{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,5]],"date-time":"2026-09-05T03:38:05Z","timestamp":1788579485591,"version":"build-2803163510"},"reference-count":35,"publisher":"BMJ","issue":"2","license":[{"start":{"date-parts":[[2026,5,21]],"date-time":"2026-05-21T00:00:00Z","timestamp":1779321600000},"content-version":"unspecified","delay-in-days":50,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Zhongnanshan Medical Foundation of Guangdong Province","award":["ZNSXS-20240011"],"award-info":[{"award-number":["ZNSXS-20240011"]}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["82271853"],"award-info":[{"award-number":["82271853"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["RMD Open"],"accepted":{"date-parts":[[2026,4,27]]},"published-print":{"date-parts":[[2026,4]]},"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Interstitial lung disease (ILD) is a major pulmonary complication of idiopathic inflammatory myopathy (IIM), where early diagnosis improves outcomes. While high-resolution CT (HRCT) remains the gold standard, its radiation exposure poses concerns. Serum Krebs von den Lungen-6 (KL-6) and lung ultrasound (LUS) B-lines offer non-invasive alternatives, though their optimal diagnostic cut-offs and combined utility for IIM-ILD remain undefined. This study aimed to establish these cut-offs, evaluate diagnostic performance and develop a clinical prediction model.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>In this single-centre observational study, 162 patients diagnosed with IIM between 2020 and 2024 were enrolled. All underwent serum KL-6 testing, and 120 received systematic 50-point LUS examinations. Using HRCT as the reference standard for ILD diagnosis, receiver operating characteristics (ROC) curve analysis was used to determine optimal cut-offs and construct a combined nomogram.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>KL-6 levels were significantly elevated in the ILD group (n=113) compared with non-ILD (n=49). The optimal KL-6 cut-off was 553 U\/mL (area under the curve (AUC)=0.895, sensitivity 69%, specificity 95.9%). For LUS B-lines number, 25 was recommended as the clinical threshold (sensitivity 98.8%). Their combination enhanced diagnostic performance (AUC=0.984). An online prediction model demonstrated strong clinical applicability. In an exploratory analysis of the rapid-progressive ILD subgroups, KL-6 and B-lines showed only modest predictive value (AUC \u2248 0.65).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>KL-6 \u2265553\u2009U\/mL and B-lines \u226525 are effective screening thresholds, with combined use significantly improving diagnostic accuracy. The prediction model provides a practical tool for early identification in similar clinical settings. To optimise and generalise its use, external validation in multicentre cohorts is warranted.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/rmdopen-2026-006708","type":"journal-article","created":{"date-parts":[[2026,5,21]],"date-time":"2026-05-21T15:35:33Z","timestamp":1779377733000},"page":"e006708","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":1,"title":["Serum KL-6 and lung ultrasound B-lines: a combined non-invasive model for screening and predicting interstitial lung disease in idiopathic inflammatory myopathy"],"prefix":"10.1136","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-1477-7465","authenticated-orcid":false,"given":"Weijin","family":"Zhang","sequence":"first","affiliation":[{"name":"Department of Rheumatology and Immunology, Shantou Central Hospital, Shantou, 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