Exciting Performance of Plasma Fibrinogen in Periprosthetic Joint Infection Diagnosis

OBJECTIVE: To test the significance of serum C‐reactive protein (CRP), the erythrocyte sedimentation rate (ESR), the platelet count/mean platelet volume ratio (PC/MPV), plasma fibrinogen, and D‐Dimer in periprosthetic joint infection (PJI) diagnosis. METHODS: We retrospectively analyzed the clinical data of 149 patients diagnosed from July 2016 to December 2019 with primary osteoarthritis (OA group, average age 63.18 years [range, 53–82 years] 18 males, 46 females), PJI (PJI group, average age 63.74 years [range, 52–81 years], 16 males, 31 females), and aseptic loosening (aseptic group, average age 63.18 years [range, 53–80 years], 12 male, 26 female) in our department. Demographic data and the sensitivity and specificity of preoperative CRP, ESR, PC/MPV, fibrinogen, and D‐Dimer in PJI diagnosis were compared. RESULTS: There were no significant differences when the demographic data of the three groups were compared. The expression level of CRP (50.67 ± 58.98 mg/L), ESR (50.55 ± 25.81 mm/h), PC/MPV (35.79 ± 18.00), and fibrinogen (4.85 ± 1.33 μg/mL) in the PJI group were higher than in the OA group (CRP: 4.09 ± 9.68 mg/L; ESR:13.44 ± 9.32 mm/1 h; PC/MPV: 24.97 ± 7.58; fibrinogen: 3.09 ± 0.55 μg/mL) and the aseptic group (CRP: 7.01 ± 11.83 mg/L; ESR: 22.47 ± 17.53 mm/1 h; PC/MPV: 25.18 ± 11.48; fibrinogen: 3.39 ± 0.80 μg/mL), respectively. The expression level of plasma D‐dimer (1.60 ± 1.29 mg/L) in the PJI group was higher than in the OA group (0.49 ± 0.42 mg/L) but similar to that in the aseptic group (1.21 ± 1.35 mg/L). Receiver operating characteristic (ROC) curve analysis demonstrated that the areas under the ROC curve (AUC) for CRP, ESR, PC/MPV, fibrinogen, and D‐dimer were 0.892 (95% confidence interval, 0.829–0.954), 0.888 (0.829–0.947), 0.686 (0.589–0.784), 0.873 (0.803–0.943), and 0.835 (0.772–0.899), respectively. When PC/MPV > 31.70, fibrinogen >4.01 μg/mL, and D‐dimer >1.17 mg/L were set as the threshold values for the diagnosis of PJI, the sensitivity of PC/MPV in PJI diagnosis was lower than that of ESR and plasma fibrinogen. In contrast, there was no significant difference when comparing the specificity of CRP, ESR, PC/MPV, fibrinogen, and D‐dimer in PJI diagnosis. CONCLUSION: Plasma fibrinogen is a good new auxiliary diagnostic marker for PJI.