Introduction Anti-HMG-CoA Reductase (anti-HMGCR) antibodies are associated with an immune-mediated necrotising myopathy related to previous ‘statin’ use. The role of this antibody in pathogenesis is incompletely understood.

We have thoroughly characterised a cohort of anti-HMGCR associated myositis patients to increase understanding of the role of this antibody.

Methods We identified patients, as part of the UKMYONET cross-sectional myositis study, with anti-HMGCR antibodies and obtained further clinical, serotypic (Immunoprecipitation and ELISA) and genetic data (HLA Imputation using SNP2HLA) for analysis.

Results Anti-HMGCR antibodies were observed in 2.7% (37/1379 patients) of the UKMYONET database. The predominant reported clinical diagnoses in these patients were polymyositis (21/37) and statin associated myositis (7/37). A positive anti-HMGCR antibody was associated with: HLA-DRB1*11 (53.8% vs 9.9% in anti-HMGCR negative patients, p=0.01), previous statin exposure (31.4% vs 28.6% p=0.032), and higher median peak-creatine kinase (6945.5U/L vs 1159.0U/L, p=0.001). The frequency of anti-HMGCR antibody positivity in the UK appears lower than that seen in other international cohorts (although this may be dependent on the type of patients targeted for collection).

Conclusion The relationship between anti-HMGCR positivity, HLA-DRB1*11 and statin exposure confirms observations made in other international cohorts. Work is on going to characterise symptomatology, disease association and treatment response.