Comparison of clinical characteristics of first-episode Thrombotic Thrombocytopenic Purpura and TTP-like syndrome: a retrospective cohort study in a level I hematology centre in China

Aims: : Comparing the characteristics of thrombotic thrombocytopenic purpura (TTP) and TTP-like syndrome patients at admission to allow early differentiation of TTP from TTP-like syndrome and help tailor initial treatment. Methods: : The medical records of 78 patients with suspected TTP in the emergency department of Peking University People’s Hospital in the past five years were retrospectively analyzed retrospectively and divided into TTP and TTP-like syndrome groups based on ADAMTS13 activity and ADAMTS13 antibody titer. Results: : There were 25 and 53 patients in the TTP group and the TTP-like syndrome group, respectively. The PLASMIC score was significantly higher in the TTP group than in the TTP-like syndrome group ( P =0.006). The TTP group were more susceptible to receiving plasma exchange and glucocorticoids ( P <0.001), and also less vulnerable to the plasma infusion ( P <0.001). The etiology induced by autoimmune disease was more prominent in the TTP group ( P <0.001). The neutrophil-to-lymphocyte ratio ( P =0.025) was tremendously higher, and albumin ( P =0.002) was lower in the TTP-like syndrome group, indicating a more severe infection. Compared with the TTP-like syndrome group, the TTP group had an approximately two-fold to three-fold higher prevalence of central nervous system dysfunction ( P <0.001). Also, hemolysis was more substantial in the TTP group as evidenced by higher schistocytes ( P <0.001), reticulocyte ( P <0.001), total bilirubin ( P =0.002), indirect bilirubin ( P <0.001), lactate dehydrogenase ( P =0.007) and cell-free hemoglobin ( P <0.001), simultaneously lower platelet ( P <0.001), haptoglobin ( P =0.044) and ADAMTS13 activity ( P <0.001). The Kaplan–Meier survival analysis showed that the TTP group significantly predicted poor prognosis (log-rank test: X 2 =5.368, P =0.021). Conclusion: TTP and TTP-like syndrome are two kinds of distinct phenotypes with different hemolysis statuses and illustrated differentiated inflammatory reactions, target organ damage (TOD), and their clinical outcome.