Marginal regression models for multivariate failure time data

In this article we propose a general Cox-type regression model to formulate the marginal distributions of multivariate failure time data. This model has a nested structure in that it allows different baseline hazard functions among distinct failure types and imposes a common baseline hazard function on the failure times of the same type. We prove that the maximum "quasi-partial-likelihood" estimator for the vector of regression parameters under the independence working assumption is consistent and asymptotically normal with a covariance matrix for which a consistent estimator is provided. Furthermore, we establish the uniform consistency and joint weak convergence of the Aalen-Breslow type estimators for the cumulative baseline hazard functions, and develop a resampling technique to approximate the joint distribution of these processes, which enables one to make simultaneous inference about the survival functions over the time axis and across failure types. Finally, we assess the small-sample properties of the proposed methods through Monte Carlo simulation, and present an application to a real dental study.