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Secular changes in disability among middle-aged and elderly finns with and without coronary heart disease from 1978–1980 to 2000–2001
Secular Changes in Disability among Middle-aged and Elderly Finns with and without Coronary Heart Disease from 1978–1980 to 2000–2001 ANNA KATTAINEN, MD, ANTTI REUNANEN, MD, PHD, SEPPO KOSKINEN, MD, PHD, ¨ IVI SAINIO, MSC, TOMMI HA ¨ RKA ¨ NEN, PHD, TUIJA MARTELIN, PHD, PAUL KNEKT, PHD, PA AND ARPO AROMAA, MD, PHD
PURPOSE: To examine time trends in the prevalence of coronary heart disease (CHD) and disability. METHODS: Data were used from two large nationally representative cross-sectional health examination surveys conducted in Finland (1978–1980 and 2000–2001). RESULTS: The prevalence of CHD decreased in men and women aged 45 to 64 years and increased among those aged 75 years or more. In men with and without CHD, and in women without CHD, the prevalence of disability decreased until the age of 75 years, but in women with CHD no statistically significant decrease was observed. CONCLUSIONS: Favorable changes in prevalence of CHD and disability have occurred in people aged 45 to 75 years, but not in older people particularly in women. The proportion of decrease in disability attributable to CHD was estimated to be up to 25%. The causes of unequal development by age and gender should be ascertained. Ann Epidemiol 2004;14:479–485. 쑕 2004 Elsevier Inc. All rights reserved. KEY WORDS:
Activities of Daily Living, Coronary Disease, Prevalence, Public Health, Health Surveys.
INTRODUCTION The population in Finland is aging, and the number of individuals aged 65 years or more will increase by almost 60% during the next 20 years (1). As a result, disability and the need for help are likely to increase significantly because the prevalence of disabilities increases rapidly with age (2, 3). Health problems are the main cause of disability (4). Cardiovascular diseases, including coronary heart disease (CHD), are important causes of illness, disability, and death (5–7). Although mortality from CHD has decreased approximately 70% during the last 25 years in middle-aged Finns (8–11), over a quarter of all deaths in Finland in 2000 were caused by CHD (10). The burden CHD places on society depends on the prevalence of CHD in each age group, the degree of disability due to CHD, and the age structure
From the National Public Health Institute, Department of Health and Functional Capacity, Helsinki, Finland (A.K., A.R., S.K., T.M., P.K., P.S., T.H., A.A.); and ORTON Orthopaedic Hospital, Rehabilitation Unit, Invalid Foundation, Helsinki, Finland (P.S.). Address correspondence to: Dr. Anna Kattainen, National Public Health Institute, Department of Health and Functional Capacity, Mannerheimintie 166, FIN-00300 Helsinki, Finland. Tel.: ⫹9-4744-8716; Fax: ⫹9-47448760. E-mail: [email protected] Received January 29, 2003; accepted September 30, 2003. 쑕 2004 Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010
of the population. The incidence and prevalence of CHD increase markedly with age; the rapid aging of the population is therefore likely to lead to a substantial increase in the number of older patients with CHD (1, 12). Information on recent trends in the functional ability of elderly persons with and without CHD is needed to anticipate the future development of the burden imposed by CHD on society. Previous studies suggest that both the prevalence of CHD (13) and of disability (14) in persons aged 65 to 74 years have decreased in Finland. The recent Health 2000 Survey also suggests that the prevalence of CHD and of disability have decreased in the Finnish population as a whole over the past 20 years (15). At the same time, survival from acute CHD has improved (16) and this might have increased the proportion of persons with poor functional capacity among CHD patients. However, we are not aware of any reports analyzing time trends in the prevalence of disability in persons with and without CHD. Due to better treatment, more CHD patients are living longer (16–18), and it is not known how the functional ability of CHD patients has changed in response to CHD morbidity being postponed to an older age. The aim of the present study is to examine changes in disability in persons suffering from CHD and changes in the prevalence of CHD and, as a result, secular changes in the disability burden caused by CHD at the population level. 1047-2797/04/$–see front matter doi:10.1016/j.annepidem.2003.09.022
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Selected Abbreviations and Acronyms CHD ⫽ coronary heart disease OECD ⫽ Organization for Economic Cooperation and Development OR ⫽ odds ratio AF ⫽ attributable fraction
also considered disabled (19, 22). This series of questions was modified from the classification of functional capacity initially introduced by Katz et al. and Lawton et al. (23– 25) by including the OECD disability questionnaire (26). Statistical Methods
METHODS This study uses data from two large Finnish cross-sectional health examination surveys having comparable methodology, performed 20 years apart. The Mini-Finland Health Survey was conducted from 1978 to 1980 (19, 20). The study population was a stratified two-stage cluster sample of 8000 individuals aged 30 years or over, representative of the Finnish population (21). In the first phase of the survey, nurses interviewed subjects in their homes or in the institutions in which they were living. The subjects were then invited to attend the second phase, a health examination. The Health 2000 Survey was conducted from 2000 to 2001 by interviewing and examining a sample of 8028 persons aged 30 years or over representing the population in Finland (15). One of the survey’s aims was to determine changes in population health and related factors since 1978– 1980. A two-stage sampling design was used, and for the population aged 80 years and over the sampling probability was twice as high as among those aged under 80. The implementation of the survey, described in detail elsewhere (15), involved a home interview followed by a comprehensive health examination. This study concerns persons aged 45 years or over. In the 1978–1980 Mini-Finland Health Survey, the sample covered 5101 individuals (2190 men, 2911 women) aged 45 years or over, of whom 88% participated in the health examination. The Health 2000 Survey sample comprised 5359 individuals (2321 men, 3038 women) in the same age range. The participation rate in the health examination was 78%. The prevalence of CHD was based on replies to the following question: Had the individual ever been diagnosed with one of the following diseases: 1) myocardial infarction, or 2) angina pectoris? The home health interview and the health questionnaire elicited information on whether the person could perform certain activities of daily living without difficulty, with some difficulty, with considerable difficulty, or not at all. For the purposes of this report, disability was defined as either being unable to perform without help or having marked difficulty performing at least one of the following tasks: 1) moving about in the house, 2) getting in and out of bed, 3) dressing and undressing, 4) carrying a 5-kg shopping bag, 5) walking 500 m without rest, 6) climbing a flight of stairs without rest, and 7) managing grocery shopping. Persons who were almost or totally blind were
We analyzed data for men and women separately. Prevalences adjusted for age were estimated using the logistic model and the maximum likelihood method (27). Stratified analyses were performed by age group, and continuous age was included in the models. To obtain age-adjusted prevalences of disability in persons with and without CHD in the 1978–1980 and 2000–2001 surveys, age (years) and the interaction term between CHD status and survey were included in the model. Statistical significance of differences between prevalences was tested with the likelihood ratio test based on the model. Attributable fractions were estimated using the method of Greenland and Drescher for cohort studies (28), and a STATA macro called aflogit by Tony Brady (PHLS Statistics Unit, London). Analyses were done with SAS, Release 6.12 (SAS Institute Inc., Cary, NC, USA) and STATA, Release 7.0 (Stata Corp., College Station, TX, USA). To assess the proportion of change in the prevalence of disability explained by changes in the prevalence of CHD and in the CHD-related disability, we used the following formula: (PDCHD2000 ⫺ PDCHD1980) / (PD2000 ⫺ PD1980) * 100 where PDCHD1980 ⫽ AF1980 * PD1980 is the prevalence of disability due to CHD in the population in 1978–1980, PDCHD2000 ⫽ AF2000 * PD2000 is the prevalence of disability due to CHD in the population in 2000–2001, AF1980 is the attributable fraction for CHD in 1978–1980, AF2000 is the attributable fraction for CHD in 2000–2001, PD1980 is the age-adjusted prevalence of disability in the population in 1978–1980, and PD2000 is the age-adjusted prevalence of disability in the population in 2000–2001.
RESULTS The prevalence of CHD was lower in men and women aged 45 to 64 years in the 2000–2001 survey than in the 1978– 1980 survey, but in the 65 to 74 year age group no significant difference was observed, and in those aged 75 years or more the prevalence of CHD was higher in the 2000–2001 survey than in the 1978–1980 survey (Table 1). In both sexes the overall prevalence of disability had significantly declined from the 1978–1980 survey to the 2000–2001 survey, until the age of 75 years. In the oldest age group the decrease was not statistically significant (Table 1).
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TABLE 1. Age-adjusted prevalences of coronary heart disease and disability in the Mini-Finland Health Survey 1978–1980 and Health 2000 Survey 2000–2001 in men and womena Prevalence of CHDb, %
No. of subjects Age Men 45–64 65–74 75–99 45–99 (total) Women 45–64 65–74 75–99 45–99 (total)
Prevalence of disabilityc, %
1978–1980
2000–2001
1978–1980
2000–2001
p-value
1978–1980
2000–2001
p-value
1383 433 159 1975
1296 343 211 1850
13.9 30.0 26.2 18.9
7.0 26.8 36.7 13.7
⬍ 0.001 0.32 0.03 ⬍ 0.001
12.3 25.3 47.4 18.3
5.2 14.2 43.2 11.0
⬍ 0.001 ⬍ 0.001 0.41 ⬍ 0.001
1572 642 307 2521
1427 459 448 2334
8.9 20.1 18.4 13.9
2.8 17.6 28.4 9.8
⬍ 0.001 0.30 0.002 ⬍ 0.001
12.6 29.8 61.5 23.8
7.8 21.6 57.2 19.2
⬍ 0.001 0.002 0.23 ⬍ 0.001
a
Age adjusted by logistic model. Models include age (years) and survey. Men and women were analyzed separately. CHD, coronary heart disease. Disability was defined as either being unable to perform without help or having marked difficulty in performing at least one of the following tasks: 1) moving about in the house, 2) getting in and out of bed, 3) dressing and undressing, 4) carrying a 5-kg shopping bag, 5) walking 500 m without rest, 6) climbing a flight of stairs without rest, and 7) managing grocery shopping. Persons who were almost or totally blind were also considered disabled. b c
Table 2 shows the prevalence of different indicators of disability by CHD status in the two surveys. Walking 500 m without rest, carrying a 5-kg shopping bag, and climbing a flight of stairs appeared to be the most demanding tasks
among men and women with or without CHD. CHD significantly increased the risk of being disabled in both surveys and in all ages in women (Table 3). The age-adjusted odds ratios for being disabled tended to be even higher
TABLE 2. Functional capacity of participants in the Mini-Finland Health Survey 1978–1980 and Health 2000 Survey 2000–2001, by gender and coronary heart disease status Subjects with CHDa
Men Number of subjects Mean age (SD) At least marked difficulties in performing the following (%)b Moving about in the house Getting in and out of bed Dressing and undressing Carrying a shopping bag of 5 kg Walking 500 m without rest Climbing a flight of stairs without rest Managing grocery shopping Almost or totally blindb Overall disability rate (%)b,c Women Number of subjects Mean age (SD) At least marked difficulties in performing following (%)b Moving about in the house Getting in and out of bed Dressing and undressing Carrying a shopping bag of 5 kg Walking 500 m without rest Climbing a flight of stairs without rest Managing grocery shopping Almost or totally blindb Overall disability rate (%)b,c a
Subjects without CHDa
1978–1980
2000–2001
1978–1980
2000–2001
366 63.1 (9.4)
259 68.7 (10.0)
1609 58.1 (9.9)
1591 58.0 (10.3)
1.35 1.36 4.43 13.05 20.44 7.69 6.25 0.23 28.24 330 65.8 (9.1) 2.74 2.15 2.17 25.43 18.73 10.03 8.91 0.53 34.85
0.20 0.60 1.19 9.27 10.49 7.41 4.40 – 16.77 246 74.1 (8.8) 1.05 0.95 1.24 25.06 15.68 14.49 8.56 0.50 32.52
2.13 2.05 3.06 8.06 9.82 5.19 5.27 0.21 15.41 2191 60.3 (10.3)
0.68 1.02 1.43 5.03 6.21 4.23 3.15 0.27 9.43 2088 60.7 (11.9)
2.91 2.52 3.02 14.98 12.31 7.27 8.98 0.23 21.59
CHD, coronary heart disease. Adjusted for age by logistic model. Models include age (years) and interaction term between CHD status and survey. Men and women were analyzed separately. Unable to perform or have marked difficulties in performing one of the above mentioned tasks or almost or totally blind.
b c
1.68 1.11 1.47 13.75 8.37 7.39 5.43 0.33 16.90
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TABLE 3. Age-adjusted odds ratios for disability in persons with coronary heart disease (CHD) compared with persons without CHD, and percentage of disability attributable to CHD in the Mini-Finland Health Survey 1978–1980 and Health 2000 Survey 2000–2001, by age group and sex Mini-Finland Survey 1978–1980 Age Men 45–64 65–74 75–99 Women 45–64 65–74 75–99
Health 2000 Survey 2000–2001
ORa,b
95% CI
AFc (%)
ORa,d
95% CI
AFc (%)
3.08 2.35 1.43
2.11, 4.48 1.49, 3.71 0.69, 2.96
19 20 5
3.47 1.87 1.39
1.87, 6.47 0.99, 3.53 0.77, 2.50
16 16 6
2.44 2.23 2.98
1.62, 3.67 1.49, 3.34 1.55, 5.75
10 12 8
3.18 3.03 3.12
1.51, 6.68 1.81, 5.09 1.91, 5.10
6 18 10
a OR, odds ratios. Adjusted for age by logistic model. Model includes age (years) and interaction term between CHD status and survey. Men and women were analyzed separately. b Reference group: persons without CHD, examined in 1978–1980. c AF, attributable fraction for CHD. d Reference group: persons without CHD, examined in 2000–2001.
in the 2000–2001 survey than in the 1978–1980 survey in women. In men, CHD significantly increased the risk of disability in the 45 to 64 year age group in both surveys, and also in the 65 to 74 year age group in the 1978–1980 survey, but not in the oldest age group. To measure the public health impact of CHD on the total disability burden, attributable fractions were estimated in the 1978–1980 survey and in the 2000–2001 survey (Table 3). The percentages of disability attributable to CHD were lower in the 2000–2001 survey than in the 1978–1980 survey until the age of 74 years in men and until the age of 64 years in women, after which the results suggested an increase over time, especially in women. In men, regardless of CHD status, the prevalence of disability had decreased significantly in the 45 to 64 and 65 to 74 year age groups (Table 4). The decrease was smaller and not statistically significant in the age group 75 years or over. In women with CHD, there was no statistically significant decrease in the prevalence of disability in any age group. However, in women without CHD, the prevalence of disability was significantly lower in the 2000–2001 survey than in the 1978–1980 survey in the 45 to 64 and 65 to 74 year age groups. Approximately a fifth of the total decrease in disability in Finnish men aged 45 to 64 years during past 20 years was due to the decrease in the prevalence of CHD together with the decrease in disability among subjects with CHD (Figure 1). In men aged 65 to 74 years, a fourth of the decrease in disability was due to these two factors. Among women aged 45 to 64 years, the contribution of CHD was 17%. Among men aged 75 years or more and among women
aged 65 years or more, CHD-related disability seemed to increase, although total disability at the population level was likely to decrease.
DISCUSSION The prevalence of CHD has decreased in men and women aged 45 to 64 years and increased in those over 75 years. Among persons aged 65 to 74 years no significant change has occurred. The prevalence of disability has decreased significantly in Finns of 45 to 74 years of age over the last 20 years. The decrease is evident in men with and without CHD and in women without CHD, but no significant decline has occurred in women with CHD. The decrease in the prevalence of CHD associated with improved functional ability of persons suffering from CHD may explain a fifth of the overall decrease in disability during the past 20 years in Finnish men aged 45 to 64 years, and a fourth in men aged 65 to 74 years. In women, the contribution of CHD to the overall decline in disability has been smaller than in men. The validity of our results is based first on the representativeness and comparability of the study samples and second on the comparability of the information on CHD and disability. The samples represented the entire Finnish population. Participation rates in both surveys were high. However, participation rates were higher in the 1978–1980 survey than in the 2000–2001 survey, reflecting a general trend of decreasing participation rates as also observed in many other surveys. Since non-participation is selective with regard to disability, resulting in an underestimation of the most severe disability, the differential in participation might account for overestimating the decline in the prevalence of both disability and severe CHD. However, the overall decline in the prevalence of disability from 1978–1980 to 2000–2001 is equally pronounced when we analyze data based on home health interviews, in which case the information is available on 90% of the sample in 2000–2001 (15). We believe that the overall trends are correct, although in both surveys the proportion of persons most disabled and with severe CHD may have been underestimated. The validity of our findings also rests on the validity and comparability of the measurements of disability and CHD morbidity. The information on CHD was based on health interviews available from all participants. The agreement between health interview and physician examination has been shown to be extremely good in assessing cardiovascular diseases (29). Similarly worded questions relating to known diseases were used in both surveys. However, the awareness of subjects regarding diseases diagnosed by their physicians could have changed. At the time of the latter survey individuals had used more healthcare and were possibly better
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TABLE 4. Age-adjusted prevalence of disability in the Mini-Finland Health Survey 1978–1980 and Health 2000 Survey 2000–2001, by gender and coronary heart disease statusa No. of subjects
Men Subjects with coronary heart disease Age 45–64 65–74 75–99 45–99 Subjects without coronary heart disease Age 45–64 65–74 75–99 45–99 Women Subjects with coronary heart disease Age 45–64 65–74 75–99 45–99 Subjects without coronary heart disease Age 45–64 65-74 75–99 45–99
Prevalence of disability
1978–1980
2000–2001
1978–1980
2000–2001
ORb
194 130 42 366
90 92 77 259
24.8 37.2 53.6 28.2
13.5 20.3 47.5 16.8
0.46 0.43 0.77 0.47
0.24, 0.23, 0.35, 0.32,
0.87 0.80 1.68 0.67
1189 303 117 1609
1206 251 134 1591
10.0 20.1 45.4 15.4
4.4 12.0 40.1 9.4
0.41 0.54 0.79 0.54
0.29, 0.34, 0.47, 0.43,
0.58 0.87 1.34 0.68
144 128 58 330
39 82 125 246
23.4 43.9 78.7 34.9
19.7 39.3 73.9 32.5
0.80 0.82 0.75 0.88
0.36, 0.47, 0.36, 0.61,
1.77 1.45 1.59 1.26
1428 514 249 2191
1388 377 323 2088
11.3 26.2 57.5 21.6
7.3 17.8 50.3 16.9
0.61 0.61 0.72 0.69
0.47, 0.44, 0.50, 0.58,
0.80 0.85 1.04 0.83
95% confidence interval
a
Adjusted for age by logistic model. Model includes age (years) and interaction term between coronary heart disease status and survey. Men and women were analyzed separately. OR, odds ratio for 2000–2001 compared with 1978–1980.
b
informed of their conditions than individuals 20 years previously, which could have resulted in the increased prevalence of CHD in the latter survey. It is also possible that less severe CHD was better diagnosed at the time of the latter
survey than 20 years before, and this could have increased the observed prevalence of CHD and at the same time decreased the prevalence of disability among persons with known CHD. However, in the calculations of attributable
FIGURE 1. Prevalence of overall disability and the proportion caused by coronary heart disease (CHD) in the two surveys (1978-1980, 2000-2001), by sex and age. aThe numbers are negative, because CHD-related disability has increased, not decreased during past 20 years.
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fractions these possible effects diverge. Their influence is thus likely to be minimal on the results concerning the contribution of changes in the prevalence of CHD and in the prevalence of disability among persons with CHD to the overall decline in disability. In both surveys, disability was measured using similarly structured questions. Most of the functional limitations were related to basic and instrumental activities of daily living, probably little influenced by environmental changes. The series of questions also included functional limitations that are typical among persons with CHD. An important strength of our study was the possibility of conducting stratified analyses by age group. These analyses demonstrated the highly interesting finding that the positive changes in the prevalence of CHD and in CHD-related disability were only observed among persons under the age of 75 years. Cardiovascular disease, and particularly CHD, incidence and mortality has decreased markedly, by up to 70%, in Finns during the past 20 to 30 years (8, 10, 11). The decline in mortality has been greatest in middle-aged persons. This report shows that the prevalence of CHD has also decreased in persons up to 64 years of age but not in older age groups. The prevalence of high blood pressure and high serum cholesterol concentration has declined in all adult age groups (15). In addition, time trends in smoking have been similar across the age groups: increasing in women and decreasing in men (15). Until the early 1990s, more than half of the decline in mortality from ischemic heart disease in Finland can be explained by changes in the main cardiovascular risk factors (30, 31). Also, the decreases in the prevalence of CHD in Finns aged 45 to 64 years can probably be explained largely by changes in risk factors for these diseases. However, in the oldest age group of 75 years or over the prevalence of CHD has not decreased but increased. The decline of risk factors in older people may not have been as effective as in those younger; the older cohorts may thus carry their disease burden until old age. Declining coronary event severity and case-fatality (8, 16, 32), and improvements in coronary disease treatment (17, 18) resulting in longer survival, have probably contributed to the shifting of CHD occurrence towards older age. It is also possible that increasing awareness of CHD due to enhanced healthcare has contributed to the increase in the prevalence of CHD in the oldest age-group. Our findings showing that the functional ability of men suffering from CHD has increased as rapidly as among men without the disease suggest that improvements in the treatment of CHD have not only saved lives, but have also maintained or improved the functional ability of persons with the disease. In women free of CHD the prevalence of disability has decreased until the age of 74 years, but in women with CHD no statistically significant decrease was
observed in any age group. This may indicate that improvements in therapeutic procedures have not been as effective in women as in men; a study from Finland has suggested that thrombolytic therapy was administered less frequently to female than to male patients (17). On the other hand, CHD is more difficult to diagnose in women than in men (33). False positive cases of CHD with less disability could have also been more common in women than in men 20 years ago. The accuracy of CHD diagnostics has probably improved, and as a result, the proportion of possible false positive CHD cases may have decreased. This could partly explain why the functional status of women suffering from CHD has not apparently improved. It is also possible that the increasing prevalence of some other chronic disabling diseases or disorders partly accounts for the missing improvement in functional ability among women with CHD. Our further analyses (data not shown) suggest that among women with CHD, the prevalence of mental disorders and smoking-related diseases such as chronic bronchitis may have increased more than in women without CHD or in men. CHD explained part of the decline in the overall disability among men and women under the age of 75 years. However, disability is of much more importance in elderly people aged 75 years and over. Among these older subjects CHD did not contribute to the slight reduction of disability. Other factors that must be contributing to the decline in disability include: changes in the prevalence of other disorders and diseases, better treatment of diseases, possible slower aging due to easier life, improvements in the physical environment making it easier to manage many tasks of daily living, and changes in the likelihood of reporting difficulties in activities of daily living due to changed role expectations of elderly persons (14, 15). These calculations concerning the contribution of CHD-related changes to the overall decline in disability are only rough estimates. Further studies are needed to estimate the impact of other factors on the secular changes in disability at population level.
CONCLUSIONS Our study demonstrates that the increase in functional ability of men with CHD has been remarkable over the past 20 years, and is of the same magnitude as in men without CHD. However, in women with CHD, the increase in functional ability has not been as large as in women without the disease. Our study also shows that the burden caused by CHD has shifted to older ages. In particular, elderly women with CHD need more attention to improve their health and functional capacity, and to prevent the burden caused by CHD and its consequences from increasing.
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16. Salomaa V, Rosamond W, Mahonen M. Decreasing mortality from acute myocardial infarction: Effect of incidence and prognosis. J Cardiovasc Risk. 1999;6:69–75.
We thank the personnel on the field and support organizations of both surveys, the former in the Social Insurance Institution and the latter in the National Public Health Institute. In addition to financial support for the studies from these organizations, this study has received support from the Academy of Finland and the Doctoral Programs in Public Health of the Department of Public Health (University of Helsinki) and the Tampere School of Public Health (University of Tampere).
17. Miettinen H, Salomaa V, Ketonen M, Niemela M, Immonen-Raiha P, Mahonen M. Trends in the treatment of patients with myocardial infarction and coronary revascularization procedures in Finland during 1986–92: the FINMONICA Myocardial Infarction Register Study. J Intern Med. 1999; 245:11–20.
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26. McWhinnie JR. Disability assessment in population surveys: Results of the OECD Common Development Effort. Rev Epidemiol Sante Publique. 1981;29:413–419. 27. Lehtonen R, Pahkinen EJ. Practical Methods for Design and Analysis of Complex Surveys. Chichester: John Wiley and Sons; 1995. 28. Greenland S, Drescher K. Maximum likelihood estimation of the attributable fraction from logistic models. Biometrics. 1993;49:865–872. 29. Heliovaara M, Aromaa A, Klaukka T, Knekt P, Joukamaa M, Impivaara O. Reliability and validity of interview data on chronic diseases. The MiniFinland Health Survey. J Clin Epidemiol. 1993;46:181–191. 30. Jousilahti P, Vartiainen E, Tuomilehto J, Pekkanen J, Puska P. Effect of risk factors and changes in risk factors on coronary mortality in three cohorts of middle-aged people in eastern Finland. Am J Epidemiol. 1995;141:50–60. 31. Vartiainen E, Puska P, Pekkanen J, Tuomilehto J, Jousilahti P. Changes in risk factors explain changes in mortality from ischaemic heart disease in Finland. BMJ. 1994;309:23–27. 32. Salomaa V, Miettinen H, Palomaki P, Arstila M, Mustaniemi H, Kuulasmaa K, et al. Diagnostic features of acute myocardial infarction changes over time from 1983 to 1990: Results from the FINMONICA AMI Register Study. J Intern Med. 1995;237:151–159. 33. Kwok Y, Kim C, Grady D, Segal M, Redberg R. Meta-analysis of exercise testing to detect coronary artery disease in women. Am J Cardiol. 1999; 83:660–666.
PURPOSE: To examine time trends in the prevalence of coronary heart disease (CHD) and disability. METHODS: Data were used from two large nationally representative cross-sectional health examination surveys conducted in Finland (1978–1980 and 2000–2001). RESULTS: The prevalence of CHD decreased in men and women aged 45 to 64 years and increased among those aged 75 years or more. In men with and without CHD, and in women without CHD, the prevalence of disability decreased until the age of 75 years, but in women with CHD no statistically significant decrease was observed. CONCLUSIONS: Favorable changes in prevalence of CHD and disability have occurred in people aged 45 to 75 years, but not in older people particularly in women. The proportion of decrease in disability attributable to CHD was estimated to be up to 25%. The causes of unequal development by age and gender should be ascertained. Ann Epidemiol 2004;14:479–485. 쑕 2004 Elsevier Inc. All rights reserved. KEY WORDS:
Activities of Daily Living, Coronary Disease, Prevalence, Public Health, Health Surveys.
INTRODUCTION The population in Finland is aging, and the number of individuals aged 65 years or more will increase by almost 60% during the next 20 years (1). As a result, disability and the need for help are likely to increase significantly because the prevalence of disabilities increases rapidly with age (2, 3). Health problems are the main cause of disability (4). Cardiovascular diseases, including coronary heart disease (CHD), are important causes of illness, disability, and death (5–7). Although mortality from CHD has decreased approximately 70% during the last 25 years in middle-aged Finns (8–11), over a quarter of all deaths in Finland in 2000 were caused by CHD (10). The burden CHD places on society depends on the prevalence of CHD in each age group, the degree of disability due to CHD, and the age structure
From the National Public Health Institute, Department of Health and Functional Capacity, Helsinki, Finland (A.K., A.R., S.K., T.M., P.K., P.S., T.H., A.A.); and ORTON Orthopaedic Hospital, Rehabilitation Unit, Invalid Foundation, Helsinki, Finland (P.S.). Address correspondence to: Dr. Anna Kattainen, National Public Health Institute, Department of Health and Functional Capacity, Mannerheimintie 166, FIN-00300 Helsinki, Finland. Tel.: ⫹9-4744-8716; Fax: ⫹9-47448760. E-mail: [email protected] Received January 29, 2003; accepted September 30, 2003. 쑕 2004 Elsevier Inc. All rights reserved. 360 Park Avenue South, New York, NY 10010
of the population. The incidence and prevalence of CHD increase markedly with age; the rapid aging of the population is therefore likely to lead to a substantial increase in the number of older patients with CHD (1, 12). Information on recent trends in the functional ability of elderly persons with and without CHD is needed to anticipate the future development of the burden imposed by CHD on society. Previous studies suggest that both the prevalence of CHD (13) and of disability (14) in persons aged 65 to 74 years have decreased in Finland. The recent Health 2000 Survey also suggests that the prevalence of CHD and of disability have decreased in the Finnish population as a whole over the past 20 years (15). At the same time, survival from acute CHD has improved (16) and this might have increased the proportion of persons with poor functional capacity among CHD patients. However, we are not aware of any reports analyzing time trends in the prevalence of disability in persons with and without CHD. Due to better treatment, more CHD patients are living longer (16–18), and it is not known how the functional ability of CHD patients has changed in response to CHD morbidity being postponed to an older age. The aim of the present study is to examine changes in disability in persons suffering from CHD and changes in the prevalence of CHD and, as a result, secular changes in the disability burden caused by CHD at the population level. 1047-2797/04/$–see front matter doi:10.1016/j.annepidem.2003.09.022
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Selected Abbreviations and Acronyms CHD ⫽ coronary heart disease OECD ⫽ Organization for Economic Cooperation and Development OR ⫽ odds ratio AF ⫽ attributable fraction
also considered disabled (19, 22). This series of questions was modified from the classification of functional capacity initially introduced by Katz et al. and Lawton et al. (23– 25) by including the OECD disability questionnaire (26). Statistical Methods
METHODS This study uses data from two large Finnish cross-sectional health examination surveys having comparable methodology, performed 20 years apart. The Mini-Finland Health Survey was conducted from 1978 to 1980 (19, 20). The study population was a stratified two-stage cluster sample of 8000 individuals aged 30 years or over, representative of the Finnish population (21). In the first phase of the survey, nurses interviewed subjects in their homes or in the institutions in which they were living. The subjects were then invited to attend the second phase, a health examination. The Health 2000 Survey was conducted from 2000 to 2001 by interviewing and examining a sample of 8028 persons aged 30 years or over representing the population in Finland (15). One of the survey’s aims was to determine changes in population health and related factors since 1978– 1980. A two-stage sampling design was used, and for the population aged 80 years and over the sampling probability was twice as high as among those aged under 80. The implementation of the survey, described in detail elsewhere (15), involved a home interview followed by a comprehensive health examination. This study concerns persons aged 45 years or over. In the 1978–1980 Mini-Finland Health Survey, the sample covered 5101 individuals (2190 men, 2911 women) aged 45 years or over, of whom 88% participated in the health examination. The Health 2000 Survey sample comprised 5359 individuals (2321 men, 3038 women) in the same age range. The participation rate in the health examination was 78%. The prevalence of CHD was based on replies to the following question: Had the individual ever been diagnosed with one of the following diseases: 1) myocardial infarction, or 2) angina pectoris? The home health interview and the health questionnaire elicited information on whether the person could perform certain activities of daily living without difficulty, with some difficulty, with considerable difficulty, or not at all. For the purposes of this report, disability was defined as either being unable to perform without help or having marked difficulty performing at least one of the following tasks: 1) moving about in the house, 2) getting in and out of bed, 3) dressing and undressing, 4) carrying a 5-kg shopping bag, 5) walking 500 m without rest, 6) climbing a flight of stairs without rest, and 7) managing grocery shopping. Persons who were almost or totally blind were
We analyzed data for men and women separately. Prevalences adjusted for age were estimated using the logistic model and the maximum likelihood method (27). Stratified analyses were performed by age group, and continuous age was included in the models. To obtain age-adjusted prevalences of disability in persons with and without CHD in the 1978–1980 and 2000–2001 surveys, age (years) and the interaction term between CHD status and survey were included in the model. Statistical significance of differences between prevalences was tested with the likelihood ratio test based on the model. Attributable fractions were estimated using the method of Greenland and Drescher for cohort studies (28), and a STATA macro called aflogit by Tony Brady (PHLS Statistics Unit, London). Analyses were done with SAS, Release 6.12 (SAS Institute Inc., Cary, NC, USA) and STATA, Release 7.0 (Stata Corp., College Station, TX, USA). To assess the proportion of change in the prevalence of disability explained by changes in the prevalence of CHD and in the CHD-related disability, we used the following formula: (PDCHD2000 ⫺ PDCHD1980) / (PD2000 ⫺ PD1980) * 100 where PDCHD1980 ⫽ AF1980 * PD1980 is the prevalence of disability due to CHD in the population in 1978–1980, PDCHD2000 ⫽ AF2000 * PD2000 is the prevalence of disability due to CHD in the population in 2000–2001, AF1980 is the attributable fraction for CHD in 1978–1980, AF2000 is the attributable fraction for CHD in 2000–2001, PD1980 is the age-adjusted prevalence of disability in the population in 1978–1980, and PD2000 is the age-adjusted prevalence of disability in the population in 2000–2001.
RESULTS The prevalence of CHD was lower in men and women aged 45 to 64 years in the 2000–2001 survey than in the 1978– 1980 survey, but in the 65 to 74 year age group no significant difference was observed, and in those aged 75 years or more the prevalence of CHD was higher in the 2000–2001 survey than in the 1978–1980 survey (Table 1). In both sexes the overall prevalence of disability had significantly declined from the 1978–1980 survey to the 2000–2001 survey, until the age of 75 years. In the oldest age group the decrease was not statistically significant (Table 1).
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TABLE 1. Age-adjusted prevalences of coronary heart disease and disability in the Mini-Finland Health Survey 1978–1980 and Health 2000 Survey 2000–2001 in men and womena Prevalence of CHDb, %
No. of subjects Age Men 45–64 65–74 75–99 45–99 (total) Women 45–64 65–74 75–99 45–99 (total)
Prevalence of disabilityc, %
1978–1980
2000–2001
1978–1980
2000–2001
p-value
1978–1980
2000–2001
p-value
1383 433 159 1975
1296 343 211 1850
13.9 30.0 26.2 18.9
7.0 26.8 36.7 13.7
⬍ 0.001 0.32 0.03 ⬍ 0.001
12.3 25.3 47.4 18.3
5.2 14.2 43.2 11.0
⬍ 0.001 ⬍ 0.001 0.41 ⬍ 0.001
1572 642 307 2521
1427 459 448 2334
8.9 20.1 18.4 13.9
2.8 17.6 28.4 9.8
⬍ 0.001 0.30 0.002 ⬍ 0.001
12.6 29.8 61.5 23.8
7.8 21.6 57.2 19.2
⬍ 0.001 0.002 0.23 ⬍ 0.001
a
Age adjusted by logistic model. Models include age (years) and survey. Men and women were analyzed separately. CHD, coronary heart disease. Disability was defined as either being unable to perform without help or having marked difficulty in performing at least one of the following tasks: 1) moving about in the house, 2) getting in and out of bed, 3) dressing and undressing, 4) carrying a 5-kg shopping bag, 5) walking 500 m without rest, 6) climbing a flight of stairs without rest, and 7) managing grocery shopping. Persons who were almost or totally blind were also considered disabled. b c
Table 2 shows the prevalence of different indicators of disability by CHD status in the two surveys. Walking 500 m without rest, carrying a 5-kg shopping bag, and climbing a flight of stairs appeared to be the most demanding tasks
among men and women with or without CHD. CHD significantly increased the risk of being disabled in both surveys and in all ages in women (Table 3). The age-adjusted odds ratios for being disabled tended to be even higher
TABLE 2. Functional capacity of participants in the Mini-Finland Health Survey 1978–1980 and Health 2000 Survey 2000–2001, by gender and coronary heart disease status Subjects with CHDa
Men Number of subjects Mean age (SD) At least marked difficulties in performing the following (%)b Moving about in the house Getting in and out of bed Dressing and undressing Carrying a shopping bag of 5 kg Walking 500 m without rest Climbing a flight of stairs without rest Managing grocery shopping Almost or totally blindb Overall disability rate (%)b,c Women Number of subjects Mean age (SD) At least marked difficulties in performing following (%)b Moving about in the house Getting in and out of bed Dressing and undressing Carrying a shopping bag of 5 kg Walking 500 m without rest Climbing a flight of stairs without rest Managing grocery shopping Almost or totally blindb Overall disability rate (%)b,c a
Subjects without CHDa
1978–1980
2000–2001
1978–1980
2000–2001
366 63.1 (9.4)
259 68.7 (10.0)
1609 58.1 (9.9)
1591 58.0 (10.3)
1.35 1.36 4.43 13.05 20.44 7.69 6.25 0.23 28.24 330 65.8 (9.1) 2.74 2.15 2.17 25.43 18.73 10.03 8.91 0.53 34.85
0.20 0.60 1.19 9.27 10.49 7.41 4.40 – 16.77 246 74.1 (8.8) 1.05 0.95 1.24 25.06 15.68 14.49 8.56 0.50 32.52
2.13 2.05 3.06 8.06 9.82 5.19 5.27 0.21 15.41 2191 60.3 (10.3)
0.68 1.02 1.43 5.03 6.21 4.23 3.15 0.27 9.43 2088 60.7 (11.9)
2.91 2.52 3.02 14.98 12.31 7.27 8.98 0.23 21.59
CHD, coronary heart disease. Adjusted for age by logistic model. Models include age (years) and interaction term between CHD status and survey. Men and women were analyzed separately. Unable to perform or have marked difficulties in performing one of the above mentioned tasks or almost or totally blind.
b c
1.68 1.11 1.47 13.75 8.37 7.39 5.43 0.33 16.90
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TABLE 3. Age-adjusted odds ratios for disability in persons with coronary heart disease (CHD) compared with persons without CHD, and percentage of disability attributable to CHD in the Mini-Finland Health Survey 1978–1980 and Health 2000 Survey 2000–2001, by age group and sex Mini-Finland Survey 1978–1980 Age Men 45–64 65–74 75–99 Women 45–64 65–74 75–99
Health 2000 Survey 2000–2001
ORa,b
95% CI
AFc (%)
ORa,d
95% CI
AFc (%)
3.08 2.35 1.43
2.11, 4.48 1.49, 3.71 0.69, 2.96
19 20 5
3.47 1.87 1.39
1.87, 6.47 0.99, 3.53 0.77, 2.50
16 16 6
2.44 2.23 2.98
1.62, 3.67 1.49, 3.34 1.55, 5.75
10 12 8
3.18 3.03 3.12
1.51, 6.68 1.81, 5.09 1.91, 5.10
6 18 10
a OR, odds ratios. Adjusted for age by logistic model. Model includes age (years) and interaction term between CHD status and survey. Men and women were analyzed separately. b Reference group: persons without CHD, examined in 1978–1980. c AF, attributable fraction for CHD. d Reference group: persons without CHD, examined in 2000–2001.
in the 2000–2001 survey than in the 1978–1980 survey in women. In men, CHD significantly increased the risk of disability in the 45 to 64 year age group in both surveys, and also in the 65 to 74 year age group in the 1978–1980 survey, but not in the oldest age group. To measure the public health impact of CHD on the total disability burden, attributable fractions were estimated in the 1978–1980 survey and in the 2000–2001 survey (Table 3). The percentages of disability attributable to CHD were lower in the 2000–2001 survey than in the 1978–1980 survey until the age of 74 years in men and until the age of 64 years in women, after which the results suggested an increase over time, especially in women. In men, regardless of CHD status, the prevalence of disability had decreased significantly in the 45 to 64 and 65 to 74 year age groups (Table 4). The decrease was smaller and not statistically significant in the age group 75 years or over. In women with CHD, there was no statistically significant decrease in the prevalence of disability in any age group. However, in women without CHD, the prevalence of disability was significantly lower in the 2000–2001 survey than in the 1978–1980 survey in the 45 to 64 and 65 to 74 year age groups. Approximately a fifth of the total decrease in disability in Finnish men aged 45 to 64 years during past 20 years was due to the decrease in the prevalence of CHD together with the decrease in disability among subjects with CHD (Figure 1). In men aged 65 to 74 years, a fourth of the decrease in disability was due to these two factors. Among women aged 45 to 64 years, the contribution of CHD was 17%. Among men aged 75 years or more and among women
aged 65 years or more, CHD-related disability seemed to increase, although total disability at the population level was likely to decrease.
DISCUSSION The prevalence of CHD has decreased in men and women aged 45 to 64 years and increased in those over 75 years. Among persons aged 65 to 74 years no significant change has occurred. The prevalence of disability has decreased significantly in Finns of 45 to 74 years of age over the last 20 years. The decrease is evident in men with and without CHD and in women without CHD, but no significant decline has occurred in women with CHD. The decrease in the prevalence of CHD associated with improved functional ability of persons suffering from CHD may explain a fifth of the overall decrease in disability during the past 20 years in Finnish men aged 45 to 64 years, and a fourth in men aged 65 to 74 years. In women, the contribution of CHD to the overall decline in disability has been smaller than in men. The validity of our results is based first on the representativeness and comparability of the study samples and second on the comparability of the information on CHD and disability. The samples represented the entire Finnish population. Participation rates in both surveys were high. However, participation rates were higher in the 1978–1980 survey than in the 2000–2001 survey, reflecting a general trend of decreasing participation rates as also observed in many other surveys. Since non-participation is selective with regard to disability, resulting in an underestimation of the most severe disability, the differential in participation might account for overestimating the decline in the prevalence of both disability and severe CHD. However, the overall decline in the prevalence of disability from 1978–1980 to 2000–2001 is equally pronounced when we analyze data based on home health interviews, in which case the information is available on 90% of the sample in 2000–2001 (15). We believe that the overall trends are correct, although in both surveys the proportion of persons most disabled and with severe CHD may have been underestimated. The validity of our findings also rests on the validity and comparability of the measurements of disability and CHD morbidity. The information on CHD was based on health interviews available from all participants. The agreement between health interview and physician examination has been shown to be extremely good in assessing cardiovascular diseases (29). Similarly worded questions relating to known diseases were used in both surveys. However, the awareness of subjects regarding diseases diagnosed by their physicians could have changed. At the time of the latter survey individuals had used more healthcare and were possibly better
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TABLE 4. Age-adjusted prevalence of disability in the Mini-Finland Health Survey 1978–1980 and Health 2000 Survey 2000–2001, by gender and coronary heart disease statusa No. of subjects
Men Subjects with coronary heart disease Age 45–64 65–74 75–99 45–99 Subjects without coronary heart disease Age 45–64 65–74 75–99 45–99 Women Subjects with coronary heart disease Age 45–64 65–74 75–99 45–99 Subjects without coronary heart disease Age 45–64 65-74 75–99 45–99
Prevalence of disability
1978–1980
2000–2001
1978–1980
2000–2001
ORb
194 130 42 366
90 92 77 259
24.8 37.2 53.6 28.2
13.5 20.3 47.5 16.8
0.46 0.43 0.77 0.47
0.24, 0.23, 0.35, 0.32,
0.87 0.80 1.68 0.67
1189 303 117 1609
1206 251 134 1591
10.0 20.1 45.4 15.4
4.4 12.0 40.1 9.4
0.41 0.54 0.79 0.54
0.29, 0.34, 0.47, 0.43,
0.58 0.87 1.34 0.68
144 128 58 330
39 82 125 246
23.4 43.9 78.7 34.9
19.7 39.3 73.9 32.5
0.80 0.82 0.75 0.88
0.36, 0.47, 0.36, 0.61,
1.77 1.45 1.59 1.26
1428 514 249 2191
1388 377 323 2088
11.3 26.2 57.5 21.6
7.3 17.8 50.3 16.9
0.61 0.61 0.72 0.69
0.47, 0.44, 0.50, 0.58,
0.80 0.85 1.04 0.83
95% confidence interval
a
Adjusted for age by logistic model. Model includes age (years) and interaction term between coronary heart disease status and survey. Men and women were analyzed separately. OR, odds ratio for 2000–2001 compared with 1978–1980.
b
informed of their conditions than individuals 20 years previously, which could have resulted in the increased prevalence of CHD in the latter survey. It is also possible that less severe CHD was better diagnosed at the time of the latter
survey than 20 years before, and this could have increased the observed prevalence of CHD and at the same time decreased the prevalence of disability among persons with known CHD. However, in the calculations of attributable
FIGURE 1. Prevalence of overall disability and the proportion caused by coronary heart disease (CHD) in the two surveys (1978-1980, 2000-2001), by sex and age. aThe numbers are negative, because CHD-related disability has increased, not decreased during past 20 years.
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fractions these possible effects diverge. Their influence is thus likely to be minimal on the results concerning the contribution of changes in the prevalence of CHD and in the prevalence of disability among persons with CHD to the overall decline in disability. In both surveys, disability was measured using similarly structured questions. Most of the functional limitations were related to basic and instrumental activities of daily living, probably little influenced by environmental changes. The series of questions also included functional limitations that are typical among persons with CHD. An important strength of our study was the possibility of conducting stratified analyses by age group. These analyses demonstrated the highly interesting finding that the positive changes in the prevalence of CHD and in CHD-related disability were only observed among persons under the age of 75 years. Cardiovascular disease, and particularly CHD, incidence and mortality has decreased markedly, by up to 70%, in Finns during the past 20 to 30 years (8, 10, 11). The decline in mortality has been greatest in middle-aged persons. This report shows that the prevalence of CHD has also decreased in persons up to 64 years of age but not in older age groups. The prevalence of high blood pressure and high serum cholesterol concentration has declined in all adult age groups (15). In addition, time trends in smoking have been similar across the age groups: increasing in women and decreasing in men (15). Until the early 1990s, more than half of the decline in mortality from ischemic heart disease in Finland can be explained by changes in the main cardiovascular risk factors (30, 31). Also, the decreases in the prevalence of CHD in Finns aged 45 to 64 years can probably be explained largely by changes in risk factors for these diseases. However, in the oldest age group of 75 years or over the prevalence of CHD has not decreased but increased. The decline of risk factors in older people may not have been as effective as in those younger; the older cohorts may thus carry their disease burden until old age. Declining coronary event severity and case-fatality (8, 16, 32), and improvements in coronary disease treatment (17, 18) resulting in longer survival, have probably contributed to the shifting of CHD occurrence towards older age. It is also possible that increasing awareness of CHD due to enhanced healthcare has contributed to the increase in the prevalence of CHD in the oldest age-group. Our findings showing that the functional ability of men suffering from CHD has increased as rapidly as among men without the disease suggest that improvements in the treatment of CHD have not only saved lives, but have also maintained or improved the functional ability of persons with the disease. In women free of CHD the prevalence of disability has decreased until the age of 74 years, but in women with CHD no statistically significant decrease was
observed in any age group. This may indicate that improvements in therapeutic procedures have not been as effective in women as in men; a study from Finland has suggested that thrombolytic therapy was administered less frequently to female than to male patients (17). On the other hand, CHD is more difficult to diagnose in women than in men (33). False positive cases of CHD with less disability could have also been more common in women than in men 20 years ago. The accuracy of CHD diagnostics has probably improved, and as a result, the proportion of possible false positive CHD cases may have decreased. This could partly explain why the functional status of women suffering from CHD has not apparently improved. It is also possible that the increasing prevalence of some other chronic disabling diseases or disorders partly accounts for the missing improvement in functional ability among women with CHD. Our further analyses (data not shown) suggest that among women with CHD, the prevalence of mental disorders and smoking-related diseases such as chronic bronchitis may have increased more than in women without CHD or in men. CHD explained part of the decline in the overall disability among men and women under the age of 75 years. However, disability is of much more importance in elderly people aged 75 years and over. Among these older subjects CHD did not contribute to the slight reduction of disability. Other factors that must be contributing to the decline in disability include: changes in the prevalence of other disorders and diseases, better treatment of diseases, possible slower aging due to easier life, improvements in the physical environment making it easier to manage many tasks of daily living, and changes in the likelihood of reporting difficulties in activities of daily living due to changed role expectations of elderly persons (14, 15). These calculations concerning the contribution of CHD-related changes to the overall decline in disability are only rough estimates. Further studies are needed to estimate the impact of other factors on the secular changes in disability at population level.
CONCLUSIONS Our study demonstrates that the increase in functional ability of men with CHD has been remarkable over the past 20 years, and is of the same magnitude as in men without CHD. However, in women with CHD, the increase in functional ability has not been as large as in women without the disease. Our study also shows that the burden caused by CHD has shifted to older ages. In particular, elderly women with CHD need more attention to improve their health and functional capacity, and to prevent the burden caused by CHD and its consequences from increasing.
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16. Salomaa V, Rosamond W, Mahonen M. Decreasing mortality from acute myocardial infarction: Effect of incidence and prognosis. J Cardiovasc Risk. 1999;6:69–75.
We thank the personnel on the field and support organizations of both surveys, the former in the Social Insurance Institution and the latter in the National Public Health Institute. In addition to financial support for the studies from these organizations, this study has received support from the Academy of Finland and the Doctoral Programs in Public Health of the Department of Public Health (University of Helsinki) and the Tampere School of Public Health (University of Tampere).
17. Miettinen H, Salomaa V, Ketonen M, Niemela M, Immonen-Raiha P, Mahonen M. Trends in the treatment of patients with myocardial infarction and coronary revascularization procedures in Finland during 1986–92: the FINMONICA Myocardial Infarction Register Study. J Intern Med. 1999; 245:11–20.
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