Social ties and mortality in Evans County, Georgia

Abstract

In an attempt to replicate Berkman and Syme's study of social networks and mortality in Alameda County, California, the authors investigated the relationship between a social network index and survivorship from 1967 to 1980 in the Evans County, Georgia, cohort. They constructed an index modeled after the Berkman Social Network Index and tested it in race- and sex-specific proportional hazards models for 2,059 subjects who were examined in 1967-1969 during the Evans County Cardiovascular Epidemiologic Study. The present study emphasized a priori specification of the social network index and statistical hypothesis test. Descriptive analyses were consistent with a modest social networks effect (e.g., hazard ratio (95 per cent confidence interval) of 1.6 (1.2-2.2) ). Among white males, the age-adjusted hazard ratio comparing the lowest to the highest value of our six-level index was 2.0 (1.2-3.4), but control for potential confounders (principally cardiovascular disease risk factors) reduced this value to 1.5 (0.8-2.6). The social networks effect among white females, black males, and black females was weaker and clearly nonsignificant. Exploratory analyses suggested that marital status, church activities, and an alternate social network index predicted survivorship, but not in a dose-response fashion. Reduced survivorship among older subjects with few social ties was the most important feature of the data.