Late Relapses in Patients Successfully Treated for Thrombotic Thrombocytopenic Purpura

doi:10.1059/0003-4819-122-8-199504150-00002

Late Relapses in Patients Successfully Treated for Thrombotic Thrombocytopenic Purpura

Kenneth H. Shumak, MD;
Gail A. Rock, PhD, MD;
Rama C. Nair, PhD; and
The Canadian Apheresis Group.

From the University of Toronto, Toronto, Canada; and the University of Ottawa, Ottawa, Canada. Requests for Reprints: Kenneth H. Shumak, MD, Toronto-Sunnybrook Regional Cancer Centre, 2075 Bayview Avenue, North York, Ontario, Canada M4N 3M5. Acknowledgments: The authors thank Carole Herbert and Ann Kasaboski for their commitment and for collecting data on patients with thrombotic thrombocytopenic purpura even after the patients were discharged from the hospital. Grant Support: In part by grant 6613-1158 from the National Health Research and Development Program, Canada, and by the provinces of Canada through the Canadian Blood Agency.

Abstract

Objective: To determine the incidence and timing of relapses in patients who have recovered from an acute episode of thrombotic thrombocytopenic purpura.

Design: Clinical follow-up for 3 to 10 years.

Setting: General community outpatient study; patients who had relapse were hospitalized.

Participants: 63 of 72 surviving patients who had participated in a randomized study that compared plasma exchange and plasma infusion as treatments for thrombotic thrombocytopenic purpura and for whom continued clinical follow-up was obtained.

Outcome Measures: Recurrence of thrombotic thrombocytopenic purpura as defined by a decrease in platelet count to less than 100 × 10⁹/L and by the onset of microangiopathic hemolytic anemia as identified by erythrocyte fragmentation in a peripheral blood film.

Results: 37 of the 63 patients have not had recurrence of thrombotic thrombocytopenic purpura and have remained completely well; 6 patients have not had recurrence but have developed other medical problems; 3 patients have not had recurrence but have residual neurologic defects from the original episode; and 17 patients have had one or more recurrences, occurring 7 months to 8 years after the original episode. As determined by Kaplan-Meier analysis, the projected 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 have at least one relapse during the following 10 years.