And what about side effects? It's long been known that statins increase the risk of hemorrhagic strokes, muscle pain and other severe (but rare) muscle and liver complications. In February 2012 the U.S. Food and Drug Administration warned consumers that the drugs might also increase the risk of diabetes and memory loss. Nevertheless, the Lancet analysis suggests that the probability of these side effects is quite low; for instance, only one person out of every 2,000 treated will suffer a hemorrhagic stroke. "The benefits are substantially bigger than the hazards, even at very low levels of risk," Baigent says.
Yet some experts worry the findings underestimate true risk. According to Rita Redberg, a cardiologist at the University of California, San Francisco, and chief editor of the Archives of Internal Medicine, prior to the start of one of the trials included in the analysis, potential subjects were given statins for several weeks to see how well they tolerated them. If any individuals experienced side effects, they weren't invited into the trial. This type of prescreening is "not clean science," says Vinay Prasad, an internist at Northwestern University Feinberg School of Medicine, because it makes drugs look safer than they really are.
There is also the issue of funding and bias. Almost all of the trials included in the meta-analysis were funded in part by pharmaceutical companies, and some of the meta-analysis's co-authors have received honoraria from drug companies, too. Although these facts do not mean that the results are invalid, a 2003 study published in the British Medical Journal suggests that trials funded by drug companies are more likely to report favorable results about their products than are trials funded by independent organizations. "Asking industry to conduct its own studies is like asking a painter to judge his own work as to whether or not it should win an award," Prasad says. "It's another reason to be skeptical."
And even if the findings of the meta-analysis are accurate and the side effects are rare, "one should question whether it is cost-effective" to put millions of people on the drugs for a small potential benefit, says James Liao, an expert in vascular medicine at Brigham and Women's Hospital in Boston. Generic low-cost versions of the drugs are available—Walmart sells a month's supply of low-dose lovastatin for $4—but many consumers choose costlier brand name options. In 2011, for instance, Americans spent $4.4 billion on AstraZeneca's Crestor and $7.7 billion on Pfizer's Lipitor.
So should more healthy people take statins? Baigent argues that doing so could save millions of lives, because many heart attacks occur in people who are considered low-risk. But at what cost? "There are a lot of people taking statins who are not getting any benefits from them, and they're subject to a lot of adverse events," Redberg says.