title: Sample sizes for proportional hazards survival studies with arbitrary patient entry and loss to follow-up distributions.
abstract: In proportional hazards survival studies, power depends on the observed number of deaths, d*. For a given choice of survival, loss, and patient entry distributions, sample sizes can be determined by equating d* to the expected number of deaths. Approximating the survival and loss distributions with piecewise exponential distributions, and patient entry with a piecewise linear distribution, significantly reduces the computational overhead, and the expected number of deaths can be evaluated routinely. The merits of this approach are illustrated by a clinical trial of chemotherapy for large bowel cancer.
authors.affiliation: Department of Mathematics, University of Nottingham, U.K.
authors.forename: N A
authors.initials: NA
authors.lastname: Yateman
authors.forename: A M
authors.initials: AM
authors.lastname: Skene
mesh_terms: D003110:Colonic Neoplasms / Q000188:drug therapy / Q000401:mortality; D003625:Data Collection / Q000592:standards*; D005472:Fluorouracil / Q000627:therapeutic use; D005500:Follow-Up Studies; D006801:Humans; D016014:Linear Models; D016016:Proportional Hazards Models; D015203:Reproducibility of Results; D016019:Survival Analysis
chemical_list: D005472:Fluorouracil