Clinical Context

Individuals with eating disorders often have comorbid substance use disorders (SUDs); both are linked to excess mortality. Eating disorder and SUD types vary in lethality. New research has shown that patients with an eating disorder who abused alcohol, cannabis, hard drugs, or other combinations had a much higher risk of dying from any cause than those with eating disorders and no SUDs. Additionally, this data has shown that comprehensive assessment of SUDs in those with eating disorders is an early and vital step in improving treatment effectiveness. Members of the healthcare team play an integral role in screening and addressing both eating disorders and SUDs, which can ultimately improve outcomes and save lives.

Study Synopsis and Perspective

SUDs, particularly alcohol abuse, are linked to excess mortality in patients with eating disorders, new research shows.

The findings, led by Angelina Mellentin, PhD, from the University of Southern Denmark, Odense, showed that comorbid SUDs were tied to up to an 11-fold increased risk for death across all eating disorder types.

"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," the researchers write.

The study was published online January 1 in The American Journal of Psychiatry.

Eating disorders are associated with high mortality, but the contribution of comorbid SUDs is unclear.

Using Danish nationwide registers, the researchers analyzed data on 20,759 patients with eating disorders.

The cohort included 8108 patients with anorexia nervosa (AN), 5485 patients with bulimia nervosa (BN), and 7166 patients with unspecified eating disorder, as well as 83,036 matched controls without an eating disorder.

The researchers compared all-cause mortality risk between patients with eating disorders and control patients both with and without a lifetime SUD diagnosis, which included abuse or dependence of alcohol, cannabis, or hard drugs.

Rates of each type of SUD were significantly higher for patients with eating disorders than control patients (alcohol: 4.7% vs 1.0%; cannabis: 4.3% vs 1.3%; hard drugs: 4.7% vs 1.3%), the researchers report.

Patients with any eating disorder but no SUD had an elevated risk for all-cause mortality (adjusted hazard ratio [aHR]: 2.85), as well as mortality from both external causes (aHR: 3.02) and internal causes (aHR: 2.78) compared with control subjects without an eating disorder or SUD.

SUD comorbidity affected mortality risk in patients with any eating disorder.

Patients with an eating disorder who abused alcohol, cannabis, hard drugs, or various combinations had a much higher risk of dying from any cause, with hazard ratios ranging from 4.55 to 22.99, than their counterparts with eating disorders and no SUDs.

"Interestingly," the investigators note, patients with eating disorders who abused alcohol alone had a higher risk (subhazard ratio: 11.35) than patients with eating disorders who abused hard drugs alone (subhazard ratio: 4.74) or hard drugs combined with alcohol (subhazard ratio: 9.68).

There is consistent evidence that both eating disorders and alcohol use disorder cause "considerable physical damage. Indeed, alcohol has been found to cause more physical damage than certain hard drugs such as cocaine and other stimulants, which may explain our results," the investigators write.

Control patients with SUDs also had an elevated risk for all-cause mortality relative to control patients without SUDs, but to a much less extent than patients with eating disorders with SUDs.

"These findings highlight the importance of focusing on the prevention and treatment of SUDs to reduce excess mortality in eating disorder patients," the researchers write.

"This is particularly relevant for AN patients who abuse hard drugs, since they were found to be the most susceptible to premature death," they add.

In BN, SUD appears to be the "driving factor" behind mortality, "and thus the prevention and treatment of SUDs would go a long way toward reducing mortality in BN," they add.

Commenting on the study for Medscape Medical News, Kamryn T. Eddy, PhD, codirector of the Eating Disorders Clinical and Research Program, Massachusetts General Hospital, and associate professor, Department of Psychiatry, Harvard Medical School, Boston, said the "findings from this large, population-based study support what is well-known in the literature: individuals with eating disorders--and in particular AN--are at increased risk for premature death.

"Importantly, these data highlight the most vulnerable group--that is, those with eating disorders and comorbid alcohol, cannabis, or other drug use disorders," said Dr Eddy, who was not involved in the study.

The research also shows that the combination of these disorders "can be deadly, and that the risk is additive; that is, having an eating disorder and 1 substance use problem is bad, but that having 2 is worse, and 3 is worse still," Dr Eddy added.

"For clinicians, these data should absolutely underscore that comprehensive assessment of substance use disorders in those with eating disorders is critical," Dr Eddy added.

"Clinical research must determine mechanisms, such as impulsivity or altered reward responsiveness, that drive both eating and substance use disorders, which we can address in order to improve treatment effectiveness and save lives," she said.

Also weighing in, Stephen Wonderlich, PhD, cochair of the research advisory board, National Eating Disorders Association, said, "The basic finding that [SUDs] contribute substantially to elevated mortality rates in both [AN and BN] is important.

"I do think that most clinical programs assess reasonably carefully for substance use of various kinds. This study suggests that such screening is even more imperative than we may have thought previously," said Dr Wonderlich, Chester Fritz Distinguished Professor, Department of Psychiatry and Behavioral Science, University of North Dakota School of Medicine and Health Sciences, in Fargo.

"The take-home message is fairly clear: If an individual has a significant eating disorder and on top of that has a significant [SUD], the outcomes are likely to be more negative, including increased risk of death. Clinicians and patients should be aware of this," Dr Wonderlich added.

This study was supported by the Psychiatric Research Foundation, University of Southern Denmark, Region of Southern Denmark. Dr Mellentin, Dr Eddy, and Dr Wonderlich have disclosed no relevant financial relationships.

Am J Psychiatry. Published online January 1, 2022.^[1]

Clinical Implications

• SUDs have an additive effect on excess mortality in eating disorders.
• The findings mandate SUD prevention and treatment in these patients to reduce mortality.
• Implications for the Health Care Team: Members of the healthcare team should thoroughly assess patients with eating disorders for SUDs.

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