Frequent emergency department (ED) users with mental health issues are particularly vulnerable patients, who often receive insufficient or inadequate outpatient care. This systematic review identified and evaluated studies on ED-based interventions to reduce acute care use by this population, while improving outpatient service use and patient outcomes.

Searches were conducted in five databases for studies published between January 1, 2000, and April 30, 2022. Eligibility criteria included: patients with mental health issues who made 2+ ED visits in the previous 6 months or were high ED users (3+ visits/year), and who received ED-based interventions to reduce ED use.

The review included 12 studies of 11,082 articles screened. Four intervention groups were identified: care plan (n = 4), case management (n = 4), peer-support (n = 2) and brief interventions (n = 2). The definitions of frequent users varied considerably, while the quality assessment rated studies from moderate to good and risk of bias from low to high. Eight studies used pre-post design, and four were randomized controlled trials. Ten studies assessed outcomes related to use of other services than ED, mainly hospitalizations, while five assessed patients' clinical conditions and three, social conditions (e.g., housing status).

This review revealed that case management and care plan interventions, based in ED, decrease ED use among frequent users, while case management also showed promising results for outpatient service use and clinical and social outcomes. Thus, the results support continued deployment of intensive ED-based interventions for frequent ED users with mental health issues although firm conclusions regarding the effectiveness of these interventions, particularly outcomes related to services other than ED, require further investigation.