Social Integration and Concentrations of C-Reactive Protein Among US Adults

Purpose This study tests whether social integration is associated with C-reactive protein (CRP) level, a biologic risk factor for cardiovascular disease. Methods Using data from 14,818 participants aged ≥ 20 years from the Third National Health and Nutrition Examination Survey (1988 to 1994), we created a social network index using marital status; number of contacts with family, friends, and neighbors; frequency of religious service attendance; and participation in voluntary organizations. Serum CRP concentration was measured by means of latex-enhanced nephelometry, a low-sensitivity assay, and dichotomized into 3 mg/L or less and greater than 3 mg/L. Results After adjustment for multiple potential confounders, men aged ≥ 60 years with the fewest ties were more likely to have an elevated CRP concentration than men with the most ties (odds ratio = 1.80; 95% confidence interval, 1.11–2.92). This occurred in a dose-response manner, with each decrease in number of ties associated with an increase in the proportion of men with elevated CRP levels. The association between social networks and CRP level after multivariate adjustment was not significant in women or younger men. Conclusion In this nationally representative cohort, CRP level was associated with social integration in older men, but not women or younger men. There may be sex- and age-related differences in biologic processes influenced by social integration.