Bone Mineral Densitometry Diagnostic Yield Remains High Beyond 10 Years Post Allogeneic Stem Cell Transplant

Introduction: Reduced bone mineral density is a complication following allogeneic hematopoietic stem cell transplant (HSCT) resulting from the complex interplay of pre-, peri- and post- HSCT factors. Whilst guidelines recommend baseline bone mineral density (BMD) testing within a year of HSCT, evidence on the optimal timing and interval of post HSCT BMD assessment limited, and literature suggests heterogeneity in the management of abnormal results. Published literature to date largely focuses on the incidence of osteopenia and osteoporosis, within 5 years post transplant. The extent of the problem in long term post HSCT survivors remains largely unknown. The population . Here we present long-term data on bone mineral deficiency in HSCT patients from Westmead Hospital, Sydney, Australia.

Method: A retrospective analysis of patients with a history of hematological malignancy who attended the long term follow up (LTFU) HSCT clinic between January 2013 and April 2022 at Westmead Hospital in Sydney, Australia, was undertaken. Patients required at least one BMD report to be included in the analysis. Data was collected from patient medical records and descriptive analysis undertaken. Timing of first post HSCT BMD was categorised as <12 months, 13-24 months, 25-36 months, 37-48 months, 49-60 months, 61-120 months, or >120 months. Bone mineral deficiency was defined according to the World Health Organization (WHO) criteria, with osteopenia at a T-score of <-1.0 to -2.5, and osteoporosis at a T-score of <-2.5.

Results: Of the 355 patients who attended the clinic, 86% (305 patients) had at least one BMD study between 6 months and 36 years post transplant, with a total of 414 studies performed. Osteoporosis or osteopenia was reported in 59% of all patients undergoing their first post HSCT BMD, irrespective of the time-point post HSCT at which the BMD was performed. The median T-score for patients diagnosed with osteopenia was -1.8 (range -2.5 to -1.1), and for those with osteoporosis was -3.0 (range -4.1 to -2.6). Patient age at time of diagnosis of bone mineral deficiency ranged from 19 to 76 years.

Amongst the 57 patients who had their first BMD more than 10 years post HSCT, 55.9% had evidence of osteoporosis or osteopenia, similar to the rate detected in patients having first BMD within 12 months of transplant (61.3%, n=80).

Conclusion: This the largest report of the ongoing diagnostic yield of BMD in long term follow up post HSCT. Osteoporosis or osteopenia was identified in almost 60% of patients at first BMD post transplant, even when the first bone density assessment occurred beyond 10 years post transplant. The stability in detection rates over time could indicate that a bone-loss-causing insult occurs at the time of HSCT and does not necessarily progress after transplant. However longitudinal studies are required for confirmation. Osteoporosis is found at first BMD assessment in up to 15% of patients underlining the importance of interventions to optimise post-transplant bone health. Our data is limited by selection bias towards patients who continued to attend the LTFU clinic, but the diagnosis of new cases beyond 10 years post transplant highlights the importance of ongoing monitoring of BMD in the post HSCT population.

Gottlieb:Abbvie: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Haemalogix Ltd: Membership on an entity's Board of Directors or advisory committees.