Abstract
Importance
Trauma is the leading cause of potential years of life lost before age 65 in the U.S. Timely care in a designated trauma center has been shown to reduce mortality by 25%. However, many severely injured patients are not transferred to trauma centers after initially presenting to non-trauma centers.
Objective
Determine patient and hospital level factors associated with the decision to admit rather than transfer severely injured patients who present to non-trauma center emergency departments (EDs). We hypothesized that insured patients would be more likely to be admitted than transferred compared to patients without insurance.
Design, Setting, and Participants
Retrospective analysis of the 2009 Nationwide Emergency Department Sample. We included all ED encounters for major trauma (injury severity score [ISS] > 15) seen at non-trauma centers in patients aged 18–64. We excluded ED discharges and ED deaths. We quantified the absolute risk difference between admission vs. transfer by insurance status while adjusting for age, sex, injury severity, injury mechanism, weekend admission, month, urban-rural status and median income of home zip code, ED volume and teaching status, and U.S. region
Main Outcome Measures
Inpatient admission vs. transfer to another acute care facility.
Results
There were 4,513 observations from 636 non-trauma centers for analysis, representing a nationally weighted population of 19,312 non-trauma center ED encounters for major trauma in 2009. In 2009 54.5% were admitted at the non-trauma center. Compared to the uninsured, the adjusted absolute risk of admission vs. transfer was 14.2% higher (95% CI: 9.2, 19.4) for patients with Medicaid and 11.1 % higher (95% CI: 6.9, 15.4) for patients with private insurance. Other factors associated with admission vs. transfer included severe abdominal injuries (risk difference 15.8%,95% CI: 9.3, 22.3) urban teaching hospital vs. non-teaching hospital ((26.2%,15.2, 37.2), and ED volume (3.4% higher (95% CI: 1.6, 5.3%) for every additional 10,000 annual ED visits).
Conclusions and Relevance
Patients with severe injuries initially evaluated at non-trauma centers were less likely to be transferred if insured, and thus were at risk of receiving sub-optimal trauma care. Monitoring and optimizing trauma interhospital transfers and outcomes at the population level is warranted.
Introduction
Trauma is the most common cause of years of life lost for those under age 65, and exacts $406 billion per year in costs, more than heart disease or cancer.1, 2 Acute care in designated, specialized trauma centers has been shown to reduce mortality by 25% in patients with major trauma.3 While direct transport from the scene of injury to a designated trauma center is optimal, patients who are taken to non-trauma center emergency departments (EDs) who are then transferred in a timely fashion to trauma centers have reduced mortality compared with those hospitalized at the non-trauma center.4, 5 Regionalized trauma systems have been developed over the last three decades to optimize population-level outcomes by facilitating the direct transport or transfer of patients with severe injuries to designated trauma centers.6, 7
Despite the development of trauma systems, between 30–50% of patients with major injuries are still hospitalized in non-trauma centers,8–10 and thus may not receive optimal care. Even with correct application of emergency medical services (EMS) field triage guidelines, at least 15% of severely injured patients will be undertriaged and transported to a non-trauma center.11 In addition, 16% of Americans lack geographic access to a trauma center within 60 minutes by emergency medical services (EMS) transport.12 For these patients, transfer from a non-trauma center ED after stabilization represents another opportunity to ensure severely injured patients get optimal care for their injuries.4, 5
The factors associated with the disposition of severely injured patients presenting initially to non-trauma center EDs in terms of hospitalization in the non-trauma center versus transfer to a higher level of care are not well characterized. Previous studies examining the transfer of trauma patients to multiple trauma centers only examine transfers from lower level trauma centers to higher trauma centers.13–15 These studies provide a limited picture since non-trauma centers, which were not included these studies, account for 75% of U.S. hospitals.16 Until recently, a major barrier to examining trauma transfer patterns has been a dearth of national data sources that include trauma encounters in non-trauma center EDs as these EDs are not typically included in trauma registries.17, 18
We analyzed the 2009 Nationwide Emergency Department Sample (NEDS) from the Health Care Utilization Project, Agency for Healthcare Research and Quality, to determine patient and hospital level factors associated with the decision to admit severely injured trauma patients rather than transfer them to a higher level of care. We hypothesized that insured patients would be more likely to be admitted at non-trauma centers than transferred to a higher level of care due to better perceived reimbursement potential. Better understanding the patient and system factors associated with the decision to transfer will help develop interventions to further optimize trauma systems and may provide insights for improving regionalized emergency care for other time-sensitive conditions.
Methods
Study Design
We performed a retrospective analysis of the 2009 NEDS to determine which patient and hospital level factors are associated the decision to admit rather than transfer patients with major injuries in non-trauma center EDs in the U.S. The NEDS is the largest all-payer ED database in the U.S, capturing both ED encounters that result in discharge or transfer and ED encounters that result in admission at the same hospital.17, 19 The 2009 NEDS contains 29 million ED visits from 964 hospital-based EDs in 29 states weighted to provide national estimates of ED care. Along with standard patient and hospital administrative data, the dataset contains a variable that classifies hospitals as either non-trauma centers or trauma centers (Level I, II, or III).19
Population Studied
We extracted all non-trauma center ED encounters for major trauma (defined as having an Injury Severity Score [ISS] > 15) in patients aged 18–64 identified from the cohort of ED encounters with diagnosis codes for trauma (International Classification of Disease, 9th Revision, Clinical Modification [ICD-9CM] 800–959). We excluded patients aged 65 and older given that they would be all be eligible for Medicare, confounding the influence of age and insurance on the decision to transfer. We followed a validated algorithm for identifying patients with valid injury diagnosis codes used in trauma studies by excluding patients that had sole trauma diagnoses of superficial injuries, late effects of injury, foreign bodies, and burns.20, 21 The 2009 NEDS provides an ISS calculated from each patient’s injury diagnosis codes. The ISS is a validated anatomical scoring system that provides a measure of the overall severity of injury for patients with multiple injuries.22 We excluded patients that did not have a NEDS ISS. We also excluded patients that had a primary payer listed as “no charge.” Finally, we excluded encounters that resulted in leaving against medical advice, discharge to home, transfer to skilled nursing care or home health care, or death in the ED.
Outcome Measures
The primary outcome of interest was inpatient admission at the non-trauma center vs. transfer to another acute care facility according to primary payer status: self-pay, Medicaid, Medicare, private insurance, and other insurance (typically automobile or worker’s compensation insurance). Based on previous studies,4, 13–15 and due to the regulation of Emergency Medical Treatment & Labor Act (EMTALA) requiring transfers out of the ED must go to a higher level of care, we assumed that all transfers of severely injured patients out of non-trauma centers would go to trauma centers.
Data Analysis
All statistical analyses used the NEDS sampling strata and discharge weights to produce nationally weighted patient-level estimates and standard errors that account for clustering of patients among hospitals. We tabulated baseline characteristics by primary payer status. We then tabulated the primary outcome of inpatient admission vs. transfer by baseline characteristics and compared unadjusted differences with Chi-square tests of categorical variables and linear regression for continuous variables. Finally, we used sample-weighted multivariate logistic regression to estimate the absolute risk difference of inpatient admission vs. transfer to another acute care facility according to primary payer status by calculating average marginal effects. We adjusted for patient-level variables including: age, sex, median income of the patient’s home zip code, ISS, body regions of injuries with Abbreviated Injury Scales ≥3 (an indicator of severe injury and component of the ISS), injury mechanism, weekend admission, month of visit, urban-rural status and median income of home zip code, and hospital–level variables including: ownership, ED volume, urban-rural and teaching status. We used Stata 12.0 (StataCorp, College Station, TX) for all statistical analyses. The appendix provides additional information on our statistical methods and assumptions.
Results
There were 15,048 observations representing 64,789 adult (aged 18 or older) major trauma (ISS>15) patient encounters in 756 non-trauma center emergency departments in 2009. After excluding elderly patients, there were 6,148 observations representing 26,429 encounters for patients aged 18–64. After excluding patients that were discharged from the ED or died in the ED, there were 4,513 observations representing 19,312 patient encounters for major trauma in 636 non-trauma center EDs in 2009 that were either admitted as inpatients to the same non-trauma center hospital (54.5%; 95% CI: 50.8–58.2%) or transferred to another acute care facility (45.5%; 95% 41.8–49.2%).
The mean age was 44 and the mean ISS was 19. The majority of patients were privately insured (43.3%), followed by being uninsured (20.6%), having Medicaid (15.1%), Medicare (11.6%), and other commercial insurance (9.3%) (Table 1). The majority of patients lived in metropolitan areas (72.7%) and had severe head injuries (70.1%). Falls were the most common cause of injury (35.8%) followed by motor vehicle collisions (25.4%). Uninsured patients tended to be younger, but did not have major clinical differences compared to the overall population of insured patients (Table 2). Among patients with insurance, those with Medicare, the vast majority of whom qualify due to disability, had a higher incidence of falls and severe head injury.
Table 1.
Characteristics of severely injured trauma patients who presented to U.S. non-trauma centers in 2009
| Total N=19,312 (%) |
|
|---|---|
| Patient-Level Characteristics | |
| Male | 13,667 (70.8) |
| Age | |
| 18–34 | 5,548 (28.7) |
| 35–54 | 7,875 (40.8) |
| 55–64 | 5,888 (30.5) |
| Primary Insurance | |
| Uninsured | 3,923 (20.6) |
| Medicaid | 2,885 (15.1) |
| Medicare | 2,214 (11.6) |
| Private | 8,249 (43.3) |
| Other | 1,772 (9.3) |
| Median Household Income of Home Zip Code | |
| <$40,000 | 5,610 (30.3) |
| $40,000–$49,999 | 5,384 (29.1) |
| $50,000–$65,999 | 2,276 (23.1) |
| ≥ $66,000 | 3,240 (17.5) |
| Patient Lives in Metro Area | 13,839 (72.7) |
| Injury Severity Score, mean (SE) | 19.3 (0.14) |
| Abbreviated Injury Scale ≥ 3 | |
| Head and Neck | 13,533 (70.1) |
| Chest | 5,123 (26.5) |
| Abdomen | 2,095 (10.8) |
| Extremities | 1,432 (7.4) |
| Mechanism of Injury | |
| Blunt, Fall | 6,908 (35.8) |
| Blunt, Motor Vehicle | 4,910 (25.4) |
| Blunt, Other | 1,972 (10.2) |
| Penetrating, Firearm | 403 (2.1) |
| Penetrating, Other | 117 (0.6) |
| Presented on Weekend | 6,408 (33.2) |
| Hospital-Level Characteristics | |
| Annual ED Visit Volume, mean (SE) | 43,609 (2.172) |
| Teaching, Urban-Rural Status | |
| Metro, nonteaching hospital | 9,360 (48.5) |
| Metro, teaching hospital | 4,592 (23.8) |
| Non-metro (rural) | 5,360 (27.8) |
| Region | |
| Northeast | 2,736 (14.2) |
| Midwest | 3,745 (19.4) |
| South | 8,009 (41.5) |
| West | 4,821 (25.0) |
SE: standard error. Data are from the 2009 National Emergency Department Sample (NEDS), which is a 20% sample of all emergency department (ED) visits. All statistics are weighted to produce national estimates. The Injury Severity Score (ISS), range 1–75, is a composite score based on the Abbreviated Injury Scale (AIS) assigned to each injury diagnosis. An ISS >15 indicating major trauma; an AIS score ≥3 indicates serous injury. A hospital located in a “Metro” area is located in a Metropolitan Statistical Area (MSA), which is defined as a region with relatively high population density by the U.S. Census Bureau. Mechanisms of injury do not add to 100%.
Table 2.
Characteristics of severely injured trauma patients who presented to U.S. non-trauma centers by primary insurance in 2009
| Primary Payer | |||||
|---|---|---|---|---|---|
| Uninsured | Medicaid | Medicare | Private | Other* | |
| Total, N (%) | 3,923 (20.6) | 2,885 (15.1) | 2,214 (11.6) | 8,249 (43.3) | 1,772 (9.3) |
| Patient-Level Characteristics | |||||
| Male | 3,047 (77.9) | 2,017 (69.9) | 1,332 (60.2) | 5,708 (69.2) | 1,374 (77.6) |
| Age | |||||
| 18–34 | 1,647 (42.0) | 928 (32.2) | 138 (6.2) | 2,087 (25.3) | 650 (36.7) |
| 35–54 | 1,711 (43.6) | 1,281 (44.4) | 763 (34.4) | 3,352 (40.6) | 645 (36.4) |
| 55–64 | 566 (14.4) | 675 (23.4) | 1,314 (59.3) | 2,811 (34.1) | 476 (26.9) |
| Patient Lives in Metro Area | 2,698 (71.3) | 1,982 (70.1) | 1,700 (77.3) | 6,138 (74.9) | 1,166 (66.2) |
| Median Household Income of Home Zip Code | |||||
| <$40,000 | 1,300 (35.2) | 1,108 (40.5) | 813 (37.8) | 1,745 (21.9) | 527 (30.8) |
| $40,000–$49,999 | 1,210 (32.8) | 825 (30.2) | 589 (27.4) | 2,222 (27.9) | 484 (28.3) |
| $50,000–$65,999 | 777 (21.0) | 542 (19.8) | 505 (23.5) | 1,971 (24.7) | 409 (23.9) |
| ≥ $66,000 | 405 (11.0) | 261.4 (9.6) | 240 (11.2) | 2,032 (25.5) | 292 (17.1) |
| Injury Severity Score, mean (SE) | 19.4 (0.25) | 18.9 (0.26) | 18.5 (0.39) | 19.5 (0.18) | 19.6 (0.41) |
| Abbreviated Injury Scale ≥ 3 | |||||
| Head and Neck | 2,926 (74.6) | 2,113 (73.2) | 1,950 (88.1) | 5,317 (64.5) | 1,061 (59.8) |
| Chest | 869 (22.1) | 566 (19.6) | 250 (11.3) | 2,732 (33.1) | 619 (34.9) |
| Abdomen | 412 (10.5) | 373 (12.9) | 64 (2.9) | 988 (12) | 232 (13.1) |
| Extremities | 254 (6.5) | 241 (8.4) | 59 (2.7) | 605 (7.3) | 239 (13.5) |
| Mechanism of Injury | |||||
| Blunt, Fall | 1,025 (26.1) | 1,195 (41.4) | 1,364 (61.6) | 2,815 (34.1) | 454 (25.6) |
| Blunt, Motor Vehicle | 1,082 (27.6) | 509 (17.6) | 116 (5.2) | 2,553 (30.9) | 566 (31.9) |
| Blunt, Other | 591 (15.1) | 300 (10.4) | 136 (6.1) | 588 (7.1) | 327 (18.4) |
| Penetrating, Firearm | 155 (4) | 113 (3.9) | 32 (1.4) | 60 (0.7) | 35 (2) |
| Penetrating, Other | 47 (1.2) | 21 (0.7) | 0 (0) | 40 (0.5) | 7 (0.4) |
| Presented on Weekend | 1,375 (35) | 975 (33.8) | 554 (25.2) | 2,948 (35.8) | 485 (27.4) |
| Hospital-Level Characteristics | |||||
| Annual ED Visit Volume, mean (SE) | 45,606 (2,728) | 44,671 (2,456) | 44,311 (2,098) | 42,773 (2,509) | 42,355 (2,830) |
| Teaching, Urban-Rural Status | |||||
| Metro, nonteaching hospital | 2,018 (51.4) | 1,328 (46) | 1,113 (50.2) | 3,966 (48.1) | 806 (45.5) |
| Metro, teaching hospital | 840 (21.4) | 757 (26.2) | 658 (29.7) | 1,930 (23.4) | 394 (22.2) |
| Non-metro (rural) | 1,066 (27.2) | 800 (27.7) | 443 (20) | 2,353 (28.5) | 573 (32.3) |
| Region | |||||
| Northeast | 474 (12.1) | 446 (15.5) | 344 (15.6) | 1284 (15.6) | 164 (9.2) |
| Midwest | 651 (16.6) | 545 (18.9) | 443 (20) | 1731 (21.0) | 338 (19.1) |
| South | 2,050 (52.3) | 994 (34.5) | 1,023 (46.2) | 2,983 (36.2) | 789 (44.5) |
| West | 748 (19.1) | 899 (31.2) | 404 (18.2) | 2,252 (27.3) | 481 (27.2) |
Other insurance is typically automobile or worker’s compensation insurance. SE: standard error.
In unadjusted analysis, patients that were admitted rather than transferred were more likely to be older, live in metropolitan areas and wealthier zip codes, have insurance, be injured as a result of a fall, and have a severe injury to the chest or abdomen (Table 3). These patients were more likely to be treated on a weekday, in higher volume EDs, metropolitan teaching hospitals located in the northeast, south, and west.
Table 3.
Characteristics of severely injured trauma patients who presented to U.S. non-trauma centers by emergency department disposition in 2009
| Admitted to Non-Trauma Center, N (Row %) | Transferred Out to Another Acute Care Facility, N (Row %) | P Value | |
|---|---|---|---|
| Total | 10,528 (54.5) | 8,784 (45.5) | |
| Patient-Level Characteristics | |||
| Male | 7,328 (53.6) | 6,339 (46.4) | 0.06 |
| Age | |||
| 18–34 | 2,618 (47.2) | 2,930 (52.8) | |
| 35–54 | 4,309 (54.7) | 3,565 (45.3) | |
| 55–64 | 3,600 (61.1) | 2,288 (38.9) | < 0.01 |
| Primary Insurance | |||
| Uninsured | 1,639 (41.8) | 2,285 (58.2) | |
| Medicaid | 1,724 (59.8) | 1,161 (40.2) | |
| Medicare | 1,336 (60.3) | 879 (39.7) | |
| Private | 4,685 (56.8) | 3,565 (43.2) | |
| Other | 1,025 (57.8) | 747 (42.2) | <0.01 |
| Median Household Income of Home Zip Code | |||
| <$40,000 | 2,777 (49.5) | 2,834 (50.5) | |
| $40,000–$49,999 | 2,737 (50.8) | 2,647 (49.2) | |
| $50,000–$65,999 | 2,502 (58.5) | 1,773 (41.5) | |
| ≥ $66,000 | 2,113 (65.2) | 1,128 (34.8) | <0.01 |
| Patient Lives in Metro Area | 8,712 (63.0) | 5,126 (37.0) | <0.01 |
| Injury Severity Score, mean (SE) | 19.4 (0.20) | 19.2 (0.17) | <0.44 |
| Abbreviated Injury Scale ≥ 3 | |||
| Head and Neck | 6,898 (51.0) | 6,636 (49.0) | <0.01 |
| Chest | 3,006 (58.7) | 2,117 (41.3) | 0.03 |
| Abdomen | 1,547 (73.9) | 548 (26.1) | <0.01 |
| Extremities | 811 (56.6) | 621 (43.4) | 0.54 |
| Mechanism of Injury | |||
| Blunt, Fall | 4,120 (59.6) | 2,787 (40.5) | <0.01 |
| Blunt, Motor Vehicle | 2,471 (50.3) | 2,440 (49.7) | 0.04 |
| Blunt, Other | 1,034 (52.4) | 938 (47.6) | 0.38 |
| Penetrating, Firearm | 209 (52.0) | 193 (48.0) | 0.66 |
| Penetrating, Other | 78 (66.4) | 39 (33.6) | 0.22 |
| Presented on Weekend | 3,274 (51.1) | 3,133 (48.9) | <0.01 |
| Hospital-Level Characteristics | |||
| Annual ED Visit Volume, mean, (SE) | 52,807 (2,853) | 32,586 (1,536) | <0.01 |
| Teaching, Urban-Rural Status | |||
| Metro, nonteaching hospital | 5,290 (56.5) | 4,071 (43.5) | |
| Metro, teaching hospital | 3,859 (84.0) | 733 (16.0) | |
| Non-metro (rural) | 1,380 (25.7) | 3,980 (74.3) | <0.01 |
| Region | |||
| Northeast | 1,609 (58.8) | 1,127 (41.2) | |
| Midwest | 1,471 (39.3) | 2,274 (60.7) | |
| South | 4,607 (57.5) | 3,402 (42.5) | |
| West | 2,841 (58.9) | 1,981 (41.1) | <0.01 |
After adjustment with multivariate regression, many of these factors remained associated with increased risk of admission compared to transfer (Table 4). Notably, compared with patients who were uninsured, those who had Medicaid had a rate of admission vs. transfer that was 14.2% (95% CI: 9.2–19.4%) higher. Likewise, the absolute risk of admission vs. transfer was also higher among patients with other types of insurance compared with being uninsured: 13.2% (95% CI: 7.5–18.9%) for Medicare, 11.2% (95% CI: 6.9–15.4%) for private insurance, and 13.1 % (95% CI: 6.6–19.6%) for other commercial insurance (Table 4 and Figure 1).
Table 4.
Factors associated with emergency department disposition of admission rather than transfer in patients with severe injuries presenting to non-trauma centers in 2009
| Variable | Adjusted Odds Ratio (95% CI) | Adjusted Absolute Risk Difference, % (95% CI)* |
|---|---|---|
| Patient-Level Characteristics | ||
| Male (vs. Female) | 0.99 (0.85–1.15) | −0.21 (−2.83, 2.41) |
| Age | ||
| 18–34 (Reference) | ||
| 35–54 | 1.21 (1.00–1.45) | 3.40 (0.02, 6.77) |
| 55–64 | 1.58 (1.27–1.96) | 8.15 (4.21, 12.09) |
| Primary Insurance | ||
| Uninsured (Reference) | ||
| Medicaid | 2.20 (1.67–2.91) | 14.28 (9.16, 19.41) |
| Medicare | 2.07 (1.53–2.81) | 13.17 (7.48, 18.87) |
| Private | 1.85 (1.48–2.32) | 11.18 (6.94, 15.42) |
| Other | 2.07 (1.44–2.97) | 13.14 (6.65, 19.63) |
| Median Household Income of Home Zip Code | ||
| <$40,000 (Reference) | ||
| $40,000–$49,999 | 0.91 (0.72–1.15) | −1.67 (−5.91, 2.57) |
| $50,000–$65,999 | 0.91 (0.68–1.22) | −1.58 (−6.68, 3.51) |
| ≥ $66,000 | 0.99 (0.65–1.51) | −0.16 (−7.6, 7.2) |
| Patient Lives in Metro Area (vs. Non-Metro) | 1.04 (0.73–1.48) | 0.70 (−5.60, 7.01) |
| Injury Severity Score, mean | 1.00 (0.99–1.01) | −0.04 (−0.24, 0.17) |
| Abbreviated Injury Scale ≥ 3 | ||
| Head and Neck | 0.47 (0.32–0.69) | −13.17 (−19.68, −6.65) |
| Chest | 1.31 (0.96–1.79) | 4.81 (−0.57, 10.20) |
| Abdomen | 2.50 (1.68–3.72) | 15.85 (9.35, 22.34) |
| Extremities | 0.91 (0.66–1.26) | −1.60 (−7.30, 4.10) |
| Mechanism of Injury | ||
| Blunt, Fall | 1.22 (0.96–1.55) | 3.56 (−0.64, 7.77) |
| Blunt, Motor Vehicle | 0.85 (0.67–1.08) | −2.93 (−7.27, 1.42) |
| Blunt, Other | 1.12 (0.81–1.54) | 1.99 (−3.65, 7.62) |
| Penetrating, Firearm | 1.09 (0.64–1.88) | 1.57 (−8.01, 11.16) |
| Penetrating, Other | 1.14 (0.43–3.03) | 2.4 (−14.79, 19.58) |
| Presented on Weekend (vs. Weekday) | 0.90 (0.77–1.06) | −1.81 (−4.72, 1.10) |
| Hospital-Level Characteristics | ||
| Annual ED Visit Volume by Increments of 10,000, mean | 1.21 (1.09–1.35) | 3.42 (1.59, 5.26) |
| Teaching, Urban-Rural Status | ||
| Metro, nonteaching hospital (Reference) | ||
| Metro, teaching hospital | 4.24 (2.1–8.58) | 26.22 (15.21, 37.23) |
| Non-metro (rural) | 0.37 (0.22–0.62) | −20.44 (−31.09, −9.78) |
| Region | ||
| Northeast (Reference) | ||
| Midwest | 0.67 (0.39–1.15) | −7.22 (−16.86, 2.41) |
| South | 0.69 (0.28–1.73) | −6.53 (−22.61, 9.56) |
| West | 1.01 (0.4–2.56) | 0.2 (−16.15, 16.54) |
Adjusted absolute risk differences were calculated by taking the difference in adjusted probabilities of the outcome for each variable in the multivariate logistic regression. This is also known as calculating average marginal effects (AME). The model was also adjusted for month of presentation (results not shown). The adjusted probabilities of admission rather than transfer according to insurance and hospital type are highlighted in Figure 1.
Figure 1. Adjusted Probability of ED Disposition of Admission Rather Than Transfer Among Patients with Severe Injuries Presenting to Non-Trauma Centers.
Metro = Metropolitan Statistical Area, an indicator of high population density according to the U.S. Census Bureau. Figure 1A demonstrates adjusted probability of admission to the non-trauma center according to the patient’s insurance type. Figure 1B demonstrates the adjusted probability of admission to the non-trauma center according to the type of hospital the patient presented to. These adjusted probabilities were calculated using the estimates of the multivariate logistic regression model presented in Table 3. Error bars represent 95% confidence intervals.
Clinical characteristics associated with increased risk of admission vs. transfer after multivariate adjustment were older age (age 35 and older) and having a severe injury to the abdomen (Table 4). Whereas patients with severe injury to the abdomen were admitted 15.9% (95% CI: 9.4, 22.3%) more often, patients with severe injuries to the head and neck were transferred 13.2% (95% CI: 6.6, 19.7%) more often.
Higher hospital ED volume and teaching status also remained independently associated with a higher risk of admission vs. transfer. The risk of admission vs. transfer was most strongly predicted by whether the hospital ED was a teaching hospital. Compared with metropolitan nonteaching hospitals, the risk of admission rather than transfer was 26.2% (95% CI: 15.2, 37.2%) higher if a severely injured patient presented to a metropolitan teaching hospital. Conversely, the risk of admission was 20.4% (95% CI: 9.8, 31.1%) less if a patient presented to a rural hospital rather than a metropolitan non-teaching hospital (Table 4 and Figure 1).
Comment
Despite adjustment for patient, injury, and hospital level characteristics, insured patients and those with initial care in higher-volume urban teaching hospitals had a significantly increased risk of hospitalization in a non-trauma center rather than transfer to a potentially higher level of care. Severely injured trauma patients require a broad spectrum of diagnostic, critical care, and surgical services to optimize outcomes. Therefore, regionalized trauma systems were established beginning in the 1980s to facilitate the field triage and interhospital transfer of severely injured trauma patients to designated trauma centers.23 Given that patients hospitalized in non-trauma centers have worse outcomes than those transferred to trauma centers,3–6 our findings suggest that insured patients may receive worse care. While unmeasured patient preferences may partially explain this phenomenon, our findings raise the possibility that insured patients are disproportionately being kept at non-trauma centers because of better reimbursement potential than uninsured patients.
The first studies examining the association between insurance status and interhospital transfer in the 1980s documented the phenomenon of “dumping” the uninsured on publicly owned tertiary hospitals.24–26 Many of these patients were transferred without any stabilizing treatment.25, 26 In response to concerns about patient dumping, Congress enacted the Emergency Medical Treatment & Labor Act (EMTALA) in 1986.27 This law imposes specific obligations on hospitals that offer emergency services to provide a medical screening examination for patients presenting to EDs regardless of an individual’s ability to pay. Hospitals are then required to provide stabilizing treatment for patients found to have an emergent condition. According to EMTALA, if a hospital is unable to stabilize or treat a patient within its capability, or if the patient requests, an appropriate transfer should be implemented.27
Our study is the first to use national emergency department data to show that severely injured patients presenting to non-trauma center EDs who are uninsured are more likely to be appropriately transferred out; whereas insured patients are more likely to hospitalized in the non-trauma center. Previous research on this phenomenon has been limited due to lack of data from non-trauma centers, which account for over 75% of the hospitals in the U.S.16 Three previous studies examining trauma registry data found that patients with noncommercial insurance or who were uninsured were more likely to be transferred from lower level trauma centers (Level III) to tertiary care trauma centers (Level I/II).13–15 Level III trauma centers have transfer agreements with Level I/II trauma centers for patients with exceptionally severe injuries. Level III trauma centers do not have the full availability of surgical subspecialists as Level I/II trauma centers, but do have the resources for emergency resuscitation, surgery, and intensive care for most trauma patients.16 Therefore, our findings demonstrating disparities in transfer patterns of severely injured patients by insurance status who present to non-trauma centers are even more concerning, since these hospitals due not have the critical care trauma resources that Level III trauma centers have.
While the focus with the implementation of EMTALA has been to ensure that uninsured patients are not “dumped” on tertiary care public hospitals, our findings suggest that additional policies are needed to ensure that critically injured insured patients are not inappropriately retained in non-trauma centers rather than transferred to a higher level of care. This is especially necessary when regionalized care for critically ill patients with certain conditions, including trauma, has been demonstrated to improve outcomes. This need to ensure an appropriate level of care extends beyond trauma patients. For example, transfer of low birth-weight infants to high volume neonatal intensive care units has been shown to improve outcomes, but infants with insurance are less likely to be transferred.28–30
There is likely a subset of critically ill or injured patients that non-trauma center clinicians are willing to admit at their hospital. However, if it is found that the patient is uninsured, and thus there is low likelihood of recouping the costs of providing intensive care, this may tip the scale to transfer the patient31, 32 Likewise, transferring rather than not transferring insured patients is associated with financial loss for the transferring hospital.33 This suggests policies that allow the sharing of reimbursement between the transferring and receiving hospital may be a solution to neutralizing the financial conflict of interest for transferring hospitals.34 Such policies have been proposed for the regionalization of out-of-hospital cardiac arrest.35 In order to facilitate this, reimbursement policies and quality measurement activities need to view the care of an emergency condition originating at one hospital and followed by transfer to another as a single “episode of care” rather than separate healthcare encounters.36–38 This would better allow regionalized acute care systems, such as trauma systems, to reduce disparities in transfer patterns by insurance status and ensure patients are being optimally regionalized.
It is possible that some privately insured patients may not want to be transferred to a trauma center, given that a high proportion of trauma centers are publicly owned and located in inner city areas. However, while there is a paucity of literature on qualitative factors behind interhospital transfer decisions for trauma, at least in the medical literature, patient preference has not been shown to be an important factor.31, 32 If it were found that patients do not want to be transferred to a trauma center, it would only highlight the importance of the Centers for Disease Control and Prevention’s efforts to educate the public about the survival benefit of trauma center care.39
Given the scarcity of neurosurgeons who take call for trauma,40, 41 it is not surprising that patients with severe head injuries were much more likely to be transferred out of non-trauma centers than those without severe head injuries. However, it is surprising that patients with severe injuries to the chest or abdomen were more likely to admitted at the non-trauma center rather than transferred. While general surgeons can manage the majority of these injuries, general surgeons working in non-trauma centers are likely to have less experience with managing these complex conditions than general surgeons who work at trauma centers and are trained in trauma resuscitation.42
We also found that presentation to higher volume, teaching hospitals located in metropolitan areas was significantly associated with a higher likelihood of being admitted rather than transferred among insured patients. While these hospitals are more likely to have a number of surgical specialists and intensive care resources, processes of care for trauma patients are not likely to be in place compared with designated trauma centers.42 Furthermore, a landmark 2006 national study comparing the outcomes of patients treated in Level I trauma centers versus high volume non-trauma centers found a 25% relative reduction in mortality among patients hospitalized in trauma centers.3
There are a number of limitations to this analysis. First, because of the limitations of administrative data, among patients who had a disposition of transfer to another care facility from the ED of a non-trauma center, we cannot determine what type of hospital patients who were actually transferred to. Based on EMTALA and previous studies,4, 13–15 we assumed that severely injured patients treated in non-trauma center EDs that were transferred would be transferred to a higher level of care, and thus would almost exclusively go to designated trauma centers rather than another non-trauma center. Second, we were unable to determine proximity of trauma centers to individual non-trauma centers. Third, administrative data lacks more granular data on clinical and physiologic characteristics, thus some of the variation in transfer rates may be explained by unobserved differences in these variables. Finally, using this dataset we are not able to determine whether transferred patients actually had better outcomes compared with patients who were not transferred.
In summary, we found that insured, critically injured trauma patients are much less likely to be transferred out of non-trauma center EDs than uninsured trauma patients after adjusting for patient, injury, and hospital characteristics. Given that transfer to a trauma center has been shown to reduce mortality, these insured patients may systemically be receiving sub-optimal care. Our findings suggest that encounters for time-sensitive critical illness such as trauma should be monitored at the regional level using an “episodes of care” approach to ensure the optimal regionalization of patients according to patient need, regardless of ability to pay. To reduce transfer disparities, shared reimbursement schemes may be needed to offset the potential loss of reimbursement that non-trauma centers may experience in transferring out rather than admitting insured trauma patients with critical injuries.
Supplementary Material
Acknowledgments
Funding: This project was supported by the National Center for Research Resources and the National Center for Advancing Translational Sciences, National Institutes of Health, through grant UL1 RR025744 (Drs. Delgado and Wang) and K12HL109009 (Delgado).
Footnotes
Conflicts of interest: The authors have no conflicts of interest to disclose.
Author contributions: Conception and design: MKD, MY, NEW; Acquisition of data: MY, NEW; Statistical analysis: MKD, MY, THB; Analysis and interpretation of data: MKD, MY, KLS, DAS, THB, NEW; Drafting of manuscript: MKD; Critical revision of manuscript for important intellectual content: MY, KLS, DAS, THB, NEW. MKD takes responsibility for the paper as a whole.
Meeting presentations: Society for Academic Emergency Medicine, Atlanta, GA, 2013. Academy Health, Baltimore, MD, 2013.
The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.
Contributor Information
M. Kit Delgado, Email: mucio.delgado@uphs.upenn.edu.
Michael A. Yokell, Email: myokell@stanford.edu.
Kristan L. Staudenmayer, Email: kristans@stanford.edu.
David A. Spain, Email: dspain@stanford.edu.
Tina Hernandez-Boussard, Email: boussard@stanford.edu.
N. Ewen Wang, Email: ewen@stanford.edu.
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