GENETIC-ANALYSIS OF DURATIONS - CORRELATED FRAILTY MODEL APPLIED TO SURVIVAL OF DANISH TWINS

Population studies of changes in human morbidity and mortality require models which take into account the influence of genetic and environme ntal factors on life-related durations, such as age at onset of the di sease or disability, age at death, etc. In this paper we show how a bi variate survival model based on the concept of correlated individual f railty can be used for the genetic analysis of durations. Six genetic models of frailty are considered and applied to Danish twin survival d ata. The results of statistical analysis allow us to conclude that at least 50% of variability in individual frailty is determined by enviro nmental factors. The approach suggests a method of estimation of the l ower bound for the biological limit of human longevity. Directions for further research are discussed. (C) 1995 WiIey-Liss,Inc.