Intention-to-treat analysis
- Analyze every participant as originally randomized, even if they did not receive or complete the assigned treatment.
- Prevents bias that can arise from participant non-adherence or dropout.
- Keeps comparison groups defined by the initial random assignment.
Definition
Section titled “Definition”Intention-to-treat (ITT) analysis is a statistical approach used in clinical trials to assess the effectiveness of a treatment. It involves analyzing the data of all participants in a trial, regardless of whether they received the treatment or not, or whether they completed the trial or not.
Explanation
Section titled “Explanation”In ITT analysis, outcomes are analyzed according to the groups to which participants were initially assigned at random. This includes participants who did not adhere to the assigned treatment, those who received a different treatment, and those who dropped out before trial completion. By preserving the original randomization in the analysis, ITT reduces bias that could result from post-randomization behaviors or attrition.
Examples
Section titled “Examples”Randomized controlled trial of a hypertension medication
Section titled “Randomized controlled trial of a hypertension medication”Participants are randomly assigned to a treatment group (new medication) or a control group (placebo). Some participants may not adhere to the assigned medication or may drop out. In an ITT analysis, data from all participants as initially assigned are included in the analysis, including those who did not take the medication or who dropped out.
Clinical trial of a therapy for depression
Section titled “Clinical trial of a therapy for depression”Participants are randomly assigned to a treatment group (new therapy) or a control group (placebo therapy). Some participants may not complete the full course of therapy or may stop due to side effects. An ITT analysis includes data from all initially assigned participants, even if they did not complete therapy or experienced side effects, to avoid bias from participant behavior or differential completion.
Use cases
Section titled “Use cases”- Evaluating the effectiveness of a treatment in clinical trials.
- Providing information for decision making in healthcare.
Notes or pitfalls
Section titled “Notes or pitfalls”- ITT ensures that trial results are not biased by participant behavior, such as non-adherence or dropout.
- Including all originally randomized participants preserves the benefits of randomization in the analysis.
Related terms
Section titled “Related terms”- Randomized controlled trial
- Treatment group
- Control group
- Placebo
- Adherence
- Dropout