Madison, WI - Myopathy associated with statin use is generally self-limiting, with a benign clinical outcome, a new retrospective observational analysis shows [1].

Dr Karen E Hansen (University of Wisconsin Medical School, Madison) and colleagues reviewed 45 cases of statin-associated myopathy from more than 13 years of inpatient and outpatient data at their hospital to define the clinical course of the complaint. They report their findings in the December 26, 2005 issue of the Archives of Internal Medicine.

"This is the largest case series to date," Hansen told heartwire, "and it gives a little more perspective on this side effect." Hansen—who is a rheumatologist—said she was inspired to do the study by a patient who had rhabdomyolysis due to statin myopathy. When he asked her what was going to happen to him, she wasn't sure. "The literature to date has tended to focus on the more dramatic cases," she notes.

Hansen et al say that although risk factors for the development of statin-associated muscle pain are known—including coexisting diseases associated with rhabdomyolysis, such as renal insufficiency, and the use of concomitant medications that interfere with statin metabolism or independently cause myositis—"the natural course of myopathy in clinical practice is unknown."

They found that every patient who discontinued statin therapy experienced rapid resolution of muscle pain, typically within a month of stopping treatment. Six (13%) of the 45 patients were hospitalized for the management of rhabdomyolysis—two had reversible renal dysfunction and one who had preexisting renal insufficiency began lifelong dialysis. There were no deaths.

More than half of the 45 patients described their muscle pain as severe and, when limb pain was reported, the pain was most commonly noted to be diffuse and in both limbs. Patients with clinically significant myopathy were older than those without this degree of myositis, and rhabdomyolysis was most commonly associated with the use of coexisting medications known to increase its risk.

"I think the problem of concomitant medications that increase the risk of statin-associated myopathy is missed quite a lot," Hansen comments.

More than 80% of patients went on to receive another statin, "which is reassuring," she says. However, more than half of these patients experienced recurrent muscle pain. Because this was a small study, it wasn't possible to identify predictors of intolerance to multiple statins, the researchers note. Nor can the study be used to assess the incidence of myopathy with each individual statin (simvastatin, atorvastatin, cerivastatin, pravastatin, fluvastatin, or lovastatin), they state.