282Social isolation and incident coronary heart disease in two large UK prospective studies

Abstract Background Social isolation is associated with CHD mortality but evidence of association with incident CHD is mixed. We prospectively examined this association in the Million Women Study (MWS) and UK Biobank (UKB). Methods 481,946 MWS and 456,612 UKB participants reported on social isolation (living alone, little contact with family/friends/groups). Excluding those reporting previous CHD or stroke, participants were followed for incident CHD using linkage to hospital admission and death records. Cox regression yielded relative risks (RR) by 3 levels of social isolation, adjusted for relevant confounders. Results During 7 years follow-up in the MWS and UKB, there were 42,402 first coronary heart disease events in total (of which 1,834 were fatal without an associated hospital admission). After adjustment, social isolation was not associated with hospital admission for first CHD events (combined RR for both studies: RR = 1.01, 95% CI: 0.98–1.04). However, the risk of fatal first CHD events without an associated hospital admission was substantially higher in the most isolated group than the least isolated group (1.86 [1.63–2.12]) This association with fatal first CHD events was driven by the association with living alone. Conclusions Social isolation was not associated with increased risk of first CHD hospital admissions but was associated with increased risk of death from CHD. Key messages Social isolation is likely not a risk factor for developing CHD, but people living alone may be at greater risk of dying from a coronary event than those not living alone.