Original Articles

BACKGROUND: The clinical signs and symptoms such as swelling, pain, and redness are unreliable markers of deep vein thrombosis (DVT). As a consequence, venous duplex scanning (VDS) has been heavily used in DVT detection. The purpose of this study was to determine if a combination of D–dimer testing and pretest clinical score could reduce the use of VDS in symptomatic patients with suspected DVT. STUDY DESIGN: One hundred seventy–four consecutive patients with suspected DVT were prospectively evaluated using pretest clinical probability (PCP) score and D–dimer testing before VDS. After calculating clinical probability scores developed by Wells and associates, patients were divided into low risk (≤ 0 points), moderate risk (1–2 points), and high risk (≥3 points) PCP. RESULTS: One hundred fifty–eight patients were enrolled. The prevalence of DVT in this study was 37%. Thirty–eight patients (24%) were classified as low risk, 64 (41%) as moderate risk, and 56 (35%) as high risk PCP. DVT was identified in only 1 patient (2.6%) with low risk PCP. In contrast, DVT was found in 22 (34%) with moderate risk, and 35 (63%) with high risk PCP. In the high and moderate risk PCP groups, positive scan patients had a significantly higher value of D–dimer assay than negative scan patients (p=0.0001 and =0.0057, respectively). In the low risk PCP patients, D–dimer testing provided 100% sensitivity, 46% specificity, 4.8% positive predictive value (PPV), and 100% negative predictive value (NPV) in the diagnosis of DVT. Similarly, in the moderate risk PCP, the D–dimer testing showed 100% sensitivity, 45% specificity, 49% PPV and 100% NPV. In the high risk group, D–dimer testing achieved 100% sensitivity, 57% specificity, 80% PPV, and 100% NPV in the diagnosis of DVT. These results suggested that 36 of 158 patients who have a non–high PCP (low and moderate PCP) and a normal D–dimer concentration considered to have no further investigation, and thus VDS could have been reduced by 23% (36/158). CONCLUSIONS: A combination of D–dimer testing and clinical probability score may be effective in terms of avoiding unnecessary VDS in suspected symptomatic DVT in the low and moderate PCP patients. The need for VDS could be reduced by 23% despite a relatively high prevalence of DVT.