title: Gray's time-varying coefficients model for posttransplant survival of pediatric liver transplant recipients with a diagnosis of cancer.
abstract: Transplantation is often the only viable treatment for pediatric patients with end-stage liver disease. Making well-informed decisions on when to proceed with transplantation requires accurate predictors of transplant survival. The standard Cox proportional hazards (PH) model assumes that covariate effects are time-invariant on right-censored failure time; however, this assumption may not always hold. Gray's piecewise constant time-varying coefficients (PC-TVC) model offers greater flexibility to capture the temporal changes of covariate effects without losing the mathematical simplicity of Cox PH model. In the present work, we examined the Cox PH and Gray PC-TVC models on the posttransplant survival analysis of 288 pediatric liver transplant patients diagnosed with cancer. We obtained potential predictors through univariable (P < 0.15) and multivariable models with forward selection (P < 0.05) for the Cox PH and Gray PC-TVC models, which coincide. While the Cox PH model provided reasonable average results in estimating covariate effects on posttransplant survival, the Gray model using piecewise constant penalized splines showed more details of how those effects change over time.
authors.affiliation: Department of Biostatistics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA.
authors.forename: Yi
authors.initials: Y
authors.lastname: Ren
authors.forename: Chung-Chou H
authors.initials: CC
authors.lastname: Chang
authors.forename: Gabriel L
authors.initials: GL
authors.lastname: Zenarosa
authors.forename: Heather E
authors.initials: HE
authors.lastname: Tomko
authors.forename: Drew Michael S
authors.initials: DM
authors.lastname: Donnell
authors.forename: Hyung-joo
authors.initials: HJ
authors.lastname: Kang
authors.forename: Mark S
authors.initials: MS
authors.lastname: Roberts
authors.forename: Cindy L
authors.initials: CL
authors.lastname: Bryce
mesh_terms: D002648:Child; D002675:Child, Preschool; D019295:Computational Biology; D058625:End Stage Liver Disease / Q000401:mortality* / Q000601:surgery*; D005260:Female; D006650:Histocompatibility Testing; D006801:Humans; D007223:Infant; D053208:Kaplan-Meier Estimate; D008113:Liver Neoplasms / Q000401:mortality* / Q000601:surgery*; D016031:Liver Transplantation / Q000401:mortality*; D008297:Male; D015233:Models, Statistical; D015999:Multivariate Analysis; D016016:Proportional Hazards Models; D016019:Survival Analysis; D014019:Tissue Donors; D009927:Tissue and Organ Procurement / Q000706:statistics & numerical data; D014481:United States / Q000453:epidemiology