7010 The Incidence Of Cushing Syndrome In Wisconsin Is More Common Than Population-Based Studies From Europe

Abstract Disclosure: T. Matoska: None. T.B. Carroll: Consulting Fee; Self; Corcept Therapeutics. Research Investigator; Self; Corcept Therapeutics. T.S. Wang: None. S. Dream: None. N. Zwagerman: None. J.W. Findling: Advisory Board Member; Self; Corcept Therapeutics, Recordati, Diurnal. Introduction: Endogenous neoplastic hypercortisolism [Cushing syndrome (CS)] is considered to be a rare disorder. Population-based studies from Europe estimate the incidence of CS to range from 1.8-3.2 cases/million patient-years, and there is limited data reporting the incidence of CS in the United States. All previous studies have shown that pituitary ACTH secreting tumors [Cushing disease (CD)] are the most common cause of CS. Based on our clinical experience, we speculated that the incidence of CS was more common than reported and that adrenal CS (ACS) was more common than CD. This study reports the incidence and etiology of CS from a single tertiary care center in Wisconsin (WI). Methods: Institutional clinic records between May 1, 2017, and December 31, 2022, were queried to identify WI residents treated for CS. Only patients diagnosed and treated at our institution during the study period were included. The diagnosis of CS was established with standard guideline-supported biochemical testing and appropriate imaging. Patients diagnosed with exogenous CS and those who did not undergo therapy for CS were excluded. Results: The query identified 185 patients who were diagnosed and treated for CS. These patients resided in 27 of the 72 WI counties representing a population of 4.5 million of the total WI population of 5.9 million. This suggests that, at a minimum, the incidence of CS in WI is 7.2 cases/million patient-years. Moreover, data from the WI Hospital Association show our institution treated <50% of all patients with CS discharged from WI hospitals from 2019-2023. Mean age at diagnosis was 52.4 years (SD 14.7) and 135 (73%) were female. Of the total cohort, 111 (60%) had ACS, 68 (36.8%) had CD, and 6 (3.2%) had ectopic ACTH syndrome (EAS). Patients with ACS had significantly lower LNSC, DST cortisol, and UFC when compared to those with CD and EAS. ACS had mean (SD) LNSC, DST cortisol, and UFC of 0.236 µg/dL (0.367), 6.5 µg/dL (8.7), and 64.2 µg/24h (92.8), respectively. CD had mean (SD) LNSC, DST cortisol, and UFC of 0.425 µg/dL (0.403), 11.7 µg/dL (7.5), and 151.1 µg/24h (287.4), respectively. EAS had mean (SD) LNSC, DST cortisol, and UFC of 3.189 µg/dL (0.931), 42.5 µg/dL (40.5), and 1514.2 µg/24h (1278.9), respectively. Overt physical features of CS were documented in the medical record of 117 (63.2%) patients at diagnosis ((ACS: 49 (44%); CD: 62 (91%); EAS: 6 (100%)). Conclusion: This study suggests that ACS is more common than CD as a cause of CS, and patients with ACS more frequently presented without physical features of hypercortisolism, probably due to the milder degree of cortisol excess. The incidence of CS in WI is at least 7.2 cases/million patient-years. As our institution cares for <50% of patients with CS in WI, the true incidence is likely far greater and may approach 14-15 cases/million patient-years. Presentation: 6/1/2024