| Part oneAnalysis of risk factors for developing deep vein thrombosis after orthopedic surgeryObjective:To research the correlations between the surgical factors of the orthopedic patients and incidence of deep vein thrombosis and reveal the independent risk factors for developing deep vein thrombosisMethods:This study was designed as a prospective cohort research with a duration of more than one years. A consecutive 360 patients were included in this study from June 2013 to July 2014. These patients were performed the surgical procedures, including of total knee arthroplasty, total hip arthroplasty, decompression of cervical and lumbar spinal stenosis, reduction and fixation of hip fractures. The patients with abnormally preoperative D-dimer were excluded. The demographic and operative data was collected and recorded. The color Doppler ultrasound was performed to all participants. All patients were divided into varied subgroups according to ages, BMI, decline value of HB, operative time, bed rest. Except of ones with spinal operations, patients were administrated anticoagulation agents to prevent deep vein thrombosis. All data was analyzed with the software of SPSS 20.0. The quantitative variable was registered with means±SEM.P≤0.05 was considered as statistically different. Incidence of deep vein thrombosis among of subgroups was compared using chi-square test. Logistic regression analysis was performed to determine the independent risk factors of deep vein thrombosis.Results:360 patients were enrolled in this prospective study (63.50±11.41 average age, 125male,235female).339 cases completed the studies and provided full data while 21 cases discontinued researches due to heart or cerebral attack or pulmonary infection etc. These cases were comprised of 108 cases of TKA,89 cases of THA,83 cases of spinal decompression,59 cases of hip fractures reduction and fixation. Deep vein thrombosis was found in 28 patients (12 male,16 female) with an incidence of 8.26% and an average age of 70.36±6.82. Other 311 cases (105 male,206 female) had no DVT found with an average age of 62.55±11.70. Out of these 28 patients with documented DVT,11 cases developed clinical symptoms of leg swelling, leg pain, tenderness and fever. No pulmonary embolism or thrombus-related deaths were found. Univariate analysis was performed and a significant difference was found in these groups of ages, BMI, operative time, decline value of HB, postoperative bed rest and whether using anticoagulant agents. No significant difference was found in other groups. Furthermore, Logistic regression analysis revealed that age more than 70 years, BMI more than 30 kg/m, operative duration more than 200 minutes, decline value of HB more than 50 g/1, time of bed rest more than 7 days and without anticoagulant agent were the independent risk factors for developing deep vein thrombosis.Conclusion:This study indicated that age more than 70 years, BMI more than 30 kg/m2, operative duration more than 200 minutes, decline value of HB more than 50 g/1, time of bed rest more than 7 days and without anticoagulant agent were the independent risk factors. The key measures to decrease the incidence of deep vein thrombosis after orthopedic surgery should be control these risk factors effectively.Part twoEffect of the orthopedic surgery on the postoperative D-dimer levelObjective:To research the correlation between orthopedic surgical factors and D-dimer value and to determine the non-thrombotic factors resulting to higher D-dimer level.Methods:This study was designed as a clinical prospective cohort research. A total consecutive 360 patients were enrolled in this study from June 2013 to July 2014. These surgical procedures were comprised of total knee arthroplasty, total hip arthroplasty, decompression of cervical and lumbar spinal stenosis, reduction and fixation of hip fractures. The patients with abnormally preoperative D-dimer were excluded. The clinical and operative data was recorded. Before operation and on first, third, seventh day after operation, blood sample was obtained to detect the D-dimer level. The color Doppler ultrasound was performed to all participants for diagnosis of deep vein thrombosis before surgery and on seventh day after surgery. Except of patients with spinal surgery, all patients adopted LMWH as a thromboembolic prophylaxis once a day and 10 days. All results were expressed as means±SEM. All statistical analysis was performed with SPSS software version 20.0. D-dimer value was compared with independent sample t-test and one-way ANOVA. Multiple linear correlation analysis was performed to determine which factors to affect the postoperative D-dimer level.Results:D-dimer value was compared with one-way ANOVA and no significant difference was found in three age subgroups (P=0.101, P=0.480) before and on third day after operation while a significant difference was found on 1,7 day after operation (P=0.001, P=0.018). One-way ANOVA found there was a significant difference in three subgroups of varied drop-out value of HB postoperatively (P=0.025, P=0.022, P=0.036). Postoperative D-dimer levels were analyzed with two independent sample t-test and found a significant difference between DVT group and non-DVT group (P=0.002,P=0.000,P=0.000). The same significant difference was found in groups of whether to use coagulation agents at three postoperative points (P=0.034, P=0.046, P=0.042). The preoperative D-dimer values of patients with hip fractures were higher than others (P=0.000). Different surgical procedures partly affected the D-dimer level. The levels of cases with TKA and hip fractures were greater than others. Twin peaks trend was observed from line chart. Positive linear correlation were found between variable of age, decline value of HB and D-dimer level(F=21.226, P< 0.001 and F=26.558,P<0.001)。Conclusion:The D-dimer level increase after orthopedic procedures with twin peaks trend. Greater age and more decline value of HB result in a higher postoperative D-dimer level. Positive linear correlation was found between variable of age, decline value of HB and D-dimer level. Trauma and TKA may affect D-dimer levels partly.Part threeResearch of the value of D-dimer for diagnosis of deep vein thrombosis after orthopedic surgeryObjective:To explore the value of D-dimer for diagnosing deep vein thrombosis after orthopedic procedures.Methods:In this prospective cohort study, a total consecutive 360 patients were enrolled from June 2013 to July 2014. These surgical procedures were comprised of total knee arthroplasty, total hip arthroplasty, decompression of cervical and lumbar spinal stenosis, reduction and fixation of hip fractures. The patients with abnormally preoperative D-dimer were excluded. The demographic and operative data was collected and recorded. Blood testing were performed to detect the D-dimer level before and on 1,3,7day after surgery. The color Doppler ultrasound was performed to all participants for diagnosis of deep vein thrombosis before surgery and on seventh day after surgery. Except of patients undergone spinal surgery, all patients adopted LMWH as a thrombotic prophylaxis once a day and 10 days. All results were expressed as means±SEM. All statistical analysis was performed with SPSS version 20.0.1. D-dimer value was compared with independent sample t-test between DVT group and non-DVT group.2. The correlation between D-dimer and deep vein thrombosis was explored with Logistic regression analysis.3. The diagnostic value were assessed through drawing receiver operating characteristic (ROC) at varied time.4. The diagnostic value of D-dimer for diagnosing DVT after varied surgical procedures were assessed by receiver operating characteristic (ROC).5. The accuracy of combing with using the mean of two D-dimer level was assessed with ROC.Results:1. The postoperative D-dimer levels were compared with independent sample t-test and a significant difference was found between DVT group and non-DVT group.2. D-dimer levels of 1,7day after surgery were found as independent risk factors of deep vein thrombosis by Logistic regression analysis (P=0.027, P=0.015). This outcome indicated that detection of D-dimer on1,7 day after surgery may be more valuable.3. Through drawing respective ROC, calculate the areas under curve (AUC) ones of seventh day after operation was found to be the biggest one. Z testing found it was significantly different (P=0.001. This indicated that D-dimer assay on seventh day after surgery had a higher accuracy.4. No significant difference of AUC was found among varied age and surgery procedure groups.5. Higher level of 98% negative cutoff in TKA and age>70years groups were calculated through drawing respective ROC.6. Drawing the ROC with the combined two levels of first and seventh day, a bigger AUC(0.906) was found, which was greater than single one on seventh day. This increase of AUC was significantly different using Z test (P=0.002).Conclusion:In this study, D-dimer was assessed as a marker for diagnosing deep vein thrombosis. The elevated D-dimer levels on 1,7day after orthopedic surgery were independent risk factors. Detecting D-dimer on seventh day after surgery was most valuable for diagnosing deep vein thrombosis. Furthermore, combining two D-dimer levels on first and seventh day may contribute to higher diagnostic accuracy. |
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