A. Russell Localio, JD, MS; Jesse A. Berlin, ScD; Thomas R. Ten Have, PhD; Stephen E. Kimmel, MD, MS
Increasingly, investigators rely on multicenter or multigroup studies to demonstrate effectiveness and generalizability. Authors too often overlook the analytic challenges in these study designs: the correlation of outcomes and exposures among patients within centers, confounding of associations by center, and effect modification of treatment or exposure across center. Correlation or clustering, resulting from the similarity of outcomes among patients within a center, requires an adjustment to confidence intervals and P values, especially in observational studies and in randomized multicenter studies in which treatment is allocated by center rather than by individual patient. Multicenter designs also warrant testing and adjustment for the potential bias of confounding by center, and for the presence of effect modification or interaction by center. This paper uses examples from the recent biomedical literature to highlight the issues and analytic options.
Learn more about subscription options.
Register Now for a free account.
Localio AR, Berlin JA, Ten Have TR, Kimmel SE. Adjustments for Center in Multicenter Studies: An Overview. Ann Intern Med. 2001;135:112-123. doi: 10.7326/0003-4819-135-2-200107170-00012
Download citation file:
Published: Ann Intern Med. 2001;135(2):112-123.
Results provided by:
Copyright © 2017 American College of Physicians. All Rights Reserved.
Print ISSN: 0003-4819 | Online ISSN: 1539-3704
Conditions of Use
This PDF is available to Subscribers Only