Pathway from poor self-rated health to mortality: Explanatory power of disease diagnosis

- Disease diagnosis causes a significant negative shock to self-rated health.
- Diagnoses for different diseases have differential impacts on self-rated health.
- Disease diagnosis partly explains why self-rated health predicts mortality.
- The “cognitive flow” theory of self-rated health is supported.

Poor self-rated health has been consistently demonstrated as a reliable predictor for mortality, often exceeding the predictive power of other “objective” medical factors. Drawing from a theoretical framework for the cognitive processes underlying the self-assessment of health, this study seeks to test the knowledge mechanisms that moderate the predictive power of poor self-rated health. Using nationally-representative longitudinal data from the Canadian National Population Health Survey (NPHS) from 1994 to 2010, this study tests the effects of physician-diagnosed disease for the life course trajectory of self-rated health, and as a moderator for the power of poor self-rated health to predict proximate mortality. Disruptions to self-rated health trajectories are measured using an interrupted time-series analysis. Predictive power is modelled using generalized estimating equation (GEE) logistic regression. Findings show that physician-diagnosed diseases cause a negative shock to self-rated health, even accounting for endogeneity. Furthermore, a major portion of the predictive power of poor self-rated health in the final years of life is explained by respondents' knowledge of the disease conditions which eventually cause their death. This novel finding supports one of the foremost theories putting cognition and knowledge at the root of why poor self-rated health is such a robust predictor of mortality.