Augmented Renal Clearance and Anti-Factor Xa Activity in Critically Ill Patients Receiving Low-Molecular-Weight Heparin: A Retrospective Cohort Study

Details

Supervisors

Sneyers, Barbara ; Marrant, Erwin

Faculty

Faculté de pharmacie et des sciences biomédicales

Degree label

Master de spécialisation en pharmacie hospitalière

Abstract

enBackground: Augmented renal clearance (ARC) affects over a third of critically ill patients, potentially leading to inadequate exposure of renally excreted drugs. The elimination of low-molecular-weight heparins (LMWHs) relies primarily on renal clearance; however, limited data exist on how ARC may impact their elimination and anti-factor Xa (anti-Xa) activity. Aim: To evaluate the impact of ARC on anti-Xa activity in intensive care unit (ICU) patients receiving LMWH. Method: A retrospective single-center cohort study was conducted in a 24-bed medico-surgical ICU at an academic hospital (CHU UCL Namur, Godinne). All adult patients admitted to the ICU who received LMWH and had at least one anti-Xa activity measurement between January 2021 and December 2025 were included. Data were collected from medical records and included patient demographics (age, sex, body weight, height), serum creatinine, estimated glomerular filtration rate (eGFR), 24-hour urine output, platelet count, international normalized ratio (INR), use of renal replacement therapy, anti-Xa activity, and information regarding LMWH administration (timing, dose, indication). Estimated ARC was defined as a mean Modification of Diet in Renal Disease (MDRD) eGFR above 130 mL/min/1.73 m². We compared anti-Xa activity in ARC and non-ARC patients. Multivariable linear and logistic mixed-effects regression models were used to evaluate factors associated with anti-Xa activity and with values below or above the expected range (0.2–0.4 IU/mL for prophylaxis and 0.6–1.0 IU/mL for treatment). Results: 250 patients were included, of whom 32 (13%) had ARC. Estimated ARC was associated with higher risk of anti-Xa activity below the expected range, although the association was not statistically significant (odds ratio [OR] 1.94, 95% confidence interval [CI] 0.60–6.24; p = 0.30). LMWH overdosing was significantly associated with lower risk of anti-Xa activity below the expected range (OR 0.20, 95% CI 0.06–0.59; p = 0.004). Conclusion: ARC was not independently associated with anti-Xa activity below the expected range in this cohort. However, the direction of effect remained biologically plausible. Dose adequacy appeared to be a stronger determinant of anti-Xa activity than ARC status alone. Prospective multicenter studies using measured creatinine clearance and systematic peak and trough anti-Xa assessment are needed.