Overall and cause-specific mortality in anorexia nervosa; impact of psychiatric comorbidity and sex in a 40-year follow-up study

Abstract

Objective: This study investigates the overall and cause-specific mortality in males and females with anorexia nervosa (AN) from 1977 to 2018, focusing on the impact of psychiatric comorbidity on mortality risk, a less explored aspect despite a high prevalence in patients with AN.

Method: We conducted a nationwide population-based cohort study in Denmark including all patients with AN (n = 14,774) with a median follow-up time of 9.1 years and a 1:10 age- and sex-matched general population comparison cohort. Using Cox proportional hazard model, we calculated adjusted hazard ratios (aHR) for death stratified by psychiatric comorbidity, sex, and age at AN onset and evaluated the causes of death using Fine and Gray sub-distribution hazard ratios (SHR).

Results: In patients with AN, the weighted average aHR for all-cause mortality was 4.5 [95% CI 4.1-4.9] with up to 40 years follow-up. Psychiatric comorbidity was present in 47% of patients with AN at index date, which was associated with a 1.9-fold increase in 10-year mortality compared with patients without comorbidity and a notably four-fold increase, when diagnosed at age 6-25 years. The mortality risk was similar according to sex. 13.9% of all deaths in patients with AN were due to suicide (SHR 10.7 [8.1-14.2]). The risk of dying of natural causes was increased with a SHR of 3.8 [95% CI 3.4-4.2].

Discussion: The increased mortality risk in both males and females with AN and psychiatric comorbidity, particularly when diagnosed at young age, underscores the need for comprehensive treatment addressing both AN and coexisting psychiatric conditions.

Public significance: The mortality in patients with anorexia nervosa (AN) is high and we show in our study that the mortality is doubled in the presence of psychiatric comorbidity particularly the first 10 years after diagnosis seen in both sexes and with suicide as a major cause of death. These findings stress the importance of detection and treatment of psychiatric comorbidities alongside the eating disorder to prevent fatal outcome.

Keywords: anorexia nervosa; causes of death; cohort study; eating disorders; mortality risk; psychiatric comorbidity; sex differences.