title: Statistical analysis of survival data from radiation countermeasure experiments.
abstract: We present an introduction to, and examples of, Cox proportional hazards regression in the context of animal lethality studies of potential radioprotective agents. This established method is seldom used to analyze survival data collected in such studies, but is appropriate in many instances. Presenting a hypothetical radiation study that examines the efficacy of a potential radioprotectant both in the absence and presence of a potential modifier, we detail how to implement and interpret results from a Cox proportional hazards regression analysis used to analyze the survival data, and we provide relevant SAS® code. Cox proportional hazards regression analysis of survival data from lethal radiation experiments (1) considers the whole distribution of survival times rather than simply the commonly used proportions of animals that survived, (2) provides a unified analysis when multiple factors are present, and (3) can increase statistical power by combining information across different levels of a factor. Cox proportional hazards regression should be considered as a potential statistical method in the toolbox of radiation researchers.
authors.affiliation: Department of Biostatistics, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA. rdlandes@uams.edu
authors.forename: Reid D
authors.initials: RD
authors.lastname: Landes
authors.forename: Shelly Y
authors.initials: SY
authors.lastname: Lensing
authors.forename: Ralph L
authors.initials: RL
authors.lastname: Kodell
authors.forename: Martin
authors.initials: M
authors.lastname: Hauer-Jensen
mesh_terms: D032761:Animal Experimentation / Q000592:standards; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004353:Drug Evaluation, Preclinical / Q000706:statistics & numerical data*; D053208:Kaplan-Meier Estimate; D007928:Lethal Dose 50; D051379:Mice; D016016:Proportional Hazards Models; D011833:Radiation Injuries, Experimental / Q000188:drug therapy* / Q000517:prevention & control; D011837:Radiation-Protective Agents / Q000008:administration & dosage / Q000627:therapeutic use*; D012107:Research Design; D018709:Statistics, Nonparametric; D016019:Survival Analysis; D014916:Whole-Body Irradiation / Q000009:adverse effects
chemical_list: D011837:Radiation-Protective Agents