Background: This 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.
Methods: From 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.
Results: Of 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.
Conclusion: D-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.
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