US scientists are trying to answer a question that has long nagged doctors and patients alike: which treatment works best for a given illness?

The US National Institutes of Health will support studies toward an answer, thanks to $400 million it received from the economic stimulus package to support research for the next two years on the comparative effectiveness of treatment options for a range of diseases from Alzheimer's to asthma. Such research may, for instance, compare competing drugs or explore the benefits of surgery versus drug therapy. The US Agency for Healthcare Research and Quality and the Department of Health and Human Services will also receive comparable amounts to support comparative effectiveness research.

“The [initiative] will have a tremendous impact on biomedical research in the United States,” says Elizabeth Nabel, director of the US National Heart, Lung and Blood Institute. “Our goal is to provide patients, physicians and health care providers evidence-based information to make informed decisions about health care.”

Karen Smith, a spokesperson for the drug giant AstraZeneca, stresses that there is already ongoing drug industry research on comparative effectiveness. “You can take any product that's either on the market or in development and say there is an element of comparative effectiveness research that's ongoing not only before but also after we launch it,” she says.

But Jerry Avorn, a Harvard Medical School researcher and frequent critic of the pharmaceutical industry, says the government initiative is crucial because drug makers don't always publicize negative findings relating to their bestsellers.

“Had we had comparative testing in the past, several blockbusters would have turned out not to be worthy of their blockbuster status,” says Avorn, referring to the arthritis drug Vioxx and the diabetes drug Avandia as two examples. “We learned belatedly that those blockbusters were not only no better but also far less safe than comparable drugs in their class.”