Explain the concept of intention-to-treat analysis.

• A. Analyze participants based on their adherence to protocol
• B. Analyze participants based on their randomized group regardless of adherence to protocol, preserving randomization balance
• C. Analyze only those who completed protocol and adhered to it
• D. Reassign participants to groups based on actual treatment received

Answer: (B)

Intention-to-treat analysis means keeping every participant in the analysis in the group to which they were randomized, regardless of whether they actually followed the assigned treatment, dropped out, or switched treatments. This preserves the randomization that created comparable groups, so the comparison reflects the treatment’s effectiveness in a real-world setting where adherence isn’t perfect.

Why this approach is the best choice here: it avoids bias that happens when you exclude nonadherent participants or reassign people based on what they ended up receiving. Those decisions can be influenced by factors related to prognosis, side effects, or other differences that muddy the true effect of the intervention. By analyzing by randomized group, the groups stay balanced as created by randomization, which supports a fair comparison.

Other approaches that focus only on adherent participants or on the treatment actually received can distort results because the groups may no longer be comparable after randomization. Intention-to-treat keeps the integrity of the randomization while still addressing practical issues like missing outcomes through appropriate data-handling methods.