Intention to treat (ITT) analysis

Intention-to-treat (ITT) analysis is a method used in clinical trials where participants are analyzed based on their initial treatment assignment, regardless of whether they completed the treatment or switched to a different one. This approach is widely regarded as the standard for clinical trial analysis because it provides an unbiased comparison across treatment groups.

The importance of ITT analysis stems from its ability to maintain the benefits of randomization. If cross-overs or drop-outs from the trial are non-random and imbalanced between groups—potentially related to characteristics of the new intervention—comparisons based on the treatment actually received (known as ‘On Therapy’ or OT analysis) can suffer from bias. ITT analysis mitigates this risk by including all participants as originally allocated, preserving the initial randomization.

When incorporating efficacy results from trials into economic models, it is crucial to select the appropriate efficacy values (either ITT or OT) from the source studies. This is especially important if the model explicitly considers movements between treatment groups of cohort members. A useful validation check for the economic model is to assess how well it replicates the results of the original source study, ensuring that the chosen analysis method accurately reflects the trial’s findings.