ArticleRMD open2026
Epidemiology of idiopathic inflammatory myopathies: a population-based cohort in England, 2002-2021.
Article in RMD open, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
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Authors and funding
10 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
objectiveIdiopathic inflammatory myopathies (IIM) are a heterogenous group of conditions with substantial morbidity but population-based epidemiology is lacking. We aimed to provide a contemporary epidemiological assessment of IIM.
methodsPopulation-based study using the Clinical Practice Research Datalink (CPRD) Aurum primary care database with linkage to hospital episode data. All patients (aged >2 years) from England registered between 1 March 2002 and 31 March 2021 were included. Incidence was estimated for three main IIM subtypes: dermatomyositis (DM), inclusion body myositis (IBM) and other IIM. Incidence rate ratios using Poisson models were compared across subgroups.
resultsWe identified n=1590 DM, n=432 IBM and n=2083 other IIM incident cases. Incidence of DM was 0.79 (95% CI 0.75 to 0.83), IBM 0.50 (95% CI 0.46 to 0.55) and other IIM 1.03 (95% CI 0.99 to 1.08) per 100 000 person-years.Females had a higher incidence of DM (adjusted incidence rate ratio (aIRR) 1.84, 95% CI 1.66 to 2.04) and other IIM (aIRR 1.09, 95% CI 1.00 to 1.19), but a lower incidence of IBM (aIRR 0.73, 95% CI 0.60 to 0.89), compared with males. South Asian, black, other and unknown ethnic groups had a higher incidence of DM and other IIM compared with those of white ethnicity, particularly individuals of black ethnicity for other IIM (aIRR 2.80, 95% CI 2.32 to 3.37).Point prevalence at study end was 0.015% for DM, 0.005% for IBM and 0.016% for other IIM.
conclusionThere are major demographic differences in IIM incidence, notably by sex and ethnicity. Resource planning should account for these marked differences.
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