A commercially available genetic test can identify patients likely to be more susceptible to statin myopathy and guide physician prescription choices to encourage adherence.

Findings from a multi-site study known as SLCO1B1 Genotype Informed Statin Therapy—directed by Duke cardiologist Deepak Voora, MD, director of the Center for Genomics & Precision Medicine—suggest that using genetic tests to guide statin prescribing lowered cholesterol in primary care patients with a history of myopathy compared to a strategy that does not incorporate the testing.

For nearly a decade, researchers have been aware of the genetic variant that predisposes patients to statin side effects. Approximately 15% of patients have the variant SCLO1B1, which reduces the ability of liver to to carry statins out of the blood. As a result, more of the drug remains in the body with higher concentrations reaching the muscles.

The causal effect of statins on muscle toxicity remains unproven, Voora cautions. In 1-to-2% of patients taking statins, evidence of muscle myopathy can be identified in blood tests. But physicians must repeatedly encourage statin use among patients reporting frequent muscular pain, stiffness and weakness. The symptoms associated with statins, Voora says, are in many patients “probably due to misattribution of non-specific conditions” common among patients in this age group likely to require cholesterol lowering therapy. 

“Our motivation with this research is to get patients who should be taking statins but can’t or won’t because of these muscle symptoms to begin taking them again," Voora says.

Presented during the scientific sessions of the American Heart Association (AHA) meeting in 2017, the randomized controlled trial involved primary care patients at Duke Health and Travis Air Force Base in California. Half of the patients received genetic testing to identify susceptibility to muscle myopathy. The tests were performed in the Duke Molecular Pathology Laboratory but are also available commercially.

Prior research identified the statins most affected by the genetic variant. Users of simvastatin experience higher concentrations of statins in muscle tissue and are more susceptible to myopathy. Atorvastatin users demonstrated similar effects but to a lesser extent. Other commonly prescribed statins—rosuvastatin, pravastatin and fluvastatin—appeared to be relatively immune to the effects of the variant.

Cardiologists encourage statin use as a lifetime therapy to reduce cholesterol. “For most patients, there is no reason to stop taking statins because their risk for cardiovascular disease do not go away,” Voora says. “If they do stop the drug, the patients will have a higher risk of cardiovascular disease due to higher cholesterol levels.”