Lateral spine dual-energy X-ray absorptiometry and the risk of fragility fractures in long-term kidney graft recipients

Background: Although the prevalence of osteoporosis and fractures in the first 6–12 months post-renal transplantation is high, little is known about the utility of bone mineral density (BMD) to predict fractures in long-term kidney graft recipients. Lateral spine dual-energy X-ray absorptiometry (DXA) scanning is a reliable tool for measuring glucocorticoid-induced and age-related bone loss in the elderly population. However, little is known about the utility of lateral spine DXA for patients with chronic kidney diseases. This study aimed to analyze the utility of lateral spine BMD for fragility fractures in long-term kidney graft recipients. Methods: A total of 357 stable kidney transplant recipients for a minimum of 1 year after kidney transplantation underwent DXA measurements at several sites, including the lateral spine between January 2017 and December 2018. We collected data on new incident fractures from the patients’ medical records. Results: The median post-transplantation time at baseline DXA measurement was 12.6 years. During the median follow-up period of 3.5 years, 41 (11.4%) fractures occurred. The lateral spine BMDs were independently associated with fractures (adjusted hazard ratio 0.076; 95% confidence interval 0.012–0.42, p = 0.003). The cumulative incidence rate of fractures was significantly higher in the lower lateral spine BMD group (< 0.471 g/cm², optimal cut-off value by receiver operating characteristic curve) than in the higher lateral spine BMD group (23.4 vs. 7.4%, adjusted hazard ratio 4.92; 95% confidence interval 2.33–10.74, p < 0.001). Conclusion: Lateral lumbar spine BMD can be used to predict the risk of fragility fractures in long-term kidney graft recipients.