Mathematical modeling of fitness and frailty in relation to biological age in individuals and populations

This project seeks to further develop and validate a quantitative framework that can account for variability in the rate of human ageing. As people age they accumulate impairments, diseases and disabilities arising from diseases (what we refer to as deficits) from many causes. We have suggested that a deficit count (taken as a proportion of deficits present, and referred to as a frailty index) provides an integrated characteristic of aging. In other words, ageing can be expressed as a single number. This number works well, and the higher it is, the greater the likelihood of either entering a nursing home or dying. Our frailty index approach has been independently verified by two other groups. This frailty index therefore allows to estimate an individual's biological age. Working with large Canadian and international databases, we plan to address several questions, including how people's health changes over time, to what extent health states are fixed, whether they generally deteriorate with time, or whether individuals move significantly from a higher frailty index value (higher number of deficits) to a lower value? How does age influence the probability of transition between one state and another? Can stochastic processes be identified that model transitions between health states? By working with existing large databases, this grant hopes to be able to suggest answers to these questions relatively quickly, and in a cost-effective way.