<i>Annals</i> Understanding Clinical Research: Intention-to-Treat Analysis
Authors: Joshua M. Liao, Catharine B. Stack, Michael E. Griswold, A. Russell Localio
Journal: Annals of Internal Medicine (2017)

Special Articles2 May 2017Annals Understanding Clinical Research: Intention-to-Treat AnalysisJoshua M. Liao, MD, Catharine B. Stack, PhD, Michael E. Griswold, PhD, and A. Russell Localio, PhDJoshua M. Liao, MDFrom University of Pennsylvania and American College of Physicians, Philadelphia, Pennsylvania, and University of Mississippi Medical Center, Jackson, Mississippi., Catharine B. Stack, PhDFrom University of Pennsylvania and American College of Physicians, Philadelphia, Pennsylvania, and University of Mississippi Medical Center, Jackson, Mississippi., Michael E. Griswold, PhDFrom University of Pennsylvania and American College of Physicians, Philadelphia, Pennsylvania, and University of Mississippi Medical Center, Jackson, Mississippi., and A. Russell Localio, PhDFrom University of Pennsylvania and American College of Physicians, Philadelphia, Pennsylvania, and University of Mississippi Medical Center, Jackson, Mississippi.Author, Article, and Disclosure Informationhttps://doi.org/10.7326/M17-0196 SectionsAboutFull TextPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail A randomized trial aims to reduce bias in comparing 2 or more treatments. An intention-to-treat (ITT) analysis theoretically evaluates all participants within their original randomly assigned group in an attempt to fulfill this primary aim. In practice, however, a true ITT analysis is often difficult when not all patients complete the trial or fully adhere to randomized treatments. Despite the challenges of dropout and nonadherence, investigators routinely report that "ITT analyses were conducted" without further explanation (1).In 2010, CONSORT (Consolidated Standards of Reporting Trials) replaced the item requiring ITT analyses with a request for a more informative description of ...References1. Gravel J, Opatrny L, Shapiro S. The intention-to-treat approach in randomized controlled trials: are authors saying what they do and doing what they say? Clin Trials. 2007;4:350-6. [PMID: 17848496] CrossrefMedlineGoogle Scholar2. Schulz KF, Altman DG, Moher D; CONSORT Group. CONSORT 2010 statement: updated guidelines for reporting parallel group randomized trials. Ann Intern Med. 2010;152:726-32. [PMID: 20335313]. doi:10.7326/0003-4819-152-11-201006010-00232 LinkGoogle Scholar3. Delitto A, Piva SR, Moore CG, Fritz JM, Wisniewski SR, Josbeno DA, et al. Surgery versus nonsurgical treatment of lumbar spinal stenosis: a randomized trial. Ann Intern Med. 2015;162:465-73. [PMID: 25844995]. doi:10.7326/M14-1420 LinkGoogle Scholar4. Liao JM, Stack CB. Annals understanding clinical research: implications of missing data due to dropout. Ann Intern Med. 2017. [Epub ahead of print]. doi:10.7326/M17-0195 LinkGoogle Scholar5. Hernán MA, Hernández-Díaz S. Beyond the intention-to-treat in comparative effectiveness research. Clin Trials. 2012;9:48-55. [PMID: 21948059] doi:10.1177/1740774511420743 CrossrefMedlineGoogle Scholar6. Little RJ, Rubin DB. Causal effects in clinical and epidemiological studies via potential outcomes: concepts and analytical approaches. Annu Rev Public Health. 2000;21:121-45. [PMID: 10884949] CrossrefMedlineGoogle Scholar7. Skrondal A, Rabe-Hesketh S. Generalized Latent Variable Modeling: Multilevel, Longitudinal, and Structural Equation Models. Boca Raton, FL: CRC Pr; 2004:427-32. Google Scholar8. Dunn G, Maracy M, Dowrick C, Ayuso-Mateos JL, Dalgard OS, Page H, et al; ODIN group. Estimating psychological treatment effects from a randomised controlled trial with both non-compliance and loss to follow-up. Br J Psychiatry. 2003;183:323-31. [PMID: 14519610] CrossrefMedlineGoogle Scholar9. Toh S, Hernán MA. Causal inference from longitudinal studies with baseline randomization. Int J Biostat. 2008;4:Article 22. [PMID: 20231914] doi:10.2202/1557-4679.1117 CrossrefMedlineGoogle Scholar10. Hernán MA, Hernández-Díaz S, Robins JM. Randomized trials analyzed as observational studies. Ann Intern Med. 2013;159:560-2. [PMID: 24018844] AbstractGoogle Scholar Author, Article, and Disclosure InformationAffiliations: From University of Pennsylvania and American College of Physicians, Philadelphia, Pennsylvania, and University of Mississippi Medical Center, Jackson, Mississippi.Acknowledgment: The authors thank the Annals senior clinical and statistical editors for their input and review of earlier drafts of the manuscript.Disclosures: Authors have disclosed no conflicts of interest. Forms can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M17-0196.Corresponding Author: Joshua M. Liao, MD, Department of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104; e-mail, [email protected]med.upenn.edu.Current Author Addresses: Dr. Liao: Department of Medicine, University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104.Dr. Stack: American College of Physicians, 190 N. Independence Mall West, Philadelphia, PA 19106-1572.Dr. Griswold: Department of Data Science, University of Mississippi Medical Center, New Guyton Suite G651, 2500 North State Street, Jackson, MS 39216.Dr. Localio: Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine, University of Pennsylvania, 635 Blockley Hall, 423 Guardian Drive, Philadelphia, PA 19104.Author Contributions: Conception and design: J.M. Liao, C.B. Stack, M.E. Griswold.Drafting of the article: J.M. Liao, C.B. Stack, M.E. Griswold, A.R. Localio.Critical revision for important intellectual content: J.M. Liao, C.B. Stack, M.E. Griswold, A.R. Localio.Final approval of the article: J.M. Liao, C.B. Stack, M.E. Griswold, A.R. Localio.Statistical expertise: C.B. Stack, M.E. Griswold, A.R. Localio.This article was published at Annals.org on 14 March 2017. 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