Life span and disability: a cross sectional comparison of Russian and Swedish community based data
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《英国医生杂志》
1 International Centre for Health and Society, University College London, London WC1E 6BT, 2 Department of Health and Society, Faculty of Health Sciences, University of Link?ping, Sweden S-58183
Correspondence to: M Bobak m.bobak@ucl.ac.uk
Abstract
Life expectancy in Russia is considerably lower than in western Europe.1 2 Some of the excess mortality is due to injuries, violence, and alcohol misuse,1 2 but the high mortality in Russia persists into older age groups, where these causes of death are much less common. So far, data on rates of non-fatal outcomes in Russia have been available for cardiovascular diseases3 4 but not for health conditions specific to elderly people, such as impaired functioning or disability. Such information is important to assess the rates of ill health in elderly people, which pose a heavy burden for health and social services.
Studying the health status of the Russian population may also be relevant to the more general question of whether increased life expectancy is associated with high rates of disability in elderly people. The morbidity compression hypothesis predicts that with increasing life span the cumulative length of time spent with disability becomes smaller.5-7 By contrast, data from the Indian state of Kerala seem to suggest the opposite.8 One way to contribute to this debate is to compare identical measures of health and functional status in populations with different life expectancies. Although the morbidity compression hypothesis has not been applied to differences between countries, one would expect that countries with high life expectancy, such as Sweden, would have lower rates of disability among elderly people than countries with low life expectancy, such as Russia.
We compared data on self rated health and physical functioning in community based population samples in Russia and southern Sweden to examine whether the high mortality in Russia is reflected in poor health among elderly people, and, if so, what are the implications for survival without disability.
Methods
The official life tables showed that mortality in those aged < 45 years was much higher in Russia than in Sweden. In Russia, 80% of males and 93% of females survived from birth to age 45 years compared with 97% and 98% in Sweden, respectively (data not shown). However, differences in mortality at older ages were also large, as documented by survival curves from the age group 45-49 years (fig 1). If these life table estimates were applied to a cohort, only 36% of Russian men 45-49 years old would survive the next 25 years compared to 75% of Swedes; similarly, 34% of Russian men aged 70-74 years would survive another 10 years compared with 57% of similarly aged men in Sweden. The differences in survival between Russian and Swedish women were smaller but also clearly marked.
Fig 1 Proportion of people alive in each five year age group, relative to age group 45-49 years, in Russian and Swedish men and women (based on national life tables)
Figure 2 and the table show prevalence of poor self rated health in the two surveys: in a national Russian population sample and in a community sample in southern Sweden. Until the age of about 55-59 years in men and 50-54 years in women, the prevalence of poor health is similar in the two populations. After those ages, the rates of poor health remain about stable in Sweden but increase rapidly with age in Russia. Physical functioning shows a similar picture (fig 3 and table). The mean scores were similar until the age group 45-49 years in men and 35-39 years in women but thereafter the decline with age was much faster in Russia than in Sweden. In both sexes, the slopes of age related decline in health and functioning were significantly steeper in Russia than in Sweden (all P values < 0.001).
Fig 2 Prevalence of poor self rated health by age group and sex in Russia and Sweden
Age specific differences in self rated health and physical functioning between Russia and Sweden, with 95% confidence intervals
Fig 3 Mean score of physical functioning by age group in Russian and Swedish men and women
In the age group 45-49 years, 99% of Russian men and 97% of Swedish men and 89% of Russian women and 94% of Swedish women were free of disability. By combining the life tables with the survey data, we estimated the proportion of people both alive and without disability between the ages of 45-49 and 70-74 years in each country, relative to the 45-49 year age group (fig 4). The differences between Russia and Sweden were remarkable. Assuming again that these were data for a cohort, 65% of healthy 45-49 year old Swedish men would be alive and without disability 25 years later compared with only 17% of Russian men. The difference was similar among women: 65% in Sweden compared with 22% in Russia. The differences between the two countries were due to high rates of both death and disability in Russia, with death rate contributing more to differences in men and disability rate more to differences in women (fig 5).
Fig 4 Survival without disability between ages 45-49 and 70-74 years in Russian and Swedish men and women
Fig 5 Total survival and survival without disability to age 70-74 years among men and women without disability at age 45-49 years (proportions)
Discussion
In these cross sectional data, we found a much steeper age related decline in health and functioning in Russia than in Sweden, resulting in much worse health and functional status in elderly Russians compared with elderly Swedes. The combination of high mortality and high disability results in a huge difference in the estimated survival without disability in people from their late 40s to mid-70s between the two countries.
Though self rated health is a purely subjective measure, physical functioning score is based on 10 relatively specific questions and is less prone to reporting bias. The SF-36, the source of the questions on physical functioning, has been validated against clinical end points in many populations, including Russian. We also considered the possibility that the different methodology (interviews in Russia and postal survey in Sweden) could have led to differential reporting of disability. One would expect that such bias would affect all age groups. However, the levels of both self rated health and physical functioning were similar in the two populations in younger people and only started to diverge after the age of 40 or 50 years. At least for self rated health, the rates of poor health in this study are, if anything, higher than in a Swedish national interview study of people aged 55-74 years.13 In another survey comparing 50 year old men in Sweden and Lithuania, which used slightly different terminology, the differences in self rated health were even larger, with 7% of Swedes and 45% of Lithuanians reporting health as "not very good" or "not good at all."14 This argues against under-reporting of ill health in Sweden in our study. Moreover, as expected, the differences between the two countries varied by sex, being mainly due to mortality in men but disability in women. All this strongly suggests that the differences in health and physical functioning between the Russians and Swedes are genuine, rather than a methodological artefact.(Martin Bobak, senior lect)
Correspondence to: M Bobak m.bobak@ucl.ac.uk
Abstract
Life expectancy in Russia is considerably lower than in western Europe.1 2 Some of the excess mortality is due to injuries, violence, and alcohol misuse,1 2 but the high mortality in Russia persists into older age groups, where these causes of death are much less common. So far, data on rates of non-fatal outcomes in Russia have been available for cardiovascular diseases3 4 but not for health conditions specific to elderly people, such as impaired functioning or disability. Such information is important to assess the rates of ill health in elderly people, which pose a heavy burden for health and social services.
Studying the health status of the Russian population may also be relevant to the more general question of whether increased life expectancy is associated with high rates of disability in elderly people. The morbidity compression hypothesis predicts that with increasing life span the cumulative length of time spent with disability becomes smaller.5-7 By contrast, data from the Indian state of Kerala seem to suggest the opposite.8 One way to contribute to this debate is to compare identical measures of health and functional status in populations with different life expectancies. Although the morbidity compression hypothesis has not been applied to differences between countries, one would expect that countries with high life expectancy, such as Sweden, would have lower rates of disability among elderly people than countries with low life expectancy, such as Russia.
We compared data on self rated health and physical functioning in community based population samples in Russia and southern Sweden to examine whether the high mortality in Russia is reflected in poor health among elderly people, and, if so, what are the implications for survival without disability.
Methods
The official life tables showed that mortality in those aged < 45 years was much higher in Russia than in Sweden. In Russia, 80% of males and 93% of females survived from birth to age 45 years compared with 97% and 98% in Sweden, respectively (data not shown). However, differences in mortality at older ages were also large, as documented by survival curves from the age group 45-49 years (fig 1). If these life table estimates were applied to a cohort, only 36% of Russian men 45-49 years old would survive the next 25 years compared to 75% of Swedes; similarly, 34% of Russian men aged 70-74 years would survive another 10 years compared with 57% of similarly aged men in Sweden. The differences in survival between Russian and Swedish women were smaller but also clearly marked.
Fig 1 Proportion of people alive in each five year age group, relative to age group 45-49 years, in Russian and Swedish men and women (based on national life tables)
Figure 2 and the table show prevalence of poor self rated health in the two surveys: in a national Russian population sample and in a community sample in southern Sweden. Until the age of about 55-59 years in men and 50-54 years in women, the prevalence of poor health is similar in the two populations. After those ages, the rates of poor health remain about stable in Sweden but increase rapidly with age in Russia. Physical functioning shows a similar picture (fig 3 and table). The mean scores were similar until the age group 45-49 years in men and 35-39 years in women but thereafter the decline with age was much faster in Russia than in Sweden. In both sexes, the slopes of age related decline in health and functioning were significantly steeper in Russia than in Sweden (all P values < 0.001).
Fig 2 Prevalence of poor self rated health by age group and sex in Russia and Sweden
Age specific differences in self rated health and physical functioning between Russia and Sweden, with 95% confidence intervals
Fig 3 Mean score of physical functioning by age group in Russian and Swedish men and women
In the age group 45-49 years, 99% of Russian men and 97% of Swedish men and 89% of Russian women and 94% of Swedish women were free of disability. By combining the life tables with the survey data, we estimated the proportion of people both alive and without disability between the ages of 45-49 and 70-74 years in each country, relative to the 45-49 year age group (fig 4). The differences between Russia and Sweden were remarkable. Assuming again that these were data for a cohort, 65% of healthy 45-49 year old Swedish men would be alive and without disability 25 years later compared with only 17% of Russian men. The difference was similar among women: 65% in Sweden compared with 22% in Russia. The differences between the two countries were due to high rates of both death and disability in Russia, with death rate contributing more to differences in men and disability rate more to differences in women (fig 5).
Fig 4 Survival without disability between ages 45-49 and 70-74 years in Russian and Swedish men and women
Fig 5 Total survival and survival without disability to age 70-74 years among men and women without disability at age 45-49 years (proportions)
Discussion
In these cross sectional data, we found a much steeper age related decline in health and functioning in Russia than in Sweden, resulting in much worse health and functional status in elderly Russians compared with elderly Swedes. The combination of high mortality and high disability results in a huge difference in the estimated survival without disability in people from their late 40s to mid-70s between the two countries.
Though self rated health is a purely subjective measure, physical functioning score is based on 10 relatively specific questions and is less prone to reporting bias. The SF-36, the source of the questions on physical functioning, has been validated against clinical end points in many populations, including Russian. We also considered the possibility that the different methodology (interviews in Russia and postal survey in Sweden) could have led to differential reporting of disability. One would expect that such bias would affect all age groups. However, the levels of both self rated health and physical functioning were similar in the two populations in younger people and only started to diverge after the age of 40 or 50 years. At least for self rated health, the rates of poor health in this study are, if anything, higher than in a Swedish national interview study of people aged 55-74 years.13 In another survey comparing 50 year old men in Sweden and Lithuania, which used slightly different terminology, the differences in self rated health were even larger, with 7% of Swedes and 45% of Lithuanians reporting health as "not very good" or "not good at all."14 This argues against under-reporting of ill health in Sweden in our study. Moreover, as expected, the differences between the two countries varied by sex, being mainly due to mortality in men but disability in women. All this strongly suggests that the differences in health and physical functioning between the Russians and Swedes are genuine, rather than a methodological artefact.(Martin Bobak, senior lect)