Osteoporosis post allogenic stem cell transplantation (alloSCT) is common (1-2), with an estimated prevalence of 50% (3), and is accelerated by GVHD prophylaxis and premature hypogonadism (4). The majority of bone loss occurs in the year following alloSCT (5-6), most commonly in the femur but also at the lumbar spine (7). Despite evidence for bone protection with Zoledronic Acid (ZA) in alloSCT (8-11), use is not universal. In 2015, a protocol for prophylactic zoledronic acid was commenced at our institution in all patients prior to alloSCT, regardless of bone density. We aimed to investigate protocol uptake and the utility of prophylactic ZA to prevent bone loss and fracture by comparing bone mineral density (BMD) and atraumatic fracture incidence in patients who received ZA compared to those who did not.
We conducted a retrospective cohort study of all patients who underwent an alloSCT at the Alfred Hospital between 2008 and 2021. Exclusion criteria comprised multiple myeloma, age <18, pre-existing anti-resorptive therapy and <1 year survival post-transplant. Patients who received prophylactic ZA (2015-2021) were compared to historical controls who did not (2008-2014). Demographics, biochemistry, ZA dosage and timing, DEXA results and fracture incidence were extracted from medical records with follow up until 31/10/22.
Of the 271 patients who underwent alloSCT, 249 patients were included (129 in pre protocol group and 120 patients post protocol). Implementation of the protocol significantly increased ZA administration (53 vs 3.9%, p<0.0001). We are currently analysing changes in BMD at the lumbar spine and femoral neck over the follow up period as well as fracture outcomes.
This is the largest study presented in the literature to date evaluating the role of prophylactic ZA post alloSCT on bone density and fracture outcomes. A protocol for bone health in alloSCT patients effectively increases use of prophylactic anti-resorptive therapy.