Application of Wells Criteria, in Combination With Serum D-dimer to Rule Out Deep Vein Thrombosis in Lower Extremities

Wells et al. developed a clinical prediction rule to estimate the probability of deep venous thrombosis (DVT), using data of secondary care outpatients. Our goal is to validate the diagnostic accuracy of this rule, in combination with D-dimer test. A cross-sectional study was performed with prospective data collection from September 2010 to December 2011. Data was collected in emergency department settings in Shohada-e Tajrish hospital, Tehran. One hundred and seventy seven consecutive patients presented with suggestive symptoms of DVT, were included. All patients underwent historytaking and physical examinations to measure the Wells rule score and D- dimer test by the agglutinin method. Leg ultrasonography was the reference gold standard to determine the presence of DVT. 14.75% of patients in the low-risk group had DVT; when it was combined with negative D-dimer test results, the Wells rule yielded a 4% prevalence of DVT in the low-risk group. The estimated Positive Predicted Value for patients in the high-risk group, based on the Wells criteria in combination with D-dimer testing, was 79.24%, while Negative Predicted Value for patients in low- risk group was calculated as 85.24%. The present study aimed to introduce a cost-effective, reliable, and available modality to recognize patients afflicted with DVT. The Wells rule, alone or in combination with D-dimer testing, does not guarantee accurate assessment of risk in primary care patients in whom DVT is suspected. Using Wells criteria in low -risk group may decrease the need for ultrasonography in up to 28% of patients, and may be cost beneficial.