Bone Health Outcomes in a Large, Diverse Pediatric Cohort Undergoing Hematopoietic Stem Cell Transplant

Abstract

<h3>Introduction</h3> Impaired bone mineral density (BMD) is a known complication of hematopoietic stem cell transplantation (HSCT) in adults and may lead to increased fracture risk. Little is known in pediatrics about the risks for impaired BMD and fragility fractures after HSCT. Factors that may influence the risk of bone disease include diagnosis, glucocorticoid exposure and GVHD. Our study aims to describe the incidence of fragility (low trauma) fractures in a large diverse pediatric HSCT population and to identify risk factors of fracture and impaired BMD. <h3>Methods</h3> We included 237 patients (age ≤ 21 years at time of transplant) who underwent HSCT at our institution between January 2015 and March 2018. Demographics are shown in Table 1. The primary endpoint was incidence of fragility fractures and the secondary endpoint was assessment of BMD on dual-energy X-ray absorptiometry (DXA). We analyzed DXA results at one-year post-HSCT in 72 out of 206 patients alive at 1 year. <h3>Results</h3> Fragility fracture data is shown in Table 2. Mortality at one-year was proportionally higher, though not significant (p=0.11) in patients who had at least one fragility fracture (24%; 6/25) compared to patients without fragility fracture (12%; 25/212). Vitamin D status at one-year post transplant was sufficient (>20ng/mL) in 94% (160/171) of patients. The median height-for-age adjusted Z-score (HAZ) for spine BMD at one-year post transplant was 0.13 in all patients. The median HAZ spine BMD Z-score in patients with fragility fracture was -1.64, though data was available for only 5 patients. <h3>Conclusion</h3> The incidence of fragility fractures after pediatric HSCT is striking and is higher than in adult populations. Furthermore, there are likely additional asymptomatic patients with occult fractures not detected in out cohort. The high incidence of fragility fractures seen in this study advocates for establishing bone health screening protocols with attention toward spinal imaging in pediatric patients undergoing HSCT.