In a cross-sectional survey, the prevalence of hypertension is compared between rural and urban populations after age-standardisation using the same reference population. The technique of age-standardisation is used to control for which type of variable?

• A Confounding variable ✓
• B Effect modifier
• C Intermediate variable
• D Precision variable

Explanation

Age-standardisation (direct or indirect) is applied when comparing rates across populations with different age structures, because age is a confounder (associated with both the exposure—urban/rural residence—and the outcome—hypertension). Standardisation mathematically removes the confounding effect of age without restricting the analysis to a single age group. Effect modification would require stratified reporting, not standardisation. Intermediate variables lie on the causal pathway and should not be adjusted.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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