Association of hemoglobin level with granulocyte engraftment and red blood cell transfusion by transplant type after hematopoietic stem cell transplantation: a retrospective cohort study

Background Hematopoietic stem cell transplantation (HSCT) cures many hematologic malignancies, but peri‑engraftment complications like delayed engraftment and high transfusion requirements remain challenging. Prior studies examined the independent effects of transplant type, hemoglobin, and platelets on post‑transplant outcomes, but whether their associations with these outcomes vary by transplant type is unknown.Methods In this retrospective cohort of 341 HSCT patients, we examined whether the associations between pre-transplant hemoglobin and platelet levels and four key peri-engraftment outcomes (RBC transfusion volume, granulocyte engraftment time, megakaryocyte engraftment time, and platelet transfusion requirements) varied by transplant type (allogeneic vs. autologous). Multiple linear regression models for each outcome included diagnosis, transplant type,centered CD34+(C_CD34+),centered prothrombin time (C_PT), centered hemoglobin (C_Hb),and centered platelet (C_PLT) as main effects, with interaction terms: transplant type × C_Hb and transplant type × C_PLT. Bootstrap with 1000 resamples was used to estimate 95% CIs.Results The transplant type × hemoglobin interaction was significant for granulocyte engraftment time (p = 0.014) and RBC transfusion volume (p = 0.029). Simple slope analyses showed that the adverse effect of allogeneic transplantation was largest at low hemoglobin (−1 SD: +2.67 days , +2.93 units) and smallest at high hemoglobin (+1 SD: +1.48 days , +1.43 units). No significant interactions were observed for platelet‑related outcomes (all p > 0.05).Conclusions Higher pre‑transplant hemoglobin attenuated the adverse effects of allogeneic HSCT on granulocyte recovery and RBC transfusion requirements, suggesting baseline hemoglobin may serve as a useful risk indicator for peri‑engraftment management in allogeneic recipients, warranting prospective validation.