I am an advanced trainee dual specialising in general and acute care medicine and rheumatology. This case series is from my time as a rheumatology registrar in Dunedin hospital. In 2018 I will be working in the Hutt hospital medical department to complete my training.
Statin-Associated Immune Mediated Necrotising Myopathy: A New Zealand Case Series Showing Possible Over-Representation In Pacific Islanders.
Michelle Woolley: Dunedin Hospital, Dunedin, New Zealand
Simon Stebbings: Dunedin Hospital and Department of Medicine - Dunedin school of Medicine, University of Otago, Dunedin, New Zealand
John Highton: Dunedin Hospital and Department of Medicine - Dunedin school of Medicine, University of Otago, Dunedin, New Zealand.
Background: Statin-associated immune-mediated necrotising myopathy (IMNM) is an emerging entity. Being an uncommon condition, our knowledge and understanding is largely based on case series.
Aims: To review incident cases of statin-associated IMNM associated with anti-HMGCR antibodies in a single New Zealand centre, over a two year period.
Methods: Four incident cases of statin-associated IMNM were seen between 2014 and 2016. Their presentation, investigation, treatment and current response to treatment are summarised. Two of the four patients were Pacific Islanders despite a small pacific island population in the southern district health board (SDHB). A literature search was performed focusing on the presentation, investigation and treatment of statin-associated IMNM and also genetic associations with this entity to determine whether Pacific Islanders may be at increased risk.
Results: All four patients presented with profound weakness and recent exposure to atorvastatin. All proceeded to muscle biopsy. Two biopsies showed typical IMNM. One biopsy had mild changes, reported as possibly being compatible with anti-HMGCR antibodies. The final biopsy had features consistent with IMNM, with some features suggestive of polymyositis. Two recent studies have shown an association between anti-HMGCR antibodies and the HLA-DRB1*11:01 haplotype.(1,2) Interestingly, HLA-DRB1 alleles (including HLA-DRB1*11:01) were observed to be among the most frequent alleles in a pacific island population study.(3)
Conclusion: This is the first case series of statin-associated IMNM with a focus on Pacific Islanders, and raises the possibility that Pacific Islanders exposed to statins may be at increased risk of developing an immune mediated myopathy.
1. Limaye V, Bundell C, Hollingsworth P, Rojana-Udomsart A, Mastaglia F, Blumbergs P, et al. Clinical and genetic associations of autoantibodies to 3-hydroxy-3-methyl-glutaryl-coenzyme a reductase in patients with immune-mediated myositis and necrotizing myopathy. Muscle and Nerve. 2015;52(2):196–203.
2. Mammen AL, Gaudet D, Brisson D, Christopher-Stine L, Lloyd TE, Leffell MS, et al. Increased frequency of DRB1*11:01 in anti-hydroxymethylglutaryl- coenzyme a reductase-associated autoimmune myopathy. Arthritis Care Res. 2012;64(8):1233–7.
3. Velickovic ZM, Delahunt B, Carter JM. HLA-DRB1 and HLA-DQB1 polymorphisms in Pacific Islands populations. Tissue Antigens [Internet]. 2002;59(5):397–406. Available from: http://www.ncbi.nlm.nih.gov/pubmed/12144623