The incidence of venous thromboembolism (VTE) in children is rising. Hence, there is an increasing off-label use of low-molecular-weight heparin (LMWH). There is little data about therapeutic and prophylactic LWMH dosages, and their safety and efficacy. This systematic review provided an oversight of the therapeutic and prophylactic dosages of LMWH required to reach therapeutic and prophylactic target ranges. Furthermore, the safety and efficacy of LMWH, in terms of bleeding complications, achieving therapeutic and prophylactic antifactor Xa levels, development of (recurrent) VTE and cloth resolution were reviewed. A total of 49 studies were included, encompassing 3101 patients. Initial weight-adjusted dosages to reach therapeutic or prophylactic target ranges decreased with age. In children with therapeutic use of LMWH, major bleeding complications occurred in 1.8% (95% CI: 1.1–2.5%) of the patients, a mean of 79.9% (95% CI: 77.5–82.3%) of the children achieved the target range with or without dosage adjustments, recurrent VTE occurred in 3.2% (95% CI: 2.1–4.3%) and thrombus resolution in 63.5% (96% CI: 60.2–66.8%) of the patients. In children with prophylactic LMWH, major bleedings occurred in 0.6% (95% CI: 0.2–1.0%) of the patients, a mean of 90.4% (95% CI: 84.6–96.2%) of the children achieved the target range, and 2.2% (95% CI: 1.3–3.1%) experienced a new VTE. In conclusion, a higher initial therapeutic dosage of LMWH was needed in comparison to advised dosages, to achieve target range, especially in neonates and children < 5 years. LMWH appeared to be safe and effective for therapeutic and prophylactic treatment of VTE in children.

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Blood Reviews
Department of Pediatrics