{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,4]],"date-time":"2026-09-04T01:26:57Z","timestamp":1788485217753,"version":"build-2803163510"},"reference-count":24,"publisher":"Wiley","issue":"6","license":[{"start":{"date-parts":[[2025,6,12]],"date-time":"2025-06-12T00:00:00Z","timestamp":1749686400000},"content-version":"vor","delay-in-days":11,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"DOI":"10.13039\/100006108","name":"National Center for Advancing Translational Sciences","doi-asserted-by":"publisher","award":["UL1TR000130"],"award-info":[{"award-number":["UL1TR000130"]}],"id":[{"id":"10.13039\/100006108","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100006108","name":"National Center for Advancing Translational Sciences","doi-asserted-by":"publisher","award":["UL1TR001855"],"award-info":[{"award-number":["UL1TR001855"]}],"id":[{"id":"10.13039\/100006108","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000002","name":"National Institutes of Health","doi-asserted-by":"publisher","award":["5T32AR069515\u201007"],"award-info":[{"award-number":["5T32AR069515\u201007"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["acrjournals.onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["ACR Open Rheumatology"],"published-print":{"date-parts":[[2025,6]]},"abstract":"<jats:sec><jats:title>Objective<\/jats:title><jats:p>The objective of this study was to assess clinical laboratory parameters that distinguish between disease flare and infection in febrile patients with systemic lupus erythematosus (SLE) at safety\u2010net hospitals in Los Angeles.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>We reviewed electronic medical records of patients admitted from August 1, 2016, through July 31, 2019, categorizing them as disease flare, bacterial infection (culture positive), culture\u2010negative infection, and both flare and infection. Laboratory parameters collected within 48 hours of admission (complete blood cell count with differential, liver function panel, erythrocyte sedimentation rate [ESR], C\u2010reactive protein [CRP], C3, C4, lactate, procalcitonin, and ferritin) were analyzed.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Several laboratory parameters significantly distinguished febrile patients with disease flare from those with infection. An optimized multivariable logistic regression model revealed that an elevated ESR:CRP ratio (&gt;1.17), low white blood cell (WBC) count (&lt;6.25 \u00d7 10<jats:sup>9<\/jats:sup>\/L), low absolute neutrophil count (&lt;5.55 \u00d7 10<jats:sup>9<\/jats:sup>\/L), and low CRP (&lt;113 mg\/L), C3 (&lt;44.5 mg\/dL), and C4 (&lt;13.5 mg\/dL) levels helped discriminate disease flare from culture\u2010positive infection. These laboratory parameters yielded areas under the receiving operating characteristic curve of 0.87 (95% confidence interval [CI] 0.76\u20130.97) for flare versus culture\u2010positive infection and 0.94 (95% CI 0.88\u20131.00) for flare versus culture\u2010negative infection. These optimized models, using multiple laboratory parameters, significantly outperformed the ESR:CRP ratio alone (<jats:italic>P<\/jats:italic> &lt; 0.02) in discriminating flare from infection.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusion<\/jats:title><jats:p>The ESR:CRP ratio plus C3 and C4 levels, WBC count, neutrophil count, and monocyte count discriminate flare from either culture\u2010positive or culture\u2010negative infection in febrile patients with SLE. Our findings warrant prospective validation.<\/jats:p><\/jats:sec>","DOI":"10.1002\/acr2.70051","type":"journal-article","created":{"date-parts":[[2025,6,16]],"date-time":"2025-06-16T20:00:26Z","timestamp":1750104026000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Discriminating Disease Flare From Infection in Febrile Patients With Systemic Lupus Erythematosus in a Safety\u2010Net Hospital System: A Multicenter Study"],"prefix":"10.1002","volume":"7","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9548-595X","authenticated-orcid":false,"given":"Abhimanyu","family":"Amarnani","sequence":"first","affiliation":[{"name":"University of Southern California Keck School of Medicine, Los Angeles, and New York University Langone Health and Bellevue Hospital Center  New York 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