Statins, the widely used cholesterol-lowering drugs, have few serious side effects, although they do slightly raise the risk of type 2 diabetes, according to a large new evidence review.
In the analysis of 135 previous studies, which included nearly 250 000 people combined, researchers found that the drugs simvastatin (Zocor) and pravastatin (Pravachol) had the fewest side effects in this class of medications. They also found that lower doses produced fewer side effects in general.
"As with any drugs, statins have both benefits and harms," said study lead author Huseyin Naci, a doctoral candidate at the London School of Economics and Political Science.
"We show that harmful side effects of statins are not common, and they are greatly outweighed by their benefits," said Naci, also a research fellow in the department of population medicine at Harvard Medical School in Boston.
Results of the study, which received no drug company funding, were released online July 9 in the journal Circulation: Cardiovascular Quality and Outcomes.
Statins are medications used to lower the amount of LDL cholesterol or "bad" cholesterol in your blood. LDL levels can be lowered through dietary changes and exercise, but many people find it difficult to maintain these lifestyle changes.
Moreover, statins may be useful for stabilising plaque in the blood vessels (plaque can break off and cause a heart attack or a stroke) and reducing inflammation, according to Dr Suzanne Steinbaum, a preventive cardiologist and director of Women and Heart Health at Lenox Hill Hospital in New York City. She was not involved with the new study.
In the analysis, the researchers reviewed data from randomized clinical trials, some of which compared statins to each other, while some compared statins to an inactive placebo pill. The average follow-up time for the studies included in the analysis was 1.3 years.
The review included data from the seven statins currently on the market. Atorvastatin (Lipitor), simvastatin and pravastatin were the most commonly used statins among participants.
Simvastatin and pravastatin had the best safety profile, according to this review.
Overall, the researchers found a 9% increased risk of type 2 diabetes in people taking statins. Naci said it's possible that statins may impair the secretion of insulin, although this study didn't examine potential mechanisms for why statins might increase diabetes risk.
"The slight increase in diabetes risk is greatly outweighed by the cardiovascular benefits of statins," he said.
Statins were not linked to any increase in the risk of cancer, according to the review. "There is conclusive evidence that statins do not raise cancer risk," Naci said.
The use of statins, particularly atorvastatin, was linked to an increase in liver enzyme irregularities. Naci said these blood test changes don't cause any symptoms, and are reversible when the drug is stopped. "If monitored closely, there is no cause for concern, and no specific precautions are warranted based on our study," he said. "Switching to a statin associated with fewer elevations may be appropriate."
The researchers also found that the higher the dose, the more likely people were to stop participating in a trial due to side effects.
"Side effects do tend to go up with higher doses," cardiologist Steinbaum said. "You want to use as little medication as possible, and combine the use of statins with lifestyle management. There's no medication that's a quick fix and a cure, but it's worth taking statins if you can manage the side effects."
She added that while simvastatin and pravastatin may have the most favourable side effect profiles. "They tend to be the least potent statins. The statins with the greatest effects tend to have the most side effects," Steinbaum said.
"Not all statins are the same," noted study author Naci. "Our study provides evidence that the side effect profiles of individual statins vary, which should be considered when making prescribing decisions."
Learn more about statins and cholesterol from the U.S. Food and Drug Administration.