linking emergency department (ed) and motor vehicle crash

Linking Emergency Department (ED) and Motor Vehicle Crash (MVC) Data for Pedestrian and Bicyclist Injury: Elucidating Health Outcomes

ANNA WALLER

SEPTEMBER 9, 2020

CSTE

© 2020 UNIVERSITY OF NORTH CAROLINA AT CHAPEL HILL 1

Co-authors & acknowledgments

• Co-authorso Katie Harmon (HSRC)

o Kathy Peticolas (NC DPH)

o Amy Ising (CCHI)

• We would like to acknowledge:o Dan Levitt, Eric Rodgman, Laura Sandt, Libby Thomas from UNC HSRC.

o Erika Redding, Clifton Barnett, Dennis Falls, and Shaun Mason from CCHI.

o Lana Deyneka, Zach Faigen, Alan Dellapenna and Scott Proescholdbell from NC DPH.


Funding Acknowledgment


• North Carolina Governor's Highway Safety Program, 2016-2021

• Centers for Disease Control & Prevention, 2019-2021

• Collaborative Sciences Center for Road Safety, 2019-2020

• This project is also supported by the North Carolina Traffic Records

Coordinating Committee.

NC DETECT is a statewide public health syndromic surveillance system, funded by the

NC Division of Public Health (NC DPH) Federal Public Health Emergency Preparedness

Grant and managed through collaboration between NC DPH and UNC-CH Department

of Emergency Medicine’s Carolina Center for Health Informatics. The NC DETECT Data

Oversight Committee does not take responsibility for the scientific validity or accuracy of

methodology, results, statistical analyses, or conclusions presented.

NC DPH Data Attribution & Disclaimer

Background• BETTER DATA NEEDED TO INFORM POLICY AND PRACTICE

• RISING PEDESTRIAN FATALITIES


MVC-Health Data Linkage Project Timeline

Year 0 Year 1 Year 2 Year 3 Year 4 Year 5

• Convene stakeholders

• Develop strategic implementation plan • Crash/ EMS

linkage pilot**

• Crash/ hospital encounter linkage pilot**

• Crash/ED linkage pilot**

Wake County Pilot Project (GHSP)

MVC Injury Data Linkage Project (GHSP)

NC Crash Injury Surveillance System (CDC)

Pedestrian/Bicyclist Project (CSCRS)

*Wake county MVCs, only.**Pedestrians/bicyclists, only.†Pedestrians/bicyclists/motorcyclists, only.

We are here

5

• Crash/ED/ EMS linkage pilot*

• Crash/ trauma registry linkage pilot

• Crash/ Medicaid linkage pilot†

• Crash/ED/ death linkage

• Ped/bike linkage

• Develop research advisory board

• Develop public facing data tool

• Develop sustainability plan

• Demonstrate success

© 2020 UNIVERSITY OF NORTH CAROLINA AT CHAPEL HILL

Rising pedestrian fatalities

• In the United States (US), the number and rate of pedestrian fatalities has increased.

• In 2018, 6,283 US pedestrians lost their lives on public trafficways, with a rate of 1.9 deaths per 100,000 person-years.

• North Carolina (NC) had the 13th highest fatality rate out of the 51 US states and District of Columbia, with a rate of 2.2 deaths per 100,000 person-years.1



Number of NC pedestrian fatalities: 2009-20182

0

50

100

150

200

250

2009 2010 2011 2012 2013 2014 2015 2016 2017 2018

Nu

mb

er

of

fata

liti

es

Year

Pedestrian fatalities

have increased by

>50% since 2009

Health disparities among pedestrian fatalities

Young children, older adults, Blacks/African-Americans, American Indians/Alaska Natives, pedestrians of Hispanic/Latino ethnicity, and residents of lower-income communities are at a greater risk of dying from pedestrian-motor vehicle collisions.3-6


Fatalities are just part of the problem


For each

pedestrian

fatality,

7-10

pedestrians

are treated in

the emergency

department

(ED).a,b

aPolice-reported crashes, only.

bBased on NC data linkages performed by study authors

(estimate varies by ED visit data source).

NC Crash Data Underestimates Total Number of Pedestrian Injuries: CSCRS, 2010-2015 (N=14,264 [Crash Report], N =19,599 [ED])


2,201

3,386

41

80

115

347

753

1,086

1,586

914

585

0 500 1,000 1,500 2,000 2,500 3,000 3,500

Female

Male

80+

70-79

60-69

50-59

40-49

30-39

20-29

10-19

0-9

Difference in pedestrian crash/ED visit counts

Age

gro

up

Sex

Certain populations are less likely to have a crash report.

Study objective

Link information for pedestrians and bicyclists from police-reported MVCs to population-based ED visit data in NC to better inform policy and practice and ultimately to reduce transportation injury and improve health outcomes.


Methods


We tried four different linkage methodologies, but focused on deterministic linkage.


Linkage methods Description

Hierarchical deterministic linkage

Matching up shared linkage variables in different patterns

Recursive partitioning trees

Calculating the ‘distance’ between linkage variables

Probabilistic linkage

Calculating the likelihood of records matching based on variable frequency

Hand review Verifying and matching up records through individual review

Strengths:• Easy to explain to a multi-

disciplinary audience • High quality results • Fast• Replicable in many applications

Challenge: A sufficient and representative linkage rate

Data linkage

• NC crash and ED visit data were linked using hierarchical deterministic methods.

• Data linkage methods are described fully in the report titled North Carolina Linkage Study for Motor Vehicle Crashes Involving Pedestrians and Bicyclists,10 available here: https://cchi.web.unc.edu


https://cchi.web.unc.edu/

Study population

• Record-level information for all pedestrians and bicyclists involved in police-reported collisionsa were linked to injury-related ED visitsb

captured by NC DETECTc, NC’s statewide syndromic surveillance system, for 2017.7,8

• Linked crash-ED visit records were then linked to 2013-2017 ACS 5-year estimates at the county level.9


aIn NC, a reportable motor vehicle crash must involve a motor vehicle and take place on a public trafficway. In addition, it must meet one of the following criteria: result in a

fatality, result in an injury, result in total property damage >$1,000, and/or involve a vehicle seizure.

bAn injury-related ED visit was defined as an ED visit with an ICD-10-CM injury diagnosis or mechanism code (S00-T88, V00-Y99).

cNC DETECT is legislatively mandated to collect ED visit records from all 24/7 acute-care, hospital-affiliated, civilian NC EDs for public health surveillance and early event

detection.

Data linkage

• Records were included only if they had valid data for• Data of Birth or Age AND

• 5-digit ZIP-code of residence

• ED records were further required to include ICD-10-CM code(s) indicating injury diagnosis and/or injury mechanism and be within 14 days of the crash date

• Two-stage stepwise linkage requiring exact matching on key variables in stage 1, with criteria adjusted (relaxing and tightening specific requirements) in stage 2

•Linked records were removed from further linkage after stage 1


Analyses

• Descriptive analyses were conducted using the linked crash-health data using SAS

• Population-based incidence rates:oThe incidence of police-reported pedestrian/bicyclist injuries treated in NC

EDs were calculated using population-based denominators obtained from the National Center for Health Statistics.11

• Categorical analysis:o Used Pearson chi-square tests to compare differences in observed

frequencies.

oSet statistical significance at alpha = 0.05.


Case definition: Serious injury• Defined a serious injury, based on a definition created by the National Transportation Safety Board (NTSB).12

• A serious injury was defined as an injury resulting in one or more of the following outcomes:o Death

o Hospital admission

o A diagnosis of an amputation, internal injury, crushing injury (except fingers and toes), fracture (except fractures of fingers, toes, or nose)

o A diagnosis of an injury to the blood vessels, nerves, muscles, and tendons (except injuries to fingers and toes)

o A diagnosis of a burn (except first degree burns and burns to fingers and toes)

o A diagnosis of an air/fat embolism

o A diagnosis of traumatic shock

o A diagnosis of traumatic compartment syndrome


Results


Linkage results

• Linkage process included• 4,213 pedestrians/bicyclists in reported MVCs in 2017

• 1,032,622 ED visits including required data elements in 2017

• Linked 44% of NC pedestrian/bicyclist crash records to a single injury-related NC ED visit (N=1,870 linked crash-ED visit records)

• 45% of pedestrian crash reports linked to an ED visit while 43% of bicyclist crash reports linked

• Another 196 (5%) linked to multiple ED visits; on review, 56% of these were multiple visits by same patient to same ED in 14-day post-crash study period; most others were transfers or returns for follow-up care to another ED


Linkage evaluation

• A sample of 100 linked crash-ED records and 100 unlinked crash records were selected for manual review• Only 1 linked record was deemed a “false link”

• 31 unlinked records were found in the ED visit data with manual review

• For missed links, the most common reason was different ZIP codes• Most of these had matching City of Residence

• Missing injury ICD codes in ED visit data was also common• Left Without Medical Advice and Pain diagnoses were common in this group


Linkage evaluation

• Unlinked crash records were more likely to have • Police-reported death or no injury than linked records

• Nighttime or early morning crashes

• Linked crash records were more likely to have• Police-suspected serious or minor injury

• Unlinked ED visits were less likely to arrive by EMS or be admitted to the hospital


Linkage evaluation

• Sensitivity = 74%

• Specificity = 99%

• PPV = 99%

• Accuracy = 83%

• Follow-up work incorporating recommendations from this study has improved pedestrian crash-ED visit linkage to 50%.

• Further work has linked all crashes with ED visits, using a 31-step hierarchical deterministic process


Incidence of police-reported pedestrian/bicyclist injuries treated in NC EDs

• Pedestrians (N=1,383): 13.6 ED visits per 100,000 person-years

• Bicyclists (N=487): 4.7 ED visits per 100,000 person-years



Geographic variation – Rates (per 100,000 p-yrs of pedestrians injured in police-reported crashes, by NCALHD region: NC, 2017

aNCALHD Map of Regions: https://www.ncalhd.org/map.bRegions classified according to “Natural Jenks” method.

b

Region 4 (includes

Charlotte) has the

highest count and rate.

https://www.ncalhd.org/map


Demographic differences – Counts & rates (per 100,000 p-yrs) of pedestrians injured in police-reported crashes by sex: NC, 2017

51

124

155

93

126

109

68

34

13

25

73

116

8479

72

61

30

19

0

40

80

120

160

200

0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80+

Co

un

t

Age group

Male Female

8.1

18.2

21.5

14.6

19.3

16.4

12.4

10.69.5

4.1

11.1

16.7

12.611.6

10.1 9.6

7.7 8.2

0

5

10

15

20

25

0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80+

Rate

Age group

Men had higher rates for all age groups.

Counts Rates per 100,000 p-yrs


Demographic differences – Counts & rates (per 100,000 p-yrs) of pedestrians injured in police-reported crashes by race: NC, 2017

20

75

110

84 8589

70

41

29

38

96

112

66

88

74

46

15

2

0

40

80

120

0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80+

Co

un

t

Age group

White Black

2.4

8.2

11.49.2 8.8 8.7

7.7 7.1

9.511.4

27.4

30.2

21.7

29.6

24.6

19.3

13.1

3.5

0

15

30

45

0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80+

Ra

te

Age group

Black/African-American pedestrians had

higher injury rates for all age groups,

except among adults >80 years.

Counts Rates per 100,000 p-yrs

Pedestrian injury severity

Based on the NTSB definition of injury severity, 515 pedestrians treated in NC EDs had serious or fatal injuries (37%), 868 pedestrians had injuries categorized as non-serious (63%).



Pedestrian injury severity: demographic characteristics

60%66%

57%68% 63% 60%

40%34%

43%32% 37% 40%

0%

20%

40%

60%

80%

100%

Male Female 1 White Black/AA Hispanic/Latino Other

Pe

rce

nt

of

ED

vis

its

Non-serious injury Serious injury

Sex

P=.027Race/ethnicity

P=.002Abbreviation: AA, African-AmericanaNC crash data does not disaggregate race and ethnicity.bOther race contains Asian, American Indian/Alaskan Native, and other race.

a b


Pedestrian injury severity: Expected source of payment

25%

19%

22%

14%

19%

Serious injury

Insurance co. Uninsured Medicaid Medicare Other

26%

20%18%

8%

21%

Non-serious injury

P=.026a

Abbreviation: Co., companyaOther expected source of payment contains workers' compensation, other type of governmental payment, other type of payment.

Pedestrian injury severity: County of crash

Urban/rural countya of crash was not identified as being associated with injury severity.

Poverty level was associated with injury severity, with 35% of pedestrians sustaining serious injuries in NC counties with poverty levels above the 75th percentile, as compared to 27% of pedestrians injured in counties with lower poverty levels (P=.003).


aBased on US Department of Agriculture’s categorization: https://www.ers.usda.gov/data-products/rural-urban-continuum-codes

https://www.ers.usda.gov/data-products/rural-urban-continuum-codes


Pedestrian injury severity: Striking vehicle type

63% 65% 62%56%

33%

56%

37% 35% 38%44%

67%

44%

0%

20%

40%

60%

80%

100%

Passenger car SUV Van Light truck Heavy truck Other

Pe

rce

nt

of

ED

vis

its

Striking vehicle type

Non-serious injury Serious injury

Abbreviation: SUV, sport utility vehicleaOther striking vehicle type contains buses, motor homes, motorcycles, mopeds, police cars, and ambulances. P=.033

Pedestrian injury severity: Crash characteristics

• In addition to striking vehicle type, other crash characteristics associated with serious injuries among pedestrians treated in NC EDs were:

o Hour of crash (serious injuries were more common in nighttime crashes)

o Ambient light level of crash (serious injuries were more common under dark conditions)

o Number of lanes (serious injuries were more common on roads with more lanes)

o Posted speed limit (serious injuries were more common on roads with higher posted speed limits).


Conclusion


Conclusion

• Pedestrian and bicycle crash injuries are not distributed evenly across the NC population. Communities of color and counties with higher levels of poverty are disproportionately impacted.

• In addition to sociodemographic factors, certain crash characteristics, such as striking vehicle type, are associated with pedestrian injury severity.


Motor vehicle crash injury prevention

• Programs like NC Vision Zero, Robeson County Vision Zero, Vision Zero Charlotte, Vision Zero Durham, and Vision Zero Greensboro are working towards reducing traffic injury deaths and injuries to zero in NC.

• Learn more here: https://ncvisionzero.org/about-us/.


https://ncvisionzero.org/about-us/

Study limitations

• Secondary analysis of NC ED and crash data.

• Rates were population-based, rather than exposure based (not available at the state/county level in NC).

• Not all pedestrians/bicyclists injured in police-reported crashes are treated in EDs and not all pedestrians/bicyclists treated in EDs are reported to the police. This study only examined injured pedestrians and bicyclists who had records in both datasets (and were linkable).


Thank you!


Questions?CONTACT INFO

ANNA WALLER: [email protected]

KATIE HARMON: [email protected]


mailto:[email protected]

mailto:[email protected]


References1. NHTSA. 2018 Ranking of state pedestrian fatality rates. FARS. https://www-fars.nhtsa.dot.gov/States/StatesPedestrians.aspx. Updated 2020.

Accessed Apr 23, 2020.

2. NC DOT. NC Bicycle and Pedestrian Crash Data Tool. Division of Bicycle and Pedestrian Transportation. http://www.pedbikeinfo.org/pbcat_nc/_pedtypefacts2.cfm. Updated 2019. Accessed Jan 2, 2020.

3. Malek M, Guyer B, Lescohier I. The epidemiology and prevention of child pedestrian injury. Accid Anal Prev. 1990; 22(4): 301-313.

4. Chong S, et al. Epidemiology of pedestrian-motor vehicle fatalities and injuries, 2006-2015. AJPM. 2018; 55(1):98-105.

5. Kaufman E, Wiebe DJ. Racial disparities in pedestrian deaths in the United States, 1999–2015. Inj Prev; 23(Supp 1): A38-A39.

6. Morency P, et al. Neighborhood social inequalities in road traffic injuries: The influence of traffic volume and road design. Am J Public Health; 102(6): 1112-1119.

7. NC DOT. DMV-349 Instructional Manual. Raleigh, NC: NC DMV, 2018.

8. CCHI. NC DETECT. https://ncdetect.org. UNC-Chapel Hill. Updated 2020. Accessed Apr 23, 2020.

9. US Census Bureau. GCT1701 - Percent of people below poverty level in the past 12 months. 2013-2017 ACS 5-Year Estimates. 2019.

10. Harmon KJ, Peticolas K, Waller AE. North Carolina Linkage Study for Motor Vehicle Crashes Involving Pedestrians and Bicyclists. Chapel Hill, NC: CCHI, 2019. http://cchi.web.unc.edu/files/2019/08/Final-NC-DETECT-Crash-Ped-Bike-Linkage-Study.pdf.

11. NCHS. Bridged-Race Population Estimates, 2017 Results. CDC WONDER. 2019. https://wonder.cdc.gov/Bridged-Race-v2018.html. Accessed Oct 1, 2019.

12. NTSB. Pilot/Operator Aircraft Accident/Incident Report. Washington, DC: NTSB; 2013.

https://www-fars.nhtsa.dot.gov/States/StatesPedestrians.aspx

http://www.pedbikeinfo.org/pbcat_nc/_pedtypefacts2.cfm

https://ncdetect.org/

http://cchi.web.unc.edu/files/2019/08/Final-NC-DETECT-Crash-Ped-Bike-Linkage-Study.pdf

https://wonder.cdc.gov/Bridged-Race-v2018.html

linking emergency department (ed) and motor vehicle crash

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