{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,28]],"date-time":"2026-10-28T18:49:37Z","timestamp":1793213377730,"version":"4.5.0"},"reference-count":0,"publisher":"The Journal of Rheumatology","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J Rheumatol"],"abstract":"<jats:sec><jats:title>Objective<\/jats:title><jats:p>Serum IgG4 concentrations are used to evaluate a diagnosis of IgG4-related disease (IgG4-RD), but the positive predictive value (PPV) of a very high IgG4 level is uncertain. This study evaluated the PPV of a very high IgG4 concentration for diagnosing IgG4-RD.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>The data warehouses of 2 large academic healthcare systems were queried for IgG4 concentration test results. Cases with serum IgG4 concentrations &gt; 5\u00d7 the upper limit of normal (ULN) were included. Cases of IgG4-RD were determined using the American College of Rheumatology\/European Alliance of Associations for Rheumatology (ACR\/EULAR) classification criteria. The PPV for IgG4-RD of an IgG4 concentration &gt; 5\u00d7 ULN was estimated. Other conditions associated with very high IgG4 concentrations and specific features of IgG4-RD cases were characterized.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>IgG4 concentrations were available in 32,206 cases. Of these, 3039 (9.4%) had elevated IgG4 concentrations, and a final cohort of 191 (0.6%) cases had IgG4 concentrations &gt; 5\u00d7 ULN (median age 66 yrs, 72% male). The PPV of an IgG4 concentration &gt; 5\u00d7 ULN for a diagnosis of IgG4-RD was 75.4% (95% CI 68.7-81.3). In the remaining cases, elevated IgG4 concentrations were observed among patients with malignancies, autoimmune diseases, and infections.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>The majority of cases with serum IgG4 concentrations &gt; 5\u00d7 ULN in this study had IgG4-RD. These data support the high weight placed on very high serum IgG4 concentrations in the ACR\/EULAR classification criteria. However, 25% of cases with very high IgG4 concentrations had an alternative diagnosis, underscoring the importance of considering the broad differential of etiologies associated with an elevated IgG4 concentration when evaluating a patient.<\/jats:p><\/jats:sec>","DOI":"10.3899\/jrheum.220423","type":"journal-article","created":{"date-parts":[[2022,11,1]],"date-time":"2022-11-01T12:15:52Z","timestamp":1667304952000},"page":"jrheum.220423","source":"Crossref","is-referenced-by-count":11,"title":["The Positive Predictive Value of a Very High Serum IgG4 Concentration for the Diagnosis of IgG4-Related Disease"],"prefix":"10.3899","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0002-1907","authenticated-orcid":false,"given":"Matthew C.","family":"Baker","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Claire","family":"Cook","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaoqing","family":"Fu","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Cory A.","family":"Perugino","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6588-9435","authenticated-orcid":false,"given":"John H.","family":"Stone","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4708-7038","authenticated-orcid":false,"given":"Zachary S.","family":"Wallace","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"2262","published-online":{"date-parts":[[2022,11,1]]},"container-title":["The Journal of Rheumatology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.3899\/jrheum.220423","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2023,1,15]],"date-time":"2023-01-15T13:25:21Z","timestamp":1673789121000},"score":1,"resource":{"primary":{"URL":"http:\/\/www.jrheum.org\/lookup\/doi\/10.3899\/jrheum.220423"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,11,1]]},"references-count":0,"alternative-id":["10.3899\/jrheum.220423"],"URL":"https:\/\/doi.org\/10.3899\/jrheum.220423","relation":{},"ISSN":["0315-162X","1499-2752","0315-162X"],"issn-type":[{"value":"0315-162X","type":"print"},{"value":"1499-2752","type":"electronic"},{"value":"0315-162X","type":"print"}],"subject":[],"published":{"date-parts":[[2022,11,1]]}}}