Background
Self-rated health is a robust predictor of mortality beyond risk associated with objective health measures. Given the subjective and holistic nature of perceived health, it may be amenable to moderation by positive psychological functioning; those with poor subjective health may have greater longevity if they also possess a greater sense of purpose in life. This hypothesis rests on extensive work showing purpose in life predicts greater longevity and moderates the adverse impact of diverse exposures. Lastly, Blacks may not benefit from experiences that typically predict better health – e.g., positive psychological interventions – to the same degree as Whites.
Aims
(1) To determine whether purpose in life moderates the association of self-rated health and mortality, (2) to determine whether that moderation varies by race.
Method
Data were from the national longitudinal Midlife in the United States (MIDUS) study. Self-rated health was from a 5-item scale (1=Poor; 5=Excellent). Purpose in life was determined using the 7-item Ryff Psychological Well-Being sub-scale. Data on mortality came from the National Death Index. Race was self-reported and categorized as 1=Black and 0=White.
Results
Self-rated health and purpose in life were more strongly correlated in White (r=0.3) than Black (r=0.2) participants. In logistic regression models stratified by race and adjusted for age, sex, education, and chronic conditions, self-rated health significantly predicted greater longevity in all MIDUS respondents, but purpose in life was inversely associated with mortality only in Whites. Models including the interaction term showed that in Whites with higher purpose in life scores, mortality probability did not increase with poorer health. There was no moderation for Black participants.
Conclusion
Purpose in life predicted greater longevity in MIDUS respondents with poor subjective health. These results suggest that whatever factors links subjective health and mortality are also sensitive to positive psychological functioning. However, this moderation was only observed in Whites, suggesting potential racial differences in how people construe purpose in life on the Ryff measures.