Clinical characteristics, treatments, and outcomes of thrombotic thrombocytopenic purpura treated with plasma exchange in Japan: a nationwide inpatient database study

Background Plasma exchange (PEX) has been the primary treatment for immune-mediated thrombotic thrombocytopenic purpura (iTTP) since the 1990s. Daily PEX is recommended in international guidelines, but PEX was only reimbursed up to three times weekly under the Japanese national health insurance system until March 2018. This study was conducted to analyze practice patterns and outcomes in patients with TTP in Japan. Methods We used the Japanese Diagnosis Procedure Combination inpatient database, including data from approximately 1,200 acute care hospitals. We identified all hospitalized adult patients who were diagnosed with TTP on admission from July 2010 to March 2017 and who received at least one PEX during hospitalization, which we defined as TTP treated with PEX. We revealed patient characteristics, treatment patterns, and outcomes. Results There were 1,559 patients with TTP treated with PEX. The median age was 64 (interquartile range [IQR] 46–74) years. There were slightly more women (59%) than men enrolled into this study. The median PEX frequency within 7 days of the initial PEX was three (IQR 2–5) times. The median total PEX number during hospitalization was six (IQR 3–10), while the median PEX duration was 10 (IQR 4–22) days. The median time from admission to the initial PEX was 4 (IQR 2–11) days. Overall, in-hospital mortality was 32%. Thirty-three percent (144/437) of hospitals reported only one case of TTP during the study period. Conclusions Our data demonstrated that clinical practice in Japan considerably varied and its standardization is warranted.