The Patient Protection and Affordable Care Act of 2010 created the Patient-Centered Outcomes Research Institute (PCORI) to fund and promote comparative clinical effectiveness research (CER) that will “assist patients, clinicians, purchasers, and policy-makers in making informed health decisions by advancing the quality and relevance of evidence concerning the manner in which diseases, disorders, and other health conditions can effectively and appropriately be prevented, diagnosed, treated, monitored, and managed through research and evidence synthesis.”1 CER is not a new concept,2,3 but appreciation of its potential for providing patients and their clinicians with uniquely valuable information on what works, tailored to the clinical situation and to patient priorities, has increased rapidly in recent years.