• Search Research Projects
  • Search Researchers
  • How to Use
  1. Back to project page

1997 Fiscal Year Final Research Report Summary

Loss of Power with Tests for Treatment Effects in Clinical Trials due to Patients' Heterogeneity and Countermeasure

Research Project

Project/Area Number 07680326
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Statistical science
Research InstitutionNagasaki University

Principal Investigator

NAKAMURA Tsuyoshi  Nagasaki University Faculty of Environmental studies Professor, 環境科学部, 教授 (80039586)

Co-Investigator(Kenkyū-buntansha) AKAZAWA Kouhei  Kyushu University School of Medicine Associate Professor, 医学部, 講師 (10175771)
Project Period (FY) 1995 – 1997
KeywordsCox-Reqression model / Decision making / Heteroqeneity / Logrank test / Piecewise linear / Power / Stratification / インバランス
Research Abstract

The logrank test is commonly used to evaluate the treatment effect in clinical trials with patients survival times as the main response measure. The usual formula to obtain the number of patients required in a clinical trial is independent of the degree of heterogeneity regarding natural prognoses of patients ; accordingly, medical researchers have not paid much attention to heterogeneity of patients in conducting the test. Recently, however, the effects of heterogeneity on the results of the test have been extensively studied.
The objective of this study is to describe the heterogeneity of cancer patients, to estimate the effects of the heterogeneity on the power of the stratified logrank tests and to study the Cox regression method with "piecewise linear hazard model" in application, which enables us to fit data to hazards specified for any forms of the covariate vector.
The heterogeneity of patients within stratum was estimated using the data of a gastric cancer clinical trial consisiting of over 6000 patients : It is revealed then from simulation studies that the stratified logrank tests may suffer serious power loss due to the observed heterogeneity of the patients. On the other hand, the Cox regression method with a misspecified hazards model may also result in a substantial loss of power. And thus, we have developed Cox regression method with "piecewise linear hazard model" of modeling hazards which takes into account the prognostic factors. It is confirmed the PL model is universally sperior to the other models in cancer clinical trials.

  • Research Products

    (4 results)

All Other

All Publications (4 results)

  • [Publications] 中村 剛・赤澤 宏平: "症例の不均一性に起因するログランク検定の検出力低下とその対策に関する推計学的研究" がん治療のあゆみ(がん集学的治療研究財団発行). 3. 57-67 (1996)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 中村 剛・赤澤 宏平: "Power of logrank test and Cox Regression Model in Clinical Trials with Heterogeneous Samples" Statistics in Medicine. 16. 583-597 (1997)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 中村 剛・赤澤 宏平: "治療法の優劣を判定するための統計的方法の現状" 日本医療情報学会10周年記念出版. 3. 73-76 (1998)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] 中村 剛・赤澤 宏平: "Piecewise Linear Cox Model for estimating relative risks adjusting for the heterogeneity of the sample" Statistics for the Environment. 4(印刷中). (1998)

    • Description
      「研究成果報告書概要(和文)」より

URL: 

Published: 1999-03-16  

Information User Guide FAQ News Terms of Use Attribution of KAKENHI

Powered by NII kakenhi