Science
Identifying people at risk of rare statins side-effects
Researchers we fund at the University of Oxford have published new findings that identify a combination of factors that put some patients at higher risk of myopathy, a rare side-effect of statin therapy. Myopathy is characterised by muscle pain or weakness in combination with high blood levels of creatine kinase, a marker of muscle damage.
The research, which is published today in The European Heart Journal , used data from nearly 60,000 people at high risk of heart attacks and strokes collected systematically during three large-scale clinical trials. Researchers analysed information on myopathy cases and reports of other muscle symptoms in patients who had been treated for an average of 3.4 years with simvastatin, one of the most commonly prescribed statins worldwide.
A rare side-effect
Myopathy was rare, occurring on average in only 1 per 1000 individuals during each year of statin treatment. There was a higher risk of myopathy in people on a higher statin dose, and in those who were older, female, of Chinese vs European ethnicity, had diabetes or lower body mass index, as well as those using certain other medications.
These predictors, when combined in a score, explained more than a 30-fold difference in risk of myopathy between patients in the top versus bottom third of the risk score. Genetic variation in the SLCO1B1 gene, which plays a role in the metabolism of statin drugs, also affected a person's susceptibility to myopathy.
By contrast, muscle-related aches and pains without elevated blood levels of creatine kinase were extremely common, being reported by more than 25% of individuals studied. However, neither the myopathy risk score nor the genetic variation in SLCO1B1 was associated with an increased risk of these common muscle symptoms. This finding is consistent with evidence from randomised placebo-controlled trials that indicates that statin therapy is not typically a cause of these symptoms.
Statins save lives
Professor Sir Nilesh Samani, our medical director, said: "Statins are important drugs for reducing the risk of heart attacks and strokes, and most people who take them do not experience side effects.
"‘This study identifies a number of patient-specific characteristics that increase the risk of developing muscle damage. These may now alert a doctor to either reduce the dose or consider alternative treatments in patients who have these factors.
"‘Apart from this rare side effect, there has been debate about whether statins cause more common muscle aches. Interestingly, this study found no evidence that the factors that affect the risk of muscle damage also increase risk of developing muscle aches, suggesting that the latter is probably not related to statins.
"This study should not in any way raise concerns in patients taking statins when their doctor thinks it will benefit them."