Risk factor assessment in the management of patients with suspected deep venous thrombosis

Background. To evaluate the prevalence of thrombosis risk factors in a grou p of patients undergoing venous duplex scanning (VDS) and to design a risk factor stratification model with the ability to improve the diagnostic yiel d of VDS. Methods. Risk factor assessment and VDS were performed on 1,000 patients wi th clinically suspected lower extremity deep vein thrombosis (DVT) and pati ents were divided into two groups based upon the outcome of their scan: tho se with and those without confirmed DVT. Univariate and multivariate logist ic regression analyses were performed in order to determine the significanc e of each risk factor in relation to having a confirmed DVT. Results. There were 181 patients (18.1%) with confirmed DVT. A prior histor y of DVT/pulmonary embolism, malignancy, prior immobilization, and age over 70 were the most important risk factors associated with having a DVT confi rmed on VDS. A novel risk factor stratification model was created utilizing the odds ratios of those factors found to be significant and the prevalenc e of DVT was found to be 92.4% in the high risk category, 11.5% in the mode rate risk category, and 3.2% in the low risk category using this model. Conclusions. Venous duplex scanning is established as the screening test of choice when one suspects the diagnosis of DVT despite the significant cost of performing and interpreting the test. We suggest that a better clinical model utilizing risk factor assessment may be the key to increasing the yi eld rate and cost-effectiveness of VDS by excluding low-risk patients from undergoing unnecessary testing.