Sposto R, Sather H N
J Chronic Dis. 1985;38(8):683-90. doi: 10.1016/0021-9681(85)90022-0.
Rubinstein et al. provide a technique for estimating the required length of accrual in a two treatment group randomized survival trial. An important parameter in this approach is the expected number of events as estimated by assuming exponential failure. When the underlying distribution of failure times displays a distinct plateau, as in many children's cancers (i.e. there is a "cure"), the assumption of exponential failure could be misleading. In this situation we propose the use of the general formulation in [1], but with the expected number of failures based on failure models with hazard functions which may decrease to zero. We suggest two such models and show that they provide a good fit in an example from Childrens Cancer Study Group (CCSG) trials, and that the determination of required trial duration depends strongly upon which model is assumed.
鲁宾斯坦等人提供了一种在双治疗组随机生存试验中估计所需累积时间长度的技术。这种方法中的一个重要参数是通过假设指数失效来估计的预期事件数。当失效时间的基础分布呈现出明显的平稳期时，如在许多儿童癌症中（即存在“治愈”情况），指数失效的假设可能会产生误导。在这种情况下，我们建议使用[1]中的一般公式，但基于具有可能降至零的危险函数的失效模型来计算预期失败数。我们提出了两个这样的模型，并表明它们在儿童癌症研究组（CCSG）试验的一个例子中拟合良好，而且所需试验持续时间的确定在很大程度上取决于所假设的模型。
