MeRIT - Venous Thromboembolism Prophylaxis in Morbidly Obese Critically Ill Patients

Introduction: Enoxaparin is commonly used in intensive care unit (ICU) to prevent venous thromboembolism (VTE) and fixed dose is recommended regardless of patient's weight. However, appropriate VTE prophylaxis dosing has been questioned and several researchers used different weight-based dosing in morbidly obese patients with monitroing of anti-factor Xa level.

Objectives: To compare the rate of VTE during hospitalization between non-morbidly obese patients (BMI <40 kg/m²) and morbidly obese patients (BMI ≥ 40 kg/m²) who received standard VTE prophylactic dose of enoxaparin in the ICU and to ssess the extent of the relationship between average enoxaparin daily dose/weight (mg/kg/day) and time to develop VTE (days).

Study Design:  A retrospective cohort study which will conduct medication chart review through ICU database (MIMIC II) between 2001 and 2008.

Methods: Inclusion criteria are ICU patients (age ≥ 18 years) who received enoxaparin (40 mg SQ daily or 30 mg SQ twice daily for CrCl >30 ml/min; 30 mg SQ daily for CrCl < 30 ml/min) for VTE prophylaxis in ICU. Patients who received non-standard doses of enoxaparin or had a missing dose of enoxaparin, no risk factor for VTE, received concomitant other anticoagulant therapy (ex: warfarin), or had missing weight or height information will be excluded. Primanry outcome is VTE rate during hospitalization and secondary outcome are average daily dose per weight, total enoxaparin dose, total duration of therapy, hospital length of stay, ICU length of stay, time to onset of VTE during hospitalization and bleeding incidence.

Results: IRB approval is not required since this study uses a publicly available database. Currently on getting data from MIMIC II clinical database.

Conclusions: Study results will reveal if VTE rate is different in morbidly obese patients and will provide a foundation for subsequent research that compares different dosing strategies in critically ill morbidly obese patients to identify optimal VTE prophylactic dosing.