OBJECTIVETo analyze early hematopoietic response and long-term survival of very severe aplastic anemia (VSAA) patients with different absolute neutrophil counts (ANC) after frontline immnunosuppressive therapy (IST).

METHODSClinical data and outcome of 145 VSAA patients treated with rabbit antithymocyte globulin combined with cyclosporine were retrospectively analyzed. Hematopoietic responses to IST and long-term survival were statistically analyzed for VSAA patients in different ANC subgroups.

RESULTSPre-IST ANC=0.05×10(9)/L acted as the best cutoff level to predict IST response at 3, 6 months. For 145 VSAA patients, early death rate was 13.4% (11/82) vs 1.6% (1/63), respectively, in the ANC≤0.05×10(9)/L group and ANC>0.05×10(9)/L group (P<0.05). Hematopoietic response rates to IST was 22.0% vs 54.0% (P=0.000) at 3 months, 34.1% vs 63.5% (P=0.000) at 6 months; the overall five-year survival rate was only (62.5±5.4) % vs (91.4±3.7) % (P=0.000) and five-year event-free survival rate was (42.3±5.5) % vs (63.1±6.5) % (P=0.003), respectively, in the ANC≤0.05×10(9)/L group and ANC>0.05×10(9)/L group.

CONCLUSIONVSAA patients with extremely low ANC (≤0.05×10(9)/L) had high early death rate and with very low response rate to frontline IST and poor survival, so it is urgent to seek for the alternative frontline therapy that will bring faster and better outcome for these patients.