Effectiveness and safety of nadroparin therapy in preterm and term neonates with venous thromboembolism

Introduction: Optimal neonatal nadroparin dosages to treat venous thromboembolism (VTE) are unknown. Objective: To evaluate therapeutic nadroparin dosages to reach therapeutic target ranges (TTR: 0.5–1.0 International Unit (IU)/mL) and the effectiveness and safety of nadroparin in neonatal VTE. Methods: Retrospective study including neonates with VTE on nadroparin in a tertiary center between 2007 and 2018. Two groups were distinguished: neonates before (group 1) and after (group 2) switch to higher starting dosages in 2014. Results: Sixty-one neonates (44 preterm, 17 term) with 64 VTEs were included. TTR was reached in 32/64 (50%) VTEs (group 1: 35.7%; group 2: 61.1%). Median nadroparin dosage to reach TTR was 197 (97.9–330.3) IU/kg/12 h. No therapy-related deaths occurred. Recurrent VTE developed in 6 (9.8%) neonates. Complete clot resolution was observed in 31/41 (75.6%) VTEs. TTR was reached in 58.1% VTEs with complete clot resolution. No major bleeding occurred. Non-major clinically relevant bleedings occurred in 3/64 (4.7%) VTEs, consisting of large hematomas due to the use of subcutaneous catheters. Conclusions: High nadroparin dosages are needed to reach TTR in neonates, which seem to be safe. Clot resolution may occur without reaching TTR. Subcutaneous catheters may cause important bleeding complications.