Aplastic anemia is pancytopenia with a hypocellular bone marrow [<25 % (or 25 to 50 % if <30 % of residual cells are hematopoietic)] due to failure of the bone marrow in the absence of marrow fibrosis or abnormal infiltrates.

For therapeutic guide, the disease is classified into moderately severe, severe and very severe aplastic anemia depending on the degree of cytopenia .Accordingly, patients with severe or very severe forms are started on therapy urgently while patients suffering from non-severe AA are treated conservatively with as needed PRBCs, platelets and growth factors support. Allogenic Hematopoietic stem cell transplantation is the standard of care for young patients with severe AA.

Survival following allogenic Hematopoietic stem cell transplantation or immunosuppressive therapy were compared in aplastic anemia according to severity and the prognostic factors related with survival identified.

This is a retrospective study of 156 patients with AA. The outcome of these patients were first analyzed according to the first-line treatment received (SCT vs. IST with no subsequent transplant). The outcome was further stratified based on their risk stratification into moderate, severe, and very severe.

Patient's characteristics were summarized using frequencies with percentages for categorical variables and medians with interquartile ranges for continuous data. Probabilities of OS and EFS were summarized using Kaplan-Meier estimator. Survival curves were compared using log-rank test. P-value< 0.05 was considered significant. Analysis was conducted using RStudio 2022.07.2 Build 576 ©ฏ 2009-2022 RStudio, PBC.

A 156 patients, 92 (59%) were treated with SCT and 64 (41.0%) with IST. 24(15.4%) patients were moderately severe AA, 56 (35.9%) severe AA and 76 (48.7%) very severe AA. Overall survival was 83.7 % in the allogenic hematopoietic stem cell transplantation and 78.8 % in patients given immunosuppressive therapy front-line group (P=0.4).In both group overall survival was 97 % for moderately severe AA, 82 % for severe AA and 77 % for very severe AA.

In the allo-SCT cohort, under multivariate analysis, Overall survival for moderately severe, severe and very severe aplastic anemia was 66.0%, 81.4% and 86.3 % respectively (P=0.5). While, in IST group OS for moderately severe, severe and very severe aplastic anemia was 93.8%, 86.6% and 56.1 % respectively (P=0.005). Age of 20 years or under positively affected overall survival in allogenic hematopoietic stem cell transplantation group, whereas age more than 20 years negatively affected overall survival in this group. The factors influencing the overall survival were use of allo-SCT, an age under 20-years-and moderately severe AA.

Aplastic anemia in adolescents has a very good outcome. If a matched sibling donor is available, Hematopoietic stem cell transplantation is the first choice treatment. If such a donor is not available, immunosuppressive treatment may still be an acceptable second choice also because, in case of failure, hematopoietic stem cell transplantation is a very good rescue option. Use of SCT, age of < 20 years in sever AA and IST in non-severe AA were favorably associated to OS. Therefore, younger age SAA patients, with HLA-matched donors, may benefit more from allo-SCT.