Limited value of patient history and physical examination in diagnosing deep vein thrombosis in primary care

BACKGROUND: Properly ruling in or out deep vein thrombosis (DVT) is important because of the risk of developing pulmonary embolism if untreated and the risk of bleeding when treated with anticoagulants. In primary care, the diagnosis in suspected DVT is non-specific and the physician has to decide which patients to refer for further diagnostic work-up on the basis of patient history and physical examination alone. OBJECTIVE: To quantify which (combination of) items from patient history and physical examination contribute to the diagnosis of DVT in primary care. METHODS: A cross-sectional study design was chosen and the setting was all primary care physicians adherent to three local hospitals. 1325 consecutive patients consulting their primary care physician with symptoms suggestive of DVT were included. RESULTS: We studied 1325 patients with suspected DVT. The prevalence of thrombosis (assessed by means of compression ultrasonography) in these patients was 29%. Multivariate regression analysis of 17 candidate predictors resulted in nine independent predictors of DVT: male gender, duration of symptoms, malignancy, immobilization, leg trauma, pain when walking, oedema, calf circumference and dilated veins. The predictive value of the combination of the nine independent variables was low, reflected in the ROC area (as a combination of the sensitivity and specificity) of this model of 0.68. The low discriminative value was also exhibited in the numbers of DVT in the different risk categories. For example, in the low-risk group, the probability of DVT was still 15%. The diagnostic performance of patient history and physical examination was similar (and thus poor) in all clinically relevant subgroups. CONCLUSION: Patient history and physical examination in patients suspected of DVT are of limited value for the primary care setting to identify patients with a low or high probability of DVT and thus in the decision to refer for further diagnostic work-up.