Effect modification (interaction) differs from confounding in that:
- A Effect modification can be adjusted for in the analysis, while confounding cannot
- B Effect modification means the exposure-outcome association differs across strata of a third variable, and this variation is a real biological phenomenon to be reported ✓
- C Effect modification is a nuisance to be removed, while confounding is a biological finding to be reported
- D Effect modification occurs only in randomised controlled trials
Correct answer: B. Effect modification means the exposure-outcome association differs across strata of a third variable, and this variation is a real biological phenomenon to be reported
Explanation
Effect modification (interaction) means the magnitude or direction of an exposure-outcome association genuinely differs in subgroups defined by a third variable; it is a true biological phenomenon that should be described and reported. Confounding is a bias caused by a common cause of exposure and outcome and should be controlled for. The two concepts are frequently confused but have fundamentally different implications.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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