LATE RELAPSES IN PATIENTS SUCCESSFULLY TREATED FOR THROMBOTIC THROMBOCYTOPENIC PURPURA

Objective: To determine the incidence and timing of relapses in patien ts who have recovered from an acute episode of thrombotic thrombocytop enic purpura. Design: Clinical follow-up for 3 to 10 years. Setting: G eneral community outpatient study; patients who had relapse were hospi talized. Participants: 63 of 72 surviving patients who had participate d in a randomized study that compared plasma exchange and plasma infus ion as treatments for thrombotic thrombocytopenic purpura and for whom continued clinical follow-up was obtained. Outcome Measures: Recurren ce of thrombotic thrombocytopenic purpura as defined by a decrease in platelet count to less than 100 x 10(9)/L and by the onset of microang iopathic hemolytic anemia as identified by erythrocyte fragmentation i n a peripheral blood film, Results: 37 of the 63 patients have not had recurrence of thrombotic thrombocytopenic purpura and have remained c ompletely well; 6 patients have not had recurrence but have developed other medical problems; 3 patients have not had recurrence but have re sidual neurologic defects from the original episode; and 17 patients h ave had one or more recurrences, occurring 7 months to 8 years after t he original episode. As determined by Kaplan-Meier analysis, the proje cted recurrence rate after 10 years in all surviving patients is 36% ( 95% CI, 23% to 59%). Conclusions: More than one third of patients who survive an acute episode of thrombotic thrombocytopenic purpura will h ave at least one relapse during the following 10 years.