Which of the following describes the Per Protocol Set's components?

• A. All randomized subjects
• B. Subjects who experienced adverse events
• C. Valid cases, efficacy sample, evaluable subjects
• D. Subjects with missing data

Answer: (C)

The Per Protocol Set includes participants who followed the study protocol as intended, with no major deviations and with complete, evaluable data for the efficacy analysis. This is why it’s described by terms like valid cases, efficacy sample, and evaluable subjects—the dataset is cleaned to reflect ideal adherence and complete endpoints.

This differs from the full randomized population, which is analyzed to preserve randomization and generalizability (intent-to-treat). It also isn’t about who had adverse events, since adverse events can occur in any adherent or non-adherent participant, and it typically excludes those with missing data, who cannot contribute to the efficacy analysis.