Stratified randomization for clinical trials.
Trialists argue about the usefulness of stratified randomization.
For investigators designing trials and readers who use them, the argument has created uncertainty regarding the importance of stratification.
In this paper, we review stratified randomization to summarize its purpose, indications, accomplishments, and alternatives.
In order to identify research papers, we performed a Medline search for 1966-1997.
The search yielded 33 articles that included original research on stratification or included stratification as the major focus.
Additional resources included textbooks.
Stratified randomization prevents imbalance between treatment groups for known factors that influence prognosis or treatment responsiveness.
As a result, stratification may prevent type I error and improve power for small trials (<400 patients), but only when the stratification factors have a large effect on prognosis.
Stratification has an important effect on sample size for active control equivalence trials, but not for superiority trials.
Theoretical benefits include facilitation of subgroup analysis and interim analysis.
The maximum desirable number of strata is unknown, but experts argue for keeping it small. (...)
Mots-clés Pascal : Etats Unis, Amérique du Nord, Amérique, Homme, Epidémiologie, Randomisation, Essai clinique, Méthodologie, Stratification population, Indication, Efficacité, Recommandation, Analyse statistique
Mots-clés Pascal anglais : United States, North America, America, Human, Epidemiology, Randomization, Clinical trial, Methodology, Population stratification, Indication, Efficiency, Recommendation, Statistical analysis
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 99-0148868
Code Inist : 002B30A01A1. Création : 16/11/1999.