Trends in mean number of joint hemorrhages in the preceding 6 months by prophylaxis status, 1999 to 2010. (A-C) The vertical axis on the right displays the mean number of joint hemorrhages per 6 months during each study year for participants using (▲) or not using (▪) continuous prophylaxis. The vertical axis on the left displays the proportion of the entire age cohort using prophylaxis for each study year (□). (A-C) Displays results for children ages 2 to 9 years (A), adolescents 10 to 19 years (B), and adults 20 to 29 years (C), respectively. Prophy, prophylaxis; Prophy +, data from patients on prophylaxis; Prophy −, data from patients not on prophylaxis.