Epidemiology and Comorbidity of Adrenal Cushing's Syndrome: A Nationwide Cohort Study.

Context Adrenal Cushing's syndrome (CS) is a major subtype of CS and has a high surgical cure rate. However, only a few studies have investigated the epidemiology and long-term outcomes of adrenal CS. Objective We aimed to investigate the nationwide epidemiology, long-term prognosis and postoperative glucocorticoid replacement therapies of adrenal CS in Korea. Design Retrospective cohort study. Setting A nationwide claim database. Patients Adrenal CS patients who were defined as having underwent adrenalectomy, a diagnosis code of CS, and not having pituitary gland surgery. Main outcome measures: Crude incidence and age-standardized incidence rates, long-term mortality, comorbidities diagnosed preoperatively or developed postoperatively, and the pattern of postoperative glucocorticoid replacement therapy. Results From 2002 to 2017, there were a total of 1,199 new adrenal CS patients, including 72 patients with adrenocortical carcinoma (malignant adrenal CS), in Korea. The crude and age-standardized incidence rates were 1.51 and 1.27 per million person-years, respectively. The overall standardized mortality ratio was 3.0 (95% confidence interval: 2.4-3.7) for benign adrenal CS and 13.1 (7.6-18.6) for malignant adrenal CS. Adrenal CS patients had a high risk of having coronary artery disease, stroke, metabolic diseases, and depression. A similar proportion of patients were diagnosed with these comorbidities both preoperatively and postoperatively, suggesting a significant residual risk even after adrenalectomy. The median time of postoperative glucocorticoid replacement therapy was 10.1 months, and the major types of glucocorticoids used were prednisolone (66.6%) and hydrocortisone (22.4%). Conclusions Adrenal CS is associated with multiple comorbidities even after treatment, which necessitates meticulous postoperative care.