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CHICAGO (Reuters) - Taking a high-dose statin to lower cholesterol may increase risk of developing diabetes by as much as 12 percent, but the heart benefits of statins still outweigh the risks, new research shows.
Statins such as Pfizer's Lipitor are the world's best-selling drugs. They work by lowering levels of low-density lipoprotein, or LDL, the so-called "bad" cholesterol.
Doctors say the new research made public on Tuesday should not prompt any patients to stop taking statins, but patients on high doses of statins should get screened regularly for diabetes.
The findings on two of the biggest-selling statins may lead doctors to choose Lipitor when high doses are needed versus the less expensive, generic version of Merck & Co's Zocor.
While both drugs raise the risk of diabetes, high-dose Lipitor worked far better than generic Zocor at cutting heart risks, the team said.
Study after study has shown that taking statins can lower the risk of heart attacks and strokes, but some studies have suggested that the drugs may raise the risk of diabetes.
To see if dose is a factor, researchers from St George's, University of London and the University of Glasgow analyzed data from five different studies involving 32,752 patients who were treated with high and moderate doses of statins.
Over a five-year period, 2,749 participants, or 8.4 percent, developed diabetes, and 6,684 participants, or 20 percent, had a major heart problem.
"Overall, we found that high doses were associated with a 12 percent increased risk of diabetes compared with standard doses," Professor Kausik Ray of St George's said in an e-mail.
He said for every 498 patients treated there was one extra case of diabetes. But use of high-dose statins reduced risk of heart attacks, strokes, and the need for artery-clearing angioplasty by 16 percent.
For every 155 people treated, one of these heart problems was prevented, the team reported in the Journal of the American Medical Association on Tuesday.
"Nobody should stop taking their prescribed statins because of the evidence shown in this research," Professor Peter Weissberg of the British Heart Foundation, who was not involved with the study, said in a statement.
"Statins play a vital role in protecting the hearts of many, many people and the benefits still far outweigh any risks associated with diabetes," he said.
"Patients who need high doses of statins are at very high risk of heart attacks and strokes. They should not come off these drugs, but simply be monitored more closely." Ray said.
The team also compared rates of heart problems in people who took high doses of Zocor, available widely as the generic simvastatin and less costly than brand-name Lipitor.
Lipitor, or atorvastatin, had global sales last year of nearly $11 billion and is expected to lose U.S. patent protection at the end of November.
The risk of developing diabetes proved to be the same with both drugs. But high-dose Lipitor cut the risk of heart attacks and strokes by 22 percent, compared with a 5 percent reduction in heart risk among those who took simvastatin, Ray said.
He said the study shows high-dose simvastatin is not the best option.
"The net benefit of simvastatin is clearly very low and patients on simvastatin 80 mg should be moved to atorvastatin 80 mg instead," Ray said. "I don't think we can wait for loss of (Lipitor's) patent to stop using simvastatin 80 mg," Ray said in an email.
Currently, the National Institute for Health and Clinical Excellence, Britain's health cost watchdog, recommends an 80 mg dose of simvastatin because it is the least costly option for patients with heart disease.
U.S. health regulators earlier this month recommended limiting the 80 mg dose of simvastatin because it increases the risk of muscle damage.
An estimated 2.1 million patients in the United States were prescribed a product containing 80 mg of simvastatin in 2010, according to the U.S. Food and Drug Administration.
Editing by Michele Gershberg and Jackie Frank