Intention-to-treat analysis

Intention-to-treat analysis (ITT analysis) is a statistical approach used in randomized controlled trials. The ITT analysis includes every subject who is randomized according to randomized treatment assignment. It ignores noncompliance, protocol deviations, withdrawal, and anything that happens after randomization. ITT analysis is intended to avoid various misleading artifacts that can arise in intervention research such as non-random attrition of participants from the study or crossover.

History

The concept of ITT analysis was first introduced in the field of clinical trials in the 1970s. The principle behind this approach is to maintain the benefits of randomization, which is crucial in determining the efficacy of a treatment.

Principle

The principle of ITT analysis is that it includes all participants in the trial regardless of whether they completed or fully adhered to the treatment. This approach is based on the principle of randomization which assumes that every participant has an equal chance of being assigned to the treatment or control group.

Advantages

ITT analysis has several advantages. It preserves the random assignment of treatments, thus maintaining baseline comparability of treatment groups, and it reflects the pragmatic clinical question of the effect of treatment assignment, not of treatment completion.

Disadvantages

Despite its advantages, ITT analysis also has some limitations. It may underestimate the potential benefits of a treatment, as it includes participants who may not have fully adhered to the treatment. It also assumes that the reason for dropout is unrelated to the treatment, which may not always be the case.

Alternatives

Alternatives to ITT analysis include per-protocol analysis and as-treated analysis. Per-protocol analysis includes only those participants who completed the treatment originally allocated. As-treated analysis includes participants according to the treatment they actually received, rather than the one they were assigned to.

See also

• Clinical trial
• Randomized controlled trial
• Per-protocol analysis
• As-treated analysis