In the treatment studies over 50% of the patients were children. In doses above the recommended dose of 25 mg/kg/day there was a higher proportion of patients with bleeding events in the high dose group but since many events occurred in the follow-up period, a clear relationship with defibrotide treatment could not be determined. In the paediatric prevention study at 25 mg/kg/day there was an increased incidence of any bleeding events in the defibrotide group compared with the treatment group. However there was no difference in incidence of serious bleeding or bleeding events with fatal outcome.