The value of anti-Xa activity and fibrin monomer in diagnosis of early thrombus after lower limb joint replacement
Objective To investigate the clinical application value of anti-Xa activity,fibrin mon-omer(FM)in early prediction of thrombosis risk after lower limb joint replacement.Methods A total of 72 patients who were admitted to the Department of Orthopedics,Affiliated Hospital of Guizhou Medical University from January 2020 to July 2021 after lower limb joint replacement were treated with fixed dose of low-molecular heparin for continuous anticoagulation treatment for more than 7 days.Among them,there were 40 patients after knee replacement and 32 patients after hip replacement.Deep venous Doppler ultra-sound of both lower limbs was completed 8 days after operation.According to the situation of deep vein thrombosis of lower limbs,the patients were divided into thrombus group and non-thrombus group.The val-ue of receiver operating curve(ROC)was developed to evaluate the diagnostic value of anti-Xa and FM in predicting the risk of thrombosis early after surgery.Independent t test,x2 test or Mann Whitney U test were used to analyze the differences between the two groups.Results At the 1st,3rd and 7th days of anticoag-ulation treatment,the thrombus group of anti-Xa activity[0.29(0.25,0.36),0.28(0.27,0.30),0.28(0.23,0.32)IU/ml]was significantly lower than the non-thrombus group[0.33(0.29,0.44),0.33(0.26,0.41),0.35(0.29,0.39)IU/ml,Z=-2.065,-2.086,-2.941,P<0.05],while the thrombus group of FM[13.08(5.11,51.79),8.40(4.91,14.02),10.98(5.86,21.77)μg/ml]was significantly higher than the non-thrombus group[3.48(2.40,5.07),3.55(2.81,4.19),4.02(3.09,5.25)μg/ml,Z=-4.505,-4.646,-5.297,P<0.01].The results showed that the cutoff value of 0.305 IU/ml could effectively prevent thrombosis,and the curve area was the largest(AUC=0.728),the sensitivity was 71.7%,the specificity was 73.70%,and the negative predictive value was 88.3%(P<0.01).The efficacy of the combination of the two is better than that of D-dimer in early postoperative thrombosis diagnosis,which was most significant at 7th day after surgery with a sensitivity of 94.7%and an AUC of0.938[95%confidence interval(CI)=0.882-0.995].Conclusion The FM level of patients with thrombosis after lower limb joint replacement is significantly increased,while the anti-Xa level is low.The combination of the two has certain clinical value for early postoperative thrombosis diagnosis and throm-bosis risk prediction.