Objectives: Frequent emergency department (ED) use is a growing problem that is associated with poor patient outcomes and increased health care costs. Our objective was to analyze the association between mood disorders and the incidence of frequent ED use.

Methods: We used the Canadian Community Health Survey conducted by Statistics Canada, 2015-2016. Mood disorder was defined as depression, bipolar disorder, mania, or dysthymia. Frequent ED use was defined as 4 or more visits in the year preceding the interview. Multivariable log-binomial regression models were used to determine the associations between mood disorders and frequent ED use.

Results: Among the 99,009 participants, 8.4% had mood disorders, 80.3% were younger than 65, and 2.2% were frequent ED users. Mood disorders were significantly associated with the 1-year cumulative incidence of frequent ED use (RR = 2.5, 95% CI 2.2-2.7), after adjusting for several potential confounders.

Conclusions: This national survey showed that people with a mood disorder had a three-fold risk of frequent ED use, compared to people without mood disorder. These results can inform the development of policies and targeted interventions aimed at identifying and supporting ED patients with mood disorder.