The incidence of anti-HMGCR immune-mediated necrotizing myopathy: an Australian and UK retrospective multi-site cohort study
Authors' conclusion
For the first time, we have calculated an incidence of anti-HMGCR IMNM using a large, multinational cohort. We highlight the refractory nature of anti-HMGCR IMNM.
Study context
- Population
- Adults (≥18 years) with anti-HMGCR immune-mediated necrotizing myopathy (IMNM) (ENMC criteria; 2018–2023), four cohorts: Manchester and Bristol (UK), Western Australia and South Australia51% female
- Participants
- 109 adults
- Exposure
- Statin-naïve vs statin-exposed anti-HMGCR IMNM
- Statin-naïven = 8
- Statin-exposedn = 101reference
- Outcome
- Incidence of anti-HMGCR IMNM
Methodological detailsmulticentre, multinational
- Multicentre
- Multinational
Main finding
As reported in the abstract
Mean annual incidence of anti-HMGCR IMNM
Mean annual incidence, cases/million person-years
2.9
Incidence in statin users, UK, cases/million statin-users/year
20.4
Incidence in statin users, Western Australia (WA)/South Australia (SA), cases/million statin-users/year
24.1
Observational data: associations, not effects.
Further findings
Age at diagnosis
P = 0.02
| Outcome | Statin-naïve | Statin-exposed | P value |
|---|---|---|---|
| Non-white ethnicity | 5/8 events | 20/77 events | P = 0.04 |
| Dysphagia | 4/8 events | 14/94 events | P = 0.03 |
Clinical characteristics, all cases
- Atorvastatin among statin-exposed
- 77/101, 76.2%
- Median statin duration before diagnosis, years (range 1 month-23 years)
- 3
- Median peak creatine kinase (CK), IU/l (range 964-39076)
- 7020
- Received IV immunoglobulin
- 48/105 (45.7%)
Normal CK and muscle power at follow-up · median follow-up 2.3 years [IQR 1.5-4.2]
- Normal CK
- 50/105 [47.6%]
- Normal muscle power
- 48/104 [46.2%]
Original publication
The incidence of anti-HMGCR immune-mediated necrotizing myopathy: an Australian and UK retrospective multi-site cohort study. Rheumatology (Oxford). Published 10 May 2025. doi:10.
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