In a randomized controlled trial, allocation concealment refers to:
- A Blinding of patients to their treatment assignment during the trial
- B Randomization after all participants are enrolled simultaneously
- C The process that prevents investigators from knowing future group assignment before enrollment ✓
- D Stratified randomization to balance prognostic variables
Correct answer: C. The process that prevents investigators from knowing future group assignment before enrollment
Explanation
Allocation concealment prevents selection bias by ensuring that investigators enrolling participants cannot predict or know the future treatment allocation before the participant is enrolled. This is distinct from blinding (masking), which refers to keeping participants, investigators, or outcome assessors unaware of treatment assignment after enrollment. Inadequate allocation concealment allows investigators to selectively enroll patients likely to benefit from active treatment.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
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