Social network interaction and mortality. A six year follow-up study of a random sample of the Swedish population

This study examined the relationship between social network interaction and total and cardiovascular mortality in 17,433 Swedish men and women between the ages of 29 and 74 during a 6 year follow-up period. The study group was interviewed concerning their social network interactions and a total score was formed which summarized the availability of social contact. A number of sociodemographic and health related background variables known to be associated with mortality risk were also considered. Mortality was examined by linking the interview material with the Swedish National Mortality Registry. In the 6-year follow-up period 841 deaths occurred. The crude relative risk of dying during this period was 3.7 (95% CL 3.2; 4.3) when the lower social network tertile was compared to the upper two tertiles. When controlling for potential confounding effects, only age had a major influence on the association between social network interaction and mortality (RR age-adjusted = 1.46, 95% CL 1.25; 1.72). Controlling for age and sex, age and educational level, age and employment status, age and immigrant status, age and smoking, age and exercise habits and age and chronic disease at interview left the relative risk virtually unchanged. Controlling simultaneously for age, smoking, exercise and chronic illness yielded a risk estimate of 1.36 (95% CL 1.06; 1.69). Similar results were obtained when separately analyzing for cardiovascular disease mortality in an identical manner.