a b s t r a c t

Objectives: Examine trends in mental health-related emergency department (ED) visits, changes in disposition and length of stay (LOS), describe disposition by age and estimate proportion of ED treatment hours dedicated to mental health-related visits.

Methods: Retrospective analysis of ED encounters in the National Hospital Ambulatory Medical Care Visit Survey with a mental health primary, secondary or tertiary discharge diagnosis from 2009 to 2015. We report survey- weighted estimates of the number and proportion of ED visits that were mental health-related and disposition by age and survey year. We estimate the proportion of ED treatment hours dedicated to mental health-related visits. We analyze trends in disposition and LOS for mental health and non-mental health-related visits using multivariate regression analysis.

Results: Mental health-related ED visits increased by 56.4% for pediatric patients and 40.8% for adults, accounting for over 10% of ED visits by 15-64 year-olds and nearly 9% by 10-14 year-olds in 2015. Mental health-related Visit disposition of admission or transfer declined from 29.8% to 20.4% (p b .001); predicted median ED LOS for admis- sions or transfers increased from 6.5 to 9.0 hours while median LOS for discharges was stable at 4.4 hours. During the study period, mental health-related visits accounted for 5.0% (95% CI 4.6-5.3) of all pediatric and 11.1% (95% CI 11.0-11.3) of adult ED treatment hours.

Conclusions: Mental health-related visits account for an increasing proportion of ED visits and a considerable pro- portion of treatment hours. A decreasing proportion of mental health-related visits resulted in inpatient disposi- tion and ED LOS increased for admissions and transfers.

(C) 2019

Introduction

Increasing use of emergency departments (EDs) for mental health conditions [1-9] has resulted in a crisis in EDs across the United States [10]. Psychiatric boarding, or holding a patient in the ED after a decision to admit or transfer has been made, is recognized as a serious and wide- spread problem [11-21,23]. However, little is known about overall na- tional trends in Disposition decisions for mental health-related ED visits. As EDs and health systems strive to improve overall ED through- put and decrease boarding [24-26], an understanding of the trends in ED

? Prior presentations: An abstract with preliminary data was presented at the American College of Emergency Physicians Scientific Assembly, San Diego, CA, October 1, 2018.

* Corresponding author at: Department of Emergency Medicine, Keck School of

Medicine of the University of Southern California, 1200 N. State Street, GNH 1011, Los Angeles, CA 90033, USA.

E-mail address: [email protected] (S. Axeen).

length of stay (LOS) and disposition for mental health-related visits is critical.

Furthermore, while EDs serve as the safety net for patients with unmet acute and chronic mental Health care needs, they are generally ill-equipped to deliver Optimal care to patients with mental health com- plaints [16,27]. In order to align resources with treatment needs, a bet- ter understanding of the patients presenting for emergency mental health care is necessary. This must include a more thorough under- standing of differences between age groups as needs may vary by age. Most previous studies of mental health-related ED visits were limited to either pediatric or adult patients, and are difficult to compare due to varying definitions of mental health-related ED visits.

We improve and build on the existing evidence by examining recent trends in mental health-related ED visits by pediatric and adult patients in a nationally-Representative sample, characterizing trends in disposi- tion and throughput (ED LOS) of mental health-related ED visits over time, describing disposition and throughput for mental health-related

https://doi.org/10.1016/j.ajem.2019.12.035

0735-6757/(C) 2019

ED visits among different age groups, and estimating the proportion of all ED treatment hours dedicated to mental health-related visits.

Methods

Study design

We conducted a retrospective analysis of ED encounters from 2009 to 2015 using the National Hospital Ambulatory Medical Care Surveys (NHAMCS). The NHAMCS is an annual, national probability sample of ambulatory visits to general, nonfederal, short-stay US hospitals, con- ducted by the Centers for Disease Control, National Center for Health Statistics [28]. The study was determined to be exempt by the local In- stitutional Review Board.

Survey details

The NHAMCS utilizes a four-stage probability design to provide na- tionally representative estimates of encounters in U.S. EDs. Designated hospital staff or US Census Bureau field representatives complete pa- tient record forms for sampled visits using data obtained from medical records during randomly assigned 4-week blocks. Unbiased estimates are derived using the multistage estimation procedure [29].

Study population

We define mental health-related ED visits as encounters in which one of the first three ED discharge diagnoses is a mental health or sub- stance abuse diagnosis. Diagnoses included in the Healthcare Cost and Utilization Project’s (HCUP) Clinical Classifications Software (CCS) cate- gorization scheme related to Mental health and substance abuse are in- cluded with the following exclusions: developMental disorders, delirium, dementia, amnestic and other Cognitive disorders, fetal/new- born complications of alcohol and substance abuse and chronic Medical complications of alcohol abuse. Exclusions were determined by consen- sus of 2 physicians (1 emergency medicine and 1 pediatric emergency medicine) after review of the CCS Diagnosis codes. A complete list of in- cluded International Classification of Diseases, 9th Revision (ICD-9) di- agnosis, E and V codes is available in Appendix Table 1a. Appendix Table 1b lists codes that are not included.

Outcome measures

The outcomes of interest are the estimated number and proportion of all ED visits that are mental health-related and the ED disposition for mental health-related visits as compared to non-mental health- related visits. We also compare throughput (defined as median ED LOS) for mental health and non-mental health-related visits. The 4 dis- position categories of interest are: discharge, admission to the same hospital (including Observation status), transfer to a psychiatric hospital and transfer to a non-psychiatric hospital. Dispositions of left before treatment complete, left before triage or medical screening, left against medical advice, dead on arrival, died in the ED or other account for a small proportion of visits and are not reported. We consider admission and transfer to psychiatric and non-psychiatric hospitals to be inPatient dispositions.

As age restrictions, particularly for psychiatric Inpatient units (e.g. psychiatric beds restricted to specific ages), could potentially impact ED Disposition decisions, survey data on visit trends and disposition are analyzed by 7 age groups (where data permitted): b10, 10-14, 15-17, 18-25, 26-44, 45-64 and 65+ years. We also estimate the total number of ED treatment hours utilized nationally for all ED visits over the entire study period. We then calculate the proportion of ED treatment hours accounted for by mental health-related visits and com- pare that to the proportion of visits that are mental health-related.

Data analysis

We analyze the NHAMCS data using sample visit weights according to weighting procedures described by the National Center for Health Statistics [30]. We perform estimations using the “svy” function in Stata 13 (StataCorp, College Station, TX). From these estimates, we re- port survey weighted estimates with confidence intervals (CIs) for an- nual visits, patient demographics, and ED disposition by patient age and year of survey. We also perform multivariate regression analysis controlling for Patient sex, race, payer, and year of encounter [31]. We report regression coefficients to determine whether the time-trend in visit characteristics is statistically significant. Where relevant, we per- form diagnosis-specific regressions to estimate trends by specific diag- nosis like suicide. In addition, we include the interaction of year and patient age group to determine whether trends in utilization vary by age. Finally, we report regression-adjusted estimates of the distribution of length of stay (25th, 50th, and 75th percentile) by year and patient disposition.

Since estimations based on 30 or fewer unweighted records are considered unreliable, we do not present findings based on fewer than 30 unweighted records-this precludes diagnosis-specific anal- yses for a number of diagnoses [28]. 10,130 of 199,718 records (5.1%) have missing LOS data; these visits are excluded from LOS analyses.

Results

Volume and characteristics of mental health-related ED visits

From 2009 to 2015, 2.5% of pediatric ED visits (5.4 million) and 8.2% of ED visits by adults (59.5 million) were mental health-related (Table 1). Mental health-related visits increased substantially during the study period, from 7.8 million in 2009 to 11.5 million in 2015 (pedi- atric and adult encounters). In contrast, the number of non-mental health-related ED visits actually declined slightly (127.1 million esti- mated visits in 2009 and 125.4 million in 2015). For adults, the propor- tion of ED visits that were mental health related increased from 6.9% to 9.9%, corresponding to a 40.8% increase in the annual number of mental health visits (7.0 million to 10.4 million visits). For pediatric patients, the proportion of ED visits that were mental health-related increased from 2.1% to 3.4% during the study period, a 56.4% increase in the total number of pediatric mental health visits (700,000 to 1.1 million visits). Fig. 1 presents the proportion of ED visits with a mental health dis- charge diagnosis for 7 age groups from 2009 to 2015. The largest in- creases were seen in adolescents and young adults with significantly higher increases for 10-17 year-olds (annual increase 0.6%), 18-25 year-olds (annual increase 0.7%) and 26-45 year-olds (annual increase 0.7%) compared to 45-64 year-olds (annual increase 0.3%; p b .05 for comparison with 10-17; p b .01 for comparison with 18-25 and 26-45 year olds) and 65+ year-olds (annual increase 0.2%) during the same period (p b .05 for comparison with 10-17; p b .01 for comparison with 18-25 and 26-45 year olds).

Disposition trends

In 2009, 29.8% of mental health-related visits resulted in admis- sion or transfer; in 2015 only 20.4% of mental health-related visits did (-2.3% per year, p b .001 for linear trend) (Fig. 2). Notably, while the proportion of mental health-related visits admitted or transferred decreased, the estimated total number of mental health-related visits resulting in admission or transfer remained sta- ble at about 2.3 million encounters per year. Fig. 2 presents diagnosis-specific trends in ED disposition of admission or transfer. Admission or transfer rates declined 4.6% per year (p b .001 for linear trend) for suicide or self-inflicted injury-related visits and declined by 2.8% per year (p = .060 for linear trend) for schizophrenia and

Table 1

Proportions of All ED Visits accounted for by mental health-related visits and characteristics of mental health-related ED Visits by adult and pediatric patients

	Pediatric mental health-related ED visits				Adult mental health-related ED visits
	Survey-weighted average national yearly visit estimate		Weighted proportion of all pediatric ED visits % (95% CI)		Survey-weighted average national yearly visit estimate	Weighted proportion of all adult ED visits % (95% CI)
Overall			2.5 (2.3-2.8)			8.2 (7.7-8.6)
2009	700,000		2.1 (1.7-2.6)		7,073,000	6.9 (6.3-7.5)
2010	614,000		2.1 (1.7-2.4)		7,007,000	7.0 (6.4-7.6)
2011	701,000		2.4 (1.8-3.0)		8,186,000	7.7 (6.9-8.4)
2012	647,000		2.3 (1.7-3.0)		8,108,000	7.9 (6.9-8.8)
2013	708,000		2.5 (1.9-3.1)		8,857,000	8.7 (7.7-9.6)
2014	893,000		2.7 (2.0-3.5)		9,854,000	9.0 (7.9-10.2)
2015	1,095,000		3.4 (2.8-4.1)		10,434,000	9.9 (8.6-11.3)
	Survey-weighted average national yearly visit estimate		Weighted proportion of pediatric mental health-related ED visits % (95% CI)		Survey-weighted average national yearly visit estimate	Weighted proportion of adult mental health-related ED visits % (95% CI)
Gender Male	372,000		48.7 (44.7-52.6)		4,485,000	52.7 (51.5-54.0)
Female	393,000		51.3 (47.4-55.3)	4,018,000		47.3 (46.0-48.5)
Ethnicity White		433,000	56.6 (52.3-60.9)	5,557,000		65.4 (63.2-67.5)
(Non-Hispanic)		160,000	20.9 (16.8-25.1)	1,660,000		19.5 (17.7-21.4)
Black		156,000	20.3 (16.9-23.8)	1,039,000		12.2 (10.8-13.6)
(Non-Hispanic) Hispanic		16,000	2.2 (1.3-3.0)	247,000		2.9 (2.3-3.5)

Other Payer

Private	234,000	30.6 (26.7-34.5)	1,936,000	22.8 (21.5-24.0)
Medicare	4000	0.6 (0.1-1.0)	1,387,000	16.3 (15.2-17.4)
Medicaid	387,000	50.5 (46.2-54.9)	2,253,000	26.5 (24.9-28.1)
Self-pay	46,000	6.0 (4.2-7.8)	1,783,000	21.0 (19.3-22.6)
Other	94,000	12.3 (8.8-15.9)	1,144,000	13.5 (11.5-15.4)
Arrival by	166,000	21.7 (18.6-24.8)	2,722,000	32.0 (30.4-33.6)

ambulance

Aggregated 2009-2015 survey-weighted estimates presented.

Note: The proportion of all ED visits that were mental health-related increased significantly over the study period (p = .006 for ED visits by pediatric patients and p b .001 for ED visits by adults).

psychosis-related visits. In comparison, admission or transfer for non-mental health-related visits decreased by 0.8% per year (p b

.001 for linear trend), significantly less than the decrease noted for all mental health-related visits (p b .001 for difference), suicide and self-inflicted injury visits (p b .01 for difference), and schizophrenia and psychosis-related ED visits (p = .027 for difference).

Variation in disposition by age

ED disposition for mental health-related and non-mental health- related visits for each age group is presented in Appendix 2. For visits by all age groups except the 65+ year-olds, the proportion resulting in admission or transfer was significantly higher for mental health-

14 Children and Adolescents

Percent of ED Visits with a Mental Health Discharge Diagnosis

12

14

12

10.2%

Adults

12.5%

11.4%

10

8

6 5.7%

4 4.7%

8.9%

10 8.6% 10.1%

8 8.0%

6 6.4%

4.1%

4

3.0%

2 0.6% 0.4%

0

2009 2010 2011 2012 2013 2014 2015

<10 years 10-14 years

15-17 years

2

0

2009 2010 2011 2012 2013 2014 2015

18-25 years 26-44 years

45-64 years 65+ years

Fig. 1. Trends in proportion of ED visits with a mental health discharge diagnosis by age.

Fig. 2. Trends in ED disposition of admission or transfer by diagnosis, 2009-2015.

100

90

80

70

60

50

40

30

20

10

0

84.5%

58.5%

-4.6% per year, p<0.001* 59.1%

46.9%

-2.8% per year,

29.8%

-2.3% per year,

14.5%

20.4%

12.2%

-0.8% per year, p<0.001*

2009 2010 2011 2012 2013 2014 2015

Suicide & Self-Inflicted Injury Schizophrenia & Psychosis All Mental Health Non-Mental Health

% of ED Visits Resulting in Admission or Transfer

related than non-mental health-related visits (p b .001). This difference was particularly striking in ED visits by adolescents. Nearly a third (31.3%, 95% CI 25.4-37.2) of mental health-related visits by 15-17 year-olds resulted in admission or transfer while only 4.7% (95% CI 3.9-5.5) of non-mental health-related visits by 15-17 year-olds did (p b .001). Similarly, 28.4% (95% CI 22.6-34.2) of mental health-related visits by 10-14 year-olds resulted in admission or transfer compared to only 4.3% (95% CI 3.6-5.0) of non-mental health-related visits by 10-14 year-olds(p b .001).

Throughput trends

Regression adjusted predicted LOS by year for visits resulting in ad- mission or transfer is presented in Fig. 3 with further detail on change in LOS over time in Appendix 3. Predicted median LOS for mental health- related visits with any inpatient disposition (admission or transfer) in- creased from 6.5 hours (388 min) in 2009 to 9.0 hours (537 min) in 2015. mental health-related visits resulting in transfer to a psychiatric hospital had particularly long LOS with predicted median LOS increas- ing from 8.0 to 11.4 hours (478 to 681 min) during the study period. In contrast, for mental health-related encounters resulting in discharge predicted median LOS was stable at 4.4 hours (267 min in 2009, 266 min in 2015).

Fig. 3. Predicted ED length of stay for mental health and non-mental health-related encounters resulting in admission or transfer, 2009-2015.

Utilization of ED hours

Mental health-related visits accounted for 4.9% (95% CI 4.6-5.3) of all ED hours utilized by pediatric patients and 11.2% (95% CI 11.0-11.3) of ED hours utilized by adults during the study period (Table 2). For pedi- atric patients, mental health-related visits accounted for 3.7% of all ED treatment hours (95% CI 3.0-4.1) in 2009, rising to 8.8% (95% CI 7.2-9.7) of treatment hours in 2015 (p = .027 for linear trend), utilizing

6.7 million (95%CI 4.2-9.2) ED treatment hours in 2015. For adults, mental health-related visits accounted for 9.4% of all ED treatment hours (95% CI 9.0-9.6) in 2009, rising to 13.2% of treatment hours

(95% CI 12.6-13.7) in 2015 (p b .001 for linear trend), utilizing 288.9

million (95% CI 263.3-314.5) ED treatment hours in 2015.

Discussion

Mental health-related ED visits increased dramatically over the 7- year study period, with a 56.4% increase in number of visits by children and adolescents and a 40.8% increase by adults. Mental health-related ED visits accounted for N10% of all ED visits by 15-64 year olds and 8.9% of ED visits by 10-14 year olds in 2015 with adolescents, and young adults appearing to drive the increase in visits. While an increase in visits has been demonstrated previously [1-7], our study highlights several important issues that help explain the significance of this in- crease in mental health-related visits. The longer LOS for mental health-related visits and the increasing LOS for admitted and trans- ferred mental health-related visits likely negatively impacts general ED operations and must be addressed in efforts to alleviate ED through- put and boarding issues. Interestingly, a decreasing proportion of men- tal health-related visits were admitted or transferred over the study period as LOS for mental health-related visits with inpatient disposi- tions increased, a finding whose underlying mechanism merits further investigation. We also discovered variations in disposition by age which carry important policy and resource allocation implications.

Due to their longer LOS, mental health-related visits utilize a dispro- portionate amount of ED time. During the study period 8.2% of all ED visits by adults were mental health-related and these visits accounted for 11.2% of all ED hours utilized by adults. For pediatric patients, the 2.5% of ED visits that were mental health-related accounted for 4.9% of ED hours. This disproportionate utilization of ED time likely contributes to overall ED crowding which is, in turn, is associated with decreased quality of care for multiple conditions [34-39]. As such, the increase in mental health-related visits may have negative spillovers onto the

Table 2

ED Treatment Hours Utilized for Mental Health-Related Visits and All ED Visits and the Proportion of ED Treatment Hours Utilized for Mental Health-Related Visits, 2009-2015

	Pediatric				Adult
	Total mental health-related visit hours	Total hours for all ED visits millions of	Proportion of ED hours accounted for by		Total mental health-related visit hours	Total hours for all ED visits millions of	Proportion of ED hours accounted for by
	millions of hours (95% CI)	hours (95% CI)	MH-related visits % (95% CI)		millions of hours (95% CI)	hours (95% CI)	MH-related visits % (95% CI)
2009	3.0 (2.0, 4.0)	81.0 (65.0, 97.1)	3.7 (3.0, 4.1)		34.2 (27.2, 41.2)	366.0 (302.0, 430.2)	9.4 (9.0, 9.6
2010	2.9 (1.8, 3.9)	72.0 (58.0, 86.0)	4.0 (3.2, 4.6)		35.0 (28.3, 42.0)	352.6 (296.7, 408.5)	9.9 (9.5, 10.2)
2011	2.8 (1.9, 3.7)	69.4 (56.2, 82.6)	4.0 (3.3, 4.4)		39.3 (32.0, 46.7)	378.8 (319.4, 438.3)	10.4 (10.0, 10.7)
2012	2.7 (1.7, 3.7)	68.4 (52.2, 84.6)	3.9 (3.2, 4.4)		41.0 (32.3, 49.0)	379.5 (319.0, 440.4)	10.7 (10.2, 11.1)
2013	3.6 (2.2, 5.0)	70.0 (53.1, 86.2)	5.2 (4.2, 5.8)		40.4 (32.1, 48.9)	356.3 (292.0, 421.0)	11.4 (11.0, 11.6)
2014	3.7 (2.3, 5.1)	72.2 (56.8, 87.6)	5.1 (4.1, 5.8)		50.1 (39.0, 61.2)	386.0 (312.7, 459.2)	13.0 (12.5, 13.3)
2015	6.7 (4.2, 9.2)	76.3 (57.5, 95.1)	8.8 (7.2, 9.7)		49.3 (38.3, 60.3)	372.5 (305.3, 439.7)	13.2 (12.6, 13.7)
Overall	25.3 (21.2, 29.4)	508.7 (460.2, 557.2)	4.9 (4.6, 5.3)		288.9 (263.3, 314.5)	2591.6 (2393.1, 2790.1)	11.2 (11.0, 11.3)

care of all ED patients. For ED visits resulting in admission or transfer in 2015, median LOS was 3 hours longer for mental health-related (9.0 hours) than non-mental health-related visits (6.0 h), an additional 3 hours of ED resources unavailable for new ED patients.

As most EDs do not have resources to provide ongoing psychiatric treatment, in addition to straining the emergency medical system, Prolonged LOS and psychiatric boarding delay necessary mental health care for patients [11,16,23,27,40]. Despite widespread con- cern about psychiatric boarding practices [19,20,28] [13,41,42], psy- chiatric Boarding times appeared to be increasing over time in our analysis. While we could not directly determine boarding time from the NHAMCS, for mental health-related visits, median ED LOS for encounters resulting in admission or transfer increased by 2.5 hours over the 7-year study period, from 6.5 to 9.0 hours, while LOS for encounters resulting in discharge was unchanged at 4.4 hours. The stable LOS for discharged visits suggests that the time to disposition decision has not increased and that increased LOS for visits resulting in inpatient disposition is due at least in part to in- creasED boarding time.

Even as the proportion, number and LOS for mental health-related visits increased, we observed a surprisingly large decrease in the pro- portion of mental health-related ED visits that resulted in admission or transfer (29.8% in 2009 to 20.4% in 2015). Reasons for this decrease may include that the acuity of mental health-related ED visits has de- creased over time, that there has been a general shift toward outpatient care, or that there is a fixED capacity of inpatient mental health services that is saturated. We find some evidence that there has been a general trend toward discharge from the ED; the proportion of non-mental health-related ED visits admitted or transferred declined slightly, from 14.5% to 12.2%. Our finding that admissions and transfers decreased sig- nificantly not only for mental health-related ED visits overall but also for ED visits related to suicide and self-harm and marginally for visits re- lated to schizophrenia/psychosis suggests that an increase in low acuity mental health-related visits does not completely explain the decrease in inpatient disposition.

Recent studies have noted a decline in inpatient psychiatric bed availability [43-45]. ED physicians, faced with increasing numbers of pa- tients with mental health-related visits and stable or diminished inpa- tient psychiatric capacity, are in an untenable position. We found that the number of mental health-related admissions and transfers was sta- ble over the study period, but that the proportion of mental health- related ED visits resulting in an inpatient disposition decreased. Our findings suggest inpatient psychiatric capacity has reached a threshold, leaving ED physicians to treat an increasing number of patients with mental health emergencies without a corresponding increase in inpa- tient bed availability. Decreased inpatient disposition for suicide and self-harm-related visits is particularly troubling in light of the increasing US suicide rate [46] and a previously demonstrated association between an increase in US suicide rates and a decrease in psychiatric inpatient beds [47,48]. The possibility that EDs, faced with a paucity of inpatient psychiatric beds, prolonged psychiatric boarding times and limited

mental health resources, must discharge patients who could previously have been admitted or transferred is highly concerning.

For adolescents, we find that the situation is exacerbated compared to adults and children. The overall proportion of mental health-related visits was 3.4% of ED visits by pediatric patients in 2015, but mental health-related visits accounted for 8.9% of ED visits by 10-14 year-olds and 10.2% of ED visits by 15-17 year-olds that year. By 2015 mental health-related visits accounted for 8.8% of all ED treatment hours by pe- diatric patients. Mental health-related visits by adolescents were more likely to result in admission or transfer than mental health-related visits by other age groups, likely contributing to the disproportionately high utilization of ED hours. Identifying available pediatric and adolescent in- patient psychiatric beds is often particularly challenging [11,27,49] and as few EDs have pediatric psychiatry services available [11,27,50], pedi- atric patients are unlikely to receive focused mental health care, much less pediatric focused mental health care during ED stays.

The surge in mental health-related ED visits and increasing psychiat- ric boarding presents a daily challenge in many EDs and EDs must play a role in addressing these issues. However, as with boarding in general, these problems reflect greater systems-wide issues. Given the obvious increase in demand for emergency mental health services, improved ac- cess to outpatient and inpatient mental health care is critical to care for patients with mental health conditions and to reduce strain on EDs. Al- ternatively, if responsibility for caring for these patients is to increas- ingly occur within EDs, additional funding and resources to support ED-based mental health care are necessary to ensure both that patients can begin meaningful treatment earlier in their course and that other ED operations remain unaffected.

While the need is obvious, there are emerging care paradigms that offer promise. Psychiatric Observation Units modeled after medical ED observation units have been proposed as a model to provide mental health care while preserving other ED operations [57]. Tele-psychiatry could expand access to emergency psychiatric consultations [51-54], but requires funding for initial and maintenance costs [55]. Expanded acute mental health services outside of traditional ED settings such as dedicated psychiatric emergency service units which provide intensive treatment and stabilization show promise in decreasing psychiatric boarding times [56]. In metropolitan areas, regionalized services for ad- olescent patients may be beneficial given the high proportion of adoles- cent mental health-related visits resulting in transfer and the specialized needs of this population. The need for acute mental health care cannot be ignored if EDs are to continue to provide high quality, timely care for all patients in need of emergency care.

Limitations

This study has several important limitations. This is a secondary analysis of survey data not designed or collected specifically to address our research questions. However, the NHAMCS is a large, nationally rep- resentative dataset collected by the CDC and has been utilized for other studies of mental health-related ED visits [1,3-6]. It is also one of the few

surveys of ED utilization with reliable, detailed estimates of LOS. One limitation of the NHAMCS dataset is that boarding time for admissions and transfers was not consistently reported during the study period. Psychiatric boarding time appears to be increasing in our study; further study is needed to reliably quantify trends in psychiatric boarding times. Our goal was to identify ED encounters related to diagnoses amena- ble to acute psychiatric treatment. No uniform definition of a mental health-related visit exists; prior studies have utilized different inclusion criteria. We based our definition on the HCUP’s CCS categorization scheme, but after review by 2 emergency medicine physicians did not include a subset of the CCS mental health and substance abuse diagno- ses unlikely to benefit from acute mental health treatment. For instance, we included attention deficit disorder (ICD-9314.0x) which was not in- cluded in some prior studies [1] and we did not include Postconcussion syndrome (ICD-9310.2) although other studies have [1,6,32]. We in- cluded suicidal ideation (V62.84) and suicide attempt (E950-E959) which some prior studies did not specifically include [4,32]. The slightly different definition of a mental health-related ED visit does limit com- parisons with other studies; but does suggested the importance of de- veloping of a universally accepted definition of a mental health-

related ED visit for research purposes.

We were unable to estimate capacity of hospitals to admit patients for mental health conditions and, therefore, could not test whether dif- ferences in LOS or disposition were affected by hospital capacity.

Unfortunately, due to small numbers of sampled encounters in the NHAMCS, for children under the age of 10 years, we could not estimate the proportion of mental health-related visits resulting in admission or transfer. Mental health emergencies are less common in young children, but data on these visits is important as this is a particularly vulnerable population presenting specific challenges to general EDs. Nationally representative data on pediatric visits to general EDs is valuable because most children are seen in general EDs [33]. As such, we suggest that the NMAHCS consider weighting sampled encounters to include more pedi- atric patients.

Conclusions

Mental health-related ED visits continue to increase in number and as a proportion of all ED visits and account for a disproportionally high utilization of ED treatment hours. Visits resulting in transfers to psychi- atric hospitals have particularly long LOS which increased drastically over the study period. Reforms are needed to address the crisis in US EDs and widespread implementation of innovative models of care may be necessary to provide adequate emergency mental health care.

Funding sources/disclosures

This research did not receive any specific grant from funding agen- cies in the public, commercial, or not-for-profit.

Author contribution

GS: Initial study concept, drafting of manuscript, data analysis and interpretation.

CNL: statistical expertise, critical revision of manuscript, data analy- sis and interpretation.

SA: statistical expertise, critical revision of manuscript, data analysis and interpretation.

MM: Initial study concept, critical revision of manuscript, data anal- ysis and interpretation.

Declaration of competing interest

None.

Acknowledgments

The authors would like to acknowledge Carla Martinez for her assis- tance with preparation of the manuscript, tables and figures.

Appendix A

Appendix 1a

Included International Classification of Diseases (ICD-9) diagnoses, E and V codes.

Included codes selected from the Clinical Classification Software (CCS) Mental Health and Substance Abuse Codes

CCS 650 Adjustment disorders

309.0 309.1 309.22 309.23 309.24 309.28 309.29 309.3 309.4 309.82 309.83 309.89 309.9

CCS 651 Anxiety disorders

293.84 300.00 300.01 300.02 300.09 300.10 300.20 300.21 300.22 300.23 300.29 300.3 300.5 300.89 300.9 308.0 308.1 308.2 308.3 308.4 308.9 309.81 313.0 313.1 313.21

313.22 313.3 313.82 313.83

CCS 652 Attention-deficit, conduct, and disruptive behavior disorder

312.00 312.01 312.02 312.03 312.10 312.11 312.12 312.13 312.20 312.21 312.22 312.23 312.4 312.8 312.81 312.82 312.89 312.9 313.81 314.00 314.01 314.1 314.2 314.8 314.9

CCS 655 Disorders usually diagnosed in infancy, childhood, or adolescence

299.00 299.01 299.10 299.11 299.80 299.81 299.90 299.91 307.20 307.21 307.22 307.23 307.3 307.6 307.7 309.21 313.23 313.89 313.9

CCS 656 Impulse control disorders, NEC

312.30 312.31 312.32 312.33 312.34 312.35 312.39

CCS 657 Mood disorders

293.83 296.00 296.01 296.02 296.03 296.04 296.05 296.06 296.10 296.11 296.12 296.13 296.14 296.15 296.16 296.20 296.21 296.22 296.23 296.24 296.25 296.26 296.30 296.31

296.32 296.33 296.34 296.35 296.36 296.40 296.41 296.42 296.43 296.44 296.45 296.46 296.50 296.51 296.52 296.53 296.54 296.55 296.56 296.60 296.61 296.62 296.63 296.64

296.65 296.66 296.7 296.80 296.81 296.82 296.89 296.90 296.99 300.4 311

CCS 658 Personality disorders

301.0 301.10 301.11 301.12 301.13 301.20 301.21 301.22 301.3 301.4 301.50 301.51 301.59 301.6 301.7 301.81 301.82 301.83 301.84 301.89 301.9

CCS 659 Schizophrenia and other psychotic disorders

293.81 293.82 295.00 295.01 295.02 295.03 295.04 295.05 295.10 295.11 295.12 295.13 295.14 295.15 295.20 295.21 295.22 295.23 295.24 295.25 295.30 295.31 295.32 295.33

295.34 295.35 295.40 295.41 295.42 295.43 295.44 295.45 295.50 295.51 295.52 295.53 295.54 295.55 295.60 295.61 295.62 295.63 295.64 295.65 295.70 295.71 295.72 295.73

295.74 295.75 295.80 295.81 295.82 295.83 295.84 295.85 295.90 295.91 295.92 295.93 295.94 295.95 297.0 297.1 297.2 297.3 297.8 297.9 298.0 298.1 298.2 298.3 298.4 298.8

298.9

CCS 661 Substance-related disorders

292.0 292.11 292.12 292.2 292.81 292.82 292.83 292.84 292.85 292.89 292.9 304.00 304.01 304.02 304.03 304.10 304.11 304.12 304.13 304.20 304.21 304.22 304.23 304.30

304.31 304.32 304.33 304.40 304.41 304.42 304.43 304.50 304.51 304.52 304.53 304.60 304.61 304.62 304.63 304.70 304.71 304.72 304.73 304.80 304.81 304.82 304.83 304.90

304.91 304.92 304.93 305.20 305.21 305.22 305.23 305.30 305.31 305.32 305.33 305.40 305.41 305.42 305.43 305.50 305.51 305.52 305.53 305.60 305.61 305.62 305.63 305.70

305.71 305.72 305.73 305.80 305.81 305.82 305.83 305.90 305.91 305.92 305.93 648.30 648.31 648.32 648.33 648.34 965.00 965.01 965.02 965.09 V65.42

CCS 660 Alcohol-related disorders

291.0 291.1 291.2 291.3 291.4 291.5 291.8 291.81 291.82 291.89 291.9 303.00 303.01 303.02 303.03 303.90 303.91 303.92 303.93 305.00 305.01 305.02 305.03 980.0

(continued on next page)

Appendix 1a (continued)

Included codes selected from the Clinical Classification Software (CCS) Mental Health and Substance Abuse Codes

CCS 662 Suicide and intentional self-inflicted injury

E950.0 E950.1 E950.2 E950.3 E950.4 E950.5 E950.6 E950.7 E950.8 E950.9 E951.0 E951.1 E951.8 E952.0 E952.1 E952.8 E952.9 E953.0 E953.1 E953.8 E953.9 E954 E955.0 E955.1 E955.2 E955.3 E955.4 E955.5 E955.6 E955.7 E955.9 E956 E957.0 E957.1 E957.2 E957.9 E958.0 E958.1 E958.2 E958.3 E958.4 E958.5 E958.6 E958.7 E958.8 E958.9 E959 V62.84

CCS 663 Screening and history of mental health and substance abuse codes

305.1 305.10 305.11 305.12 305.13 333.92 790.3 V11.0 V11.1 V11.2 V11.3 V11.4 V11.8 V11.9 V15.4 V15.41 V15.42 V15.49 V15.82 V62.85 V66.3 V70.1 V70.2 V71.01 V71.02 V71.09 V79.0 V79.1 V79.2 V79.3 V79.8 V79.9

CCS 670 Miscellaneous mental health disorders

293.89 293.9 300.11 300.12 300.13 300.14 300.15 300.16 300.19 300.6 300.7 300.81 300.82 302.1 302.2 302.3 302.4 302.50 302.51 302.52 302.53 302.6 302.70 302.71 302.72

302.73 302.74 302.75 302.76 302.79 302.81 302.82 302.83 302.84 302.85 302.89 302.9 306.0 306.1 306.2 306.3 306.4 306.50 306.51 306.52 306.53 306.59 306.6 306.7 306.8

306.9 307.1 307.40 307.41 307.42 307.43 307.44 307.45 307.46 307.47 307.48 307.49 307.50 307.51 307.52 307.53 307.54 307.59 307.80 307.81 307.89 310.1 316 648.40

648.41 648.42 648.43 648.44 V40.2 V40.3 V40.31 V40.39 V40.9 V67.3

Appendix 1b

ICD-9 diagnosis, E and V codes from the Clinical Classification Software (CCS) Mental Health and Substance Abuse Codes that were not included in our definition of a mental health-related emergency visit.

CCS 653 Delirium, dementia, and amnestic and other cognitive disorders

290.0 290.10 290.11 290.12 290.13 290.20 290.21 290.3 290.40 290.41 290.42 290.43 290.8 290.9 293.0 293.1 294.0 294.1 294.10 294.11 294.20 294.21 294.8 294.9 310.0 310.2

310.8 310.81 310.89 310.9 331.0 331.1 331.11 331.19 331.2 331.82 797

CCS 654 Developmental disorders

307.0 307.9 315.00 315.01 315.02 315.09 315.1 315.2 315.31 315.32 315.34 315.35 315.39 315.4 315.5 315.8 315.9 317 318.0 318.1 318.2 319 V40.0 V40.1

CCS 660 Alcohol-related disorders

357.5 425.5 535.3 535.30 535.31 571.0 571.1 571.2 571.3 760.71

CCS 661 Substance-related disorders

655.50 655.51 655.53 760.72 760.73 760.75 779.5

Appendix 2

ED visit disposition by age group.

	Mental health-related ED visits			Non-mental health-related ED Visits
	Discharge % (95% CI)	Inpatient % (95% CI)		Discharge % (95% CI)	Inpatient % (95% CI)
	b10 years 82.0	*		91.8	4.7
	(74.3-89.7)			(90.8-92.7)	(4.0-5.3)
	10-14 years 69.0 (63.1-75.0) 15-17 years 64.4	28.4 (22.6-34.2) 31.3		92.5 (91.5-93.5) 91.9	4.3 (3.6-5.0) 4.7
	(58.3-70.4)	(25.4-37.2)		(90.7-93.0)	(3.9-5.5)
	18-25 years 75.4 (72.7-78.1) 26-44 years 72.9 (70.7-75.1) 45-64 years 68.2 (65.9-70.6) 65+ years 62.8	18.8 (16.2-21.4) 21.9 (19.9-24.0) 26.8 (24.5-29.1) 31.1		90.3 (89.6-91.0) 87.8 (87.1-88.5) 78.3 (77.2-79.4) 60.7	4.7 (4.2-5.1) 7.7 (7.1-8.2) 18.2 (17.1-19.3) 36.0
	(58.3-67.4)	(26.8-35.4)		(59.1-62.2)	(34.4-37.6)

*Not reported due to insufficient number of observations.

Inpatient disposition is aggregate of admission to same hospital, transfer to psychiatric hospital and transfer to nonpsychiatric hospital. Columns do not add to 100% because dis- positions of left before triage or medical screening, left before treatment complete, left against medical advice, dead on arrival, died in ED or other disposition not presented.

Appendix 3

Predicted ED length of stay in minutes, 2009-2015.

		2009	2010	2011	2012	2013	2014	2015
Any admission or transfer
Mental health-related	25th	342	366	393	427	455	478	506
	Median	388	416	425	459	500	509	537
	75th	439	454	478	523	551	566	595
Non-mental health-related	25th	305	312	320	328	336	344	352
	Median	316	324	331	340	347	355	360
	75th	352	365	367	388	389	397	399
Admission Mental health-related	25th	301	318	335	355	372	387	406
	Median	356	373	390	408	425	442	459
	75th	413	430	447	485	481	499	516

Appendix 3 (continued)
		2009	2010	2011	2012	2013	2014	2015
Non-mental health-related	25th	308	317	326	335	344	353	362
	Median	326	335	344	353	362	371	380
	75th	361	370	379	404	404	406	410
Transfer
Mental health-related (transfer to psychiatric hospital)	25th	420	459	464	515	561	600	654
	Median	478	517	525	562	634	642	681
	75th	502	541	564	618	690	691	724
Non-mental health-related	25th	221	227	233	239	245	251	257
(transfer to non-psychiatric hospital)	Median	228	237	250	259	262	271	276
	75th	246	259	258	278	270	290	294
Discharge
Mental health-related	25th	229	230	231	232	233	235	235
	Median	267	268	269	270	267	273	266
	75th	279	280	278	283	284	285	286
Non-mental health-related	25th	157	158	158	159	160	161	161
	Median	173	174	174	175	176	177	177
	75th	192	192	195	195	198	197	197

Predicted values adjusted for sex, race/ethnicity, and type of health insurance.

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