{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,9]],"date-time":"2026-07-09T06:18:08Z","timestamp":1783577888704,"version":"3.55.0"},"reference-count":32,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,7,9]],"date-time":"2026-07-09T00:00:00Z","timestamp":1783555200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Cell. Infect. Microbiol."],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Periprosthetic joint infection (PJI) is a severe complication after total joint arthroplasty (TJA). Conventional biomarkers like C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) often show limited accuracy in complex cases. Complement C1q is a critical initiator of the classical complement pathway, but its diagnostic value in PJI has not been investigated.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>We retrospectively analyzed 168 patients undergoing revision arthroplasty (71 PJI and 97 aseptic loosening [AL]). Preoperative serum levels of C1q, CRP, ESR, and fibrinogen (FIB) were measured. Diagnostic models including the C1q-to-CRP ratio (CCR), ESR-to-C1q ratio (ECR), and FIB-to-C1q ratio (FCR) were calculated. ROC curve analysis and DeLong\u2019s test were used to assess diagnostic performance. Decision curve analysis (DCA) was conducted to assess the clinical net benefit of the CCR model. An exploratory stratified analysis was further performed in the diabetic subgroup (n=48).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>Serum C1q levels were significantly higher in the PJI group compared to the AL group (236.00 vs. 180.00 mg\/L, P &amp;lt; 0.001). C1q positively correlated with CRP (rho = 0.62), ESR (rho = 0.33), and FIB (rho = 0.31). The CCR model demonstrated the highest diagnostic accuracy with an AUC of 0.949, which was significantly superior to CRP alone (AUC\u00a0=\u00a00.931, P\u00a0=\u00a00.022). At a cut-off of 0.03, CCR yielded a sensitivity of 95.77% and a negative predictive value of 96.20%. In the diabetic subgroup, CCR remained effective with an AUC of 0.928.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>Serum C1q is a reliable novel biomarker for PJI. The CCR model demonstrates promising research prospects and can serve as a reliable tool for clinical decision-making in the diagnosis and treatment of PJI, including for diabetic patients. DCA showed that CCR provided superior net clinical benefit across most threshold probabilities in both the overall and diabetic cohorts, supporting its potential clinical utility in PJI diagnosis.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fcimb.2026.1831300","type":"journal-article","created":{"date-parts":[[2026,7,9]],"date-time":"2026-07-09T05:36:10Z","timestamp":1783575370000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["The serum C1q-to-CRP ratio performs well for diagnosing periprosthetic joint infection in revision arthroplasty"],"prefix":"10.3389","volume":"16","author":[{"given":"Xiaodong","family":"Jia","sequence":"first","affiliation":[{"name":"Knee Preservation Center, The Affiliated Hospital of Qingdao University","place":["Qingdao, Shandong, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shuhang","family":"Dong","sequence":"additional","affiliation":[{"name":"Knee Preservation Center, The Affiliated Hospital of Qingdao University","place":["Qingdao, Shandong, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jinli","family":"Chen","sequence":"additional","affiliation":[{"name":"Knee Preservation Center, The Affiliated Hospital of Qingdao University","place":["Qingdao, Shandong, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xia","family":"Zhao","sequence":"additional","affiliation":[{"name":"Department of Sports Medicine, The Affiliated Hospital of Qingdao University","place":["Qingdao, Shandong, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yingze","family":"Zhang","sequence":"additional","affiliation":[{"name":"Knee Preservation Center, The Affiliated Hospital of Qingdao University","place":["Qingdao, Shandong, China"]},{"name":"Department of Orthopedics, The Third Affiliated Hospital of Hebei Medical University","place":["Shijiazhuang, Hebei, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kuishuai","family":"Xu","sequence":"additional","affiliation":[{"name":"Knee Preservation Center, The Affiliated Hospital of Qingdao University","place":["Qingdao, Shandong, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,7,9]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pone.0092340","article-title":"Increased complement C1q level marks active disease in human tuberculosis","volume":"9","author":"Cai","year":"2014","journal-title":"PloS One"},{"key":"B2","doi-asserted-by":"publisher","first-page":"1","DOI":"10.1016\/j.arth.2026.01.014","article-title":"Diagnosing seronegative periprosthetic joint infection after total hip and knee arthroplasties","volume":"41","author":"Elmenawi","year":"2026","journal-title":"J. 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