SAT-539 The Utility of Prophylactic Zoledronic Acid in Patients Undergoing Lung Transplantation: A Retrospective Analysis

Abstract

Purpose Osteoporosis is prevalent among lung transplant candidates and exacerbated post-transplant by immunosuppressive therapy (glucocorticoids and calcineurin inhibitors). Many groups, ours included, prophylactically treat lung transplant recipients with bisphosphonate therapy to prevent bone mineral density (BMD) loss and reduce fracture rates. However, no documented national or international consensus protocols exist to date. Given the early and dose-related fracture increase seen with glucocorticoids, our protocol comprises 6-monthly intravenous zoledronic acid (ZA) from wait-listing to 1 year post-transplant, with interval reassessment to guide ongoing treatment. Use of ZA to protect bone health in transplant recipients has been tested and proven efficacious in liver and bone marrow transplantation, however, its effect in the lung transplant population has not previously been described in the literature. The purpose of our study is to audit the impact of this protocol on BMD and fracture occurrence in lung transplant patients. Methods A retrospective analysis was performed on all adult lung transplant recipients between April 2012 and October 2014. 60 of 142 met inclusion criteria, which included a 3-year follow up period post-transplant with BMD assessment 1) within 24 months pre-transplant and 2) 36-60 months post-transplant. Those who received ZA within 6 months of their transplant as per protocol (n=37) were compared to those who did not (n=23). The outcome measures were change in BMD at the lumbar spine and hip (primary), and fracture occurrence (secondary). Results Primarily due to a non-uniform referral system, 61.7% of patients received ZA as per protocol. The median baseline BMD (g/cm2) in this group was 0.99 (IQR: 0.90-1.08) at the spine and 0.80 (IQR: 0.71-0.93) at the femur, while the non-protocol group had a baseline BMD of 1.08 (IQR:0.99-1.13) and 0.88 (IQR:0.81-0.92), respectively. The protocol treated group experienced a median change in BMD of 8.1% (IQR:-2.8%-10.8%) at the spine and 1.4% (IQR:-4.1%-7.4%) at the femur, compared to -1.2% (IQR:-5.2%-5.9%) and -3.9% (IQR:-8.6%-2.8%), respectively, in the non-protocol group (p=0.003). In the protocol treated group, 6 (16.2%) patients suffered an atraumatic fracture, compared to 7 (30.4%) in the non-protocol group (p=0.22). Fractures in traditional osteoporotic sites accounted for 3 (8.1%) and 5 (21.7%) of these, in the two groups respectively (p=0.24). Despite improvement in BMD there was no significant difference seen in fracture rates, likely due to cohort size. Conclusion Our results suggest that prophylactic ZA in the lung transplant cohort is effective in reducing BMD loss and may reduce fracture rates. Proven benefit of this protocol may influence clinical practice not only at our center but may contribute to an international consensus on the best management of bone health in lung transplant patients.