title: Multivariate permutation test to compare survival curves for matched data.
abstract: BACKGROUND
  In the absence of randomization, the comparison of an experimental treatment with respect to the standard may be done based on a matched design. When there is a limited set of cases receiving the experimental treatment, matching of a proper set of controls in a non fixed proportion is convenient.
  
  
  METHODS
  In order to deal with the highly stratified survival data generated by multiple matching, we extend the multivariate permutation testing approach, since standard nonparametric methods for the comparison of survival curves cannot be applied in this setting.
  
  
  RESULTS
  We demonstrate the validity of the proposed method with simulations, and we illustrate its application to data from an observational study for the comparison of bone marrow transplantation and chemotherapy in the treatment of paediatric leukaemia.
  
  
  CONCLUSIONS
  The use of the multivariate permutation testing approach is recommended in the highly stratified context of survival matched data, especially when the proportional hazards assumption does not hold.
authors: Center of Biostatistics for Clinical Epidemiology, Department of Health Sciences, University of Milano-Bicocca, 20900, Monza, Italy. stefania.galimberti@unimib.it
authors: Stefania
authors: S
authors: Galimberti
authors: Maria Grazia
authors: MG
authors: Valsecchi
mesh_terms: D000970:Antineoplastic Agents / Q000627:therapeutic use; D001699:Biometry / Q000379:methods*; D016026:Bone Marrow Transplantation / Q000379:methods; D002648:Child; D006801:Humans; D007558:Italy; D053208:Kaplan-Meier Estimate; D016555:Matched-Pair Analysis; D009010:Monte Carlo Method; D015999:Multivariate Analysis; D016012:Poisson Distribution; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000188:drug therapy; D015203:Reproducibility of Results; D012107:Research Design; D012189:Retrospective Studies
chemical_list: D000970:Antineoplastic Agents
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