title: Sensitivity analysis of longitudinal binary quality of life data with drop-out: an example using the EORTC QLQ-C30.
abstract: Analysing quality of life data (QOL) may be complicated for several reasons. Quality of life data not only involves repeated measures but is also usually collected on ordered categorical responses. In addition, it is evident that not all patients provide the same number of assessments, due to attrition caused by death or other medical reasons. In the recent statistical literature, increasing attention is given to methods which can handle non-continuous outcomes in the presence of missing data. The aim of this paper is to investigate the effect on statistical conclusions of applying different modelling techniques to QOL data generated from an EORTC phase III trial. Treatment effects and treatment differences are of major concern. First, a random-effects model is fitted, relating a binary longitudinal response (derived from the physical functioning scale of the QLQ-C30) to several covariates. In a second approach, marginal models are fitted, retaining the response variable and the mean structure used before. The fitted marginal models only differ with respect to the considered estimation procedure: generalized estimating equations (GEE); weighted generalized estimating equations (WGEE), and maximum likelihood (ML).
authors.affiliation: Limburgs Universitair Centrum, Center for Statistics, Biostatistics, Universitaire Campus, B-3590 Diepenbeek, Belgium. kristel.vansteen@luc.ac.be
authors.forename: K
authors.initials: K
authors.lastname: Van Steen
authors.forename: D
authors.initials: D
authors.lastname: Curran
authors.forename: G
authors.initials: G
authors.lastname: Molenberghs
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000627:therapeutic use; D017326:Clinical Trials, Phase III as Topic / Q000379:methods; D003627:Data Interpretation, Statistical; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D016685:Mitomycin / Q000627:therapeutic use; D008954:Models, Biological; D015233:Models, Statistical; D009919:Orchiectomy; D010352:Patient Dropouts; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000601:surgery; D011788:Quality of Life
chemical_list: D000903:Antibiotics, Antineoplastic; D016685:Mitomycin