Diagnostic value of serum Interleukin-6 combined with synovial IL-6 and C-reactive protein for prosthesis joint infection in patients after joint arthroplasty

Objective:To explore the diagnostic value of serum Interleukin-6(IL-6)combined with synovial IL-6 and C-reactive protein for prosthesis joint infection(PJI)in patients after joint arthroplasty.Methods:A total of 253 patients undergoing revision surgery after the first total hip and total knee arthroplasty in the Second Affiliated Hospital of Hainan Medical College from January 2018 to April 2020 were recruited as the study object.The patients were divided into the PJI group(n=85)and non-PJI group(n=168)according to whether there was PJI,and the baseline characteristics and the laboratory indexe were collected and compared between the two groups.the factors associated with PJI in patients after joint arthroplasty were analyzed by multivariate logistic regression model.And the diagnostic value of each marker for PJI in patients after joint arthroplasty was evaluated by Receiver Operating Characteristic(ROC)curve.Results:The incidence of PJI in this study was 33.6%.Compared with the non-PJI group,the patients in the PJI group had more diabetes mellitus and shorter prosthesis duration(P<0.05).The levels of serum C-reactive protein(CRP),serum interleukin-6(IL-6),synovial IL-6,synovial CRP,synovial leukocyte,synovial neutrophil and ESR in the PJI group were higher than those in non-PJI group,and the level of synovial lymphocyte was lower,with statistically significant differences(P<0.05).Multivariate logistic regression analysis showed that diabetes mellitus(OR=1.706,95%CI:1.02~2.376,P=0.037),prosthesis duration(OR=0.781,95%CI:0.690~0.884,P<0.001),serum IL-6(OR=1.008,95%CI:1.004~1.012,P=0.046),synovial IL-6(OR=1.004,95%CI:1.002~1.006,P=0.011)and synovial CRP(OR=1.481,95%CI:1.010~2.170,P=0.044)were independently related to PJI in patients after joint arthroplasty.ROC curve analysis showed that the area under ROC curve(AUC)of serum IL-6 combined with synovial IL-6 and CRP for diagnose PJI in patients after joint arthroplasty was significantly greater than each marker(0.941 vs 0.760,Z=6.333,P<0.001;0.941 vs 0.743,Z=7.189,P<0.001;0.941 vs 0.785,Z=4.999,P=0.006).Conclusion:Serum IL-6,synovial IL-6 and CRP were independently related to PJI in patients after joint arthroplasty.They all had some diagnostic value,and serum IL-6 combined with synovial IL-6 and CRP had higher capability to diagnose PJI in patients after joint arthroplasty than each marker alone.