The clinical features, risk factors and outcome of thrombotic thrombocytopenic purpura occurring after bone marrow transplantation

In this study, we retrospectively analysed the clinical features, risk fact ors and outcome of 22 patients with thrombotic thrombocytopenic purpura (TT P) occurring after allogeneic stem cell transplantation. All but two of the se patients received stem cells from unrelated donors (UDs), two-thirds wer e female. three-quarters were adults and leukaemia was the major reason for transplant. The incidence of TTP was 20 out of 332 patients (6%) with UD t ransplants and two out of 104 recipients (2%) of matched sibling allografts (P = 0.16). In order to ascertain basic demographic risk factors for the d evelopment of TTP, we compared the 22 patients with 434 patients who did no t deoelop TTP. Compared with patients who did not develop TTP, patients wit h TTP were nearly three times older (P < 0.001) and were more than twice as likely to be female (P = 0.001). Because > 90% of patients were recipients of UD marrow, we then compared the 20 UD-bone marrow transplantation (BMT) patients with 60 randomly selected UD-BMT patients who did not develop TTP . On univariate analysis, age and female gender were again significant risk factors, as was grade II-IV acute graft-versus-host disease (GvHD) (P = 0. 002), and there was a trend towards an association with chronic GvHD (P = 0 .083). However, after logistic regression analysis, only age and sex remain ed significant (P < 0.001 and 0.009 respectively), We report an 86% mortali ty with only three survivors out of 22 patients, and one of these remains t hrombocytopenic and red cell transfusion dependent, possibly in part becaus e of graft hypoplasia. Six out of 17 patients responded to plasmapheresis, but the majority of them ultimately succumbed because of TTP, often in asso ciation with GVHD or fungal infection.