Katherine S. Panageas, DrPH; Deborah Schrag, MD, MPH; Elyn Riedel, MA; Peter B. Bach, MD, MAPP; Colin B. Begg, PhD
Acknowledgments: The authors thank 2 anonymous reviewers for help with the article. They also thank the groups responsible for the creation and dissemination of the linked database, including the Applied Research Branch, Division of Cancer Control and Population Sciences, National Cancer Institute; the Office of Strategic Planning and the Office of Informational Services, Centers for Medicare & Medicaid Services; Information Management Services; and the Surveillance, Epidemiology, and End Results tumor registries.
Grant Support: In part by grants from the National Cancer Institute (CA83950 [Dr. Schrag], CA90226 [Dr. Bach], and CA08748 [Dr. Begg]).
Potential Financial Conflicts of Interest: None disclosed.
Requests for Single Reprints: Colin B. Begg, PhD, Memorial Sloan-Kettering Cancer Center, 307 East 63rd Street (3rd Floor), New York, NY 10021; e-mail, firstname.lastname@example.org.
Current Author Addresses: Drs. Panageas, Schrag, Bach, and Begg and Ms. Riedel: Memorial Sloan-Kettering Cancer Center, 307 East 63rd Street (3rd Floor), New York, NY 10021.
Author Contributions: Conception and design: K.S. Panageas, D. Schrag, E. Riedel, C.B. Begg.
Analysis and interpretation of the data: K.S. Panageas, D. Schrag, E. Riedel, C.B. Begg.
Drafting of the article: K.S. Panageas, D. Schrag, C.B. Begg.
Critical revision of the article for important intellectual content: K.S. Panageas, D. Schrag, P.B. Bach, C.B. Begg.
Final approval of the article: K.S. Panageas, P.B. Bach, C.B. Begg.
Provision of study materials or patients: D. Schrag, C.B. Begg.
Statistical expertise: K.S. Panageas, E. Riedel, C.B. Begg.
Obtaining of funding: C.B. Begg.
Administrative, technical, or logistic support: C.B. Begg.
Collection and assembly of data: D. Schrag, C.B. Begg.
Panageas KS, Schrag D, Riedel E, Bach PB, Begg CB. The Effect of Clustering of Outcomes on the Association of Procedure Volume and Surgical Outcomes. Ann Intern Med. 2003;139:658-665. doi: 10.7326/0003-4819-139-8-200310210-00009
Download citation file:
Published: Ann Intern Med. 2003;139(8):658-665.
In an attempt to evaluate the degree to which the choice of provider affects outcomes of major medical procedures, numerous investigators have used procedure volume as a proxy for expertise and have conducted studies correlating volume with outcomes. However, volume is a crude, easily calculated measure, and its use may overlook large variations in quality among providers that are independent of the number of procedures performed. If there are such large variations in outcomes among providers, the outcomes of patients treated by the same provider are necessarily correlated, or “clustered.” Clustering of this nature invalidates conventional statistical analyses. Patients treated at the same hospital or by the same surgeon may be more likely to experience similar outcomes if surgical technique or supportive care practices vary among providers and if these factors affect outcomes. It is well established that statistical methods must correct for the effect of clustering of this nature if it exists (1-3). In general, correction for clustering attenuates the statistical significance of observed trends.
to gain full access to the content and tools.
Learn more about subscription options.
Register Now for a free account.
Gastroenterology/Hepatology, Hematology/Oncology, Hospital Medicine, Healthcare Delivery and Policy, Prostate Cancer.
Results provided by:
Copyright © 2016 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