A stratified analysis reveals that the association between smoking and lung cancer is 8.0 (OR) in men and 7.8 in women, with a Mantel-Haenszel pooled OR of 7.9. The sex-stratified ORs differ from the crude OR of 7.9 by <5%. This finding is most consistent with:

• A Effect modification by sex
• B Neither confounding nor effect modification by sex ✓
• C Confounding by sex with no effect modification
• D Negative confounding by sex

Explanation

When stratum-specific estimates are similar to each other AND to the crude estimate, sex is neither a confounder nor an effect modifier. Confounding is present when the crude OR differs meaningfully from the pooled adjusted OR; effect modification (interaction) is present when stratum-specific estimates differ substantially from each other. Here both conditions are absent.

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

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