Vioxx was a blockbuster drug. Launched by Merck & Co., Inc., in 1999 as a treatment for painful arthritis, its annual sales soon reached $2 billion. The benefits were much the same as other anti-inflammatory painkillers, which sold for a fraction of the cost, but Vioxx (the generic name is rofecoxib) was designed to be less irritating to people's stomachs than older drugs in this class, cutting the risk of potentially dangerous internal bleeding. A multi-million dollar advertising budget didn't hurt its popularity either.

The success story came to an abrupt end in 2004, when Merck voluntarily pulled Vioxx from the market. A large trial had been stopped early when it became obvious that the drug was increasing the risk of heart attacks and strokes. In 2007, Merck agreed to pay $4.85 billion to settle thousands of lawsuits brought by people claiming to have been harmed by Vioxx.

The litigation over Vioxx has meant the release of some previously unpublished trials, which have now been analyzed by researchers. The researchers—who have all acted as consultants for patients taking legal action against Merck—wanted to know whether, if the trial data had been available earlier and analyzed on an ongoing basis, we could have discovered the risks of Vioxx sooner.