The study demonstrated that muscle pain or weakness is common in adults, regardless of whether they take a statin tablet or not. 14 out of 15 reported cases of muscle pain or weakness were not due to statin therapy, and those cases that were due to statins occurred mainly within the first year of treatment.
The researchers gathered together data from 23 large-scale randomised studies from the Cholesterol Treatment Trialists’ Collaboration, including information from almost 155,000 individuals. They used this information to assess the effect of statin treatments on the frequency of muscle-related symptoms across many different types of patient, and found that muscle symptoms such as muscle pain or weakness were common, even in those allocated a placebo (or dummy) tablet. In 19 trials of statin therapy versus placebo, similar numbers of people reported such symptoms (16,835; 27.1%) in the statin group and (16,446; 26.6%) in the placebo group.
They also found that statin treatments marginally increased the frequency of muscle-related symptoms. In those taking statins, about 14 out of 15 reports of muscle symptoms were not attributed to statins, falling to about 9 in 10 for patients taking a high intensity treatment. This means that statins are not the cause of muscle pain in over 90% of people who report symptoms.
Most of the reports of muscle symptoms in those taking statins occurred within the first year of treatment. After the first year of starting treatment, low/moderate intensity statin therapy caused no increase in the frequency of muscle symptoms.
Higher intensity statin treatments (those designed to produce greater reductions in low‑density lipoprotein (LDL) cholesterol) were more likely than low/moderate intensity statins to increase the risk of muscle symptoms with some persistent effect after the first year. (Overall low/moderate intensity regimens yielded a 3% increase in first reports, with higher intensity regimens resulting in an 8% increase in first reports.) There was no evidence of a relationship between the statin dose and muscle symptoms.
For every 1000 people taking a moderate intensity statin, the treatment would cause 11 (generally mild) episodes of muscle pain or weakness. This means that the slightly increased risk of muscle symptoms is greatly outweighed by the previously known benefits of statin therapy in preventing cardiovascular disease, including heart attacks and strokes. For example, for every 1000 people taking a moderate intensity statin, the treatment would typically prevent 50 major vascular events (such as heart attacks and strokes) in those with pre-existing vascular disease (secondary prevention), and 25 major vascular events if used for primary prevention.