Association between conditioning intensity and height growth after allogeneic hematopoietic stem cell transplantation in children

Background: The present study aimed to examine the association between the conditioning intensity and height growth in pediatric patients who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT). Methods: We reviewed the clinical records of 89 children with malignant diseases who underwent initial allo-HSCT between 2003 and 2021. Height measurements were standardized using standard height charts prepared by the Japanese Society for Pediatric Endocrinology to calculate standard deviation score (SDS). We defined short stature as a height SDS less than -2.0 in that reference. Myeloablative conditioning (MAC) comprised total-body irradiation at more than 8 Gy and busulfan administration at more than 8 mg/kg (more than 280 mg/m(2)). Other conditioning regimens were defined as reduced intensity conditioning (RIC). Results: A total of 58 patients underwent allo-HSCT with MAC, and 31 patients received allo-HSCT with RIC. There were significant differences in the height SDS at 2 and 3 years after allo-HSCT between MAC and RIC group (-1.33 +/- 1.20 vs. -0.76 +/- 1.12, p = 0.047, -1.55 +/- 1.28 vs. -0.75 +/- 1.11, p = 0.022, respectively). Multivariate logistic regression analysis with the adjustments for potential confounding factors of patients less than 10 years of age at allo-HSCT and chronic graft-versus host disease demonstrated that MAC regimen was associated with a markedly increased risk of a short stature at 3 years after allo-HSCT (adjusted odds ratio, 5.61; 95% confidence interval, 1.07-29.4; p = 0.041). Conclusion: The intensity of conditioning regimen may be associated with short statures after allo-HSCT.