Article, Pediatrics

Characterizing pediatric high frequency users of California emergency departments

a b s t r a c t

Objective: Emergency department (ED) utilization has increased for the last several decades. Despite a focus on adult Frequent ED users, little research has examined pediatric frequent ED users. The purpose of this study was to assess pediatric ED utilization in California and to describe those identified as frequent ED users.

Methods: This was a retrospective multi-facility study of ED visits by children 1-17 years of age using statewide

data from the California Office of Statewide Health Planning and Development. Patients were classified into uti- lization groups by the number of ED visits in a one-year period prior to their last visit in 2016: occasional (1-5 visits) vs. frequent (N5 visits). Differences in patient characteristics were compared between occasional and fre- quent users.

Results: There were 690,130 patients between 1 and 17 years of age with 1,238,262 visits during the study period. Children with >=6 visits (2.3%) accounted for 9.3% of all visits. 67% of frequent users had no visits to a pediatric ED. Over 40% (41.4%) of frequent users visited 2 or more hospitals, compared to 7.7% of occasional users. In multivar- iate analysis, the characteristics with the largest associations with frequent ED use were age, payer, and being ad- mitted/transferred.

Conclusions: The majority of pediatric frequent users do not seek care in pediatric EDs. Age, prior admission, and Medicare/Medicaid appear to have the largest associations with pediatric patient frequent ED utilization.

(C) 2018

Introduction

Over the past several decades, the rate of emergency department (ED) utilization in the U.S. has increased across nearly all age groups [1]. During 2010, hospital-affiliated EDs experienced approximately

Abbreviations: AHRF, Area Health Resource Files; AHRQ, Agency for Healthcare Research and Quality; CCS, Clinical Classifications Software; CI, Confidence Intervals; ED, Emergency Department; HRSA, Health Resources and Services Administration; IBM, International Business Machines Corporation; ID, Identification; ICD-9, Ninth Revision of the International Classification of Diseases; NCHS, National Center of Health Statistics; OR, Odds Ratio; OSHPD, Office of Statewide Health Planning and Development; PCP, Primary Care Physician; RLN, Record Linkage Number; RUCA, Rural-Urban Commuting Area; SPSS, Statistical Package for the Social Sciences; ZIP Code, Zone Improvement Plan.

* Corresponding author at: 200 W. Arbor Drive #8676, San Diego, CA 92103-8676, United States.

E-mail address: [email protected] (B. Supat).

128.9 million visits nationally, one fifth of which (25.5 million) involved children b18 years of age [7]. While much research has examined char- acteristics and ED utilization patterns of the adult U.S. population, rela- tively little research has specifically examined pediatric high frequency users of emergency department services [1-5]. What research is avail- able indicates that, among pediatric patients, increased likelihood of re- peat visits to the ED is positively associated with being b1 year of age, non-white race/ethnicity (i.e. non-Hispanic Black, Hispanic, and Native American), public health insurance, urban residence, hospital proxim- ity, and presence of a chronic condition [1-5]. One study found higher frequency pediatric ED use to be associated with greater density of pri- mary care physicians in the patient’s county of residence [2].

However, significant gaps in the research of pediatric frequent users remain to be filled. While it is known that adult frequent users often visit multiple hospitals, this pattern has not yet been explored among pediatric patients [6]. Previous research has also described that real dif- ferences exist in the care of pediatric patients seen in pediatric vs gen- eral EDs. However, it remains unclear to what extent the pediatric frequent user population accesses general vs pediatric EDs [7].

https://doi.org/10.1016/j.ajem.2018.12.015

0735-6757/(C) 2018

The purpose of this study was to assess pediatric ED utilization in California and to describe those identified as frequent ED users.

Methods

Study design

This was a multicenter retrospective cohort study using visit-level data from all non-military acute care hospitals across the entire state of California using non-public data from the California Office of State- wide Health Planning and Development (OSHPD). All licensed hospitals in the state of California are subject to mandatory reporting of utiliza- tion data in a standardized format to OSHPD. The data presented in this study is available in two non-public OSHPD datasets: The Patient Discharge Dataset and the Emergency Department Dataset. Patients in- cluded in the Patient Discharge Dataset who were admitted through the ED were merged with the Emergency Department Dataset to construct a complete ED utilization database. More detailed descriptions of these data sources can be found elsewhere [8,9]. County-level measures were based on those used by the University of Washington and the Health Re- sources and Services Administration (HRSA). Patient index visits were defined as the last recorded visit in the calendar year 2016, with individ- ual 365-day look back periods extending into 2015. This study was ap- proved by the University of California, San Diego Human Research Protections Program.

Study population

The study population included children who visited any of the 323 California non-military emergency departments during the calendar year 2016 and were age 1 to 17 at the last ED visit in the year (index visit). Patients b1 year of age at index visit were excluded as they would have been born during the 365-day lookback period. Patients 18 years or older were excluded as they fell outside the target pediatric age range. Patient visits were linked within and across hospitals using unique patient record linkage numbers (RLN). Patient visits without valid RLNs were excluded from the study. Valid RLNs were absent for 60.7% of pediatric visits identified during the study period, most likely due to delays in obtaining SSNs.

Measures

Frequent use was defined as having 6 or more ED visits within 365 days. Occasional use was defined as having 1-5 ED visits within 365 days. The authors of this study acknowledge that a level of 4+ ED visits is a frequently used definition for frequent use. However, the def- initions for frequent and occasional use reported here are supported in previous literature [6,10-12]. Furthermore, given that OSHPD data al- lows for patient tracking across multiple sites, as opposed to a single hospital or single system, a more robust definition for frequent use was deemed to be more appropriate for this study. Recurrent visits were defined as any recorded patient visit within the 365-day lookback period in addition to the patient’s index visit. Patient-level demographic variables were assigned to each patient based on reported values at the index visit. Variables available included race/ethnicity, age in years, zip code of residence, sex, and expected source of payment. Age groups were created to be consistent with previous research and Centers for Disease Control and Prevention age groupings [1,2,13]. Rural or urban designation of patient zip codes was determined using the 2006 Rural-Urban Commuting Area (RUCA) zip code approximations [14]. Patient access to primary care was approximated using Primary care physician density based on patients’ zip codes of residence. PCP density for 2012 was obtained through the Area Health Resource Files (AHRF) provided by HRSA. The AHRF data includes general family med- icine, General practice, general internal medicine, and general pediatrics

in its definition of primary care. Subspecialties within the previously mentioned specialties are excluded [15].

Visit-level measures included up to 25 diagnoses from the Tenth Re- vision of the International Classification of Diseases (ICD-10), ED Visit disposition, and facility ID. Primary diagnoses were aggregated using the Clinical Classifications Software (CCS) developed by the Agency for Healthcare Research and Quality (AHRQ) [16]. EDs were stratified into pediatric and general EDs based on recorded principal service types in the 2016 State Utilization Data File of Hospitals. EDs listed as “level I – pediatric,” “level II – pediatric,” or contained within facilities with a re- corded primary service type of “pediatric” were coded as pediatric EDs in the dataset. All other EDs were coded as general EDs.

Data analysis

Descriptive statistics are presented as total figures and stratified by occasional and frequent user status. Continuous variables are presented as a mean, minimum, and maximum value. Categorical variables are presented as counts and percentages. The PCP densities of patients’ counties of residence are reported as quartiles, with the first quartile representing counties with the lowest PCP density. For each frequent user, the number of visits made to general and pediatric EDs were deter- mined, and the results are reported as the percentage of visits made to each type of ED. The most common primary clinical classifications are reported and stratified by user status.

Multivariate logistic regression was used to evaluate factors associ-

ated with frequent user status. Frequent or occasional user status was used as the dependent (or outcome) variable. All predictors included in the model were used as categorical variables with the first category serving as the reference. Predictors included age (1 y-4 y, 5 y-9 y, 10 y-14 y, 15 y-17 y), race/ethnicity (non-Hispanic White, non- Hispanic Black, non-Hispanic Asian/Pacific Islander, Hispanic, Other), expected payer (private, public, self-pay/indigent), history of hospital admission/transfer during the study period (yes or no), rural or urban zip code of patient residence, and quartile of PCP density in county of patient residence. Multicollinearity diagnostics were assessed for the model and collinearity was not found to be a significant issue; tolerance and variance inflation factor (VIF) values for all variables were found to be acceptable, ranging from 0.4 to 1.0, and 1.0 to 2.6, respectively. Odds ratios (OR) and 95% confidence intervals (CI) are reported. Missing data for all variables was minimal (b0.1%). All statistical analyses were con- ducted using the IBM SPSS Statistics 24.0 software package.

Results

Study sample

The current study includes 690,130 patients between 1 and 17 years of age, accounting for 1,238,262 visits across all 323 non-military EDs in the state of California. Frequent users accounted for 2.3% of the study population and 9.3% of visits.

Demographic characteristics

Demographic characteristics are summarized in Table 1. Both user groups were skewed toward younger age ranges with a greater trend exhibited among frequent users. Among frequent users, 38.2% (5941) were between the ages of 1-4 as opposed to 25.2% (170,062) of occa- sional users. The proportion of females among frequent users (52.4%) was slightly higher than that of occasional users (47.6%). Both frequent and occasional users featured roughly equal proportions of White, Non- Hispanic (24.7% vs 24.1%) and Hispanic (55.0% vs 53.3%) patients. A higher proportion of frequent users accessed Public insurance (82.3% vs 65.4%). Frequent users were more likely to have at least one ED visit leading to admission and/or transfer (26.6% vs 5.9%) during the study period than occasional users.

Table 1

Description of cohort by user status.

Patient Characteristics Overall

(n = 690,130)

Age, yr

1 to 4

176,003

(25.5)

170,062

(25.2)

5941

(38.2)

5 to 9

185,441

(26.9)

182,317

(27.0)

3124

(20.1)

10 to 14

177,641

(25.7)

174,810

(25.9)

2831

(18.2)

15 to 17

151,045

(21.9)

147,379

(21.8)

3666

(23.6)

Sex

Male

360,934

(52.3)

353,533

(52.4)

7401

(47.6)

Female

329,184

(47.7)

321,023

(47.6)

8161

(52.4)

Unknown

12

(0.0)

12

(0.0)

0

(0.0)

Race/ethnicity Hispanic

368,300

(53.4)

359,745

(53.3)

8555

(55.0)

White, non-Hispanic

166,518

(24.1)

162,675

(24.1)

3843

(24.7)

Black, non-Hispanic

75,412

(10.9)

73,375

(10.9)

2037

(13.1)

Asian/Pacific Islander

40,277

(5.8)

39,843

(5.9)

434

(2.8)

Other

39,623

(5.7)

38,930

(5.8)

693

(4.5)

Primary payer

Private

204,085

(29.6)

201,773

(29.9)

2312

(14.9)

Medicare

4443

(0.6)

4336

(0.6)

107

(0.7)

Medicaid

449,628

(65.2)

436,920

(64.8)

12,708

(81.7)

Self-pay/indigent

31,974

(4.6)

31,539

(4.7)

435

(2.8)

Patient admitted

No

645,899

(93.6)

634,474

(94.1)

11,425

(73.4)

Yes

44,231

(6.4)

40,094

(5.9)

4137

(26.6)

Urbanicity of patient zip

code

Urban

615,090

(89.1)

601,816

(89.2)

13,274

(85.3)

Rural

70,368

(10.2)

68,104

(10.1)

2264

(14.5)

Out of state/unknown

4672

(0.7)

4648

(0.7)

24

(0.2)

Primary care density Quartile 1

73,924

(10.7)

72,078

(10.7)

1846

(11.9)

Quartile 2

180,074

(26.1)

174,610

(25.9)

5464

(35.1)

Quartile 3

280,077

(40.6)

274,312

(40.7)

5765

(37.0)

Quartile 4

152,480

(22.1)

149,996

(22.2)

2484

(16.0)

Out of state/unknown

3575

(0.5)

3572

(0.5)

3

(0.0)

Occasional

(n = 674,568)

Frequent

(n = 15,562)

accounting for 0.007% of the total study population. Overall, the study captured 220,394 visits made to pediatric EDs and 1,017,868 visits made to general EDs. Fig. 4 summarizes frequent user utilization of pe- diatric vs general EDs. Among frequent users, 66.9% (10,412) exclusively visited general EDs and had no recorded visits to a pediatric ED during the study period. Only 17.4% (2713) of frequent users made at least one visit to a pediatric ED and 15.7% (2437) of frequent users used pedi- atric EDs for all recorded ED visits.

Major diagnoses

Table 2 summarizes the 10 most common primary visit clinical clas- sifications for frequent and occasional users. Upper respiratory infec- tions, abdominal pain, and Otitis media and related conditions were among the top 5 most common clinical classifications for both frequent and occasional users. Conditions such as asthma (4.7%) and fever (3.4%) were more common clinical classifications among frequent users. Acute physical injuries including superficial injury or contusion (5.6%), sprains and strains (4.6%), and other injuries and conditions due to external causes (4.0%) were more common among occasional users.

Logistic regression

Data are reported as n (%).

Patterns of emergency department use

Fig. 1 summarizes the recurrent visit rate by age at index visit. Fig. 2 displays a similar trend using age groups. In the study population as a whole, higher levels of ED use were found among younger age ranges, particularly those age 1y-4y. Fig. 3 summarizes the number of distinct EDs visited by each user category. Over 40% (41.4%) of frequent users visited 2 or more EDs, compared to 7.7% of occasional users. Only 50 fre- quent users exhibited “super user” levels of ED utilization (N20 visits),

Fig. 1. Recurrent visit rate by age at index visit.

The logistic regression model comparing independent predictors of frequent ED use is summarized in Table 3. The characteristics that had the largest associations with frequent ED use were age, payer, and being admitted/transferred. Those aged 5 y-9 y and 10 y-14 y were less likely to be frequent users than those age 1 y-4 y (OR 0.49, 95% CI 0.46-0.51 and OR 0.45, 95% CI 0.43-0.47, respectively). Asian patients were less likely to be frequent users than their White counterparts (OR 0.53, 95% CI 0.48-0.58). Public health insurance (OR 2.40, 95% CI 2.29-2.51) was associated with greater odds of frequent use than pri- vate insurance. A history of at least one admission and/or transfer dur- ing the study period was also associated with frequent use (OR 5.93, 95% CI 5.71-6.16). There was not a strong relationship between PCP density in patients’ counties of residence and frequent ED use.

Discussion

This is the first statewide study to specifically examine pediatric fre- quent users of the emergency department. One previous statewide study identified a pediatric frequent user cohort amidst the general population but did not pursue further specific analysis of pediatric fre- quent users [17]. Another recent study examined ED utilization across multiple EDs among privately insured patients; however, this study did not address frequent users or specifically examine pediatric users [18]. The current study is therefore the first to examine pediatric fre- quent users accessing multiple EDs, and to quantify pediatric frequent use of non-military pediatric and general emergency departments. Two previous large, multicenter studies have specifically focused upon pediatric utilization of EDs. However, these studies only utilized data from pediatric EDs [1,2]. Given the relative geographic isolation of pedi- atric EDs (generally 1 per major metropolitan area), these previous studies could not capture frequent users who accessed multiple EDs within close proximity of one another.

Overall, frequent users, defined as patients with 6 or more visits in a

365-day period, in this study accounted for 2.3% of pediatric patients and 9.3% of visits to non-military EDs in California. This percentage is smaller than previous pediatric and adult studies of frequent users, and may be due to our use 6 or more visits, rather than 4 or more, to de- fine frequent use [2,17-21]. Previous studies of adult frequent users have identified a “super user” cohort, defined as those with N20 visits per year and who tend to have lower acuity visits [6,22]. However, only 50 children in this study exhibited such levels of ED utilization, constituting just 0.007% of the total study population. This leads us to

Fig. 2. Number of recorded ED visits by age group.

conclude that the “super user” phenomenon is exceedingly rare in the pediatric population.

Just as prior research has highlighted the tendency of adult frequent users to utilize multiple EDs, we found that 41.4% of pediatric patients visited more than one ED during the study period [6]. Even more strik- ing, we found that the majority of pediatric frequent users, 66.9%, did not access services from pediatric EDs. These findings have important implications for future research, interventions, and practicing clinicians. Optimal identification of pediatric frequent users may require access to data across general and pediatric hospitals, as a sole focus on pediatric EDs will potentially miss 7 out of 10 pediatric frequent users. Moreover, emergency physicians practicing in non-pediatric EDs must remain pre- pared to treat complex pediatric patients.

As in earlier studies, our multivariate analysis revealed a strong asso- ciation between those age 1 y-4 y and frequent ED use. Prior research suggests that first-time mothers, lacking in experience and less able to interpret their children’s symptoms, may play a role in non-urgent ED utilization among very young children and may benefit from simple ed- ucational interventions [23,24]. On the other hand, data from the AHRQ indicates that this age group accounts for the largest proportion of pedi- atric ED usage, including the largest proportions of ED visits resulting in

discharge and ED visits resulting in hospital admission [25]. Therefore, frequent use in this age range appears to be driven by both non- urgent usage and serious medical needs.

Consistent with previous research, our data ties public health insur- ance to a greater likelihood of frequent ED use [1,2,4,5]. In the absence of data indicating parental level of education and Household income, the use of public insurance is our only surrogate for estimating socioeco- nomic status. Lower socioeconomic status is a well-documented risk factor for decreased Access to healthcare and unequal health outcomes. Over 65% of the children identified in this study accessed public health insurance. Altogether, this points to the prominent role that public health insurance plays in promoting healthcare access.

Interestingly, a number of the findings from our multivariate analy- sis deviate from previous literature. First, this study does not re- demonstrate a Clinically meaningful increase in likelihood of frequent use among African American or Hispanic patients when compared to white patients, as described in previous pediatric and adult research [1-3,18,26,27]. In fact, the most notable difference in terms of race is that children with Asian racial/ethnic backgrounds are roughly half as likely to be frequent users as their White counterparts. Second, previous pediatric literature has found frequent ED use to be associated with

Fig. 3. Number of EDs visited per user category. Fig. 4. Number of visits to pediatric EDs per frequent user.

Table 2

Ten most common primary clinical classifications by frequent user status.

Other upper Respiratory infections

125,365

(11.2)

Superficial injury; contusion

62,392

(5.6)

Abdominal pain

54,685

(4.9)

Sprains and strains

51,999

(4.6)

Otitis media and related conditions

45,891

(4.1)

Other injuries and conditions due to external causes

45,076

(4.0)

Viral infection

39,720

(3.5)

Open wounds of head; neck; and trunk

36,090

(3.2)

Fracture of upper limb

34,078

(3.0)

Nausea and vomiting

34,037

(3.0)

Frequent Users (n = 115,467 visits) Other upper respiratory infections

15,286

(13.2)

Asthma

5470

(4.7)

Abdominal pain

5230

(4.5)

Otitis media and related conditions

4774

(4.1)

Superficial injury; contusion

4305

(3.7)

Viral infection

4071

(3.5)

Fever of unknown origin

3979

(3.4)

Nausea and vomiting

3814

(3.3)

Sprains and strains

3031

(2.6)

Other gastrointestinal disorders

2959

(2.6)

Primary clinical classification n (%) Occasional users (n = 1,122,795 visits)

urban residence [1]. Our findings indicate the opposite association, with patients reporting a rural residence being slightly more likely to exhibit frequent ED use. This data parallels previous findings of greater ED use among patients in Rural settings using data from all age groups [28,29]. Third, our study indicates a negative association between PCP density in a patient’s county of residence and the likelihood of frequent use, running counter to the findings of Neuman et al. [1] These last two discrepancies may be due to differences in perspective afforded by our data and the use of both pediatric and general EDs. This study used data from all non-federal pediatric and adult ED’s, but preceding litera- ture has utilized data from pediatric EDs, which are largely located in urban areas. Data from pediatric EDs may demonstrate a skewed or in- adequate sampling of Rural patients and patients residing in areas of lower PCP density on account of distance. This study adds to the ongoing discussion of the association between primary care and frequent ED use. While the National Center of Health Statistics (NCHS) indicates that 28.7% of children who visit an ED do so because it is the closest healthcare provider, various pediatric and adult studies have shown that most frequent users have a usual source of care and also use pri- mary care more often than non-frequent users [5,19,29-31].

Table 3

Regression analysis.

Variable Frequent vs Occasional Use

Adjusted OR (95% CI)

Age (yr) (Ref = 1-4)

5-9 0.49 (0.46-0.51)

10-14 0.45 (0.43-0.47)

15-17 0.65 (0.63-0.68)

Female 1.22 (1.78-1.26)

Ethnicity (Ref = NH White)

Hispanic/Latino 0.90 (0.86-0.94)

NH Black 1.11 (1.05-1.18)

NH Asian 0.53 (0.48-0.58)

NH Other 0.78 (0.72-0.85)

Payer (Ref = Private)

Public 2.40 (2.29-2.51)

Self-pay/indigent 1.28 (1.15-1.42)

Admitted/transferred 5.93 (5.71-6.16)

Rural residence 1.34 (1.28-1.41)

PCP density (Ref = Quartile 1)

Quartile 2 1.17 (1.11-1.24)

Quartile 3 0.89 (0.85-0.94)

Quartile 4 0.82 (0.77-0.87)

Limitations

The most significant limitation of the study is that 60.7% of the pedi- atric visits within the study time frame lacked a valid RLN and were ex- cluded from analysis. Visits lacking valid RLNs are likely explained by delays in obtaining SSNs among children. As a result, our findings likely underestimate the true prevalence of frequent pediatric use of emer- gency departments. Furthermore, patient-level data used for analysis in this study were limited to those available through OSHPD. As such, our study does not include pediatric patients treated in military facili- ties. We attempted to approximate rurality and access to primary care through zip code RUCA approximation and data from the AHRF, but the absence of exact patient addresses and survey questions regarding access to care may limit the accuracy of these estimates. As previously noted, patient index visits were identified as the last visit in 2016, with 365-day lookback periods extending into 2015 when necessary. However, in an effort to provide the most recent data at the time of anal- ysis, we did not incorporate a similar look-forward period into 2017. Therefore, if a frequent user visited an ED twice in 2016, but four more times in 2017, they would not be identified in our analysis. Lastly, this study is limited to all non-military EDs across the state of California. As such, the study’s findings may not be generalizable to other states with different demographics, healthcare systems, and levels of access to public health insurance.

Conclusion

The majority of pediatric frequent users do not seek care in pediatric emergency departments. Emergency physicians practicing in non- pediatric EDs must remain prepared for complex pediatric patients. Age, prior admission, and Medicare/Medicaid appear to have the largest associations with pediatric patient frequent ED utilization.

Declarations of interest

None.

Acknowledgments

This study was partially supported by the National Institutes of Health, Grant 5T35HL007491. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.

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