The proportion of patients who are intolerant to statins is far lower than previous estimates suggest, according to the world’s largest study of the issue.
According to the British Heart Foundation, an estimated 7-8 million adults in the UK take statins, which reduce the risk of heart attack and strokes. However, concerns around side-effects mean some people reduce their dose or stop taking them altogether.
Previous studies have estimated that the prevalence of statin intolerance may be as high as 50%, but new research drawing on data from more than 4 million people suggests it is likely below 10%.
Prof Maciej Banach of the Medical University of Łódź and the University of Zielona Góra in Poland, who led the work, said it had been known for some time that most cases of statin intolerance were down to patients’ expectations of side-effects as a result of information they had received from the internet, neighbours or other sources.
While the new research supports this view, Banach said it also shed light on characteristics of people who may be at risk of statin intolerance.
“Our analysis gives strong message for the physicians, that there are some risk factors and conditions that might increase the risk of statin intolerance that everyone should always take into account,” he said, adding that it could help to exclude other reasons for an apparent statin intolerance and help doctors to think about using alternative treatments or doses.
Writing in the European Heart Journal, Banach and colleagues report how they analysed data from 4,143,517 patients worldwide across 176 studies, including about 200,000 participants across 112 randomised control trials.
The team’s analysis involved several different definitions for statin intolerance, including symptoms bad enough for patients to stop taking the drugs, an inability to tolerate the drugs at the dose needed for their cardiovascular risk, or a rise in levels of certain biological molecules or muscle symptoms that come and go as the pills are started or stopped.
The results showed a prevalence of 9.1% when a range of definitions were considered, and as low as 5.9% under some individual definitions.
The team said statin intolerance was associated with a number of factors including being older, female, black or Asian, drinking alcohol, having diabetes, being obese, or taking certain medications such as calcium channel blockers.
The study adds to a growing body of evidence that statins have few side-effects. Research published last year revealed that statins are generally not behind the muscle aches and pains that persuade some people to ditch the drugs, while other studies have found that patients experience the same or fewer side-effects from taking statins than from placebo pills.
Riyaz Patel, a professor of cardiology at University College London and a consultant cardiologist at Barts Health NHS trust, who was not involved in the study, said one limitation was that the prevalence of side-effects differed between different types of studies. Indeed, while the prevalence of statin intolerance was almost 5% when randomised control trials alone were considered, it was 17% among observational studies.
Prof Liam Smeeth, of the London School of Hygiene and Tropical Medicine, said the higher levels in observational studies were possibly because of biases or factors such as the “drucebo” effect, where people expect side-effects when taking a certain drug. The authors noted, however, it was also possible randomised control trials underestimated the prevalence by excluding certain patients.
Nonetheless, Patel suggested the findings chimed with previous research. “Based on what we know about statin side-effects to date, the results are likely to be broadly valid, and indicate that we should not overestimate statin side-effects or be too quick to stop statins without due consideration,” he said.
Smeeth suggested the results should offer reassurance. “It is a reality that statins can cause symptomatic side-effects that can be quite bad. But they are relatively rare,” he said, adding that the drugs would be well tolerated by the vast majority of people.
“When you look at how effective and cheap [statins] are, reducing your risk of a heart attack by a third or more, it is a huge benefit.”
