What does intent-to-treat analysis involve?

What does intent-to-treat analysis involve?

• A. Only participants who fully adhered to the assigned intervention are analyzed
• B. Outcomes are analyzed according to the groups to which subjects were randomized, regardless of adherence
• C. Outcomes are analyzed by the groups that actually received the intervention
• D. The analysis excludes data from participants who did not complete the study

Answer: (B)

Intent-to-treat analysis preserves the benefits of randomization by analyzing participants in the groups to which they were randomized, regardless of whether they actually adhered to the assigned intervention. This means every randomized participant is included in the analysis and assigned to the original group, even if they didn’t follow the protocol or dropped out, which helps reflect how the intervention would work in typical practice and avoids biases from selective adherence. If you only include people who fully adhered to the assigned treatment, you’re performing a per-protocol analysis, which can bias results because adherence often relates to prognosis or other factors. If you analyze by the treatment actually received (as-treated), you also lose the balance created by randomization and can distort comparisons. Excluding those who didn’t complete the study similarly biases outcomes because it drops systematic differences between completers and non-completers.

Intent-to-treat analysis preserves the benefits of randomization by analyzing participants in the groups to which they were randomized, regardless of whether they actually adhered to the assigned intervention. This means every randomized participant is included in the analysis and assigned to the original group, even if they didn’t follow the protocol or dropped out, which helps reflect how the intervention would work in typical practice and avoids biases from selective adherence.

If you only include people who fully adhered to the assigned treatment, you’re performing a per-protocol analysis, which can bias results because adherence often relates to prognosis or other factors. If you analyze by the treatment actually received (as-treated), you also lose the balance created by randomization and can distort comparisons. Excluding those who didn’t complete the study similarly biases outcomes because it drops systematic differences between completers and non-completers.