Sample Size Estimates for Cluster-Randomized Trials in Hospital Infection Control and Antimicrobial Stewardship

Abstract

Key Points Question What are the estimated sample sizes needed to adequately power parallel cluster-randomized trials with common health care–associated infection outcomes, and how do the parameters affect these estimates in the field of hospital infection control and antimicrobial stewardship? Findings This cohort study found that large sample sizes were needed to appropriately power cluster-randomized trials in the field of hospital epidemiology, because the outcomes are rare. The expected effectiveness of the intervention and the strength of correlation within a cluster had the greatest association with the estimated sample size. Meaning These findings suggest that better-designed cluster-randomized trials in the field of hospital epidemiology and antimicrobial stewardship that appropriately account for clustering and realistic effect sizes will provide a more reliable evidence base for advancing recommendations and best practices.