Social Isolation Is Associated With Peripheral Endothelial Dysfunction

OBJECTIVE: To evaluate the association between social isolation and peripheral endothelial dysfunction (PED) as a marker of early atherosclerosis. METHODS: In this cross-sectional cohort study, patients referred to Mayo Clinic between January 1, 2018, and December 30, 2021, for assessment of PED by reactive hyperemia-peripheral arterial tonometry were included if they had completed a social determinants of health survey (including questions addressing social isolation) within 1 year of enrollment. Peripheral endothelial dysfunction was defined as a reactive hyperemia index (RHI) of 1.8 or less. Social isolation was measured by the social network index (SNI), ranging from 0 (indicating severe isolation) to 4 (indicating least social isolation). The prevalence of PED was compared across individuals with none (SNI=3 or 4), moderate (SNI=2), and severe (SNI=0 or 1) social isolation. Binary logistic regression analysis was used to assess the association between social isolation and PED. RESULTS: A total of 312 patients were included (mean age, 49±15 years; 68.3% female). Peripheral endothelial dysfunction was present in 92 (29.5%) patients. There was a significant correlation between SNI and RHI (r=0.24; P<.001). The RHI was significantly lower in severely isolated individuals compared with moderately or not isolated individuals (1.95 [1.51 to 2.39], 2.22 [1.71 to 2.73], 2.35 [1.82 to 2.88], respectively; P=.02). SNI was inversely associated with PED in univariable and multivariable binary regression analysis adjusted for cardiovascular risk factors (odds ratio, 0.73 [95% CI, 0.59 to 0.90; P=.003] and odds ratio, 0.73 [95% CI, 0.58 to 0.92; P=.006], respectively). In sex-stratified analysis, severely isolated women were more likely to have lower RHIs (P=.005), whereas there was no significant difference in RHI for men with different levels of social connection (P=.82). CONCLUSION: Social isolation is independently associated with PED, indicating a potential mechanistic link between social isolation and increased cardiovascular risk, particularly for women.