MON-219 Prevalence and Incidence of Fractures in Patients with Adrenal Adenomas: A Population-Based Study of 1003 Patients

Background: Adrenal adenoma is reported in around 5% of adults undergoing cross-sectional imaging. Although most adenomas are considered non-functioning (NFAT), up to 48% present with mild autonomous cortisol secretion (MACS). Several studies reported increased prevalence and incidence of vertebral fractures in MACS; however conclusions are limited by small sample size, selection bias, inadequate reference population and length of follow up. Objective: To determine the prevalence and incidence of site-specific fragility fractures in a population-based cohort of patients with adrenal adenomas. Methods: Residents of local community with a radiographic diagnosis of adrenal adenoma between 1995 and 2017 were identified using a centralized epidemiologic database and matched with reference subjects for sex and age. All subjects were followed through 2017, until death or migration from the community. MACS was diagnosed based on cortisol level ≥1.8 mcg/dl after overnight 1mg dexamethasone suppression, NFAT based on cortisol level <1.8 mcg/dl, and patients not tested with dexamethasone were considered as adenoma with unknown cortisol secretion (AUCS). Results: Of 1003 patients with adrenal adenomas (581 women (58%), median age of diagnosis 63 years (20–96)), 136 (14%) were diagnosed with NFAT, 86 (9%) with MACS, and 781(78%) with AUCS. At the time of diagnosis, patients had higher BMI (median 30 vs 28 kg/m(2), p<0.001), and higher prevalence of tobacco use (70% vs 54%, p<0.001) than reference subjects. Of 154 patients and 113 reference subjects with BMD available at baseline, patients had a higher median BMD at the total hips (0.93 vs 0.89, p=0.02) but similar median BMD at lumbar spine (1.05 vs 1.03, p=0.49) when compared to reference subjects. However, patients had a higher prevalence of fractures than reference subjects (any fracture: 50% vs 42%, p<0.001, vertebral fracture: 6.5% vs 3.7%, P=0.004). When adjusted for age, sex, and prior history of fracture, patients with adenoma had HR of 1.24 (CI 95% 1.04–1.48) for developing a new fracture and HR of 1.18 (CI 95% 0.97–1.44) when also adjusted for BMI and smoking. Subgroup analysis demonstrated that the prevalence of fractures at the time of diagnosis was higher in all 3 subgroups at any fragility fracture site when compared to reference subjects (NFAT: 44% vs 37%, MACS: 48% vs 43%, AUCS: 51% vs 43%); patients with MACS had the highest incidence of new fracture after 5 years of follow up when compared to AUCS and NFAT (cumulative incidence: MACS 25% vs NFAT 19% vs AUCS 16%), though the differences were not significant. Conclusions: Patients with adrenal adenomas have higher prevalence of fractures at the time of diagnosis. During follow up, patients with adenoma have a higher incidence of fractures even when adjusted for sex, age, and prior history of fracture, possibly due to underlying undiagnosed abnormal cortisol secretion.