Risk factors associated with poor response to immunosuppressive therapy in acquired aplastic anemia: A meta-analysis of retrospective studies.

Acquired aplastic anemia (AA) is a rare hematological disease characterized by bone marrow hypocellularity and varying degrees of pancytopenia. Immunosuppressive therapy (IST) is currently one of the first-line treatments for AA; however, unresponsiveness remains a major concern. Although previous studies have suggested several common risk factors for unresponsiveness, there are currently no widely accepted predictors. Therefore, a meta-analysis of clinical trials including information on factors associated with unresponsiveness of AA to IST was performed in the present study. The PubMed, Embase and Cochrane Library databases were searched for clinical studies on AA evaluating the association between risk factors and unresponsiveness to IST. After the factors were defined from the selected studies, the association between these factors and unresponsiveness to IST was analyzed using Review Manager software. A total of 10 studies comprising 1,820 cases were included in the present meta-analysis. The following factors were identified as predictors of unresponsiveness: Age (≥60 years), sex, absolute neutrophil count, severity of the disease, paroxysmal nocturnal hemoglobinuria clone, human leukocyte antigen (HLA)-DR2 and cytogenetic abnormalities (CAs). Among these factors, only age (≥60 years) [odds ratio (OR)=1.65], HLA-DR2 negativity (OR=2.72) and CAs (OR=1.93) exhibited a statistically significant association with unresponsiveness to IST (P=0.006, P=0.04 and P=0.01, respectively). In conclusion, the present meta-analysis revealed that age ≥60 years, HLA-DR2 negativity and CAs are risk factors for unresponsiveness to IST. This result may enable clinicians to select an effective therapeutic scheme for patients with AA and even provide novel clues to the pathogenesis of AA.