The Intention-to-Treat Principle

JAMA Guide to Statistics and Methods | July 2, 2014

The intention-to-treat (ITT) principle is a cornerstone in the interpretation of randomized clinical trials (RCTs) conducted with the goal of influencing the selection of medical therapy for well-defined groups of patients. The ITT principle defines both the study population included in the primary efficacy analysis and how the outcomes are analyzed. Under ITT, study participants are analyzed as members of the treatment group to which they were randomized regardless of their adherence to, or whether they received, the intended treatment.1– 3 For example, in a trial in which patients are randomized to receive either treatment A or treatment B, a patient may be randomized to receive treatment A but erroneously receive treatment B, or never receive any treatment, or not adhere to treatment A. Read More