Quality of life independently predicts long-term mortality but not vascular events: the Northern Manhattan Study

Purpose: Cardiovascular disease is a major contributor to morbidity and mortality, and prevention relies on accurate identification of those at risk. Studies of the association between quality of life (QOL) and mortality and vascular events incompletely accounted for depression, cognitive status, social support, and functional status, all of which have an impact on vascular outcomes. We hypothesized that baseline QOL is independently associated with long-term mortality in a large, multi-ethnic urban cohort. Methods: In the prospective, population-based Northern Manhattan Study, Spitzer QOL index (SQI, range 0–10, with ten signifying the highest QOL) was assessed at baseline. Participants were followed over a median 11 years for stroke, myocardial infarction (MI), and vascular and non-vascular death. Multivariable Cox proportional hazards regression estimated hazard ratio and 95% confidence interval (HR, 95% CI) for each outcome, with SQI as the main predictor, dichotomized at 10, adjusting for baseline demographics, vascular risk factors, history of cancer, social support, cognitive status, depression, and functional status. Results: Among 3298 participants, mean age was 69.7 + 10.3 years; 1795 (54.5%) had SQI of 10. In fully adjusted models, SQI of 10 (compared to SQI <10) was associated with reduced risk of all-cause mortality (HR 0.80, 95% CI 0.72–0.90), vascular death (0.81, 0.69–0.97), non-vascular death (0.78, 0.67–0.91), and stroke or MI or death (0.82, 0.74–0.91). In fully adjusted competing risk models, there was no association with stroke (0.93, 0.74–1.17), MI (0.98, 0.75–1.28), and stroke or MI (1.03, 0.86–1.24). Results were consistent when SQI was analyzed continuously. Conclusion: In this large population-based cohort, highest QOL was inversely associated with long-term mortality, vascular and non-vascular, independently of baseline primary vascular risk factors, social support, cognition, depression, and functional status. QOL was not associated with non-fatal vascular events.