In a randomised controlled trial, the analysis includes all patients as randomised regardless of whether they completed the protocol or switched treatment arms. This is called:

• A Intention-to-treat (ITT) analysis ✓
• B Per-protocol analysis
• C As-treated analysis
• D Modified intention-to-treat (mITT) analysis

Explanation

Intention-to-Treat (ITT) analysis includes all randomised participants in their assigned treatment group regardless of protocol deviations, crossover, or withdrawal. It preserves the protective value of randomisation against confounding and gives a conservative real-world estimate of efficacy (closer to effectiveness). Per-protocol analysis includes only those who completed the protocol as planned — potentially introducing selection bias. As-treated analysis groups patients by treatment actually received. ITT is the primary analysis recommended by CONSORT for superiority trials.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.