Why distinguish specific drug vs drug class in exposure measurement?

• A. To simplify data
• B. To reduce confounding by indication
• C. To increase sample size
• D. To capture heterogeneity in effect

Answer: (D)

Distinguishing a specific drug from its class is about capturing heterogeneity in effect. Different drugs within the same class can have distinct pharmacologic properties, dosing patterns, or indications, leading to varying risks and benefits. If you only use the class as the exposure, you’re assuming every drug in that class has the same impact on the outcome, which can mask important differences. By measuring exposure at the individual drug level, you can identify which drugs are driving any observed association and estimate drug-specific effects, rather than averaging across drugs. For example, some NSAIDs or anticoagulants may carry higher or lower risks than others, so detailing the exact drug helps reveal true variation in effect. The other options don’t fit as well: distinguishing drugs does not simplify data or increase sample size (it often adds complexity or reduces per-drug counts), and while it can aid interpretation of differential effects, it’s not primarily a method for reducing confounding by indication.