Fixing Misallocation with Guidelines: Awareness vs. Adherence

Expert decisions often deviate from evidence-based guidelines. If experts are unaware of guidelines, dissemination may improve outcomes. If experts are aware of guidelines but continue to deviate, promoting stricter adherence has ambiguous effects on outcomes depending on whether experts have information not in guidelines. We study guidelines for anticoagulant use to prevent strokes among atrial fibrillation patients. By text-mining physician notes, we identify when physicians start using guidelines. After mentioning guidelines, physicians become more guideline-concordant, but adherence remains far from perfect. To evaluate whether nonadherence reflects physicians’ superior information, we combine observational data on treatment choices with machine learning estimates of heterogeneous treatment effects from eight randomized trials. Most departures from guidelines are not justified by measurable treatment effect heterogeneity. Promoting stricter adherence to guidelines could prevent 24% more strokes, producing much larger gains than broader guideline awareness.