Estudio de efectividad y seguridad de la enoxaparina para la profilaxis de la enfermedad tromboembólica venosa en pacientes hospitalizados por patología médica

Abstract

Background: Deep venous thromboembolism is a usual and dangerous complication among hospitalised patients that can be prevented. Clinical symptoms are usually absent or are unspecific. Therefore, adequate primary prevention in high risk patients is of great importance. Thromboembolism prophylaxis is quite well established in surgical patients while knowledge about its benefit in medical patients is not as clear. Published studies are few and some important groups of patients with frequent syndromes have been excluded. Thus, it is very important to know how thromboporphylaxis is performed in daily clinical practice in the medical area, its effectiveness and its safety. The aims of this study were to assess the efficacy and safety of enoxaparin in the prevention of venous thromboembolism in medical inpatients in daily clinical practice, to assess the association between enoxaparin administration delay and venous thromboembolism development and to perform a pharmacoeconomic evaluation. Methods: This was a retrospective, observational longitudinal descriptive study performed at the “Hospital Universitario Príncipe de Asturias”. Patients included were medical inpatients older than fifteen years that were hospitalized between April 1st 1999 and December 31st 2005. Haematological patients were excluded. Administrative databases and the patient’s clinical record were used to obtain the data (Conjunto Mínimo Básico de Datos, Pharmacy database, analytic database). Patients were stratified in those receiving subcutaneous enoxaparin daily and those who did not; those receiving 20 mg of enoxaparin, 40 mg of enoxaparin or more than 40 mg of enoxaparin. The efficacy outcome was thromboembolism event defined as the combination of deep vein thrombosis and symptomatic pulmonary embolism detected by imaging methods. Safety outcomes were bleeding complications and thrombocytopenia during the hospitalisation time. The outcomes were adjusted for confounding factors (age, sex and Charlson index). Results: 20.515 patients in the “enoxaparin group” and 19.834 patients in the “non-enoxaparin group” were evaluated for effectiveness analysis. Among patients who received enoxaparin, 3.095 took 20 mg once daily, 17.003 received 40 mg once daily and 417 patients more than 40 mg. 36.052 patients (19.417 enoxaparin vs. 16.635 non-enoxaparin) and 40.165 patients (20.465 enoxaparin vs. non-enoxaparin) were evaluated for safety analysis of bleeding complications and thrombocytopenia respectively. Symptomatic venous thromboembolism was detected in 0,61 % (120/19.834) of patients not treated with enoxaparin and 0,44 % (91/20.515) of patients treated with enoxaparin (OR=0,73; 95% CI: 0,56-0,96; p=0,025). There was a significant reduction in mortality rates once adjusted for confounding factors (age, sex and Charlson Index). The incidence of adverse effects, either bleeding or thrombocytopenia, did not differ significantly between groups. Conclusions: - Anticoagulant prophylaxis with enoxaparin was effective in preventing symptomatic venous thromboembolic events in hospitalized medical patients and reduced mortality. - 40 mg of subcutaneous enoxaparin once daily was the most effective dose in the preventing thromboembolic events and in reducing mortality rates. - Prophylaxis administration of enoxaparin once daily was safe (it was associated with low risk of bleeding or thrombocytopenia). It was also considered cost-effective as it’s very low increase in total treatment cost per patient occurred.