Decomposition of Differentials in Health Expectancies From Multistate Life Tables: A Research Note

Abstract

Multistate modeling is a commonly used method to compute healthy life expectancy. However, there is currently no analytical method to decompose the components of change in summary measures calculated from multistate models. In this paper, we develop and describe a derivative-based method to decompose the difference in population-based health expectancies estimated via a multistate model into two main components: the proportion resulting from differences in initial health structure, and the proportion resulting from differences in health transitions. We illustrate the method using data on Activities of Daily Living disability from the US Health and Retirement Study to decompose the sex differential in disability-free life expectancy (HLE) among older Americans. Our results suggest that the sex gap in HLE results primarily from differences in transition rates between disability states, rather than from the initial health structure of male and female populations. The methods introduced in this paper enable researchers, including those working in fields other than health, to decompose the relative contribution of initial population structure and transition probabilities to differences in state-specific life expectancies from multistate models.