Title: Modelling the hazard of transition into the absorbing state in the illness-death survival model
Authors: Laura Antolini - Universita Milano Bicocca (Italy) [presenting]
Elena Tassistro - Universita Milano-Bicocca (Italy)
Davide Paolo Bernasconi - Universita Milano Bicocca (Italy)
Paola Rebora - Universita Milano Bicocca (Italy)
Maria Grazia Valsecchi - Universita Milano Bicocca (Italy)
Abstract: The illness-death survival model is the simplest multi-state model where the transition from the initial state 0 to the absorbing state 2 may involve an intermediate state 1 (e.g. disease relapse). The impact of the transition into 1 on the subsequent transition hazard to 2 enables to gain insights into the disease course. In this setting, the standard approach of analysis is the joint model of the transition hazards from 0 to 2 and from 1 to 2, including time to illness as a time-varying covariate and measuring time from origin even after the transition into state 1. The hazard from 1 to 2 can be also modelled separately only on patients in state 1, measuring time from illness and including time to illness as a fixed covariate. A recently proposed approach is a joint model where time after the transition into state 1 is measured in both scales and time to illness is included as a time varying covariate. A further possibility is a joint model where time after the transition into state 1 is measured only from illness and time to illness is included as a fixed covariate. Through theoretical reasoning and simulation protocols the use of these models will be discussed when aiming at: a) validating the properties of the illness-death process, b) estimating the impact of time to illness on the hazard from 1 to 2, c) quantifying the impact that the transition into 1 has on the hazard of the absorbing state.