title: A random pattern mixture model for ordinal outcomes with informative dropouts.
abstract: We extend a random pattern mixture joint model for longitudinal ordinal outcomes and informative dropouts. The patients are generalized to 'pattern' groups based on known covariates that are potentially surrogated for the severity of the underlying condition. The random pattern effects are defined as the latent effects linking the dropout process and the ordinal longitudinal outcome. Conditional on the random pattern effects, the longitudinal outcome and the dropout times are assumed independent. Estimates are obtained via the Expectation-maximization algorithm. We applied the model to the end-stage renal disease data. Anemia was found to be significantly affected by the baseline iron treatment when the dropout information was adjusted via the study model; as opposed to an independent or shared parameter model. Simulations were performed to evaluate the performance of the random pattern mixture model under various assumptions.
authors.affiliation: Allergan, Inc., 200 Somerset Corporate Blvd, Suite 6001, Bridgewater, NJ, 08807, U.S.A.
authors.forename: Chengcheng
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104-6021, U.S.A.
authors.forename: Sarah J
authors.identifier: http://orcid.org/0000-0002-6644-8284
authors.initials: SJ
authors.lastname: Ratcliffe
authors.affiliation: Department of Biostatistics and Epidemiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104-6021, U.S.A.
authors.forename: Wensheng
authors.initials: W
authors.lastname: Guo
mesh_terms: D000465:Algorithms; D018798:Anemia, Iron-Deficiency / Q000097:blood / Q000209:etiology; D056808:Biostatistics; D003198:Computer Simulation; D005260:Female; D006801:Humans; D007501:Iron / Q000627:therapeutic use; D007676:Kidney Failure, Chronic / Q000150:complications / Q000188:drug therapy; D008137:Longitudinal Studies; D008297:Male; D015233:Models, Statistical; D010352:Patient Dropouts / Q000706:statistics & numerical data*
chemical_list: D007501:Iron
keywords: EM algorithm; Newton-Raphson algorithm; Pattern mixture model; adaptive gaussian quadrature; ordinal outcome