title: Frailty models with missing covariates.
abstract: We present a method for estimating the parameters in random effects models for survival data when covariates are subject to missingness. Our method is more general than the usual frailty model as it accommodates a wide range of distributions for the random effects, which are included as an offset in the linear predictor in a manner analogous to that used in generalized linear mixed models. We propose using a Monte Carlo EM algorithm along with the Gibbs sampler to obtain parameter estimates. This method is useful in reducing the bias that may be incurred using complete-case methods in this setting. The methodology is applied to data from Eastern Cooperative Oncology Group melanoma clinical trials in which observations were believed to be clustered and several tumor characteristics were not always observed.
authors.affiliation: Department of Biostatistics, University of North Carolina, Chapel Hill 27599, USA. aherring@bios.unc.edu
authors.forename: Amy H
authors.initials: AH
authors.lastname: Herring
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Ibrahim
authors.forename: Stuart R
authors.initials: SR
authors.lastname: Lipsitz
mesh_terms: D017326:Clinical Trials, Phase III as Topic / Q000379:methods*; D016000:Cluster Analysis; D003198:Computer Simulation; D018572:Disease-Free Survival; D006801:Humans; D016898:Interferon-alpha / Q000008:administration & dosage / Q000627:therapeutic use; D016013:Likelihood Functions; D008545:Melanoma / Q000188:drug therapy; D015233:Models, Statistical; D009010:Monte Carlo Method; D015999:Multivariate Analysis; D016019:Survival Analysis
chemical_list: D016898:Interferon-alpha