Outcomes of Acquired Aplastic Anemia after HLA-Identical Sibling Donor Transplantation in Pakistan: A Multicentre Study on Behalf of the Pakistan Blood and Marrow Transplant Group.

Haematopoietic stem cell transplantation (HSCT) from an HLA-identical sibling is the primary curative therapy for acquired aplastic anemia (AA). Outcomes from large cohorts in low- and middle-income countries (LMIC) are scarce. To evaluate survival outcomes of patients with acquired AA undergoing matched sibling donor (MSD) HSCT in Pakistan and to identify key transplant- and patient-related factors influencing outcomes in a resource-limited, LMIC setting. Multicenter retrospective cohort study. We retrospectively analyzed 596 consecutive patients with acquired AA who underwent HSCT from an HLA-identical sibling donor at seven Pakistani centers between January 2001 and August 2023. Patients receiving haploidentical, unrelated, or other alternative-donor grafts were excluded. Overall survival (OS) was estimated using Kaplan-Meier method. Univariable and multivariable Cox regression identified predictors of OS; logistic regression identified predictors of graft failure. Median age at transplant was 18 yr (IQR:13 to 24), median time to neutrophil and platelet engraftment was 12 d (11 to 14 d) and 19 d (14 to 28 d), respectively. Primary graft failure occurred in 39 (6.6%) and secondary graft failure in 52 (8.8%) patients. Incidence of acute and chronic graft-versus-host disease was 70 (11.2%) and 97 (19%), respectively. At a median follow-up of 59.4 mo (95% CI 47.9 to 68.4), OS was 69.6%. The leading cause of mortality was graft failure and poor graft function in 91 (49.4%) followed by sepsis in 60 (32.6%) patients. On multivariable Cox regression, RCC <20 (adjusted HR 0.43, 95% CI 0.25 to 0.73, P = .002), CsA + MMF prophylaxis (adjusted HR 2.57, 95% CI 1.47 to 4.51, P = .001), and BMH + PBSC stem cell source (adjusted HR 0.61, 95% CI 0.36 to 1.07, P = .001) were independent predictors of OS. MSD-HSCT achieves durable survival for AA patients in resource-limited settings. Early referral strategies, infection control, and optimization of graft characteristics are required to improve survival in these settings.