Differential dropout and bias in randomised controlled trials: when it matters and when it may not

Creator	Horton, Nicholas J.
Creator	Bell, Melanie L.
Creator	Kenward, Michael G., 1956-
Creator	Fairclough, Diane Lynn
Title	Differential dropout and bias in randomised controlled trials: when it matters and when it may not
Abstract	Dropout in randomised controlled trials is common and threatens the validity of results, as completers may differ from people who drop out. Differing dropout rates between treatment arms is sometimes called differential dropout or attrition. Although differential dropout can bias results, it does not always do so. Similarly, equal dropout may or may not lead to biased results. Depending on the type of missingness and the analysis used, one can get a biased estimate of the treatment effect with equal dropout rates and an unbiased estimate with unequal dropout rates. We reinforce this point with data from a randomised controlled trial in patients with renal cancer and a simulation study.
Publication Date	January 21, 2013
Identifier (DOI)	10.1136/bmj.e8668
Citation	Bell, Melanie L., et al. "Differential Dropout and Bias in Randomised Controlled Trials: When it Matters and When it May Not." BMJ 346 (2013):e8668.
Languages	English
Edition	Published Version
Genre	Articles
Subject	Statistics
Subject	Research--Statistical methods
Part of	The Amherst College Octagon
Repository	The Amherst College Octagon
Access and Use	Creative Commons Attribution-NonCommercial-NoDerivatives license (CC BY NC ND 4.0)