A medical education committee is reviewing several published clinical studies to teach residents how to critically appraise medical literature. Match each specific study finding or methodological characteristic described below to the most appropriate epidemiological or statistical concept.
- An initial strong association between moderate alcohol intake and increased lung cancer risk becomes statistically non-significant after researchers mathematically adjust the data for concurrent tobacco smoking.Confounding
- A randomized controlled trial for a novel weight-loss medication reports outcomes only for patients who completed the full 12 weeks, excluding 30% of the intervention group who dropped out due to severe gastrointestinal side effects.Attrition bias
- A clinical study comparing surgical versus medical management for severe osteoarthritis assigns patients to the surgical arm if they present to the clinic on Mondays, and to the medical arm if they present on Tuesdays.Selection bias
- A new biologic agent demonstrates a significant reduction in asthma exacerbations among patients with high baseline eosinophil counts but shows no benefit in those with low eosinophils, yielding a significant p-value for interaction.Effect modification
Cevap
1 matches with Confounding; 2 matches with Attrition bias; 3 matches with Selection bias; 4 matches with Effect modification.
Confounding distorts the true association because a third variable is linked to both exposure and outcome. Attrition bias happens when non-random loss to follow-up skews final analysis. Selection bias occurs when treatment assignment is predictable, violating randomization. Effect modification reflects a true difference in clinical response based on a patient characteristic.
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Methodological flaws and epidemiological phenomena in study design
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