Group 1. Epidemiology of primary and secondary adrenal insufficiency: Prevalence and incidence, acute adrenal insufficiency, long-term morbidity and mortality.
The prevalence of primary adrenal insufficiency is estimated at between 82-144/million, with auto-immunity being the most common cause in adults and genetic causes, especially enzyme defects, being the most common cause in children. The prevalence of secondary adrenal deficiency is estimated to be between 150-280/million. The most frequent occurrence is believed to be corticosteroid-induced insufficiency, despite the incidence of clinically relevant deficiency after cessation of glucocorticoid treatment being widely debated. Data on mortality in adrenal insufficiency are contradictory, with studies from Sweden suggesting a two-fold increase in comparison to the general population, but this is not consistently reported in all studies. However, increased mortality has been consistently reported in young patients, associated with infection and/or acute adrenal insufficiency. Acute adrenal deficiency (adrenal crisis) occurs in primary as well as secondary adrenal insufficiency. Its incidence, mostly determined in retrospective studies, is estimated in Europe at 6-8/100 patients/year. A prospective study reported 0.5 deaths/100 patient-years from adrenal crisis. Long-term morbidity of adrenal insufficiency is not well-established, the increased cardiovascular risk or bone demineralization which are not consistently reported may also be due to a supraphysiological glucocorticoid replacement therapy. However, alteration in quality of life, both in physical and mental health components, has been demonstrated by several studies in both primary and secondary adrenal insufficiency.