Enoxaparin treatment dosing for venous thromboembolism in pediatric patients with obesity.

BACKGROUND: The optimal enoxaparin dosing for treatment of venous thromboembolism (VTE) in pediatric patients with obesity remains uncertain. We described the mean enoxaparin dose required to attain anti-factor Xa (anti-Xa) levels of 0.5-1 unit/mL in pediatric patients with obesity. METHODS: Pediatric patients with obesity (body mass index [BMI] ≥95th percentile) who received treatment dose of enoxaparin from 2013 to 2022 and had at least one appropriately timed anti-Xa level were retrospectively evaluated. Daily enoxaparin dose required to achieve an anti-Xa level of 0.5-1 unit/mL was reviewed and compared by the severity of obesity. The correlation coefficients between enoxaparin dose requirement and BMI, BMI percentile, and weight were measured by Spearman's rank correlation coefficient. RESULTS: Pediatric patients with obesity (n = 89) required a mean enoxaparin dose of 0.8 ± 0.18 mg/kg twice daily to attain a therapeutic anti-Xa level. Children with BMI 95th-99th percentile and weight ≤100 kg achieved the target level on a significantly higher weight-based enoxaparin dose compared to BMI greater than 99th percentile (0.95 ± 0.15 vs. 0.75 ± 0.15 mg/kg twice daily; p < .001) and weight greater than 100 kg (0.95 ± 0.14 vs. 0.7 ± 0.12 mg/kg twice daily; p < .001). BMI, BMI percentile, and weight showed a moderate to strong negative correlation with enoxaparin dose requirement. CONCLUSIONS: Pediatric patients with obesity required a lower weight-based dose of enoxaparin to achieve a therapeutic anti-Xa than the recommended starting dose of 1 mg/kg twice daily for treatment of VTE. Among obesity indices, weight showed the strongest negative correlation with total daily enoxaparin requirement.

Enoxaparin thromboprophylaxis in hospitalized obese pediatric patients.

BACKGROUND: Enoxaparin is an anticoagulant used for pharmacologic thromboprophylaxis in pediatrics. Enoxaparin pharmacokinetics can be altered in the setting of obesity. Optimal enoxaparin dosing for thromboprophylaxis in children with obesity remains unclear. PROCEDURE: A retrospective review was conducted of pediatric patients who weighed ≥60 kg with BMI ≥ 95th percentile, received enoxaparin for thromboprophylaxis, and had at least one appropriately drawn anti-factor Xa (anti-Xa) from 2013 to 2022. Anti-Xa levels were reviewed for patients initially treated with enoxaparin 30 mg every 12 h. The average daily enoxaparin dose required to achieve an anti-Xa of 0.2-0.4 unit/mL, which was stratified by BMI percentile and weight, was calculated. RESULTS: Of 116 patients (median age 15.8 years) included for analysis, 106 patients were initially treated with enoxaparin 30 mg every 12 h. Anti-Xa levels were <0.2 unit/mL in 53% of patients with BMI > 99th percentile and 54% of patients >100 kg. Ninety-one patients had at least one anti-Xa 0.2-0.4 unit/mL with an average daily enoxaparin dosing of 66 mg. When stratified by severity of obesity, higher doses were required to attain an anti-Xa 0.2-0.4 unit/mL in patients with BMI > 99th percentile compared with those with 95th-99th percentile (67.8 ± 15.7 vs. 62 ± 5.6 mg/day, p = .01). Patients > 100 kg required significantly higher dose than those ≤100 kg (69.1 ± 15.5 vs 61.2 ± 7.3 mg/day, p = .002). CONCLUSIONS: Increased initial dosing and/or anti-Xa level monitoring should be considered in adolescents with severe obesity receiving enoxaparin thromboprophylaxis.

Technical Feasibility and Clinical Efficacy of Iliac Vein Stent Placement in Adolescents and Young Adults with May-Thurner Syndrome.

PURPOSE: To report technical feasibility and clinical efficacy of iliac vein stent placement in adolescent patients with May-Thurner Syndrome (MTS). MATERIALS AND METHODS: Single-institution retrospective review of the medical record between 2014 and 2021 found 63 symptomatic patients (F = 40/63; mean age 16.1 years, 12-20 years) who underwent left common iliac vein (LCIV) stent placement for treatment of LCIV compression from an overriding right common iliac artery, or equivalent (n = 1, left IVC). 32/63 (50.7%) patients presented with non-thrombotic iliac vein lesions (NIVL). 31/63 (49.2%) patients presented with deep vein thrombosis of the lower extremity and required catheter-directed thrombolysis after stent placement (tMTS). Outcomes include technically successful stent placement with resolution of anatomic compression and symptom improvement. Stent patency was monitored with Kaplan-Meier analysis at 3, 6, 12, 24, and 36 months. Anticoagulation and antiplatelet (AC/AP) regimens were reported. RESULTS: Technical success rate was 98.4%. 74 bare-metal self-expanding stents were placed in 63 patients. Primary patency at 12, and 24-months was 93.5%, and 88.9% for the NIVL group and 84.4% and 84.4% for the tMTS group for the same period. Overall patency for the same time intervals was 100%, and 95.4% for the NIVL group and 96.9%, and 96.9% for the tMTS group. Procedural complication rate was 3.2% (2/63) with no thrombolysis-related bleeding complications. Clinical success was achieved in 30/32 (93.8%) and 29/31 (93.5%) patients with tMTS and NIVL groups, respectively. CONCLUSION: CIV stent placement in the setting of tMTS and NIVL is technically feasible and clinically efficacious in young patients with excellent patency rates and a favorable safety profile.