The Impact of Systematic Trend and Uncertainty on Mortality and Disability in a Multi-State Latent Factor Model for Transition Rates

Zixi Li, Adam W. Shao and Michael Sherris

Multiple state functional disability models do not generally include systematic trend and uncertainty. We develop and estimate a multi-state latent factor intensity model with transition and recovery rates depending on a stochastic frailty factor to capture trend and uncertainty. We estimate the model parameters using U.S. Health and Retirement Study (HRS) data between 1998 and 2012 with Monte Carlo maximum likelihood estimation method.

The model shows significant reductions in disability and mortality rates during this period and allows us to quantify uncertainty in transition rates arising from the stochastic frailty factor. Recovery rates are very sensitive to the stochastic frailty. There is an increase in expected future lifetimes as well as an increase in future healthy life expectancy.