A prospective longitudinal multicenter study of coagulation in pediatric patients undergoing allogeneic stem cell transplantation.

Background: Thrombotic complications occur in adult patients undergoing stem cell transplantation (SCT), especially following high dose chemo-radiotherapy. There is little published information in children on the impact of SCT on coagulation, as well as potential correlations between altered coagulation and SCT-associated thrombosis and organ failure.

Procedure: Forty three pediatric subjects who underwent allogeneic SCT were prospectively evaluated for congenital thrombophilia, anticoagulant levels, coagulation activation, and fibrinolysis at pre-established set points encompassing the period from the 2 to 4 weeks prior to conditioning to 28 days post-transplantation.

Results: A significant decrease of protein C and antithrombin levels was found in 39% and 31% of subjects respectively, between SCT days +6 and +7. A peak in plasminogen activator inhibitor-1 levels in 31% of subjects was noted between days +9 and +10. No subject experienced a thrombotic event or other SCT-related organ failure. Antithrombin deficiency correlated with underlying malignancy, donor HLA-mismatch, and TBI, whereas decreased PC activity demonstrated a trend of association with lack of T-cell depletion and TBI. Prophylactic heparin did not influence the pattern of acquired hemostatic abnormalities observed in this cohort.

Conclusions: Children undergoing allogeneic SCT develop a state of acquired thrombophilia in the early post-transplantation period. Although no SCT-related thromboembolic events were observed, our results provide new information about the hemostatic changes in children undergoing allogeneic SCT and their potential clinical triggers. The significance of these findings requires further prospective evaluation in a larger cohort of patients.