Table 1.

Definitions of primary prophylaxis.

European Paediatric Network for Haemophilia Management, 1999	Primary prophylaxis determined by age	Long-term continuousa treatment started before the age of 2 years and prior to any clinically evident joint bleeding.
	Primary prophylaxis determined by first bleed	Long-term continuousa treatment started prior to the onset of joint involvement (presumptively defined as having had no more than one joint bleed), irrespective of age.
European Paediatric Network for Haemophilia Management, 2006		Regular continuous treatment started after the first joint bleed and before the age of 2 years.
International Society on Thrombosis and Haemostasis, 2014		Regular continuousb replacement therapy started in the absence of documented joint disease, determined by physical examination and/or imaging studies, and before the second clinically evident joint bleed and age 3 years.

^aWith the intent of treating 52 weeks/year up to adulthood and receiving treatment a minimum of 46 weeks/year.

^bContinuous is defined as the intent to treat for 52 weeks/year and receiving a minimum of an a priori defined frequency of infusions for at least 45 weeks (85%) of the year under consideration.