Is positive affect associated with survival? a population-based study of elderly persons
Study results on the association of positive affect with survival are conflicting. This disagreement potentially arises from poor control for health or negative affect and for the various age groups studied. The authors examined if positive affect predicts survival; whether this association is preserved after controlling for negative affect, socioeconomic status, lifestyle, and health; and whether this association varies with age. The study is set within the population-based Rotterdam Study (1997-2007) and included 4,411 participants aged 61 years or older, followed for on average 7.19 (standard deviation = 2.20) years. Positive affect was not consistently associated with survival across all ages. A significant interaction of positive affect with age on survival (P = 0.02) was found. Subsequent age stratification revealed that positive affect independently predicted survival in elderly persons aged <80 years (per affect score, hazard ratio = 0.96, 95% confidence interval: 0.93, 0.99) but not in those aged ≥80 years in fully adjusted models (hazard ratio = 1.00, 95% confidence interval: 0.96, 1.04). In the oldest old, the association was partly explained by differences in baseline health. In conclusion, the results suggest that there may be an association of positive affect with survival in the younger and middle old but not in the oldest old in whom perception of positive affect is more likely to be determined by health.