Risk Factors for Deep Vein Thrombosis after Orthopedic Surgery and the Diagnostic Value of D-Dimer

BackgroundThis study was prospectively designed to determine the risk factors of deep vein thrombosis (DVT) in patients who underwent different surgeries, and to evaluate the efficacy and accuracy of plasma D-dimer level as a screening test.MethodsFrom June 2013 to June 2014, 360 consecutive patients undergoing orthopedic surgery were evaluated. All patients underwent ultrasonography preoperatively and on postoperative day 7. Plasma D-dimer levels were estimated by latex immunoturbidimetry on the day of surgery and on postoperative days 1, 3, and 7.ResultsOf the 360 patients in this study, 339 patients completed the analysis. Among them, DVT was confirmed in 28 (8.26%) patients based on ultrasonographic findings. Multivariate logistic analysis revealed that body mass index was an independent risk factor for developing DVT (P = 0.018) and D-dimer levels on postoperative days 1 and 7 were independently correlated with the development of DVT (P = 0.019 and P < 0.001, respectively). The receiver operating characteristic curve analysis determined that the area under the curve was largest (0.752) when using D-dimer level on postoperative day 7 as diagnostic index, and the sensitivity and specificity were 71.4% and 81.7% at the cut-off value of 6.17 μg/mL, respectively. The elevated D-dimer levels followed the same tendency toward a double-peaked distribution with peaks at days 1 and 7 postoperatively.ConclusionD-dimer level was a useful screening test to exclude DVT, and the cut-off values of D-dimer determined in this study will provide a reference for the absence of DVT to a certain extent.