Incidence of eating disorders in Danish psychiatric secondary healthcare 1970-2008

Objective: Is an increased focus on eating disorders during the past few decades reflected by increasing occurrence in the psychiatric health service system.

Method: All first-time diagnoses of eating disorders identified in the Danish Central Psychiatric Research Register 1970-2008 constitute the present research database. Age-standardized rates per 100,000 inhabitants were calculated and autoregressive models were fitted for males and females separately as well as for in- and outpatients.

Results: The incidence of eating disorders diagnosed in Danish psychiatric secondary healthcare has increased considerably during a nearly 40-year period of observation both within the general category of eating disorders and also specifically for anorexia nervosa. The steepest increase is seen within females aged 15-19 years, where the highest incidences are also found. Anorexia nervosa constitutes the vast majority of all eating disorders. Throughout the time interval investigated, the number of males, however, is negligible compared to females. Most patients are seen in outpatient services, increasing towards recent years. However, the number of patients being treated as inpatients has increased linearly through the entire four decenniums investigated.

Conclusions: Changes in registration principles, public awareness and higher acceptance of mental disorders in the public is the most obvious explanation for the incidence increase of anorexia nervosa and other eating disorders. This study does not answer whether there has been an increase in true incidence in the population.