Does social integration confound the relation between alcohol consumption and mortality in the multiple risk factor intervention trial (MRFIT)?

Objective: It has been proposed that social integration would act as a conf ounder in the relationship between alcohol consumption and all-cause mortal ity. This study tested the assumption that the J-shaped relationship betwee n drinking and all-cause mortality may partly reflect a protective effect o f social integration, to the extent that moderate drinkers are more sociall y integrated than either abstainers or heavy drinkers, and to the extent th at social integration offers direct protection from mortality. Method: This hypothesis was tested using data from 10,832 of the 12,866 men in the Mult iple Risk Factor Intervention Trial (MRFIT). Indicators of social integrati on were derived from an exploratory factor analysis of 25 relevant items in the MRFIT data and from a scale of six items selected by the investigators . Results: We failed to confirm a direct protective effect of social integr ation. Nondrinkers had the highest rates of all-cause mortality. Compared w ith heavy drinking, relative risks of all-cause mortality for abstinence, l ight and moderate drinking were unaffected by inclusion of social integrati on variables in the proportional hazards models. Conclusions: The MRFIT dat a fail to confirm a confounding effect of social integration.