Outcomes following low-dose rituximab and plasma exchange for the treatment of acquired TTP. (A) Time to initial treatment response (ie, platelet count >150 000/mL on 2 consecutive days). (B) The incidence of exacerbation prior to day 30 was 12%. (C) The relapse-free survival at 2 years was 72%. The cumulative incidence of response and relapse was estimated by the method of Kaplan-Meier.