Anorexia Nervosa (AN) is a serious psychiatric disorder associated with high mortality.

To examine mortality patterns in patients with anorexia nervosa and psychiatric comorbidity.

6009 women who received in-patient treatment for AN between 1973-2003 were followed up retrospectively using Swedish registers. SMR were calculated on the basis of 74 523 person-years for natural causes of death and 80 388 personyears for unnatural causes of death. SMR was calculated for the group as a whole but also for patients with comorbid inpatient-treated psychiatric disorders, defined by respective ICD-codes from the Swedish patient discharge register.

Nearly half of the patients (44.9%) received in-patient treatment for a psychiatric disorder other than AN during the follow-up time. The overall SMR for anorexia nervosa with psychiatric comorbidity was 6.5 (95% CI: 5.2–7.9) for natural causes and 17.6 (95% CI:14.3–21.4) for unnatural causes of death. Comorbid psychiatric disorders yielded very high SMR for unnatural causes of death. The highest SMR for natural causes was estimated for anorexia nervosa with comorbid alcohol use disorder (16.8; 95% CI: 11.7–23.3).

Anorexia nervosa is a disorder with high mortality for natural and unnatural causes of death, especially when psychiatric comorbidity is involved. To correctly diagnose psychiatric comorbidity, particularly alcohol use disorder, and initiate early treatment could be a way to decrease mortality.