An initial triple steroid/intravenous immunoglobulin (IVIG)/steroid-sparing immunosuppressant (SSI) induction strategy was effective for the treatment of statin-induced anti-3-hydroxy-3-methyl-glutaryl-coenzyme A reductase (anti-HMGCR) myopathy, according to study results published in Arthritis Research & Therapy. In addition, early treatment initiation was associated with greater odds of successful maintenance with SSI monotherapy.
Investigators abstracted data from the Phenotype, Serology, and Successful Monotherapy Maintenance in Autoimmune Myositis (PHESMO) study, a retrospective study of patients with autoimmune myositis who received care at 2 participating hospitals in Quebec, Canada. Patients were followed up longitudinally between 2001 and 2018. The current analysis used data from patients with statin-induced anti-HMGCR myopathy, defined as having a positive anti-HMGCR autoantibody test, elevated serum creatine kinase levels, and proximal skeletal muscle weakness. Demographic and clinical data were extracted through medical record review, and therapeutic strategies used to combat anti-HMGCR myopathy were assessed. Multivariate logistic regression was performed to identify predictors of maintenance with SSI monotherapy. Sensitivity analyses adjusted for age, sex, strength, creatine kinase levels, dysphagia, and corticosteroid use.
Data from 55 patients with anti-HMGCR myopathy were used for the study. Median age at diagnosis was 67.7 years; 95% of patients were white; and 72% had diabetes mellitus. The most commonly prescribed statin was atorvastatin (84%). Statin therapy was discontinued in all patients. At initiation of anti-HMGCR myopathy treatment, 46 patients (84%) presented with proximal weakness, 48 (87%) had biopsy evidence of necrotizing myopathy, and all patients were positive for anti-HMGCR autoantibodies. Median creatine kinase elevation was 5000 U/L (range, 554-23,000 U/L).
Overall, 14 patients (25%) achieved remission with a corticosteroid-free induction strategy. The remaining 41 patients were treated with corticosteroids, either through dual steroid/SSI induction (n=19) or triple steroid/IVIG/SSI induction (n=22). A total of 4 patients failed the initial triple steroid/IVIG/SSI induction strategy, with all 41 patients achieving remission eventually. A corticosteroid-free SSI monotherapy maintenance strategy was successful in 73% of patients initially treated with corticosteroids.
Greater treatment delay predicted lower odds of successful maintenance with SSI monotherapy (odds ratio, 0.92; 95% CI, 0.85-0.97; P =.015). In patients with successful SSI monotherapy maintenance (n=23) vs those without (n=18), mean treatment delays were 1.7 months and 12.7 months, respectively (P =.048).
In addition, a significant percentage of patients presented with normal strength (n=22; 40%), suggesting that anti-HMGCR myopathy has diverse clinical presentations.
While corticosteroid-free induction was a safe option for select patients, initial induction with triple steroid/IVIG/SSI was highly efficacious in the treatment of anti-HMGCR myopathy. Success with SSI monotherapy appeared to favor early intervention. “[A]voiding delays in treatment, most notably in patients with normal strength, may reset the natural history of anti-HMGCR myopathy from a refractory entity to a treatable disease,” the investigators wrote.
Meyer A, Troyanov Y, Drouin J, et al. Statin-induced anti-HMGCR myopathy: successful therapeutic strategies for corticosteroid-free remission in 55 patients. Arthritis Res Ther. 2020;22(1):5.