Making policy when the evidence is in dispute.

Policymakers often struggle with medical issues that are the subject of fierce scientific debate. On closer examination, many of these debates are manifestations of conflicting perspectives and values as much as disagreements over the evidence. We summarize common factors underlying recent debates and outline a series of questions that can help disentangle questions of evidence from those of values. These questions focus on identifying the most important outcomes, evaluating the quality of evidence, and assessing the trade-offs involved. We then use four recent policy debates-involving prostate-specific antigen (PSA) screening, high-dose chemotherapy for breast cancer, antibiotic therapy for otitis media, and newborn hearing screening-to illustrate how this approach can help clarify areas of agreement and disagreement of the opposing sides.