Antiplatelet agents in thrombotic thrombocytopenic purpura (TTP). Results of a randomized multicenter trial by the Italian Cooperative Group for TTP

Abstract

BACKGROUND AND OBJECTIVE: Antiplatelet agents are often included in plasma exchange-based regimens for thrombotic thrombocytopenic purpura (TTP) patients; however, the opportuneness of their use in TTP is still controversial. The italian Cooperative Group for TTP carried out a randomized trial to investigate their actual effectiveness, both in acute TTP and as maintenance treatment. METHODS: Seventy-two TTP patients were randomized to receive plasma exchange and steroids with (group B) or without (group A) aspirin and dipyridamole. Treatment efficacy was evaluated after 15 days and salvage treatments were also considered for non-responders. Upon disease remission, the patients already treated with antiplatelet agents received ticlopidine for one year. RESULTS: Regarding the treatment of acute phase TTP, similar overall response rates were observed in the two groups (91.4% in group B vs. 75.6% in group A), but lower mortality rates were observed at 15 days in the patients treated with antiplatelet agents; as a matter of fact, 5 patients from arm A died in the first 15 days (13.5%) versus only one in arm B (2.8%). These figures, while not statistically significant, seem to suggest that antiplatelet agents might be useful in preventing deaths in acute TTP; moreover, bleeding did not worsen in antiplatelet agent-treated patients. As for the role of maintenance treatment, our results support the efficacy and safety of one-year ticlopidine therapy since the current relapse rate is significantly higher in non-treated patients; as a matter of fact, 6 patients (21.4%) in the non-ticlopidine group and only 2 (6.25%) in the ticlopidine group relapsed (P = .0182 in favor of maintenance treatment). INTERPRETATION AND CONCLUSIONS: Our results suggest the usefulness of antiplatelet agents in the treatment of acute phase TTP patients. Moreover, one-year ticlopidine maintenance therapy appears to be beneficial in preventing TTP relapses; however, only the completion of an adequate follow-up for all patients will definitively confirm this observation.