What is the best way to reduce knee pain? Which cholesterol medicine will fend off heart disease better than the others? What is the most reliable test to diagnose cancer?

Physicians, patients and insurers confront questions like these every day, but often lack solid information about how one treatment approach might work compared to another. While many different treatments are effective, which is best is difficult to determine.

As part of the sweeping U.S. health system reform, a new emphasis is being placed on comparative effectiveness research (CER), which pits treatments against one another to determine the method that leads to the best results for patients.…