What role can rigorous observational comparative effectiveness studies play in guiding clinical decision making? What criteria should be used in determining whether the results of such studies should be communicated to clinicians and to patients? We address these questions by considering two hypothetical observational studies in patients with migraine against the backdrop of the review criteria drawn up by the Patient-Centered Outcomes Research Institute (PCORI). These criteria emphasize that patient-centered comparative effectiveness research should exhibit relevance to patients, have great potential to affect practice and improve outcomes, and be conducted using rigorous analytic methods. We conclude that these hypothetical studies would be unlikely to have been funded or communicated by PCORI, and we offer suggestions for improving their relevance and analytic approaches. We also conclude that high-quality observational studies can effectively complement findings from randomized trials, and that communicating their results to patients and clinicians is warranted.