Violence towards professionals within the emergency department (ED) occurs at a concerning rate. We hypothesized that increased violence may be associated with the number of patients on mental health holds (MHHs) boarding in the ED.

This study investigates factors that may be associated with assault in the ED.

This was an exploratory, retrospective study of pre-existing data from assault code activations, involuntary MHHs, and ED metrics at a level 2 trauma center and regional referral center, from May 2016 through April 2017.

Of the 297 assault code activations in the hospital, 57 (19.2%) occurred in the ED. For ED MHHs, there were 524 holds written during the study period. Assault code activations were associated with an increased number of patients on MHHs (P=0.04). Even when controlling for overall ED volume, activations were more likely to occur when there were more than 3 patients on MHHs (OR=4.44, 95% CI: 1.49 - 19.07) and more likely to occur later in the month compared to the beginning of the month (OR=2.39, 95% CI: 1.11 - 5.36). There was a diurnal pattern of activations, with more occurring between the hours of 12:00–23:59 (P=0.03).

The number MHHs in the ED was associated with an increase in ED violence. While a causal association cannot be established at this time, further investigation and discussion on the topic is warranted. System-wide efforts to improve acute psychiatric care, and therefore reduce the number of patients on MHHs boarding in the ED, could potentially reduce ED workplace violence.