Whose Mortality Decelerates? Multi-Stage Mortality Selection and the Poverty Puzzle

Elizabeth Wrigley-Field, University of Wisconsin at Madison
Felix Elwert, University of Wisconsin at Madison

We analyze mortality deceleration on nearly the entire U.S. elderly population, incorporating new dimensions of stratification--poverty and health--into nearly non-parametric mortality hazards. Our results create a puzzle for the traditional explanation for deceleration: mortality selection. Conventional interpretations posit that populations with higher mortality should decelerate at younger ages since they are subject to greater selective pressure. We find the expected pattern along lines of race and sex: higher-mortality African-Americans and men decelerate earliest. For poverty, however, the pattern reverses: although the poor presumably are more selected by mortality, it is the non-poor who decelerate. To explain this puzzle, we develop a dynamic selection model suggesting that the frail tend to become poor. This model’s success offers empirical support for health selection, yet its dynamism comes at a price: the relationship between populations' frailty distributions makes deceleration order essentially unpredictable. We discuss implications for using deceleration patterns to understand health inequalities.