Prophylaxis of venous thrombosis in medical patients: A real-world perspective

Although low-molecular weight heparins (LMWH) have been proven to be efficacious for prophylaxis of venous thrombo-embolism (VTE) in non-surgical patients, their use and safety outside the setting of a clinical trial has not been investigated.

The objective of this survey was to determine the efficacy and safety of LMWH (enoxaparin) in the prevention of VTE in a study population comprising general medical patients.

The study involved an open-label, non-controlled, multicentre survey of any patient confined to bed due to medical illness, where the physician had made an independent decision to prescribe LMWH as prophylaxis for VTE. The demographic information and risk factors for venous thrombosis and dose of enoxaparin were recorded. Patients were assessed for clinical evidence of VTE. Only if this was present were further invasive investigations performed. Adverse events relating to the use of LMWH were recorded.

Four hundred and seventy-one patients were enrolled from 53 centres. Five per cent of the patients were treated for up to and including three days, 4.4% for four days or less, 49.6% for six days or less, and a further 45.5 % for seven to 21 days. The most frequently prescribed dose was enoxaparin 40 mg once daily (86%). Of the enrolled patients, 28.2% had one risk factor and 69.8% had two or more risk factors for the development of VTE. The incidence of clinically suspected deep-vein thrombosis (DVT) or pulmonary embolism (PE) in this survey was three out of 457 patients at risk, ie, 0.66%. One serious adverse event occurred in an incorrectly enrolled surgical patient and 22 minor adverse events occurred that were thought by the enrolling physician to be related to the study drug.

This survey was not designed to test for efficacy in DVT prevention. However the incidence of clinically identified DVT was low and there were no deaths from PE. This probably represents a considerable reduction in morbidity and mortality from that described in studies comparing LMWH with placebo. Enoxaparin may be used with confidence in a 'real-world' situation out of the confines of a study in which exclusions, inclusions and therapy are rigorously controlled.