INFLUENCE OF VARIOUS FACTORS ON ANTI-XA LEVELS IN HOSPITALIZED MEDICAL PATIENTS RECEIVING PARENTERAL THROMBOPROPHYLAXIS

Abstract

Objective: Venous thromboembolism (VTE) stands as a prevalent vascular disease, intimately linked to increased risk for morbidity and mortality. The aim of this study was to investigate the influence of various factors on anti-Xa levels in hospitalized medical patients receiving parenteral thromboprophylaxis. Design and method: This is a single-center cohort study encompassing patients admitted to the Internal Medicine Department of the University Hospital of Heraklion, from March to August 2023. These patients were placed on thromboprophylaxis due to a heightened risk of developing VTE. Data regarding demographics, past medical history, somatometric and laboratory findings as well as the type and dose of parenteral anticoagulant were recorded. The measurement of anti-Xa levels were conducted 4 hours subsequent to the third subcutaneous administration of anticoagulant. Results: In this study, we enrolled 150 individuals [91 women (60.7%)], with an average age of 80 years. Sixty-two (41.4%) patients exhibited non-therapeutic anti-Xa levels. The levels were subtherapeutic (<0.2units/mL) in 36 patients and supratherapeutic (>0.5units/mL) in 26 patients. Non-therapeutic anti-Xa levels were observed in all underweight patients and in 12 out of 13 obese class II and III patients. It's noteworthy that therapeutic anti-Xa levels were observed in more than half of healthy-weight and overweight patients. A univariate logistic regression analyses was conducted to explore factors (age, sex, past medical history, somatometric and laboratory findings) that had impact on anti-Xa levels. Among these, only body weight emerged as independent factor influencing anti-Xa levels. Conclusions: In our study, we demonstrated that 41.3% of medical patients who were administered parenteral thromboprophylaxis exhibited non-therapeutic anti-Xa levels. This was more profound for underweight or obese class II and III patients. Body weight was emerged as independent factor influencing anti-Xa levels. Further studies on weight-based LMWH thromboprophylaxis dosing in this population are likely to yield new insights improving decisions in daily clinical practice.