Outcomes of Prophylactic Enoxaparin Against Venous Thromboembolism in Hospitalized Children

OBJECTIVES: To assess the biochemical and clinical outcomes of hospitalized children who received prophylactic enoxaparin. METHODS: We conducted a retrospective observational study of hospitalized children aged <18 years who received prophylactic enoxaparin against hospital-acquired venous thromboembolism (HA-VTE). Weight-based enoxaparin dosing was administered using a pharmacy-driven protocol, which later included a low molecular weight, anti-Xa level directed-dose adjustment strategy. Primary biochemical and clinical outcomes were achievement of goal anti-Xa range of 0.2 to 0.5 IU/mL and development of HA-VTE, respectively. Secondary clinical outcome was development of clinically relevant bleed. RESULTS: We analyzed 194 children with 13 (6.7%) infants aged <1 year and 181 (93.3%) older children aged >= 1 year. After the initial dose, only 1 (11.1%) infant, but 62 (57.9%) older children, achieved goal. Median number of anti-Xa levels until goal was 2 (interquartile range: 2-3) in infants and 1 (interquartile range: 1-2) in older children (P = .01). HA-VTE developed in 2 (15.4%) infants and 9 (5.0%) older children. Among children with anti-Xa level, HA-VTE developed less frequently in children who achieved (2.1%) than in those who did not achieve (13.6%) goal (P = .046). A total of 4 (2.1%) older children and no infants developed clinically relevant bleed. Among children with anti-Xa level, frequency of bleeding was comparable between children who did (3.2%) and did not achieve (0%) goal (P >.99). CONCLUSIONS: Our findings suggest the effectiveness and safety of an anti-Xa level directed strategy of prophylactic enoxaparin. However, this strategy should be investigated in prospective controlled studies.