{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T13:04:40Z","timestamp":1784120680038,"version":"3.55.0"},"reference-count":51,"publisher":"BMJ","issue":"3","license":[{"start":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T00:00:00Z","timestamp":1784073600000},"content-version":"unspecified","delay-in-days":14,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"DOI":"10.13039\/100004319","name":"Pfizer","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100004319","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["RMD Open"],"accepted":{"date-parts":[[2026,6,17]]},"published-print":{"date-parts":[[2026,7]]},"abstract":"<jats:sec>\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>Idiopathic 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.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Population-based study using the Clinical Practice Research Datalink (CPRD) Aurum primary care database with linkage to hospital episode data. All patients (aged &gt;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.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>We identified n=1590\u2009DM, 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\u2009000 person-years.<\/jats:p>\n                    <jats:p>Females had a higher incidence of DM (adjusted incidence rate ratio (aIRR) 1.84, 95%\u2009CI 1.66 to 2.04) and other IIM (aIRR 1.09, 95%\u2009CI 1.00 to 1.19), but a lower incidence of IBM (aIRR 0.73, 95%\u2009CI 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%\u2009CI 2.32 to 3.37).<\/jats:p>\n                    <jats:p>Point prevalence at study end was 0.015% for DM, 0.005% for IBM and 0.016% for other IIM.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>There are major demographic differences in IIM incidence, notably by sex and ethnicity. Resource planning should account for these marked differences.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/rmdopen-2026-006966","type":"journal-article","created":{"date-parts":[[2026,7,15]],"date-time":"2026-07-15T12:10:27Z","timestamp":1784117427000},"page":"e006966","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":0,"title":["Epidemiology of idiopathic inflammatory myopathies: a population-based cohort in England, 2002\u20132021"],"prefix":"10.1136","volume":"12","author":[{"given":"Patrick","family":"Gordon","sequence":"first","affiliation":[{"name":"Department of Academic Rheumatology, King\u2019s College London, London, UK"},{"name":"Department of Rheumatology, King\u2019s College London, London, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Michael","family":"McLean","sequence":"additional","affiliation":[{"name":"Pfizer Ltd, Tadworth, 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