Analysis Of Risk Factors Of Preoperative Deep Venous Thrombosis In Middle-aged And Elderly With Proximal Femur Fractures

Objective:To investigate the general data and the influencing factors of the formation of deep vein thrombosis(DVT)in middle-aged and elderly patients undergoing hip replacement,and to screen the DVT of lower limbs for further vascular Doppler ultrasound examination.conditions of.Methods:Retrospective analysis was performed in September 2015 to January 2018 for patients with proximal femoral fractures(femoral neck fractures or femoral intertrochanteric fractures)scheduled for joint replacement in our department.Statistical data:(1)General data: age,sex,body mass index(BMI);(2)fracture related data: fracture time,fracture type,and fracture site;(3)first blood test results: fibrin degradation product(FDP),D-dimer,prothrombin time(PT),activated partial thromboplastin time(APTT),thrombin time(TT),hemoglobin(HB),hematocrit,platelet count;(4)lower limb blood vessel type B color Doppler ultrasound results.Qualitative data were analyzed using a chi-square test.Quantitative data were analyzed using t test of two independent samples.Logistics regression analysis was used to determine the influencing factors of preoperative DVT.The odds ratio(OR)was used to measure the effect of preoperative DVT.The critical value of the statistically significant factor and the area under the curve(AUC)were determined using a receiver-characteristic(ROC)curve.The critical value was determined by the Yourden's index.This study used SPSS 22.0 software(SPSS Inc.,USA)Statistical analysis was performed.Measured data were expressed as mean ± standard deviation.The test level was ?=0.05.Results:A total of 92 patients were included in the study,30 patients had DVT,and 62 patients had no DVT.There was no statistical difference in age(p=0.256),D-dimer(p=0.394),and BMI(p=0.444)between preoperative and non-DVT patients,fracture time(p=0.041)and erythrocyte pressure.The product(p=0.012)was statistically different.Two-class Logistic regression analysis showed that age(p=0.253),D-dimer(p=0.388),and BMI(p=0.139)were not significant factors affecting lower extremity DVT diagnosed by color Doppler ultrasound.Fracture time(p=0.014)and hematocrit(p=0.012)were statistically significant factors.Further two-category Logistic regression analysis showed that fracture time(OR=1.007,p=0.015)was a significant risk factor for preoperative DVT,and hematocrit(OR=0.9,p=0.008)was a significant protective factor for DVT and was obtained.Equations related to fracture duration and hematocrit: DVT index = 2.735 + 0.007 x fracture time(h)-0.105 x hematocrit(%).The optimal cut-off value for the DVT index was-1.129,which was 86.7% sensitive and 59.7% specific,the area under the ROC curve(AUC)was 0.738,and the best cut-off value for fracture time was 16 hours.With 76.7% sensitivity and 53.2% specificity,the area under the ROC curve(AUC)was 0.684;the best critical value for hematocrit was 37.87%,which was 40% sensitive and 33.9% specific.The area under the ROC curve(AUC)is 0.347.Conclusions:This study shows that:(1)The significant risk factor for lower extremity DVT in patients with proximal femoral fracture(unilateral femoral neck fracture or femoral intertrochanteric fracture)is fracture time(OR=1.007,p=0.015);the significant protective factor is hematocrit(OR=0.9,p=0.008).Hematocrit has the greatest effect on lower extremity DVT.(2)For the index of DVT risk prediction before surgery——DVT index,the DVT index discriminant equation was obtained:DVT index = 2.735+0.007×fracture time(h)-0.105×hematocrit(%).Note: When the DVT index is ?-1.129,all patients need to further perform color Doppler ultrasonography to detect DVT;when the DVT index is <-1.129,it can be determined based on the patient's clinical symptoms and signs.This may be helpful for clinical work,however,further studies are still needed to verify this finding to ensure more accurate diagnosis.