Comparison of clinical characteristics of first-episode thrombotic thrombocytopenic purpura and TTP-like syndrome: a retrospective cohort study in a level I hematology center in China.

Comparing the characteristics of thrombotic thrombocytopenic purpura (TTP) and TTP-like syndrome patients at admission will allow early differentiation of TTP from TTP-like syndrome and help tailor initial treatment. The medical records of 78 patients with suspected TTP in the Emergency Department of Peking University People's Hospital in the past 5 years were retrospectively analyzed and divided into TTP and TTP-like syndrome groups based on ADAMTS13 activity and ADAMTS13 antibody titer. There were 25 and 53 patients in the TTP group and the TTP-like syndrome group, respectively. 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 inflammation. 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: X2 = 5.368, P = 0.021). 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 the clinical outcome.