{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,28]],"date-time":"2026-10-28T18:05:20Z","timestamp":1793210720612,"version":"4.5.0"},"reference-count":23,"publisher":"BMJ","issue":"1","license":[{"start":{"date-parts":[[2025,1,20]],"date-time":"2025-01-20T00:00:00Z","timestamp":1737331200000},"content-version":"unspecified","delay-in-days":19,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"name":"Diagnostic Laboratory Division of the South-West Finland's Wellbeing District"}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["RMD Open"],"accepted":{"date-parts":[[2024,12,11]]},"published-print":{"date-parts":[[2025,1]]},"abstract":"<jats:sec>\n                  <jats:title>Objectives<\/jats:title>\n                  <jats:p>We assessed the positive predictive value (PPV) of 17 myositis antibodies for having a diagnosis of myositis and other myositis-spectrum conditions (interstitial lung disease (ILD), connective tissue diseases (CTD), malignancy) and evaluated the impact of semiquantitative classification and antibody overlap on the PPVs.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Materials and methods<\/jats:title>\n                  <jats:p>We retrospectively identified 1068 individuals \u226518 years who tested positive for \u22651 antibody in the EUROLINE myositis line blot assay or positive for anti-3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR) in an ELISA-based test between 2015 and 2020 in 15 out of the 20 hospital districts in Finland. We extracted clinical diagnoses from the Care Register for Health Care between January 2013 and June 2022.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Results<\/jats:title>\n                  <jats:p>The PPV for a myositis diagnosis (ever during data collection) was highest for anti-HMGCR antibodies (94%), followed by anti-MDA5, anti-Jo-1 and anti-TIF1-\u03b3 (49\u201354%). Regarding other myositis antibodies, 18\u201342% of cases had myositis. Anti-synthetase antibodies, anti-MDA5, anti-PM-Scl100, anti-SAE1 and anti-Ro52 had a PPV for ILD of 25\u201347%. A PPV for CTD was highest for anti-Ro52 (57%). The PPV for malignancy was highest for anti-TIF1-\u03b3 (38%), followed by anti-PL-7 (32%). Stronger antibody band intensity was associated with higher PPVs for myositis and CTD but not for ILD or malignancies. Simultaneous positivity for \u22652 antibodies compared with single antibody was associated with higher PPVs for myositis, CTD and ILD.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Conclusion<\/jats:title>\n                  <jats:p>The PPV of myositis antibodies for diagnoses of myositis or other myositis spectrum diseases vary considerably between individual autoantibodies. Higher PPVs can be expected with stronger band intensities and with the presence of \u22652 overlapping myositis antibodies.<\/jats:p>\n               <\/jats:sec>","DOI":"10.1136\/rmdopen-2024-005007","type":"journal-article","created":{"date-parts":[[2025,1,21]],"date-time":"2025-01-21T02:45:17Z","timestamp":1737427517000},"page":"e005007","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":9,"title":["Predictive value of myositis antibodies: role of semiquantitative classification and positivity for more than one autoantibody"],"prefix":"10.1136","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-2257-3291","authenticated-orcid":false,"given":"Anne M","family":"Kerola","sequence":"first","affiliation":[{"name":"Institute for Molecular Medicine Finland, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland"},{"name":"Department of Internal Medicine, P\u00e4ij\u00e4t-H\u00e4me Central Hospital, Wellbeing services county of P\u00e4ij\u00e4t-H\u00e4me, Lahti, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3554-0683","authenticated-orcid":false,"given":"Annukka","family":"Pietik\u00e4inen","sequence":"additional","affiliation":[{"name":"Institute of Biomedicine, Faculty of Medicine, University of Turku, Turku, Finland"},{"name":"TYKS laboratories, Clinical Microbiology, Turku University Hospital, Turku, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9695-8971","authenticated-orcid":false,"given":"Julia","family":"Barantseva","sequence":"additional","affiliation":[{"name":"Department of Internal Medicine, Kuopio University Hospital, Kuopio, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Annaleena","family":"Pajander","sequence":"additional","affiliation":[{"name":"TYKS laboratories, Clinical Microbiology, Turku University Hospital, Turku, Finland"},{"name":"University of Turku, Turku, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Arno","family":"H\u00e4nninen","sequence":"additional","affiliation":[{"name":"TYKS laboratories, Clinical Microbiology, Turku University Hospital, Turku, Finland"},{"name":"Institute of Biomedicine and InFLAMES Research Flagship, University of Turku, Turku, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2025,1,20]]},"reference":[{"key":"2025090312051727000_11.1.e005007.1","doi-asserted-by":"crossref","first-page":"383","DOI":"10.1097\/BOR.0000000000000957","article-title":"Update on autoantibodies and related biomarkers in autoimmune inflammatory myopathies","volume":"35","author":"Choi","year":"2023","journal-title":"Curr Opin Rheumatol"},{"key":"2025090312051727000_11.1.e005007.2","doi-asserted-by":"publisher","DOI":"10.1038\/nrrheum.2018.56"},{"key":"2025090312051727000_11.1.e005007.3","doi-asserted-by":"crossref","DOI":"10.1186\/s13075-020-02210-2","article-title":"The promise, perceptions, and pitfalls of immunoassays for autoantibody testing in myositis","volume":"22","author":"Tansley","year":"2020","journal-title":"Arthritis Res Ther"},{"key":"2025090312051727000_11.1.e005007.4","doi-asserted-by":"crossref","first-page":"1101","DOI":"10.1007\/s00296-023-05279-5","article-title":"Myositis autoantibodies detected by line blot immunoassay: clinical associations and correlation with antibody signal intensity","volume":"43","author":"Loarce-Martos","year":"2023","journal-title":"Rheumatol Int"},{"key":"2025090312051727000_11.1.e005007.5","doi-asserted-by":"crossref","first-page":"1167","DOI":"10.1111\/1756-185X.14174","article-title":"Performance of myositis-specific antibodies detected on myositis line immunoassay to diagnose and sub-classify patients with suspected idiopathic inflammatory myopathy, a retrospective records-based review","volume":"24","author":"Beaton","year":"2021","journal-title":"Int J Rheum Dis"},{"key":"2025090312051727000_11.1.e005007.6","doi-asserted-by":"crossref","first-page":"626","DOI":"10.1002\/mus.28050","article-title":"Positive predictive value of myositis antibody line blot testing in patients with suspected idiopathic inflammatory myopathy","volume":"69","author":"Chang","year":"2024","journal-title":"Muscle Nerve"},{"key":"2025090312051727000_11.1.e005007.7","doi-asserted-by":"crossref","unstructured":"Lackner A , Tiefenthaler V , Mirzayeva J , et al . The use and diagnostic value of testing myositis-specific and myositis-associated autoantibodies by line immuno-assay: a retrospective study. 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