Objective: To determine the clinical course and optimum treatment of human immunodeficiency virus (HIV)-associated myositis.
Methods: Sixty-four patients attending a county outpatient HIV/acquired immunodeficiency syndrome facility were referred for the presence of elevated creatine kinase (CK) levels or muscle weakness. Patients underwent neurologic and rheumatologic evaluation, electromyography, and muscle biopsy after exclusion for recreational drug or alcohol use, metabolic/endocrine disorders, zidovudine therapy, and other infections.
Results: Thirteen patients (20%) had biopsy-proven myositis. The median duration of HIV infection prior to diagnosis of myositis was 4.3 years (range 0-11 years). Six patients had concomitant diffuse infiltrative lymphocytosis syndrome. There was no correlation of severity of weakness, stage of HIV infection, or retroviral treatment with the CK level at diagnosis. Eight patients received prednisone (60 mg/day) with 5 attaining complete resolution of myositis. The remaining 3 patients received immunosuppressive therapy (azathioprine or methotrexate and intravenous immunoglobulin) and had normalization of strength and CK. Four patients had spontaneous resolution of their myositis without treatment.
Conclusion: HIV-associated myositis occurs at any stage of HIV infection, has a relatively good prognosis, responds well to immunosuppressive therapy, and has little evidence of adverse outcome on the HIV infection.