A new Johns Hopkins review of 20 years’ worth of published research suggests that risks linked to long-term use of statins, including muscle toxicity, diabetes and dementia, are very low and that the potential benefit is very high. And although some experts say statins may be overprescribed, the new analysis could provide reassurance of the relative safety of the cholesterol-lowering drugs for the more than 200 million people worldwide who take them.

“For most at-risk patients,” says study author Chintan S. Desai, M.D., a clinical cardiology fellow at The Johns Hopkins Hospital, “the cardiovascular benefits far exceed the risks.”

Statins have been prescribed for decades to reduce the risk of heart attacks, stroke and hardening of the arteries, particularly among those who have already had these events in an effort to avoid a repeat cardiovascular occurrence. However, explains Desai, statins have gotten a bad rap in recent years, with some studies assigning a risk of adverse side effects from statins as high as 20 percent.

To get a better sense of statin effects throughout the body, Desai and his Johns Hopkins colleagues Seth S. Martin, M.D., a Pollin cardiology fellow, and Roger S. Blumenthal, M.D., director of the Johns Hopkins Ciccarone Center for the Prevention of Heart Disease and the Kenneth Jay Pollin Professor of Cardiology, combed through hundreds of papers citing research performed on statins since 1994 to search for evidence on side effects. They focused on randomized clinical trials, the gold standard for clinical research, to get the most accurate data. Individual clinical trials included middle- and older-aged adults, and pooled analyses of randomized trials included over 150,000 men and women followed for about five years.

Their review, published July 31 in BMJ, suggests only a modest increased risk of some side effects attributed to these drugs and no increased risk for others. For example, Desai says, the study roundup shows little evidence of muscle aches and pains with statins and only a small increase in the risk of muscle inflammation. A serious condition called rhabdomyolysis, a rapid breakdown of muscle tissue, was primarily associated with high statin dosage regimens that are no longer recommended.

The evidence review also found a modest increase in the risk of type 2 diabetes with statins. However, Desai says, that increase was only present among people who already had other risk factors for diabetes, raising the question of whether diabetes might have developed inevitably even without statin use.

The researchers found reassuring evidence regarding risks for dementia, blood clots, cataracts and fatigue. The review also suggested a modest protective effect of statins among those at risk for inflammation of the pancreas and contrast-induced nephropathy — kidney disease caused by the dye necessary for some imaging techniques.

Desai notes that future research should focus on what genetic and clinical factors might predispose the small minority of patients who experience serious side effects from statins.

This study was supported by the National Heart, Lung and Blood Institute (grant T32HL07024).