The principle of intention-to-treat (ITT) has become the standard policy for comparing treatment and control groups in clinical studies. Yet, ITT is not without its critics, controversies, and misunderstandings. To properly judge results reported from clinical studies, it is imperative that pharmacists be able to assess the underlying assumptions and the methodological issues associated with ITT. This article will provide an exposition of the history, assumptions, definitions, methodology, and controversies of ITT.
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