To our knowledge, this is the first, most comprehensive study describing the national characteristics of ED patients with depression. An insightful study by Ballou et al.  looked at US ED visits by depressed patients, but there are key differences between their work and ours. Namely, Ballou et al.’s scope was limited to ED visits for depressive complaints; further, they analyzed ED data from a different database (the Nationwide Emergency Department Sample), sampling two years (2006 and 2014) of data . Studies on general ED use by patients with depression have been more limited than the present study in terms of sample size and national representativeness. For example, a prospective cohort study by Beiser et al. included a comparatively small sample (n = 999), as did Kumar et al.’s study of depression prevalence assessed in ED admissions (n = 536) [11, 12]. Beiser et al. and Kumar et al. reported markedly higher rates of depression (27 and 30%, respectively) among ED patients than the rate noted here (11.4%) [11, 12]. However, we must point out methodologic differences between their studies [11, 12] and ours. Whereas we used NHAMCS data on ED patients’ depression status, these studies [11, 12] relied on self-reported depression questionnaires administered to patients in their ED. Further, our study characterizes ED patients with depression with greater power by using three years of data from a larger, more representative sample. Our study also provides previously unreported data concerning vitals and other clinical information in ED patients with depression.
From 2014 to 2016, patients with depression made more than 10 million ED visits annually. Compared to patients without depression, those with depression had higher rates of hospital admission and ICU admission. We did not observe associations between ED patients’ depression and any somatic reasons for ED visit. This finding suggests that comorbid conditions that have previously been correlated with depression (e.g., rheumatoid arthritis) may not strongly predict these patients’ emergency care needs . However, patients with depression were more likely to seek emergency treatment for psychiatric symptoms and for acute overdose/poisoning.
Demographic factors were associated with the prevalence of depression in ED patients. In terms of region, EDs in the Midwest had the greatest proportion of visits by patients with depression. Female ED patients were more likely than males to have depression, as were non-Hispanic Whites compared to other races/ethnicities, particularly Asians. These gender and racial/ethnic differences are roughly concordant with US demographic patterns in depression prevalence observed beyond the ED setting . However, these patterns have been problematized by research indicating that certain non-White minority populations are less likely to receive or seek mental health diagnoses and care [14–16]. If the large proportion of Whites among patients with depression partly reflects such differences in diagnosis and treatment seeking, there may in fact be a number of non-White patients with unaddressed mental health care needs in the ED.
Notably, patients with depression who sought ED treatment for psychiatric symptoms were roughly two times more likely to be male than female, consistent with findings by Ballou et al. . Because our psychiatric ED visit classification excluded visits related to alcoholism and other substance use disorders, our finding of higher rates of psychiatric ED visits for depressed male patients cannot be well explained by males’ higher rates of alcoholism and substance use disorders in the general population . Given the social barriers that men, relative to women, face in seeking mental health care, this disparity may indicate a need for more routine depression care and/or screening in men to reduce their rate of psychiatric emergencies [17, 18]. Further, in Ballou et al.’s study, men were modestly more likely to present to the ED with self-harm . In our sample, males with depression were more likely to present with overdose/poisoning—a finding that does not necessarily point to increased self-harm but bears highlighting for future inquiry. Additional data are needed to clarify the reasons for and extent of these gender-based disparities.
Compared to their non-depressed counterparts, patients with depression in the ED have higher ESI scores, hospital admission, and ICU admission, indicating that patients with depression require a higher level of emergency care. With regard to these outcomes, it is worth noting similarities between ED patients with depression and ED patients with cancer, whose utilization is higher across many dimensions of care [7, 19]. ED patients with cancer were also had higher odds of having depression . The factors contributing to these outcomes in both patient populations may be the subject of future research. Understanding the reasons for ED revisits among patients with depression may facilitate the development of interventions or guidelines to reduce ED visit and revisit rates. Considering the substantial number of patients with depression in the ED, we suggest that the ED is an understudied setting for depression treatment. Finer-grained data on patients with a history of depression may inform ways of increasing this population’s use of routine care over emergency care options.
In the patient histories documented in the NHAMCS-ED data, patients are coded as either having or not having “depression status.” Information including depression severity, subtype, and duration were not specified in this dataset. Such information may have predictive value; for example, in Beiser et al.’s prospective cohort study, a 10% increase in depression severity was correlated with a 10% increase in future ED visits . Further, apart from depression, the NHAMCS-ED dataset does not indicate other mental disorders in the ED patient sample. We therefore could not adjust for potential psychiatric comorbidities. More generally, other comorbidities that are not documented in the dataset, such as chronic pain disorders, could play a role in mediating some of the associations we observed . Another limitation of the NHAMCS-ED dataset is a lack of information on treatment history (pharmacologic or otherwise) for depression. Future studies may examine ED patients’ specific depression characteristics, comorbidities, treatment history, and other finer-grained clinical data allowing for more refined associative and predictive models.