| Objective:To investigate the clinical application value of anti-Xa activity,fibrin monomer and D-dimer in early prediction of thrombosis risk after lower limb joint replacement and to evaluate the anticoagulant efficacy of fixed dose of low-molecular-weight heparin,so as to optimize the anticoagulant regimen for the prevention of thrombosis and reduce the occurrence of postoperative thrombosis events.Methods:According to the inclusion and exclusion criteria,72 patients who received continuous anticoagulant therapy with fixed dose of low molecular weight heparin more than 7 days(enoxaparin 4000IU,once a day)after lower extremity joint replacement in the Department of Orthopaedics,Affiliated Hospital of Guizhou Medical University from January 2020 to January 2021 were selected according to the inclusion and exclusion criteria.Deep vein ultrasound of both lower extremity was performed on the 8th day after surgery.According to whether lower extremity deep vein thrombosis was formed,the patients were divided into thrombus group and non-thrombus group.According to reports in the literature in postoperative 1 week thrombosis risk is bigger,therefore this study monitored anti-Xa activity,fibrin monomer,D-dimer,fibrin degradation products,activated clotting time live enzymes,prothrombin time,fibrinogen,preoperative and postoperative liver and kidney function of the patients 4 hours after the application of LMWH on the first,third and seventh day after surgery,record into the demographic data of patients,complications and past medical history.The correlation between each index and postoperative thrombosis was analyzed,and the sensitivity and specificity of anti-Xa activity,fibrin monomer and D-dimer in monitoring postoperative anticoagulant efficacy were discussed.Results:(1)On day 1,3 and 7 after LMWH treatment,the anti-Xa activity of the thrombus group was significantly lower than that of the non-thrombus group,while the fibrin monomer and D-dimer thrombus group were significantly higher than that of the non-thrombus group,the differences between the two groups were statistically significant(P<0.05).(2)Multiple linear regression analysis showed that antithrombin-Ⅲ,creatinine clearance rate and BMI were the influencing factors of low molecular weight heparin activity.The regression function equation related to anti-Xa activity was as follows:anti-Xa activity=-0.388×BMI-0.223×Ccr+0.243×AT-Ⅲ+0.082(R~2=0.283;R~2=0.252after adjustment;F=8.956;P<0.05).(3)The results of univariate and multivariate logistic regression analysis showed that FM was the first day after surgery(OR=1.193,95%CI=1.021-1.394,P=0.027)and the third day after surgery(OR=1.307,95%CI=1.058-1.616).P=0.013),the 7th day after surgery(OR=1.563,95%CI=1.158-2.110,P=0.003),independent risk factors for thrombosis(P<0.05);Postoperative anti-Xa activity was a protective factor for DVT,and the protective effect was more significant on the first day after surgery(OR=0.001,95%CI=0-0.961,P=0.049).(4)The predictive value of anticoagulant efficacy after anti-Xa activity was evaluated by ROC curve.The results showed that when the cutoff value was 0.305IU/m L,thrombosis could be effectively prevented,the curve area was the largest(AUC=0.728),the sensitivity was 71.7%,the specificity was 73.70%,and the positive predictive value was 50%.The negative predictive value was 88.3%(P=0.003).(5)The sensitivity and specificity of fibrin monomer or anti-Xa activity combined with D-dimer in predicting the risk of postoperative thrombosis were better than that of D-dimer alone,and the combination of the three showed the best diagnostic efficacy,with sensitivity and specificity up to 94.7%and 90.0%,and AUC of 0.940(95%CI=0.883～0.998).Conclusions:(1)The cut-off value of anti-Xa activity peak value of 0.305IU/m L was measured 4 hours after the administration of LMWH,which could effectively prevent the formation of postoperative thrombosis.(2)The combination of anti-Xa activity with fibrin monomer and D-dimer increased the sensitivity and specificity of predicting the risk of thrombosis and the early diagnosis of thrombosis,with the best diagnostic performance.(3)FM is an independent risk factor for postoperative thrombosis and can be used as a risk predictor for the occurrence of postoperative DVT.Anti-Xa activity is a protective factor for the prevention of thrombosis,which can effectively reflect the anticoagulation effect of postoperative low molecular weight heparin. |
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