2002 年 23 巻 1 号 p. 27-35
In the design of clinical trials in which the primary endpoint is time to occurrence of a clinical event, sample size calculation should be based on the subsequent survival analysis. This paper gives sample size formulas based on the conditional score test for the hazard ratio, which is equivalent to the normal approximation of the Cox F test. The proposed method is adopted to uniform patient entry, loss to follow-up, and treatment switching. In cancer clinical trials, it is sometimes required to show that the two treatments have equivalent survival benefit when the new treatment has apparent advantages on toxicity. Application of the proposed sample size formula to the equivalence test of two treatments is also given.