The Impact of Alcohol and Other Substance Use Disorders on Mortality in Patients With Eating Disorders: A Nationwide Register-Based Retrospective Cohort Study

Objective: Research is lacking on the contribution of different types of substance use disorders (SUDs) to excess mortality across the full spectrum of eating disorders. The authors assessed the association of alcohol use disorders and other SUDs with mortality in anorexia nervosa, bulimia nervosa, and unspecified eating disorder compared with matched control subjects. Methods: A retrospective cohort study was conducted using Danish nationwide registers. The study included 20,759 patients with eating disorders and 83,036 matched control subjects. Hazard ratios were calculated to compare all-cause mortality risk between eating disorder patients and control subjects both with and without a lifetime SUD diagnosis (abuse or dependence of alcohol, cannabis, or hard drugs). Results: For patients with each type of eating disorder, a higher risk of all-cause mortality was observed relative to control subjects without SUDs among those who abused alcohol and/or cannabis (adjusted hazard ratios for the anorexia nervosa, bulimia nervosa, and unspecified eating disorder patients, respectively, were 11.28 [95% CI=7.01, 18.16], 5.86 [95% CI=3.37, 10.1], and 10.86 [95% CI=6.74, 17.50]), or hard drugs alone or in combination with alcohol and/or cannabis (adjusted hazard ratios, respectively, were 22.34 [95% CI=15.13, 33.00], 11.43 [95% CI=7.14, 18.28], and 15.53 [95% CI=10.15, 23.78]), than in those without SUDs (adjusted hazard ratios, respectively, were 3.21 [95% CI=2.43, 4.23], 1.24 [95% CI=0.88, 1.77], and 4.75 [95% CI=3.57, 6.31]). Control subjects with SUDs also exhibited an elevated risk of all-cause mortality relative to control subjects without SUDs, although to a much lesser extent than eating disorder patients with SUDs. Conclusions: SUDs have an additive effect on excess mortality in patients with eating disorders. The prevention and treatment of SUDs in this patient group is thus imperative to reduce mortality.