Objective: To test the significance of serum C-reactive protein (CRP), the erythrocyte sedimentation rate (ESR), globulin(GLN) ,albumin to globulin ratio(A/G), and neutrophil to lymphocyterate(NLR) in periprosthetic joint infection (PJI) diagnosis.
Methods: We retrospectively analyzed the clinical data of 115 patients diagnosed from January 2017 to December 2020 with PJI (PJI group, median age 71.00 years [range, 41-94 years], 24 males, 29 females), and aseptic loosening (aseptic group, median age 68.50 years [range, 34–85 years], 32 male, 30 female) in our department. Demographic data and thesensitivity and specificity of preoperative CRP, ESR, GLB,A/G, and NLR in PJI diagnosis were compared.
Results: There were no significant differences when the demographic data of the two groups were compared. The expression level of CRP (24.89 mg/L([IQR], 0.1 to 200)), ESR (3 mm/h([IQR], 6 to 120)), GLB (31.70 g/L ( [IQR], 18.50 to 60.60)), and NLR (2.51([IQR], 0.93 to 12.23)) in the PJI group were higher than in the aseptic loosening group (CRP: 2.245 mg/L([IQR], 0.2 to 111.94);ESR: 16 mm/h ([IQR], 2 to 76); GLB: 26.60 g/L([IQR], 17.90 to 68.20); NLR: 1.85([IQR], 0.63 to 9.09)). The expression level of A/G (1.15([IQR], 0.55 to 2.16)) in the PJI group was lower than in the aseptic loosening group (1.51([IQR], 0.71 to 2.40)). Receiver operating characteristic (ROC) curve analysis demonstrated that the areas under the ROC curve (AUC) for CRP, ESR, GLB,A/G, and NLR were 0.841 (95% confidence interval, 0.761-0.903), 0.850 (0.771-0.910),0.747(0.658-0.824),0.779(0.692–0.851), and 0.708 (0.616–0.789), respectively. When GLB > 26.6g/L, A/G ＜1.32, and NLR >2.1 were set as the threshold values for the diagnosis of PJI, The sensitivity of GLB and A/G (90.57%, 81.13%) is higher than CRP (71.70%) and ESR (79.25%), but the specificity (GLB: 51.61%, A/G: 72.58%) was significantly lower than of CRP (87.10%) and ESR (75.81%). The ROC analysis of NLR showed that its sensitivity (73.58%) and specificity (70.97) had no significant advantages over CRP and ESR.
Conclusion: globulin, A/G and NLR do not perform better than CRP and ESR in PJI diagnosis.