The diagnostic role of albumin-based ratio markers for periprosthetic joint infection

Panlong Fan, Qianqian Cao, Liya Sun, Ke Wang, Keli Guo, Yi Jin, Zhipeng Dai

Background Periprosthetic joint infection (PJI) is a serious complication following total joint arthroplasty. Timely and accurate diagnosis is crucial for the management of PJI. Numerous biomarkers are currently available for the diagnosis of PJI; however, a single indicator often fails to meet clinical requirements. In recent years, combinations of multiple biomarkers have demonstrated diagnostic potential in other infectious diseases. Nevertheless, the application of inflammatory marker combinations based on albumin (ALB) ratios in PJI diagnosis remains underexplored. Therefore, this study aims to investigate the diagnostic efficacy of novel biomarkers based on albumin ratios for PJI. Methods A retrospective analysis was conducted on 257 patients with periprosthetic joint infection (PJI) and 137 with aseptic loosening (AL) who underwent revision arthroplasty at our institution between January 2019 and December 2024. We compared serum levels of C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), albumin (ALB), the CRP/ALB ratio (CAR), the ESR/ALB ratio (EAR), and the composite index CAR + EAR (CEAR) between the two groups. Diagnostic performance was assessed using receiver operating characteristic (ROC) curves and the corresponding area under the ROC curve (AUC). Results Patients with PJI exhibited significantly higher circulating levels of CRP, ESR, CAR, EAR and CEAR, whereas serum albumin was markedly lower than in the AL cohort. Subgroup analyses revealed no significant differences in the levels of these inflammatory biomarkers among the subgroups (P > 0.05). Based on ROC curve analysis, the novel inflammatory biomarker panels (CAR, EAR, CEAR) demonstrated high diagnostic accuracy: CAR yielded an AUC of 0.929 (95% CI: 0.905-0.953), EAR 0.890 (95% CI: 0.860-0.921), and CEAR 0.917 (95% CI: 0.890-0.943). Conclusion Ratio-based markers based on ALB show promise as valuable new adjunctive diagnostic markers for PJI. The diagnostic efficacy of CEAR was comparable to that of CAR (AUC: 0.917 vs. 0.929, respectively), and both outperformed EAR (AUC = 0.890).