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Does adjustment for stress levels explain the protective effect of moderate drinking on the risk of mortality?

An inverse or reduced risk association between moderate alcohol consumption and total mortality has been reported in most prospective epidemiologic studies, even after adjustments for all known potential confounders such as educational level, job and health. The present analysis was carried out specifically to focus on the effects of psycho-social stressors on the association, using a large population-based German cohort from the WHO MONICA study. No alcohol intake was reported by 15.3% of males and 41.8% of females; “moderate drinking” was defined as an average intake of 0.1-39.9 g/day for men (making up 51.1% of the cohort) and 0.1 – 19.9 g/day for women (38.8% of the cohort). Although data are not presented, there were apparently few women in the higher drinking categories.

The authors related the effects of including, or not including, in their equations a large number of psychosocial stressors, including educational level, occupational status, several indices of social support, job strain symptoms, depressive symptoms, somatic symptoms, and self-perceived health status, in the estimation of the effects of alcohol consumption on risk of total mortality over an average follow-up period of 12 years. In their analyses, there was little effect on risk estimates for mortality when these factors were added to the multi-variable analysis. The authors conclude: “The observed protective effect of moderate drinking could not be attributed to misclassification or confounding by psychosocial stressors.”

The authors have demonstrated among men a “U-shaped” curve, with the risk for moderate drinkers being 25-30% lower than that of both non-drinkers and heavier drinkers. For women, there was a lower estimated mortality risk ratio for all drinkers when compared with non-drinkers, although the confidence intervals included 1.0 in all categories (perhaps, as the authors’ state, there were few women in their higher categories of alcohol intake).

Forum reviewers thought that this was a well-done analysis of a large population-based population. It did not support the hypothesis that social support, job strain, depressive symptoms, and other such psychosocial factors have a strong influence on the demonstrated inverse (i.e. protective) relation between moderate alcohol consumption and total mortality. Thus, this study provides additional evidence that the observed reduction in total mortality seen among moderate drinkers is not due to confounding by other lifestyle factors, including psychosocial stressors.

Reference: Ruf E, Baumert J, Meisinger C, Döring A, Ladwig K-H, and for the MONICA/KORA Investigators. Are psychosocial stressors associated with the relationship of alcohol consumption and all-cause mortality? BMC Public Health 2014, 14:312.

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