The Epidemiology of Pediatric Head Injury Treated Outside of Hospital Emergency Departments : Epidemiology

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Perinatal and Pediatric Epidemiology

The Epidemiology of Pediatric Head Injury Treated Outside of Hospital Emergency Departments

Zogg, Cheryl K.a,b,c; Haring, R. Sterlingb,c,d; Xu, Likange; Canner, Joseph K.c; AlSulaim, Hatim A.c; Hashmi, Zain G.b,c; Salim, Alib,f; Engineer, Lilly D.c,g; Haider, Adil H.b,f; Bell, Jeneita M.e; Schneider, Eric B.b,c,h

Author Information
Epidemiology 29(2):p 269-279, March 2018. | DOI: 10.1097/EDE.0000000000000791


Head trauma is an important cause of death and disability among pediatric patients aged 0–17 years.1–6 In 2013, head trauma–related injuries were implicated in 2438 pediatric deaths, 23,980 hospital discharges, and 792,111 nonhospitalized emergency department visits.6 Much of our understanding of this burden comes from work by the Centers for Disease Control and Prevention (CDC), who in 2004 first illustrated the extent of variability in head trauma treatment as a pyramid, with deaths at the pyramid’s peak, followed by inpatient hospitalizations, emergency department visits, and a collective group, expected to be the largest in number, who seek other types of care or receive no care (Figure 1).1–3,6 At the time, the CDC noted that “[t]here is no estimate for the number of people with non-fatal [head trauma] seen outside of an emergency department or hospital setting.”2,3 More than a decade later (Figure 1), a robust understanding of deaths, hospitalizations, and emergency department presentations for pediatric patients has been developed; however, national estimates of head trauma and treatment outside of the emergency department remain largely unreported. Previous studies that have sought to estimate the volume of pediatric patients consulting nonemergency department providers (e.g., community-based physician’s offices or urgent care clinics) have been small in scope, frequently relied on locally collected data, and demonstrated substantial variability in the criteria used to define the study population, thus limiting the possibility of extrapolation to the national level.7–14

Head trauma (traumatic brain injury) pyramid as first conceptualized by the Centers for Disease Control and Prevention (CDC) in 2004. Values represent the national burden of deaths, hospitalizations, and emergency department visits among pediatric patients aged 0–17 years estimated by the CDC in 2013. Reported deaths represent Record-Axis Condition codes collected by the CDC’s National Center for Injury Prevention and Control; nonfatal inpatient hospitalizations were taken from the Agency for Healthcare Research and Quality’s (AHRQ’s) Healthcare Cost and Utilization Project (HCUP) National Inpatient Sample; and nonhospitalized emergency department visits were taken from the AHRQ’s HCUP Nationwide emergency department Sample—consistent with methods currently employed by the CDC. *There is no estimate for the number of people with nonfatal TBI seen outside of an Emergency Department or hospital setting. TBI indicates traumatic brain injury.

Recognizing the importance of this issue, providers and policymakers have begun to call for enhanced surveillance and a more nuanced understanding of the epidemiology of minor head injury and concussion.15,16 To plan for the proper prevention, acute care, rehabilitation, and disability support services required to maximize the quality of life for pediatric patients with head trauma, the extent of the problem needs to be better understood.3,15 The challenge is that, consistent with the CDC’s pyramid, surveillance has also primarily focused on deaths, inpatients, and emergency department patients,4,5,17 limiting our ability to account for healthcare-seeking patients within the lowest pyramid tier. Estimates that exclude such patients “cannot be assumed to reflect the entire population of persons with [head trauma]” because they have no way to account for the portion of the population who are never treated within the hospital system.17

To address these concerns and begin characterizing the national burden of head trauma treated in nonhospital outpatient settings, the objectives of this study were the following:

  1. to estimate the national burden of pediatric head trauma in patients seeking care as outpatients
  2. to define epidemiologic characteristics of the population, including demographic and injury-specific factors, CDC-defined head trauma diagnoses, and the extent of and reasons for post-index visit ambulatory care use within 30/90/180 days
  3. to examine temporal and seasonal variability in outpatient presentation.


Study Population

We abstracted 10 years of data, 2004–2013, from the Truven Health Analytics MarketScan Research Databases: Medicaid and Commercial Claims and Encounters.18,19 MarketScan provides longitudinal information on adjudicated and paid insurance claims filed for the care of individuals with employment-based private insurance and coverage provided by the Centers for Medicare & Medicaid Services. It represents the largest national record of pediatric outpatient data.

eFigure 1; details inclusion/exclusion criteria. We included index outpatient visits—defined as initial office/clinic or urgent care presentations with subsequent care received exclusively in ambulatory settings—with International Classification of Diseases (ICD)-9-CM diagnosis codes consistent with the CDC’s traumatic brain injury definition.1–3,6 For the purposes of this analysis, we defined ambulatory visits to include presentations to both outpatient and emergency department settings. Index emergency department visits meeting the same criteria were included as a reference. We excluded visits treated in other locations or that contained information for follow-up visits after the provision of inpatient care as well as any visits corresponding to referrals to higher levels of care, such as subsequent inpatient admissions. The first point of contact in an outpatient or emergency department setting was defined as the location for the index visit. For patients with multiple visits, 180 days were required to have passed since a previous index visit to constitute a second index visit with no indication of follow-up care in the 30 days before the second visit. The work also excluded visits for patients aged >17 years and for patients missing information, unless otherwise specified by missing indicator variables.

We categorized included index visits into three groups: urgent care, office/clinic, and emergency department. We compared demographic and injury-specific patient-level characteristics for office/clinic and urgent care visits relative to nonhospitalized emergency department visits. Demographic factors included age, sex, insurance, region, and year. Injury-specific characteristics included loss of consciousness derived from ICD-9-CM codes, Charlson Comorbidity Index, Pediatric Surgical Risk Score,20 maximum-head Abbreviated Injury Scale, and overall Injury Severity Score. Comorbidity indexes and injury severity scores were calculated using ICD-9-CM diagnosis and E-codes. Analogous assessment was conducted for CDC-defined head trauma diagnoses and for differences in post-index visit ambulatory care use.

Temporal and Seasonal Trends

We examined temporal trends by year, stratified by index-visit location and type of insurance, using joinpoint regression.21–23 Joinpoint regression is a segmented linear-modeling technique that describes changing trends over successive segments of time and the amount of increase/decrease associated with each.22–24 Segment connections, termed “joinpoints,” are assigned by the model at places where changes in trend in excess of a predetermined frequentist threshold occur (two-sided β = 0.20, α = 0.05). Slopes join linear segments between them and provide estimates of the annual percent change during that period. An overall average annual percent change is calculated as the weighted geometric average of the segment slopes with weights set equal to the segment lengths.22–24 Two joinpoints were allowed. Seasonal trends in the rate of healthcare-seeking outpatient head trauma per 100,000 pediatric enrollees were also examined by month from January 2010 to December 2013. Variations were assessed overall and stratified by insurance.

National Estimates of the Outpatient Burden

National estimates in 2013 were obtained by taking observed rates of (insurance-specific) office/clinic, urgent care, and emergency department visits per 100,000 pediatric enrollees and multiplying by the size of the (insurance-specific) segment of the 2013 US pediatric population.25 Uninsured use was assumed equal to the national Medicaid rate. Sensitivity analyses assessed alternative specifications in which the uninsured rate was set equal to 10%, 25%, 50%, or 150% of the Medicaid rate. None appreciably changed estimated burden size (eTable 1; A second set of sensitivity analyses addressed the possibility of misclassification, adjusting 2013 population estimates to account for 5%, 10%, or 20% over- or underestimation (eTable 2; Comparison of MarketScan data to CDC Healthcare Cost and Utilization Project–based surveillance data for pyramid treatment tiers two and three is presented in eTable 3; Extrapolation of uncertainty reported in US Census Bureau25 data provided 90% confidence intervals (CI).

The study calculated provider time for index visits based on the average length of time (≈7 minutes) anticipated for a routine office or emergency department visit. Information for this calculation was derived from ambulatory care data from the CDC’s National Center for Health Statistics and previously published research on time allocation in primary care.26,27 Statistical analyses were conducted using Stata Statistical Software: Release 14.1 and SAS/STAT: Release 9.4. The CDC and Johns Hopkins Institutional Review Board approved the study.


National Burden of Outpatient Pediatric Head Trauma

A combined total of 1,683,097 index ambulatory pediatric visits were included. Approximately one-third (32%) were treated in a hospital emergency department, 66% in a physician’s office/clinic, and 2% in a dedicated urgent care center. Outpatient visits consistent with the lowest pyramid tier—office/clinic, urgent care—represented more than two-thirds of visits for ambulatory care. Nationwide in 2013, they corresponded to an estimated annual incidence of 844,660 outpatient visits (90% CI: 830,797, 858,524) and 98,544 hours of provider time (Table 1). When emergency department visits were included, the numbers increased to 1.26 million annual index visits (90% CI: 1.24, 1.28 million) and 146,704 hours of provider time.

Nationwide Estimates of the Annual Burden of Pediatric Outpatient Head Trauma Visits in 2013 (Uninsured Assumed 100% of the National Medicaid Rate)

Epidemiologic Characteristics

Tables 2–4 and Figure 2 detail distributions of epidemiologic characteristics stratified by index-visit location, including variations in demographic and injury-specific factors, CDC-defined head trauma diagnoses, and post-index visit ambulatory care use.

Demographic and Injury-specific Factors, Stratified by Place of Presentation
Subsequent ambulatory visits within 30, 90, and 180 days. A, Average (mean) number of subsequent ambulatory visits within 30, 90, and 180 days per index ambulatory pediatric head trauma presentation from 2010 to 2013. B, Extrapolated 2013 national burden of pediatric index and subsequent ambulatory care visits (routine and injury-related) within 30, 90, and 180 days. Estimates are inclusive of uninsured patients. ED indicates emergency department.

Demographic Patient Factors

In the emergency department, the proportion of ambulatory visits decreased as pediatric patients aged, dropping from 33% among children aged 0–2 years to 14% among adolescents aged 15–17 years (Table 2). Children 0–2 years comprised the highest proportion of visits to urgent care (26%) and 21% of office/clinic visits. The proportion of urgent care visits also decreased with age, while the proportion of office/clinic visits increased (3–5 years 14% vs. 15–17 years 24%). In all three locations, males presented with head trauma more commonly than females (61%–62% vs. 38%–39%, respectively). Differences in insurance were the least pronounced within the emergency department, where Medicaid insured 51% of ambulatory patients. Insurance differences were more pronounced within urgent care (26% Medicaid versus 74% private) and office/clinic settings (19% Medicaid versus 81% private). In 2013, 38% of children in the United States aged 0–17 years had Medicaid or another form of government-based health insurance plan (e.g., TRICARE from a parent working for the Department of Defense); 56% were privately insured25—a distribution which suggests an apparent overrepresentation of Medicaid among ambulatory emergency department visits and underrepresentation among visits to outpatient settings.

Injury-specific Patient Factors

The majority of visits were consistent with isolated (Injury Severity Score of 4–8: emergency department 96%, urgent care 97%, office/clinic 93%), nonsevere head injuries (maximum-head Abbreviated Injury Scale <3: 99%, 99%, 97%); 1% (urgent care) to 4% (office/clinic) were diagnosed with ICD-9-CM codes, suggestive of loss of consciousness (Table 2). Most did not present with any pre-existing comorbidity (Charlson Comorbidity Index of 0: 98–99%).

CDC-defined Diagnoses

The majority of patients, regardless of location, presented with a diagnosis of “unspecified head injury” (959.01: emergency department 86%, urgent care 80%, office/clinic 71%; Table 3). In the emergency department, >60% were not diagnosed with other coded head trauma diagnoses—a number that decreased to 30% among office/clinic visits. One in four patients were diagnosed with a concussion (850.x: emergency department 17%, office/clinic 31%), and 7% were diagnosed with “other or unspecified” intracranial injuries (854.x: emergency department 6%, office/clinic 8%).

Variations in CDC-defined Head Trauma Diagnoses on Index Presentation, Stratified by Place of Presentation

Post-index Visit Ambulatory Care Use

Ambulatory patients initially managed in office/clinic settings, on average, presented for 8.9 subsequent ambulatory visits within 180 days (2.3 visits within 30 days; Figure 2A), resulting in >8 million annual ambulatory visits nationwide (Figure 2B). Emergency department index visits presented for an average of 10.7 post-index visits within 180 days (2.5 visits within 30 days), resulting in approximately 5 million annual ambulatory visits nationwide. These numbers present a striking contrast to the overall population-wide average of 1.2 ambulatory visits reported every 180 days for children and adolescents aged 0–17 years in 2012 in the United States (an average of 0.2 visits in 30 days).27

The 20 most prevalent primary diagnoses recorded on subsequent ambulatory presentation within 30 and 180 days are presented in Table 4. While many corresponded to routine forms of pediatric outpatient care (e.g., routine child health exams, influenza vaccinations, acne, and infections), 13 of the 20 most frequent diagnoses within 30 days of head trauma presentation were consistent with head trauma recovery (e.g., contusions and open wounds of the head) and associated sequelae (e.g., headaches, post-concussion syndrome, and documented changes in consciousness, attention, and activity). Within 180 days, the relative frequency of contusions and open wounds declined as outpatient presentations for childhood infections became more common. Longer-lasting sequelae consistent with head trauma, however, remained among the most frequent diagnoses reported.

The 20 Most Prevalent Primary Diagnoses for Subsequent Ambulatory Visits Within 30 and 180 Days

Temporal and Seasonal Trends

The overall annual rate of presentation for outpatient treatment of head trauma increased by more than 50% across the study period, growing from 1,021.3 per 100,000 pediatric enrollees in 2004 to 1,575.0 in 2013 (eTable 4;, average annual percent change of +7% (95% CI: +5%, 9%). Annual rates of emergency department visits did not change (2004: 439.8 versus 2013: 455.9; average annual percentage change +1% [95% CI: −2%, +4%]); however, rates of office/clinic (average annual percentage change +9% [95% CI: +7%, 12%]) and urgent care (+32% [95% CI: 27%, 37%]) visits both substantially increased. Urgent care use rose from a baseline of 4.5 visits per 100,000 pediatric enrollees in 2004 to 25.7 per 100,000 in 2009 (annual percent change of +39%). From 2010 to 2013, growth slowed slightly, reaching 47.8 visits per 100,000 in 2013 (annual percent change +23%). Office/clinic visits climbed from 577.0 per 100,000 in 2004 to 1,071.3 per 100,000 in 2013. Changes were primarily driven by an annual percent change of +11% from 2006 to 2013. In the emergency department, use increased from 439.8 per 100,000 in 2004 to 456.5 in 100,000 in 2009; however, it remained unchanged from 2010 to 2013.

Temporal trends stratified by insurance and visit location are presented in Figure 3. Patients with private insurance (Figure 3A) and Medicaid (Figure 3B) both exhibited overall increases (average annual percentage change private: +8% [95% CI: 6%, 10%]; Medicaid: +5% [95% CI: 3%, 7%]). However, while annual rates of office/clinic visits increased among privately insured patients (average annual percentage change +9% [95% CI: 7%, 11%]), corresponding changes among Medicaid patients did not reach threshold (average annual percentage change +5% [95% CI: −1%, +12%]). Office/clinic visit rates for both groups in 2004 were similar (private: 614.1 versus Medicaid: 528.3 per 100,000).

Annual rates of healthcare-seeking head trauma presentation per 100,000 pediatric enrollees from 2004 to 2013 and joinpoint-regression results (overall and stratified by index-visit location) among (A) privately insured and (B) Medicaid patients. Percentages represent the average annual percent change. C, Seasonal variation in outpatient presentation. Results represent monthly rates of healthcare-seeking head trauma visits per 100,000 pediatric enrollees from January 2010 to December 2013.

Seasonal trends in the monthly rate of outpatient head trauma visits are presented in Figure 3C (values eTable 5; Privately insured and Medicaid patients had similar trends, with annual incidence peaks during March–April and, more pronounced, during September–October; decreases during June–August; and a more moderate peak during January each year. The size of seasonal fluctuations among Medicaid patients appeared to remain largely unchanged (e.g., October 2010: 182.8 versus 2013: 198.4, a relative +9% increase), while September–October peaks among privately insured patients more substantially increased (October 2010: 184.3 versus 2013: 233.1, a relative +27% increase).


This study of the epidemiology and burden of pediatric outpatient head trauma used national data to demonstrate that more than one-half (51%) of all known healthcare-seeking visits for head trauma among pediatric patients occur in nonhospital outpatient settings, primarily in physician’s offices and clinics. The observed sample of 1,188,096 privately insured and 495,001 Medicaid index outpatient visits is, to our knowledge, the largest pediatric population examined to date and one of the first to consider the burden of pediatric head trauma presenting for care outside of a hospital emergency department setting. Annual rates among privately insured and Medicaid outpatients suggest that when applied to the national US pediatric population in 2013 (inclusive of uninsured patients),25 previously unaccounted for treatment of head trauma in office/clinic and urgent care settings would have encompassed as many as 844,660 initial physician visits and 98,544 hours of provider time.

Little is known about the burden of outpatient pediatric head trauma on a national scale. Work by Taylor et al7 conducted among 10,942 privately insured ambulatory patients in Massachusetts, aged 6–21 years, found that from 2007 to 2013, the proportion of children and adolescents diagnosed with concussion and/or minor head injury increased from 1% to 3%. Outpatient visits for head trauma increased from 16.9 to 67.0 per 1000 patient-years, with the greatest increases seen in specialist (+919%) and primary-care provider settings (+485%). Emergency department visits increased by a relative +42%.7 Macpherson et al14 demonstrated a similar increase in emergency department and office visits for concussion among children and adolescents in Ontario, aged 3–18 years, climbing from 340.5 visits per 100,000 pediatric population in 2003 to 601.3 in 2010. In a 5-year assessment of data from National Ambulatory Medical Care Survey (NAMCS)/National Hospital Ambulatory Medical Care Survey (NHAMCS), 2005–2009, Mannix et al8 further identified a total of 111 pediatric outpatient office and clinic visits for minor head injury, representing a weighted estimate of 2,045,900 outpatient visits nationwide (an average of 409,200 visits per year).8 At The Children’s Hospital of Philadelphia, 2010–2014, 8083 patients with concussion were categorized according to their initial place of presentation: 82% presented to primary care, 5% to specialty care, and 12% to the emergency department.13 Consistent with our findings, they noted that insurance influenced patients’ index-visit location, with Medicaid patients being the most likely to present to the emergency department, while privately insured patients were the most likely to present to primary care.13 Finally, among privately insured patients in MarketScan in 2013, Bryan et al12 identified 377,978 office/clinic visits for patients diagnosed with concussion without prior healthcare utilization for concussion in the preceding 30 days. Their estimates12 suggest that there could also be >500,000 additional children and adolescents with sports- and recreation-related concussions not treated in a healthcare setting based on extrapolated projections from injuries for nine high-school sports28 and published research,29–31 which suggests that 23%–53% of such injuries do not receive formal medical care. Our results build on this work,7–13 providing a more nuanced estimate among observed Medicaid and privately insured index outpatient visits of both the size of the pediatric burden and how it has varied—temporally and seasonally—on a national scale.

Akin to work by Taylor et al7 and Macpherson et al,14 assessment of temporal trends demonstrated increases in outpatient presentation (overall relative change, 2004–2013: +54%) that were primarily driven by increasing rates of office/clinic visits (+86%) among privately insured patients (+96%). Seasonal variation revealed changes in outpatient presentations throughout the calendar year. Annual peaks during March to April and September to October correspond to the timing of participation in school sports. Drops from June to August coincide with the time when children and adolescents are out of school. Further research is needed to determine how these injuries were sustained. Comparison with known seasonal trends in sports- and recreation-related injuries within the emergency department demonstrate a high degree of similarity to patterns reported for adolescents playing school sports,32,33 particularly among male patients in the fall, which work by Coronado et al32 suggests is largely a result of football. Increased awareness of the need for sports/recreational safety,34–36 introduction of “return to play” laws in all 50 states, which require medical clearance for concussion,37–39 and increased pressure to promote enhanced reporting of concussion and mild head injury, which have historically been underdiagnosed,40–42 could be driving the increases in outpatient utilization observed. High presentation prevalence among children aged 0–2 years in all three index ambulatory locations is in keeping with expectations based on existing emergency department data.40–42 It likely reflects a tendency for young children to encounter misadventures while learning to walk and crawl at home combined with a heightened awareness of potential head injury among parents of children of younger age.

Increasing outpatient utilization for head injury parallels increasing trends in pediatric emergency department utilization for head injury (subsequent inpatient admissions plus ambulatory-only visits) reported in a recent 8-year weighted assessment of data from the National Emergency Department Sample, 2006–2013.43 In the study, increasing trends for head injury and for specifically diagnosed concussion were contrasted by declining rates of “severe traumatic brain injury” (defined as an ICD-9-CM/E-code-derived Abbreviated Injury Scale ≥3).43 Similar declines among inpatient admissions and fatalities have also been reported as have other instances of increasing pediatric emergency department trends.6 Taken together, these findings suggest a potentially high level of effectiveness of ongoing head injury prevention work—including increased awareness, policy changes, improved treatment and access to care, equipment and rule modifications in sports, etc.—that are shifting the distribution of head injury among pediatric patients toward less severe clinical indications and less centralized avenues of care. In the coming years, enhanced surveillance capable of addressing these issues and identifying these patients will be essential to continuing to improve the quality of life of pediatric patients with head injury and to appropriately direct resources and attention toward where the problem persists.

Most patients were diagnosed with minor head injuries, 76% with unspecified head injury and 26% with concussion. Thirty percent of index office/clinic visits did not have a second diagnosis recorded during initial presentation other than 959.01, “head injury unspecified.” The interpretation of this code has been a source of controversy, with research suggesting that inclusion/exclusion could result in either over- or underestimation.43–47 In some studies, it has been assumed to represent mild head injury and/or concussion.44 Signs and symptoms of concussion are often nonspecific. None are pathognomonic, with thresholds for diagnosis tending to vary among clinicians. As a result, it is possible that in a study of index outpatient visits, part of the prevalence of this code could be due to providers’ decision to reserve a definitive diagnosis while considering others in the differential, particularly, if patients require follow-up care. Further studies are needed to determine the clinical picture and trajectory of this group of outpatients, including an understanding of how they present in clinical settings, their clinical course, and whether they eventually receive a concussion diagnosis.

The study has limitations, several of which come from its reliance on a retrospective administrative database where completeness of information, lack of clinical detail, and accuracy of reporting can be concerns. The study allowed for one of the first assessments of pediatric head trauma treated in an outpatient setting using a large national sample of Medicaid and privately insured cases. It did not, however, allow for direct assessment of uninsured patients who, while not expected to represent a large proportion of outpatient office/clinic or urgent care use, did constitute 7% of the national pediatric population in 2013.25 Initial assessment of subsequent ambulatory care use included all patient presentations. Further research is warranted to understand how head trauma–specific trajectories of patients within this population progress over time, relative to other patients and beyond 180 days.

In conclusion, our findings suggest that >800,000 healthcare-seeking pediatric patients with head trauma obtain treatment in nonhospital and nonemergency department settings each year, with most care occurring in physician’s offices/clinics. The data demonstrate substantial variations in both temporal and seasonal trends. As efforts to plan for and provide enhanced services to head trauma patients continue to increase, it will be essential to recognize that more than one-half of all pediatric patients with head injury present for initial care outside of a hospital emergency department. Further research is needed to better understand the clinical course and long-term outcomes for pediatric patients with head trauma who are treated exclusively outside of the hospital system. The results illustrate the importance of expanding inclusion criteria in surveillance and prevention efforts designed to inform head trauma treatment, awareness, prevention, and care for children and adolescents at all levels of the head trauma pyramid.


The authors thank Fizan Abdullah, MD, PhD, Daniel Rhee, MD, MPH, and Jose H. Salazar Osuna, MD, from the Department of Surgery at Johns Hopkins University School of Medicine and the Division of Pediatric Surgery at Ann & Robert H. Lurie Children’s Hospital of Chicago for allowing us to use the analytical files for their Pediatric Surgical Risk Score.


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