Analysis of Echocardiographic Allograft Valve Function Using Joint Modelling of Continuous and Discrete, Longitudinal and Time to Event Data

Abstract

Longitudinal data on aortic gradient (measure of stenosis) and measure of severity of regurgitation along with event outcomes reoperation and death were observed. A general linear, generalized linear, or nonlinear mixed model is used to describe the longitudinal profile of each marker. To account for the correlation between markers, the univariate mixed models are combined into a multivariate mixed model (MMM) by specifying a joint distribution for the random effects. To predict the failure time of a allograft valve the joint distribution of the event times and the longitudinal measurements is modelled via a set of random effects that are assumed to account for the associations between these two outcomes.