Cushing's Disease May Have Higher Incidence than Previously Thought: A Nationwide Study in Iceland 2010-2019

In 2011, we reported the overall incidence of Cushing's disease (CD) in Iceland from 1955 through 2009 to be 1.5 cases per million per year with highest incidence in the last decade of the study, a higher incidence then earlier reported. We now present a follow-up study reporting the epidemiology of the disease in Iceland during the 10-year period from 2010 to 2019.

In this nationwide retrospective study, clinical information on patients diagnosed with CD was obtained from electronic medical records, reviewed by consulting endocrinologists.

Seventeen patients were diagnosed with CD, 12 women (71%) and 5 men (29%) giving an overall incidence of 5.2 cases per million per year. The mean age at diagnosis was 46 years (range 13-85 years). Biochemical analysis was recorded for all patients and 12 patients (71%) had visible pituitary adenoma on imaging studies. Sixteen patients (94%) were treated with transsphenoidal surgery of which 4 patients (24%) had gamma knife radiosurgery and three (18%) bilateral adrenalectomy after pituitary surgery. Two patients died during the study period.

The overall incidence of CD of 5.2 cases per million per year is higher than previously reported, indicating the importance of awareness of CD. As all patients with CD are diagnosed and/or treated at the only University Hospital in Iceland, housing the only department of endocrinology as well as neurosurgery, we are confident that all cases diagnosed during the study period were included in the study.