highly significantP <0.0001
A multivariate analysis adjusted for etiology, site, age, and weight in comparison with ideal weight showed that in both young children and in the older population, time spent with plasma FVIII <1 IU/dL was a highly significant predictor of the rate of all bleeding ( P <0.0001 for young children; P <0.05 for older patients) and the rate of joint bleeds ( P <0.0001 for young children; P <0.02 for older patients).