Many multicenter trials had few events per center, requiring analysis via random-effects models or GEEs

摘要

Objectives: Adjustment for center in multicenter trials is recommended when there are between-center differences or when randomization has been stratified by center. However, common methods of analysis (such as fixed-effects, Mantel-Haenszel, or stratified Cox models) often require a large number of patients or events per center to perform well.