Management of primary care patients with suspected deep vein thrombosis: use of a therapeutic dose of low-molecular-weight heparin to avoid urgent ultrasonographic evaluation

BACKGROUND: Out of hospital management of patients with suspected deep vein thrombosis (DVT) can be problematic. The accuracy of clinical prediction rules in the primary care setting may be inadequate, D-dimer testing may not be available, and the cost-effectiveness of urgent ultrasonographic evaluation is uncertain. OBJECTIVE: The purpose of this study was to determine the efficacy and safety of an empiric single therapeutic dose of low-molecular weight heparin (LMWH) in the time interval preceding ultrasound investigation in patients presenting to primary care physicians (PCPs) for suspicion of DVT. METHODS: Consecutive patients with suspected DVT who presented to the office of a PCP outside regular thrombosis center working hours were enrolled. All eligible patients received a single therapeutic dose of LMWH (100 anti-Xa IU kg(-1) weight) and were scheduled to undergo clinical and instrumental evaluation at the thrombosis center the morning after. Clinical events were documented after a 3-month follow-up. RESULTS: A total of 534 consecutive patients with suspected DVT were included in this study; of these 102 patients had subsequent diagnosis of DVT. We detected no episodes of pulmonary embolism, major bleeding, or death during the 18-h window between the administration of LMWH and objective evaluation. Of the 432 patients in whom diagnosis of DVT was subsequently excluded, only three (0.7%; CI: 0.2-2.0%) developed venous thromboembolic events during the 3-month follow-up period. CONCLUSIONS: Empiric treatment with a single therapeutic dose of LMWH is effective and safe for outpatients with suspected DVT initially managed in a primary care setting. This strategy has the potential to reduce the need for urgent diagnostic imaging.