The estimation of lifetime risk and average age at onset of a disease using a multivariate exponential hazard rate model

Readily grasped concepts such as lifetime risk of, and expected age at onse t of, a disease, cannot be easily estimated by the relative risk methods co mmonly used in epidemiology. Here we develop a method for estimating these quantities with confidence intervals, where the likelihood is a multivariat e function of exposure variables. The model is basically non-parametric, ex cept for a proportional hazards assumption on exposures, and except for the youngest data-poor ages, where an exponential model in age is assumed. Tes ts of goodness-of-fit of the model are described, these allowing for produc t terms between exposures and age. Application of the method is made to the Adventist Health Study cohort, where the independent effects of several ex posures on these outcomes are demonstrated. Copyright (C) 1999 John Wiley & Sons, Ltd.