Statins are not likely to be the cause of muscle pain in over 90 per cent of cases where a person takes these blood cholesterol-lowering drugs, according to the most comprehensive analysis of the risks to date published in The Lancet journal on August 29.

The researchers from the University of Oxford, UK noted that statin therapy is widely prescribed as effective prevention of cardiovascular disease, but there have been widespread concerns that statins may frequently cause muscle pain or weakness.

They looked at individual patient data to provide a more detailed analysis of the risk of muscle pain caused by statins than has previously been possible and concluded that this is low and does not outweigh the benefits of statin therapy.

"The idea that statins may cause frequent muscle pain has been a persistent belief among some patients and clinicians, however, our study confirms that the statin is rarely the cause of muscle pain in those taking statins," said Professor Colin Baigent, from the University of Oxford, and joint lead author of the study.

"These findings suggest that if a patient on statins reports muscle pain, then it should first be assumed that the symptoms are not due to the statin and are most likely due to other causes," Baigent said.

The researchers said statin therapy should continue until other potential causes have been explored. There is a need to revise the information in the medication label for statins to clarify that most muscle pain experienced during statin therapy is not due to the statins, they said.

The study analysed data from 155,000 patients from 23 trials of statin therapy. Each trial had over 1,000 patients and a follow-up time of over two years.

The researchers compared rates of muscle symptoms in the group undergoing statin treatment with the placebo group to calculate the proportion of symptoms directly caused by the statin therapy.

The study found that among 19 placebo-controlled trials with an average follow-up period of four years, 27.1 per cent of patients who were given statins reported muscle pain or weakness, compared to 26.6 per cent of those who were given the placebo.

During the first year of treatment, statin therapy produced a 7 per cent relative increase in muscle pain or weakness compared to placebo, suggesting that only one in 15 of these muscle-related reports by patients given statins were due to the statin, the researchers said.

The absolute excess risk of muscle symptoms due to a statin was 11 per 1,000 patients treated during the first year, they said. After the first year of treatment, there was no significant difference in reports of muscle pain or weakness between those given statins and those given the placebo.

"Our research shows that whilst people on statin therapy may develop muscle symptoms, it is important to note that people not on statins also commonly get such symptoms," said Christina Reith, Senior Clinical Research Fellow at Oxford Population Health and joint lead author of the study.

"For people on statins who do develop muscle symptoms, most of the time statins will not be the cause. We hope that these results will help doctors and patients to make informed decisions about whether to start or remain on statin therapy, bearing in mind its known significant benefits in reducing the risk of cardiovascular disease," Reith added.