Management of HMG-CoA Statin-Induced Autoimmune Myositis: A Case Study

Summary: Background: Statins, widely prescribed for hyperlipidemia, rarely induce autoimmune myositis, posing significant challenges in diagnosis and management. The incidence and prevalence of statin-induced autoimmune myositis remain poorly defined, with limited guidelines for its management. Previous treatment regimens typically involve corticosteroids, intravenous immunoglobulin (IVIG), and immunosuppressive agents, with varying success rates. The sensitivity and specificity of HMG-CoA antibody positivity in diagnosing this condition highlight its utility as a diagnostic marker. Case Presentation: The patient is a 49-year-old African-American female, experienced muscle weakness attributed to HMG-CoA statin-induced autoimmune myositis. Initially managed with IVIG, methotrexate (MTX) intramuscular therapy, and a steroid taper, she achieved partial remission. After completing the course of IVIG and prednisone taper, six months later, she experienced a recurrence of symptoms and elevation of creatine kinase (CK) levels. This necessitated repeated IVIG dosing and a switch from MTX to mycophenolate mofetil therapy for disease control. MRI findings of diffuse myositis of the right thigh, including edema and inflammatory changes, supported the clinical suspicion, prompting therapeutic initiation without biopsy. Management: Despite initial treatment with prednisone and IVIG, the patient's clinical course was characterized by recurrence of symptoms and re-elevation of CK levels six months later. This necessitated a second round of IVIG dosing to address the persistent disease activity. Transitioning to mycophenolate mofetil therapy resulted in a significant clinical improvement, albeit with challenges in achieving sustained remission. Regular monitoring of CK levels and vitamin D status guided therapeutic adjustments. Physical therapy interventions were integral in addressing persistent muscle weakness and functional impairment. Outcome: The management approach involving IVIG, MTX, and steroids initially provided symptomatic relief but was associated with disease recurrence. Transitioning to mycophenolate mofetil therapy resulted in better disease control, emphasizing the importance of individualized treatment strategies in autoimmune myositis. Conclusion: Statin-induced autoimmune myositis presents diagnostic and therapeutic dilemmas due to its rarity and complex pathophysiology. Early recognition of clinical features, alongside judicious use of diagnostic modalities such as MRI and serological testing, is paramount. Multimodal management strategies, including immunosuppressive therapy and physical rehabilitation, are crucial for optimizing outcomes in these patients. Further research and collaboration are needed to establish standardized management protocols and improve long-term prognosis in this challenging condition.