Invited article: comparative effectiveness research, evidence-based medicine, and the AAN.

Comparative effectiveness research (CER) is the study of the relative effects of treatments to determine which will be most likely to improve overall health for a specific condition. This area has received a great deal of political focus, and substantial funding for CER is included in the American Reinvestment and Recovery Act of 2009. The results of CER are intended to inform evidence-based guidelines and to improve the quality and effectiveness of medical care. In the absence of such research, guidelines often depend on consensus to rank available therapies. We believe that an increase in CER would clearly enhance evidence-based guidelines. However, the research must be performed and analyzed with great care to avoid reaching unhelpful, or even harmful, conclusions. Specifically, individual patient characteristics must be taken into account, study endpoints must approximate the most important patient outcomes, therapies must be used optimally within the studies, and the most relevant therapies for a given indication must be included for comparison. CER that is not performed or interpreted correctly could have the potential to affect negatively our choices of therapies. The neurology community must help inform the process of CER to ensure the highest-quality research, which in turn will result in the most valid outcomes.