Statistical Test for Ordered Categorical Data in Clinical Trials

  • Shein-Chung ChowEmail author
  • Siu-Keung Tse
  • Chunyan Yang
  • Dennis Cosmatos
  • Eric Chi


In clinical trials, subjects are often classified into ordered categories (eg, worsening, no change, and improvement) based on their post-treatment clinical response changes from baseline. The usual approach in using a multinomial model for assessing treatment effects between treatment groups is not efficient because it demands intense computation to evaluate the corresponding probabilities across these ordered categories. In this study, we propose to model the response probabilities via a parametric form, and the comparison of these probabilities is translated into the comparison of the associated model parameters. Maximum likelihood estimates are then derived and the required sample size for achieving a desired statistical power at a prespecified level of significance is also obtained. A simulation study is performed to evaluate finite sample size performance. An example concerning the evaluation of the efficacy of a test treatment for subjects with moderate to severe Crohn disease that is refractory to steroids and immunosuppressants is presented to illustrate the proposed method.

Key Words

Clinical trials Likelihood ratio test Multinomial model Ordered categorical data Sample size determination 


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Copyright information

© Drug Information Association, Inc 2008

Authors and Affiliations

  • Shein-Chung Chow
    • 1
    Email author
  • Siu-Keung Tse
    • 2
  • Chunyan Yang
    • 3
  • Dennis Cosmatos
    • 4
  • Eric Chi
    • 5
  1. 1.Department of Biostatistics and BioinformaticsDuke University School of MedicineDurhamUSA
  2. 2.City University of Hong KongHong Kong
  3. 3.Yunnan UniversityYunnanChina
  4. 4.Wyeth ResearchCollegevilleUSA
  5. 5.Amgen, Inc.Thousand OaksUSA

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