Social factors and increase in mortality in Russia in the 1990s: prospective cohort study

Introduction

The rapid increase in mortality in Russia in the 1990s was a development previously not reported in any economically developed country. For men life expectancy decreased from about 64 years in 1990 to 59 years in 1993.1 There is still controversy as to who suffered most from concurrent economic breakdown. Several large prospective studies on mortality from ischaemic heart disease in Russia offer a unique opportunity to identify subpopulations that were more affected.

Methods

The study sample comprised two cohorts of men living in the Petrogradsky district of Leningrad (now Saint Petersburg). The first cohort was 5000 randomly selected men from the 1974 voting list who were born from 1916 to 1935. The response rate was 78% (3907 men were screened). The second cohort was selected from the 1985 voting list (men born from 1927 to 1946). In total 1000 men aged 40–49 and 1000 aged 50–59 were randomly selected for screening. The response rate was 71% for 40–49 year olds and 76% for 50–59 year olds (total 1467 men screened). The screening procedure has been described in detail elsewhere2–4 and was the same for the two groups.

The follow up study began in January 1979. If the state registration organ (ZAGS) indicated that participants were no longer registered at the designated addresses we tried to contact them if they had moved away or contacted their relatives or neighbours if they had died. Overall loss to follow up was 3%. In the second cohort we were unable to get data for 15 men who had died.

The first cohort was followed up for a mean of 18.1 years, and there were 1890 deaths. The second cohort was followed up for a mean of 11.2 years, and there were 323 deaths. The first day of follow up was the day the last participant from this cohort was screened: 6 July 1977 for the first cohort and 21 August 1988 for the second cohort (see webextra figure). We have presented data for the first 10 years of follow up.

We used Kaplan-Meier survival curves and calculated relative risks and confidence intervals from person time data. We used the exact Poisson method to calculate confidence intervals.5 Statistical analysis was performed with SAS system, version 6.12 for Windows (SAS Institutes, Cary, NC).

Results

The two groups screened closely resembled each other in terms of age, place of residence, structure, behavioural risk factors, and biological indicators (table 1). The number of people with education less than high school decreased because the second cohort included only those born after the Bolshevik revolution, when high school education became mandatory.

Table 2 and the figure show our main results. Among participants with university education all cause mortality in both cohorts was almost the same: 12.8 per 1000 person years of observation for the first cohort and 11.7 for the second (relative risk 0.92, 95% confidence interval 0.67 to 1.24). Mortality among men with only high school education was the same in both cohorts for the first six years of follow up (figure), but then diverged and at the end of follow up was significantly higher in the second cohort (1.32, 1.02 to 1.71). The largest differences were in men with the least education (less than high school). All cause mortality was higher almost from the beginning of the follow up, steadily rising with time and reaching 48.6 per 1000 person years for the second cohort at the end of follow up. Ten years before it was 43% lower (27.8 per 1000 person years; 1.75, 1.44 to 2.12). The increase in mortality has been noted for cardiovascular disease and cancer, though it was not significant for coronary heart disease. Increases in mortality from cardiovascular disease and cancer were highest among men with the least education (1.99, 1.49 to 2.63; and 1.78, 1.20 to 2.58, respectively). Surprisingly, there was no significant increase in the rate of accidental/violent deaths.

All cause mortality among two cohorts according to level of education (group 1 screened in 1975-7, group 2 screened in 1986-8)

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We divided participants into two groups: those who drank more than 150 g of alcohol during the week before screening and those who drank less. In both groups mortality increased in the 1990s (see webextra table A). This increase was more pronounced than the increase in mortality associated with increased alcohol consumption within each cohort. Among men with the least education, mortality in the 1990s increased 60-80% compared with 8-22% increase associated with increased alcohol consumption (the relative risk for alcohol related mortality was 1.27, 1.02 to 1.57, in the first cohort and 1.08, 0.73 to 1.57, in the second cohort).

Discussion

In 1980 the Black report first presented evidence to show the links between the socioeconomic environment and health and wellbeing.6 In the United Kingdom between 1976–81 and 1986–92 the mortality gap between socioeconomic classes I and II and classes IV and V increased.7 The higher mortality among people with little education has also been well documented in Russian epidemiological studies.3 8

Our data show that the increase in mortality in the mid-1990s disproportionately affected men with low education, with an increase of almost 75% from the level of the mid-1980s. The reason why social changes have struck mostly the least educated could be that for those sectors of society, breakdown of the socialist state could engender a sense of catastrophe.9 The mediator between stress and mortality could be alcohol. Russian men commonly use alcohol because it “helps them to forget everyday cares and difficulties.”10 Also alcohol related problems were more common among the less educated respondents. However, our analysis shows that the increase in mortality in Russia was socially determined, and though alcohol may play a part in this process it is not the sole factor.