time but which were not necessarily related to the current visit, and a checklist of diagnostic procedures including blood pressure measurement. '°°r
A symptom classification developed for use in NAMCS was used to code patients' reasons for visit.8 Physicians' diagnoses were coded by the American Medical Records Association, under contract to the National Center for Health Statistics, based on the International Classification of Diseases, Adapted for Use in the United States (ICDA).9 Rates of blood pressure measurement were obtained by dividing the number of blood pressure checks performed during visits of a specific group or to a specific specialty by the total number of visits to a specific group or specialty. An examination of the NAMCS "regular care" or "well-person" visits was also performed.* The earlier NAMCS report on visits for hypertension indicated that most visits for treatment of hypertension (87 per cent) were to offices of general and family practitioners and internists, with the remaining 13 per cent distributed among specialists in cardiovascular disease, general surgeons, and other specialists.6 It was therefore instructive to examine the rates of blood pressure measurement performed by the most frequently visited specialists to consider their potential contribution to continuous hypertension screening.
Results In the 79 per cent of visits where blood pressure was measured in the presence of hypertension, there were no significant differences by age or sex. In contrast, demographic variables differed significantly among visits in which hypertension was absent (see Figure 1). Blood pressure was rarely measured for patients under 15 years of age; but the tendency for measurement increased *These data were derived from one item in the Patient Record in which major reasons for visit were categorized.
HYPERTENSION DIAGNOSIS LISTED
80
Female = 79% Male = 78%
U.
60
0 H z w
0
wL
_OURCE.
40
N
HYPERTENSION DIAGNOSIS LDl etefHalNOT DoSE
AmuoyMcCaeSre.Nt
= 24% ~~~~~~~~~~~~Male
/
20 t
o
L
Less than 15
15-24
~~~~~~~SOURCE: National Ambulatory Medical Care Survey, National Center for Health Statistics.
25-34
35-44
45-54
55-64
65-74
75 and over
VISIT AGE IN YEARS
FIGURE 1-Per Cent of Office Visits Which Included Blood Pressire Measurement in the Presence and Absence of Hypertension by Age: United States, January 1975-December 1976 AJPH January 1979, Vol. 69, No. 1
HYPERTENSION SCREENING IN AMBULATORY CARE
with increasing age except for a drop in the 35-44 years category, which was probably due to the decrease in prenatal visits for that age group (see Figure 2). The rate of blood pressure checks was significantly greater for females than for males (p < .001), with the higher proportions of females in all age groups accounted for by members of the black race. Rates were lowest for white males of all ages. It appears that in the absence of hypertension, sex, race, and age were related to use of the measurement procedure. Examination of the reason for visit (or patient's chief complaint) showed that about seven of every 10 visits where hypertension was diagnosed were motivated by abnormally high blood pressure, general medical examination, or by an appointment for a progress visit.** While hypertension is very often asymptomatic, it is interesting that the chief complaints for another two of 10 visits for hypertension were headache, vertigo, fatigue, and nervousness. When these four complaints were presented in the absence of hypertension, blood pressure was measured, on the average, only about one-half the time although they were the leading symptomatic reasons (other than "abnormally high blood pressure") given by the group of patients who were subsequently diagnosed as hypertensive. Except for visits in which the patient expressly indicated that blood pressure was a problem, the rate of blood pressure measurement during visits for each complaint listed in Table 1 was significantly greater when hypertension was present than when it was absent. The coexistence of hypertension with diabetes mellitus, obesity, neuroses, arteriosclerosis, bronchitis, emphysema and asthma, and arthritis and rheumatism was suggested by
the earlier study.6 When these hypertension associated diagnoses were presented by patients in the absence of hypertension, blood pressure was less frequently reported than when a diagnosis of hypertension was present (see Table 2). Blood pressure was measured more often for certain major ICDA categories than for others regardless of the presence or absence of hypertension. Diseases of the circulatory system reflected blood pressure measurement in 72 per cent of visits. About 63 per cent of visits for endocrine, nutritional, and metabolic diseases (the category which includes diabetes mellitus and obesity) included blood pressure checks. However, only about 12 per cent of patient encounters included blood pressure measurement when the diagnosis fell in the categories of diseases of the nervous system and sense organs or diseases of the skin and subcutaneous tissue (see Table 3). The analysis of routine care type visits revealed that 75 per cent of visits for prenatal care included blood pressure checks in contrast to 46 per cent of visits for postnatal care. When the patient visited for regular care of a preexisting condition and hypertension was absent, 36 per cent of this type of visit included blood pressure measurement. Blood pressure was measured in 54 per cent of nonhypertension visits for family planning and 35 per cent of visits for counseling or advice. Finally, among the most frequently visited medical and surgical specialties, the frequency of blood pressure measurement ranged broadly from about 2 per cent each of visits to otolaryngologists, dermatologists, ophthalmologists, and orthopedic surgeons, to 72 per cent of visits to specialists in cardiovascular disease. Psychiatrists measure blood pressure about 5 per cent of the time. Internists, whose practices included 28 per cent of all hypertension-related office visits in calendar years 1975 and 1976, included blood pressure measurement in three of five visits for all problems. However, visits to general and family practitioners, which com-
**These follow-up visits did not necessarily represent all follow-up visits since the reason for visit was coded according to the reason expressed by the patient which may give no clue to its status. 80
+
....+.......
Black male Black female
60 _
,.
+
lo;*eeee
z
w 0
White female White male
40
20 Source:
National Ambulatory Medical Care Survey, National Center for Health Statistics.
0 Less than 15 15-24
25-34
35-44
45-54
55-64
65-74 75 and over
VISIT AGE
FIGURE 2-Per Cent of Office Visits Which Included Blood Pressure Measurement by Age, Sex, and Race: United States, January 1975-December 1976 AJPH January 1979, Vol. 69, No. 1
21
CYPRESS
TABLE 1 Per Cent of Office Visits for Most Frequent Hypertension-associated Patient's Principal Problem, Complaint, or Symptom Which Included Blood Pressure Measurement, in the Presence and Absence of a Hypertension Diagnosis: United States, January 1975-December 1976 Per Cent of Visits Blood Pressure Checked Patient's Principal Problem, Complaint, or Symptom
Fatigue Headache Vertigo Abnormally high blood pressure Nervousness General medical exam Progress visits
Hypertension Diagnosis Usted
Hypertension Diagnosis Not Listed
004 056 069
77.6 79.7 76.8
56.9 43.9 61.0
205 810 900 980,985
77.2 80.3 83.8 84.1
73.2 43.7 50.9 40.0
NAMCS Code
Source: National Ambulatory Medical Care Survey, National Center for Health Statistics
prised the majority of hypertension visits (60 per cent) reflected blood pressure measurement in about two of five visits for all diagnoses including hypertension (see Table 4). Since it was shown that the general rate of blood pressure measurement increased with patient age, visits were divided into two groups in order to estimate the effect of age on the measurement rates of different specialists: those by patients under 25 years and those by patients 45 years and over. As expected, rates were generally higher for the older group than for the younger group (not including obstetricsgynecology and urological surgery where rates were fairly constant regardless of age). Among the specialties of neurology, general and family practice, internal medicine, and cardiovascular diseases, increasingly higher proportions of visits by patients 45 years and older reflected increasingly higher rates of blood pressure measurement. Discussion The analysis of NAMCS data was undertaken to determine the conditions under which blood pressure was measured during visits and to identify characteristics and prob-
lems related to patients at risk of hypertension. If certain patient characteristics, symptoms, and other morbid conditions could be shown to be related to hypertension visits, then visits which exhibited these factors in the absence of hypertension would be logical selections for blood pressure measurement. That is, blood pressure measurement would be concentrated in the visits most likely to include a potential hypertension patient. Data collected in the Health and Nutrition Examination Survey from 1971 to 1974 revealed that hypertension was more prevalent among males than among females, particularly in the 12-54 years age group; and that the proportion of hypertensives whose condition had not been previously diagnosed was significantly greater among men than among women.10 Since NAMCS data indicated that females visited physicians more frequently and also had a higher rate of blood pressure measurement than males, the health-careseeking patterns of males may account for their higher proportion of undiagnosed hypertension as well as their higher prevalence rate. It was apparent, and not unexpected, that the rate of blood pressure checks for females rose during the
TABLE 2-Per Cent of Office Visits for Hypertension-Associated Principal Diagnoses which Included Blood Pressure Measurement In the Presence and Absence of a Hypertension Diagnosis: United States, January 1975-December 1976 Per Cent of Visits Blood Pressure Checked
Principal Diagnosis Diabetes mellitus Obesity Neuroses Arterosclerosis Bronchitis, emphysema, asthma Arthritis and rheumatism, except rheumatic fever
Hypertension Diagnosis
Hypertension Diagnosis
Listed
Not Usted
250 277 300 440
85.5 78.7 71.3 72.8
61.7 66.1 24.2 55.7
490-493
74.5
31.6
710-718
78.1
39.8
ICDA Code
Source: National Ambulatory Medical Care Survey, National Center for Health Statistics
22
AJPH January 1979, Vol. 69, No. 1
HYPERTENSION SCREENING IN AMBULATORY CARE
TABLE 3-Per Cent of Office Visits Which Included Blood Presure Measurement by Principal Diagnosis Classified by Major 3-digit ICDA Category Per Cent Major 3-digit Diagnostic
Category'
Infective and parasitic diseases Neoplasms Endocrine, nutritional and metabolic diseases Mental disorders Diseases of the nervous system and sense organs Diseases of the circulatory system Diseases of the respiratory system Diseases of the digestive system Diseases of the genitourinary system Diseases of the skin and subcutaneous tissue Diseases of the musculoskeletal system and connective tissue Symptoms and ill-defined conditions Accidents, poisonings and violence Special conditions and examinations without sickness
ICDA Code
of Visits
000-136 140-239
24.0 28.9
240-279 290-315
63.0 24.2
320-389
12.5
390-458
71.9
460-519
23.6
520-577
39.0
580-629
36.3
680-709
12.4
710-738
33.3
780-796
39.6
800-999
15.5
YO0-Y13
37.3
'Based on the Eighth Revision, International Classification of Diseases, Adapted for Use in the United States, 1967. Source: National Ambulatory Medical Care Survey, National Center for Heaith Statistics
childbearing years. However, this is also a time when additional medical attention to males vis a vis hypertension appears to be needed. HANES data also showed that the prevalence of hypertension was substantially higher among black adults than among white adults. Awareness of this statistic
probably contributed to the higher rates of blood pressure measurement among black females of all ages than among other groups. It was apparent from this study of physician-visit data that more attention could be given to blood pressure measurement when hypertension is not a reason for the patient's visit, especially when the patient presents symptoms of headache, vertigo, fatigue, or nervousness; and when certain diagnostic categories, and specific diagnoses identified as associated with hypertension are presented in the absence of confirmed hypertension. Given the incidence of these problems in the presence of hypertension, it appears that more frequent blood pressure measurement when they are presented, but when hypertension has not yet been diagnosed, is likely to detect previously unsuspected cases of hypertension. Blood pressure measurement for the purpose of hypertension detection may not be valid during some visits when elevated readings are due to other causes, which could account for the reduced rate, such as in the accidents, poisonings, and violence category. However this does not account for the diminished use of the diagnostic procedure in visits for other categories, particularly those of a more routine nature. Opportunities for hypertension screening exist during routine care visits which were not fully utilized during the period of the study. Examination of blood pressure measurement rates among specialties indicated that unless the visit was directly related to a known hypertension diagnosis, prenatal care, or older patients, blood pressure measurement was not a highly frequent occurrence. A significant contribution to hypertension screening would be made by specialists whose practices include few or no visits for hypertension. This study investigated the extent of physician compliance with the JNC recommendation regarding routine blood pressure measurement. Findings indicated incomplete compliance, partially supporting the report by Gold, et al that many significant areas of noncompliance with JNC guidelines remain."1 However, some practitioners question
TABLE 4-Per Cent of Visits by Patients under 25 Years and 45 Years and Over, and Per Cent of Visits Blood Pressure Checked by Physician's Specialty: United States, January 1975-Dcember 1976 All Ages
General and Family Practice Intemal medicine General surgery Cardiovascular diseases Obstetrics-gynecology Urological surgery Neurology
Under 25 Years
45 Years and Over
Per Cent Blood Pressure Checked
Per Cent of Visits
Per Cent Blood Pressure Checked
Per Cent of Visits
Per Cent Blood Pressure Checked
41.3 59.7 23.0 71.6 59.7 13.5 22.4
30.4 10.8 20.5 4.1 34.4 14.7 20.9
22.5 40.1 17.4 42.7 59.8 13.4 14.3
45.0 67.8 50.6 82.7 14.4 60.1 43.7
54.6 65.4 27.1 74.2 56.6 14.7 26.7
Source: National Ambulatory Medical Care Survey, National Center for Heaith Statistics.
AJPH January 1979, Vol. 69, No. 1
23
CYPRESS
the practicality of measuring blood pressure at every office visit, particularly when a recent normal reading was obtained. Rakel advised family physicians to measure blood pressure during every office visit in order to identify hypertension before it became symptomatic.12 He stated further that since hypertension occurs gradually with time, gradual increases in blood pressure over time could flag cases needing closer attention. That it was a feasible approach in office practice was shown by Rudnick who described a program conducted in a family practice which resulted in 98 per cent blood pressure measurement rate and the detection of many symptomless hypertensives.13 However, little research has been done to determine optimum tracking intervals. It was not possible to use NAMCS data to determine the time interval between visits or the interval between blood pressure checks. Nor was the study designed to investigate the feasibility of continuous blood pressure monitoring when blood pressure readings are normal. However, the NAMCS analysis suggested that blood pressure measurement could be made more functional if its use were increased in the presence of conditions related to hypertension, or when visits are not crisis-oriented. The average annual rate of office visits in 1975-76 was 2.8 visits for each person in the civilian noninstitutionalized population. Blood pressure was measured in physicians' offices, on the average, during .9 visits a year per person. Considering that more than one-half of all persons found to be hypertensive in 1974 had never been diagnosed as having hypertension, an increase in the average national blood pressure measurement rate is likely to decrease the number of undetected cases.
3. 4.
5.
6.
7.
8.
9.
10.
11.
REFERENCES 1. National Heart, Lung, and Blood Institute: Report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure. DHEW Pub. No. (NIH) 77-1088. National Institues of Health, Bethesda, MD, 1977. 2. National Center for Health Statistics: Current Estimates from the Health Interview Survey, United States-1976 by C. R. Black. Vital and Health Statistics. Series 10-Number 119.
I
12. 13.
DHEW Pub. No. (PHS) 78-1547. Washington, DC, U.S. Government Printing Office, Nov. 77. Armitage P and Rose GA: The variability of measurements in casual blood pressure. Clin Sci 30:(2) 325-336, 1966. Rosner B: Screening for hypertension-some statistical observations. Journal of Chronic Diseases, 30:7-18, 1977. Berkson DM, et al: Difficulties in screening and recruiting low income community residents into a free hypertensive treatment program. Abstracts: Fourth National Conference on High Blood Pressure Control. Preventive Medicine, 7:(1) 42, 1978. National Center for Health Statistics: Office Visits for Hypertension: National Ambulatory Medical Care Survey, United States, 1975-1976, by B. K. Cypress. Advance Data from Vital and Health Statistics, No. 28, April 1978. National Center for Health Statistics: The National Ambulatory Medical Care Survey. 1975 Summary, United States, by H. Koch and T. McLemore, Vital and Health Statistics. Series 13-No. 33. DHEW Pub. No. (PHS) 78-1784. Public Health Service, Washington, D.C., U.S. Government Printing Office, January 1978. National Center for Health Statistics: The National Ambulatory Medical Care Survey-Symptom Classification, by S. Meads and T. McLemore. Vital and Health Statistics. Series 2-Number 63. DHEW Pub. No. (HRA) 75-1337. Health Resources Administration, Washington, DC, U.S. Government Printing Office, Dec. 1974. National Center for Health Statistics: Eighth Revision International Classification of Diseases, Adapted for Use in the United States. PHS Pub. No. 1693. Public Health Service, Washington, DC, U.S. Government Printing Office, 1967. National Center for Health Statistics: Blood Pressure Levels of Persons 6-74 Years in the United States, 1971-1974, by J. Roberts and K. Maurer. Vital and Health Statistics. Series 11 No. 203. DHEW Pub. No. (HRA) 78-1648. Health Resources Administration, Washington, DC, U.S. Government Printing Office, Sept. 1977. Gold RA, et al: Physician compliance with recommendations of the Joint National Committee on Detection, Evaluation and Treatment of High Blood Pressure: findings of a national probability sample survey. Abstracts: Fourth National Conference on High Blood Pressure Control. Preventive Medicine, 7:(1) 77, 1978. Rakel, RE: Principles of Family Medicine. Philadelphia: W. B. Saunders Company, 1977. Rudnick KV: Screening for hypertension: case finding. Abstracts: Fourth National Conference on High Blood Pressure Control. Preventive Medicine, 7:(1) 129, 1978.
Plus ca change, plus cost la m6me chose.
l
During the year 1899, a university professor ofmedicine . .. received by mail 424 circulars relative to medicines and their uses. Of these there were only 54 which he was able to class as "respectable" . . . the remaining he divides into "ordinary" and "disgusting". Dykstra, DL The Medical Profession and Patent and Proprietary Medicines during the Nineteenth Century. Bull Hist Med 29:401-419, 1955.
24
AJPH January 1979, Vol. 69, No. 1
Abstract: Data from the 1975-1976 National Ambulatory Medical Care Survey conducted by the National Center for Health Statistics were examined retrospectively to determine the extent to which blood pressure was measured during visits to office-based physicians in the conterminous United States. Blood pressure was more often measured for females (especially black) than for males although males (especially black) in certain age groups had a higher prevalence of hypertension and comprised the higher proportion of undiagnosed hypertensives. Blood pressure measurement increased with age, but was rarely measured for those under 15 years of age. Blood pressure was measured about 79 per cent of the time when hypertension was present but only 30 per cent of the time when hypertension was absent. When diseases shown to be frequently concomitant with hypertension were diag-
nosed in the absence of hypertension, blood pressure checks ranged from 24 per cent of visits diagnosed neuroses to 66 per cent diagnosed obesity. Blood pressure was measured during about 12 per cent of visits for diseases of the nervous system and sense organs as well as diseases of the skin and subcutaneous tissue; 24 per cent of visits for infective and parasitic diseases, diseases of the respiratory system, and mental disorders. Blood pressure was measured most often when diagnoses were in the categories of diseases of the circulatory system and endocrine, nutritional, and metabolic diseases. Opportunities for blood pressure measurement during routine visits did not appear to be fully utilized, nor did some specialists take frequent blood pressure measurements. (Am. J. Public Health 69:19-24, 1979.)
Introduction
cost. Indeed, many problems other than cost operate against the long range success of mass screening programs. The poor reliability associated with one-time or casual measurement was documented by Armitage and Rose.3 Rosner offered a screening procedure designed to reduce measurement variability but implementation was dependent on sequential patient visits.4 Public screening programs, however, have been unsuccessful with follow-up visits. For example, Berkson, et al., had difficulty persuading patients to return for second determinations although their initial diastolic blood pressure was 2 90 mm Hg.5 However, the success of hypertension case finding during office visits requires that all patients visiting a physician for whatever reason have their blood pressure measured. Analysis of National Ambulatory Medical Care Survey (NAMCS) data for the years 1975 and 1976 revealed that an estimated 1 billion, 155 million visits were made to officebased physicians in the United States. Essential benign hypertension was the leading morbidity-related problem, accounting for an estimated 46.1 million visits. During the same two-year period an additional 29 million visits occurred in which hypertension was the diagnosis listed second or third, in order of importance at that encounter, making a total of about 75 million visits in which hypertension was a recognized and diagnosed condition. About 79 per cent of these hypertension-related visits included blood pressure checks. However, blood pressure was measured in only about 30 per cent of the remaining 1 billion, 80 million visits for other reasons.6 This figure was only slightly improved (to about 37 per cent) when visits by children under 6 years of age were not included. These data indicated that the physician's office may be an underutilized resource for hyper-
In its 1977 report, the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure (JNC) recommended that all health care professionals routinely take a patient's blood pressure regardless of the patient's reason for visit.' The private office of the practicing physician often has health care personnel available who are trained to measure blood pressure, record findings, and provide patient counseling under clinical conditions. When elevated blood pressure is detected during an office visit, immediate arrangements for follow-up can be made, thus increasing the likelihood of early patient therapy. Furthermore, hypertensive status can be more accurately gauged if the patient is available for sequential measurements. Blood pressure measurement is probably one of the least costly diagnostic tools in the physician's armamentarium in terms of professional time and services. Routine blood pressure measurement during office visits also offers a significant means of reducing the need for expensive mass screening since, according to a national survey, about 76 per cent of the population in the United States saw a physician at least once during 1976 for some reason.2 It is doubtful that so high a proportion of the population could be reached in a reasonable time by a public screening program for the same Address reprint requests to Beulah K. Cypress, PhD, Ambulatory Care Statistics Branch, Division of Health Resources Utilization Statistics, National Center for Health Statistics, DHEW, 3700 East-West Highway, Hyattsville, MD 20782. This paper, submitted to the Journal April 24, 1978, was revised and accepted for publication July 21, 1978.
AJPH January 1979, Vol. 69, No. 1
19
CYPRESS
-~ ~emal=34%
tension screening. In order to explore further the extent to which blood pressure was measured in physicians' offices, additional analyses of physician data obtained during the 1975-76 NAMCS were undertaken.
Source of the Data NAMCS is a sample survey conducted annually in the conterminous United States by the Division of Health Resources Utilization Statistics in the National Center for Health Statistics (NCHS). Samples of approximately 3,500 physicians in 1975 and 3,000 physicians in 1976 were selected from master files maintained by the American Medical Association and the American Osteopathic Association. Sampled physicians, randomly assigned to one of the 52 weeks in the survey year, were requested to complete brief encounter forms (Patient Records) for a systematic random sample of office visits taking place within their practice during the assigned reporting period. Additional data concerning physician practice characteristics, such as primary specialty, were obtained during an induction interview. The response rate was about 80 per cent for both 1975 and 1976. Detailed information regarding survey design and methodology, instruments, definitions, and estimates of sampling variability has been published by NCHS.7
Methodology In addition to demographic and other data, the Patient Record used in the 1975-1976 surveys included: the patient's principal complaint or other reason for visit as nearly as possible in the patient's own words, the physician's principal diagnosis, other significant diagnoses known to exist for the patient at the time but which were not necessarily related to the current visit, and a checklist of diagnostic procedures including blood pressure measurement. '°°r
A symptom classification developed for use in NAMCS was used to code patients' reasons for visit.8 Physicians' diagnoses were coded by the American Medical Records Association, under contract to the National Center for Health Statistics, based on the International Classification of Diseases, Adapted for Use in the United States (ICDA).9 Rates of blood pressure measurement were obtained by dividing the number of blood pressure checks performed during visits of a specific group or to a specific specialty by the total number of visits to a specific group or specialty. An examination of the NAMCS "regular care" or "well-person" visits was also performed.* The earlier NAMCS report on visits for hypertension indicated that most visits for treatment of hypertension (87 per cent) were to offices of general and family practitioners and internists, with the remaining 13 per cent distributed among specialists in cardiovascular disease, general surgeons, and other specialists.6 It was therefore instructive to examine the rates of blood pressure measurement performed by the most frequently visited specialists to consider their potential contribution to continuous hypertension screening.
Results In the 79 per cent of visits where blood pressure was measured in the presence of hypertension, there were no significant differences by age or sex. In contrast, demographic variables differed significantly among visits in which hypertension was absent (see Figure 1). Blood pressure was rarely measured for patients under 15 years of age; but the tendency for measurement increased *These data were derived from one item in the Patient Record in which major reasons for visit were categorized.
HYPERTENSION DIAGNOSIS LISTED
80
Female = 79% Male = 78%
U.
60
0 H z w
0
wL
_OURCE.
40
N
HYPERTENSION DIAGNOSIS LDl etefHalNOT DoSE
AmuoyMcCaeSre.Nt
= 24% ~~~~~~~~~~~~Male
/
20 t
o
L
Less than 15
15-24
~~~~~~~SOURCE: National Ambulatory Medical Care Survey, National Center for Health Statistics.
25-34
35-44
45-54
55-64
65-74
75 and over
VISIT AGE IN YEARS
FIGURE 1-Per Cent of Office Visits Which Included Blood Pressire Measurement in the Presence and Absence of Hypertension by Age: United States, January 1975-December 1976 AJPH January 1979, Vol. 69, No. 1
HYPERTENSION SCREENING IN AMBULATORY CARE
with increasing age except for a drop in the 35-44 years category, which was probably due to the decrease in prenatal visits for that age group (see Figure 2). The rate of blood pressure checks was significantly greater for females than for males (p < .001), with the higher proportions of females in all age groups accounted for by members of the black race. Rates were lowest for white males of all ages. It appears that in the absence of hypertension, sex, race, and age were related to use of the measurement procedure. Examination of the reason for visit (or patient's chief complaint) showed that about seven of every 10 visits where hypertension was diagnosed were motivated by abnormally high blood pressure, general medical examination, or by an appointment for a progress visit.** While hypertension is very often asymptomatic, it is interesting that the chief complaints for another two of 10 visits for hypertension were headache, vertigo, fatigue, and nervousness. When these four complaints were presented in the absence of hypertension, blood pressure was measured, on the average, only about one-half the time although they were the leading symptomatic reasons (other than "abnormally high blood pressure") given by the group of patients who were subsequently diagnosed as hypertensive. Except for visits in which the patient expressly indicated that blood pressure was a problem, the rate of blood pressure measurement during visits for each complaint listed in Table 1 was significantly greater when hypertension was present than when it was absent. The coexistence of hypertension with diabetes mellitus, obesity, neuroses, arteriosclerosis, bronchitis, emphysema and asthma, and arthritis and rheumatism was suggested by
the earlier study.6 When these hypertension associated diagnoses were presented by patients in the absence of hypertension, blood pressure was less frequently reported than when a diagnosis of hypertension was present (see Table 2). Blood pressure was measured more often for certain major ICDA categories than for others regardless of the presence or absence of hypertension. Diseases of the circulatory system reflected blood pressure measurement in 72 per cent of visits. About 63 per cent of visits for endocrine, nutritional, and metabolic diseases (the category which includes diabetes mellitus and obesity) included blood pressure checks. However, only about 12 per cent of patient encounters included blood pressure measurement when the diagnosis fell in the categories of diseases of the nervous system and sense organs or diseases of the skin and subcutaneous tissue (see Table 3). The analysis of routine care type visits revealed that 75 per cent of visits for prenatal care included blood pressure checks in contrast to 46 per cent of visits for postnatal care. When the patient visited for regular care of a preexisting condition and hypertension was absent, 36 per cent of this type of visit included blood pressure measurement. Blood pressure was measured in 54 per cent of nonhypertension visits for family planning and 35 per cent of visits for counseling or advice. Finally, among the most frequently visited medical and surgical specialties, the frequency of blood pressure measurement ranged broadly from about 2 per cent each of visits to otolaryngologists, dermatologists, ophthalmologists, and orthopedic surgeons, to 72 per cent of visits to specialists in cardiovascular disease. Psychiatrists measure blood pressure about 5 per cent of the time. Internists, whose practices included 28 per cent of all hypertension-related office visits in calendar years 1975 and 1976, included blood pressure measurement in three of five visits for all problems. However, visits to general and family practitioners, which com-
**These follow-up visits did not necessarily represent all follow-up visits since the reason for visit was coded according to the reason expressed by the patient which may give no clue to its status. 80
+
....+.......
Black male Black female
60 _
,.
+
lo;*eeee
z
w 0
White female White male
40
20 Source:
National Ambulatory Medical Care Survey, National Center for Health Statistics.
0 Less than 15 15-24
25-34
35-44
45-54
55-64
65-74 75 and over
VISIT AGE
FIGURE 2-Per Cent of Office Visits Which Included Blood Pressure Measurement by Age, Sex, and Race: United States, January 1975-December 1976 AJPH January 1979, Vol. 69, No. 1
21
CYPRESS
TABLE 1 Per Cent of Office Visits for Most Frequent Hypertension-associated Patient's Principal Problem, Complaint, or Symptom Which Included Blood Pressure Measurement, in the Presence and Absence of a Hypertension Diagnosis: United States, January 1975-December 1976 Per Cent of Visits Blood Pressure Checked Patient's Principal Problem, Complaint, or Symptom
Fatigue Headache Vertigo Abnormally high blood pressure Nervousness General medical exam Progress visits
Hypertension Diagnosis Usted
Hypertension Diagnosis Not Listed
004 056 069
77.6 79.7 76.8
56.9 43.9 61.0
205 810 900 980,985
77.2 80.3 83.8 84.1
73.2 43.7 50.9 40.0
NAMCS Code
Source: National Ambulatory Medical Care Survey, National Center for Health Statistics
prised the majority of hypertension visits (60 per cent) reflected blood pressure measurement in about two of five visits for all diagnoses including hypertension (see Table 4). Since it was shown that the general rate of blood pressure measurement increased with patient age, visits were divided into two groups in order to estimate the effect of age on the measurement rates of different specialists: those by patients under 25 years and those by patients 45 years and over. As expected, rates were generally higher for the older group than for the younger group (not including obstetricsgynecology and urological surgery where rates were fairly constant regardless of age). Among the specialties of neurology, general and family practice, internal medicine, and cardiovascular diseases, increasingly higher proportions of visits by patients 45 years and older reflected increasingly higher rates of blood pressure measurement. Discussion The analysis of NAMCS data was undertaken to determine the conditions under which blood pressure was measured during visits and to identify characteristics and prob-
lems related to patients at risk of hypertension. If certain patient characteristics, symptoms, and other morbid conditions could be shown to be related to hypertension visits, then visits which exhibited these factors in the absence of hypertension would be logical selections for blood pressure measurement. That is, blood pressure measurement would be concentrated in the visits most likely to include a potential hypertension patient. Data collected in the Health and Nutrition Examination Survey from 1971 to 1974 revealed that hypertension was more prevalent among males than among females, particularly in the 12-54 years age group; and that the proportion of hypertensives whose condition had not been previously diagnosed was significantly greater among men than among women.10 Since NAMCS data indicated that females visited physicians more frequently and also had a higher rate of blood pressure measurement than males, the health-careseeking patterns of males may account for their higher proportion of undiagnosed hypertension as well as their higher prevalence rate. It was apparent, and not unexpected, that the rate of blood pressure checks for females rose during the
TABLE 2-Per Cent of Office Visits for Hypertension-Associated Principal Diagnoses which Included Blood Pressure Measurement In the Presence and Absence of a Hypertension Diagnosis: United States, January 1975-December 1976 Per Cent of Visits Blood Pressure Checked
Principal Diagnosis Diabetes mellitus Obesity Neuroses Arterosclerosis Bronchitis, emphysema, asthma Arthritis and rheumatism, except rheumatic fever
Hypertension Diagnosis
Hypertension Diagnosis
Listed
Not Usted
250 277 300 440
85.5 78.7 71.3 72.8
61.7 66.1 24.2 55.7
490-493
74.5
31.6
710-718
78.1
39.8
ICDA Code
Source: National Ambulatory Medical Care Survey, National Center for Health Statistics
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AJPH January 1979, Vol. 69, No. 1
HYPERTENSION SCREENING IN AMBULATORY CARE
TABLE 3-Per Cent of Office Visits Which Included Blood Presure Measurement by Principal Diagnosis Classified by Major 3-digit ICDA Category Per Cent Major 3-digit Diagnostic
Category'
Infective and parasitic diseases Neoplasms Endocrine, nutritional and metabolic diseases Mental disorders Diseases of the nervous system and sense organs Diseases of the circulatory system Diseases of the respiratory system Diseases of the digestive system Diseases of the genitourinary system Diseases of the skin and subcutaneous tissue Diseases of the musculoskeletal system and connective tissue Symptoms and ill-defined conditions Accidents, poisonings and violence Special conditions and examinations without sickness
ICDA Code
of Visits
000-136 140-239
24.0 28.9
240-279 290-315
63.0 24.2
320-389
12.5
390-458
71.9
460-519
23.6
520-577
39.0
580-629
36.3
680-709
12.4
710-738
33.3
780-796
39.6
800-999
15.5
YO0-Y13
37.3
'Based on the Eighth Revision, International Classification of Diseases, Adapted for Use in the United States, 1967. Source: National Ambulatory Medical Care Survey, National Center for Heaith Statistics
childbearing years. However, this is also a time when additional medical attention to males vis a vis hypertension appears to be needed. HANES data also showed that the prevalence of hypertension was substantially higher among black adults than among white adults. Awareness of this statistic
probably contributed to the higher rates of blood pressure measurement among black females of all ages than among other groups. It was apparent from this study of physician-visit data that more attention could be given to blood pressure measurement when hypertension is not a reason for the patient's visit, especially when the patient presents symptoms of headache, vertigo, fatigue, or nervousness; and when certain diagnostic categories, and specific diagnoses identified as associated with hypertension are presented in the absence of confirmed hypertension. Given the incidence of these problems in the presence of hypertension, it appears that more frequent blood pressure measurement when they are presented, but when hypertension has not yet been diagnosed, is likely to detect previously unsuspected cases of hypertension. Blood pressure measurement for the purpose of hypertension detection may not be valid during some visits when elevated readings are due to other causes, which could account for the reduced rate, such as in the accidents, poisonings, and violence category. However this does not account for the diminished use of the diagnostic procedure in visits for other categories, particularly those of a more routine nature. Opportunities for hypertension screening exist during routine care visits which were not fully utilized during the period of the study. Examination of blood pressure measurement rates among specialties indicated that unless the visit was directly related to a known hypertension diagnosis, prenatal care, or older patients, blood pressure measurement was not a highly frequent occurrence. A significant contribution to hypertension screening would be made by specialists whose practices include few or no visits for hypertension. This study investigated the extent of physician compliance with the JNC recommendation regarding routine blood pressure measurement. Findings indicated incomplete compliance, partially supporting the report by Gold, et al that many significant areas of noncompliance with JNC guidelines remain."1 However, some practitioners question
TABLE 4-Per Cent of Visits by Patients under 25 Years and 45 Years and Over, and Per Cent of Visits Blood Pressure Checked by Physician's Specialty: United States, January 1975-Dcember 1976 All Ages
General and Family Practice Intemal medicine General surgery Cardiovascular diseases Obstetrics-gynecology Urological surgery Neurology
Under 25 Years
45 Years and Over
Per Cent Blood Pressure Checked
Per Cent of Visits
Per Cent Blood Pressure Checked
Per Cent of Visits
Per Cent Blood Pressure Checked
41.3 59.7 23.0 71.6 59.7 13.5 22.4
30.4 10.8 20.5 4.1 34.4 14.7 20.9
22.5 40.1 17.4 42.7 59.8 13.4 14.3
45.0 67.8 50.6 82.7 14.4 60.1 43.7
54.6 65.4 27.1 74.2 56.6 14.7 26.7
Source: National Ambulatory Medical Care Survey, National Center for Heaith Statistics.
AJPH January 1979, Vol. 69, No. 1
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CYPRESS
the practicality of measuring blood pressure at every office visit, particularly when a recent normal reading was obtained. Rakel advised family physicians to measure blood pressure during every office visit in order to identify hypertension before it became symptomatic.12 He stated further that since hypertension occurs gradually with time, gradual increases in blood pressure over time could flag cases needing closer attention. That it was a feasible approach in office practice was shown by Rudnick who described a program conducted in a family practice which resulted in 98 per cent blood pressure measurement rate and the detection of many symptomless hypertensives.13 However, little research has been done to determine optimum tracking intervals. It was not possible to use NAMCS data to determine the time interval between visits or the interval between blood pressure checks. Nor was the study designed to investigate the feasibility of continuous blood pressure monitoring when blood pressure readings are normal. However, the NAMCS analysis suggested that blood pressure measurement could be made more functional if its use were increased in the presence of conditions related to hypertension, or when visits are not crisis-oriented. The average annual rate of office visits in 1975-76 was 2.8 visits for each person in the civilian noninstitutionalized population. Blood pressure was measured in physicians' offices, on the average, during .9 visits a year per person. Considering that more than one-half of all persons found to be hypertensive in 1974 had never been diagnosed as having hypertension, an increase in the average national blood pressure measurement rate is likely to decrease the number of undetected cases.
3. 4.
5.
6.
7.
8.
9.
10.
11.
REFERENCES 1. National Heart, Lung, and Blood Institute: Report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure. DHEW Pub. No. (NIH) 77-1088. National Institues of Health, Bethesda, MD, 1977. 2. National Center for Health Statistics: Current Estimates from the Health Interview Survey, United States-1976 by C. R. Black. Vital and Health Statistics. Series 10-Number 119.
I
12. 13.
DHEW Pub. No. (PHS) 78-1547. Washington, DC, U.S. Government Printing Office, Nov. 77. Armitage P and Rose GA: The variability of measurements in casual blood pressure. Clin Sci 30:(2) 325-336, 1966. Rosner B: Screening for hypertension-some statistical observations. Journal of Chronic Diseases, 30:7-18, 1977. Berkson DM, et al: Difficulties in screening and recruiting low income community residents into a free hypertensive treatment program. Abstracts: Fourth National Conference on High Blood Pressure Control. Preventive Medicine, 7:(1) 42, 1978. National Center for Health Statistics: Office Visits for Hypertension: National Ambulatory Medical Care Survey, United States, 1975-1976, by B. K. Cypress. Advance Data from Vital and Health Statistics, No. 28, April 1978. National Center for Health Statistics: The National Ambulatory Medical Care Survey. 1975 Summary, United States, by H. Koch and T. McLemore, Vital and Health Statistics. Series 13-No. 33. DHEW Pub. No. (PHS) 78-1784. Public Health Service, Washington, D.C., U.S. Government Printing Office, January 1978. National Center for Health Statistics: The National Ambulatory Medical Care Survey-Symptom Classification, by S. Meads and T. McLemore. Vital and Health Statistics. Series 2-Number 63. DHEW Pub. No. (HRA) 75-1337. Health Resources Administration, Washington, DC, U.S. Government Printing Office, Dec. 1974. National Center for Health Statistics: Eighth Revision International Classification of Diseases, Adapted for Use in the United States. PHS Pub. No. 1693. Public Health Service, Washington, DC, U.S. Government Printing Office, 1967. National Center for Health Statistics: Blood Pressure Levels of Persons 6-74 Years in the United States, 1971-1974, by J. Roberts and K. Maurer. Vital and Health Statistics. Series 11 No. 203. DHEW Pub. No. (HRA) 78-1648. Health Resources Administration, Washington, DC, U.S. Government Printing Office, Sept. 1977. Gold RA, et al: Physician compliance with recommendations of the Joint National Committee on Detection, Evaluation and Treatment of High Blood Pressure: findings of a national probability sample survey. Abstracts: Fourth National Conference on High Blood Pressure Control. Preventive Medicine, 7:(1) 77, 1978. Rakel, RE: Principles of Family Medicine. Philadelphia: W. B. Saunders Company, 1977. Rudnick KV: Screening for hypertension: case finding. Abstracts: Fourth National Conference on High Blood Pressure Control. Preventive Medicine, 7:(1) 129, 1978.
Plus ca change, plus cost la m6me chose.
l
During the year 1899, a university professor ofmedicine . .. received by mail 424 circulars relative to medicines and their uses. Of these there were only 54 which he was able to class as "respectable" . . . the remaining he divides into "ordinary" and "disgusting". Dykstra, DL The Medical Profession and Patent and Proprietary Medicines during the Nineteenth Century. Bull Hist Med 29:401-419, 1955.
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