The Operational Impact of Behavioral Health on the Emergency Department

Emergency department performance is measured in throughput, capacity, and time. Behavioral health has a big impact on all three.

Across hospitals, leaders are tracking longer lengths of stay, rising boarding hours, and growing pressure on staff, bed availability, and patient flow. Behavioral health patients are at the center of those trends.

The issue is not just volume. It is how these patients move through the system. The challenge is not how many behavioral health patients arrive, but how long they stay, how much capacity they consume, and how much they affect flow for everyone else.

Across all visits, behavioral health accounts for roughly 10% of ED volume but a disproportionate share of total bed hours. It is also heavily concentrated among the patients who use the ED most frequently. Half of frequent ED users have a behavioral health diagnosis.¹

Together, these dynamics create a measurable operational burden that shows up in the metrics health systems care about most.

Understanding that impact is the first step toward improving it.

One in five American adults lives with a mental illness, yet fewer than half receive treatment.² At the same time, many communities lack sufficient psychiatric providers, leaving patients with limited options for timely care.³

As a result, the emergency department has become a primary access point for behavioral health. Each year, roughly 10 to 12 million ED visits are related to mental health and substance use conditions.⁴ But once these patients arrive, they do not move through the ED in the same way as most medical patients.

Most medical patients can be flexibly managed within the ED: placed in hallways during surges, doubled up in rooms, or moved quickly to open beds. Behavioral health patients cannot.

They often require:

Adding to the complexity, about 70% of patients with a behavioral health disorder have a co-occurring physical condition, making evaluation and disposition more time-consuming.⁵

In ED operations, boarding begins once a disposition decision has been made but the patient cannot yet be moved. For behavioral health patients, boarding times are significantly longer.

The median ED length of stay for a behavioral health patient is 8 hours, roughly three times longer than for a medical patient.⁶ Many board far longer, waiting hours or even days for an appropriate placement.

Once behavioral health patients arrive in the ED, disposition options are often limited. With few available psychiatric beds and constrained outpatient resources, hospitals are frequently required to continue managing these patients for extended periods. Hospitals absorb the full operational burden of extended stays with little or no additional reimbursement.

Too often, the approach is to “sedate and wait” and default to inpatient admission rather than to actively stabilize and reassess. During extended boarding periods, many patients are not reassessed or treated in ways that meaningfully advance their care, meaning some could potentially have been safely stabilized and discharged rather than admitted.

Analysis of psychiatric boarding estimates the cost at $2,264 per behavioral health patient, based on lost ED bed capacity and throughput, and that figure does not include the additional expense of sitters and safety attendants.⁶

The impact goes well beyond the patients themselves. On average, each behavioral health patient in the ED prevents 2.2 bed turnovers during their stay.⁶ When hospitals rely on the ED for roughly 70% of inpatient admissions, a small number of boarded behavioral health patients can meaningfully reduce throughput across the entire department.

This creates a cascading effect:

Health system leaders often describe the ED as the “front door” of the hospital. When that front door is congested, patients who leave without being seen represent not only a clinical risk, but a missed medical or surgical admission, often valued at approximately $8,000 each.

That congestion does not stay contained within the ED. It constrains capacity across the system, affecting both medical and behavioral health patients and creating ripple effects upstream and downstream.

Twenty-six percent of patients account for 56% of total healthcare costs,⁷ underscoring how a relatively small subset of patients can drive disproportionate demand on the system. Behavioral health is not a niche issue within the ED. It is a core driver of system performance, and the operational strain has a measurable cost.

In Part 2, we’ll quantify the financial impact of behavioral health boarding and show why the cost of inaction is higher than most health systems realize.