Thrombotic adverse events to coagulation factor concentrates for treatment of patients with haemophilia and von Willebrand disease: a systematic review of prospective studies.

Thrombotic adverse events (AEs) after clotting factor concentrate administration are rare but the actual rate is unknown. A systematic review of prospective studies (1990-2011) reporting safety data of factor concentrates in patients with haemophilia A (HA), haemophilia B (HB) and von Willebrand disease (VWD) was conducted to identify the incidence and type of thrombotic AEs. In 71 studies (45 in HA, 15 HB, 11 VWD) enrolling 5528 patients treated with 27 different concentrates (20 plasma-derived, 7 recombinant), 20 thrombotic AEs (2 HA, 11 HB, 7 VWD) were reported, including two major venous thromboembolic episodes (both in VWD patients on prolonged replacement for surgery). The remaining thrombotic AEs were superficial thrombophlebitis, mostly occurring at infusion sites in surgical patients and/or during concentrate continuous infusion. The overall prevalence was 3.6 per 10(3) patients (3.6 per 10(4) for severe AEs) and 1.13 per 10(5) infusions, with higher figures in VWD than in haemophilia. Thrombotic AEs accounted for 1.9% of non-inhibitor-related AEs. Thrombosis-related complications occurred in 10.8% of patients with central venous access devices (CVADs) reported in six studies, the risk increasing with time of CVAD use. Data from prospective studies over the last 20 years suggest that the risk of thrombotic AEs from factor concentrate administration is small and mainly represented by superficial thrombophlebitis. These findings support the high degree of safety of products currently used for replacement treatment.