[Delayed hematologic response to immunosuppressive therapy in severe aplastic anemia].

To explore the characteristics of delayed hematologic response in very/severe aplastic anemia (V/SAA) patients who were treated with immunosuppressive treatment (IST) as first-line approach, and investigate the rationality of early salvage treatment in refractory patients. The data of V/SAA patients front-line treated with IST were retrospectively analyzed. Delayed response was defined as acquiring hematologic response between 6 and 12 months after 1 course of IST. The clinical as well as hematologic characteristics of the delayed responded patients were investigated. Of the 533 patients, 45 (8.44%, 45/533) were delayed hematologic responders, which accounted for 29.03% (45/155) of the whole non-responders at 6 months. The quality of response in delayed responders analyzed at 12 months (χ=62.616, <0.001) and at the end of follow-up (χ=6.299, =0.043) was significantly worse than that of robust response group. There were more VSAA patients in delayed response group compared with robust response group (57.8% 38.3%, =0.013), and all the baseline absolute reticulocyte (ARC) count, ARC proportion and absolute neutrophil count (ANC) were much lower than that in delayed response group. Multivariate analysis about the above 2 groups showed that the baseline ARC count <10×10/L significanty reduced the chance of hematologic response within 6 months [=3.641(95% 1.718-7.719) , =0.001], and not any factor was found to predict delayed hematologic response in non-responders at 6 months. The 5-year overall survival of 76.50% (95% 71.6%-81.4%) and event free survival of 29.10%(95% 25.2%-33.0% ) in non-responders at 6 months, both were worse than 97.6% (95% 96.6%-98.6% ) and 84.0% (95% 81.1%-86.9% ) ( <0.001) of robust response group. The incidence of delayed hematologic response in V/SAA patients by IST is low. The quality of delayed response is not satisfactory and there is no effective means to predict the delayed response. It is reasonable to carry out salvage treatment as early as possible.