Objective:
Statin-associated autoimmune
myopathy (SAAM) is a rare adverse event characterized by progressive muscle symptoms despite discontinuation, requiring immunosuppressive therapy for remission. The objective of this review was to characterize SAAM, for timely detection, while examining the literature for effective treatment considerations. Methods: PubMed search was conducted from 2010 to 2020 was for relevant case series and studies of at least 8 patients displaying muscle discomfort or weakness, anti-HMGCR
antibodies, exposure to
statins, and biopsies consistent with SAAM. Results: Three case series and 3 case cohort studies identified 199 patients with SAAM. Exhibiting a mean age of 63.74 years, patients were more likely Caucasian (81%) and female (1.2X), and required a mean duration of 4.75 years before symptomatic. The presentation involved proximal
muscle weakness (94%), myalgias (37%) and
dysphagia (23%), accompanied by a mean
creatinine kinase of 6383 IU/L. Most patients (57%) required 2 or more immunosuppressive (IMS) agents to achieve 62% remission. After 2 years of treatment, 15% of patients without remission reported symptomatic improvement, while another 12% were refractory to treatment. Conclusion: Delayed onset of SAAM greater than 4 years from
statin initiation may create a low index of suspicion. However, progression of symptoms beyond 2 months from
statin discontinuation and positive anti-HMGCR
antibodies requires
immunosuppressive agents. Data and expert opinion support use of at least two IMS medications upon diagnosis for a minimum of 2 years.
Therapy success depends on timely recognition and initiation of IMS combinations to achieve earlier remission and symptomatic improvement.