Social isolation is associated with higher mortality in studies of mostly white adults, yet associations among black adults is unclear.
This prospective cohort study evaluated whether associations of social isolation with all-cause, cardiovascular disease and cancer mortality differ by race and sex. Adults enrolled into Cancer Prevention Study-II in 1982/1983 were followed for mortality through 2012 (n = 580,182). Sex- and race-specific multivariable-adjusted hazard ratios and 95% confidence intervals were estimated for associations of a five-point social isolation score with risk of death.
Social isolation was associated with all-cause mortality in all subgroups (P-trend ≤ 0.005); for the most versus the least isolated, the hazard ratios (95% confidence intervals) were 2.34 (1.58, 3.46) and 1.60 (1.41, 1.82) among black and white men, respectively (P-interaction = 0.40), and 2.13 (1.44, 3.15) and 1.84 (1.68, 2.01) among black and white women, respectively (P-interaction = 0.89). The association did not differ between black men and women (P-interaction = 0.33) but was slightly stronger in white women than white men (P-interaction = 0.01). Social isolation was associated with cardiovascular disease mortality in each subgroup (P-trend < 0.03) but with cancer mortality only among whites (P-trend < 0.0001). Subgroup differences in the influence of specific social isolation components were identified.
Identifying and intervening with socially isolated adults could improve health outcomes.