A study finds that both physical activity and fruit consumption are inversely associated with cardiovascular disease, and physically active people also tend to eat more fruit. This introduces a potential:

• A Confounding ✓
• B Effect modification
• C Reverse causality
• D Detection bias

Explanation

Confounding occurs when a third variable (fruit consumption) is associated with both the exposure (physical activity) and the outcome (CVD) without being on the causal pathway. This can distort the true association between physical activity and CVD. Effect modification (interaction) would mean the effect of physical activity on CVD differs by level of fruit consumption. Reverse causality refers to disease influencing the exposure.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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