This study analyzed 345 patients with ATV-related injuries from 2002-2009 to better understand crash mechanisms and factors related to passengers. Rollovers (42%) and collisions (20%) were common mechanisms. Passengers increased risks of rollovers, especially backward rollovers on slopes, and falls/ejections to the rear. Rearward ejections were linked to more severe head injuries. Strict enforcement of no-passenger rules could help reduce crashes and injuries. Improved data collection and educational approaches targeting passenger dangers were recommended.

1. The Effect of Passengers on All-Terrain
Vehicle Crash Mechanisms and Injuries
Charles Jennissen, MD
Gerene Denning, PhD
Kari Harding, PhD
Department of Emergency Medicine,
University of Iowa Carver College of Medicine
1

2. Background
105,000
Adult  The incidence of ATV-
90,000 Pediatric (< 16 years old) related injuries and
deaths has escalated
75,000 over the past 15 years
60,000
 Roughly 1/3 are children
45,000 <16 years of age
30,000  Well-over ½ are under
24 years of age
15,000
0
Year
Data from the National Electronic Injury Surveillance System (NEISS)
2

3. Background
In fact, more children die from ATV-related
events than from bicycle crashes.
Helmkamp JC, Aitken ME, Lawrence BA. ATV and bicycle deaths and associated costs in the United States, 2000-2005. Public
Health Rep. 2009;124(3):409-418.
3

4. Background
 833 ATV-related deaths in the U.S. in
2006.
 Since 1982, children < 16 yrs have
comprised just over a quarter of ATV
crash fatalities.
US Consumer Product Safety Commission: 2010 Annual Report of ATV Deaths and Injuries.
4

5. Purpose
 While common types of ATV-
related injuries have been
described, the circumstances
under which they occur are
poorly defined in the literature.
 The objective of the study was
to better understand the
mechanisms and contributing
factors of ATV-related injuries,
especially related to the
presence of passengers.
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6. Methods
 A retrospective chart analysis of all patients entered into the
University of Iowa Hospitals and Clinics Trauma Registry
with ATV-related injuries from 2002-2009.
 Potential subjects coded as having had an off-road vehicle
incident were identified.
 Vehicles other than traditional 3 or 4-wheeled ATVs
(motorbikes, scooters, utility vehicles, etc.) were excluded.
 A systematic review of each medical chart was performed.
 Details of injury events, potential contributing factors, and
resulting injuries were determined and evaluated.
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7. Results
345 ATV-related cases Patients with ATV Injuries by Gender
were identified. Male
79%
Female
• 79 % of patients were males.
21%
Patients with ATV Injuries by Age
• 32 % were children <18 years
of age. Adults
68%
Children
(<18)
32%
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8. Documentation
Medical Record Documentation of Contributing Factors
Seating Position 97.1%
Helmet Use 94.8%
Time of Day 92.2%
4 vs. 3 Wheels 90.3%
Contributing Factors
Road/trail/offroad 50.3%
Slope of Terrain 39.4%
Speed 35.3%
Surface Type 33.2%
Path(straight/turning) 7.7%
ATV Size 2.4%
ATV Model 0.9%
Electronic Device Use 0.0%
Weather 0.0%
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Percent of Medical Records that Featured Documentation
8

9. Passengers
• 20 % of victims were passengers or had passengers with
them on the ATV.
Patients with ATV Injuries by Seating
Driver Alone
77%
Driver with
Passenger
or Passenger
Unknown 20%
3%
Other
0%
9

10. Passengers
• Females were more likely to be passengers (p<.0001).
Seating Position by Gender
Driver
100%
80% Passenger
% of Each Gender
60%
40%
20%
0%
Male Female
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11. Helmet Use
• 21 % of all patients were reportedly wearing helmets.
Helmet Use by ATV Crash Victims
No Helmet
74%
Helmet
21%
Unknown
5%
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12. Helmet Use
• Drivers were more likely to wear helmets than passengers (22.5% vs.6.1%) (p<0.01).
Helmet Use by Age, Gender, & Seating Position
40%
38%
% of Pts Documented as Wearing Helmets
35%
29%
30%
25%
22%
20%
15%
10% 8% 8%
8%
6%
5%
0%
0%
Male, <16 y.o. Female, <16 Male, ≥16 y.o. Female, ≥16 Male, <16 y.o. Female, <16 Male, ≥16 y.o. Female, ≥16
Driver y.o. Driver Driver y.o. Driver Passenger y.o. Passenger Passenger y.o. Passenger
Age, Gender, & Seating Position
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13. Crash Mechanism
• Crash Mechanism
– Rollovers (42%) were the most common mechanism of injury.
– Collision with an object (20%) and ejection/fall from the machine (13%)
were also common.
– Collision with another ATV occurred in 7%.
• The victim was struck by the ATV in 21% and pinned in 9% of
the cases.
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14. Rollovers while Turning
• Turning or spinning the ATV was more likely to result in a
rollover compared to all other/unknown direction of travel.
(p=0.085)
http://www.atvconnection.com/Features/Feature_Articles/ATV-Riding-Techniques.cfm
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15. Rollovers on Sloped Terrain
• ATV rollovers on sloped terrain were more likely to have
passengers
– Than rollovers on Other and Unknown terrain (p=0.18)
– Than Non-rollovers (p=0.13)
%Drivers
% Drivers +Passengers
Rollovers Total only Passengers %Other
Sloped terrain 69 69.6% 27.5% 2.9%
Other and
unknown terrain 121 77.7% 18.2% 4.1%
Non-rollovers 155 78.71% 18.71% 2.58%
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16. Backward Rollovers
• Backward rollovers were almost twice as likely to have passengers as
all other rollovers (p=0.09, OR = 2.0, [0.9-4.2])
– Also, more likely to have passengers than non-rollovers (p=0.06)
• Forward rollovers appeared less likely to have passengers than all
other rollovers (p=0.27)
%Drivers
Type of % Drivers +Passengers
Rollover Total only Passengers %Other
Unspecified 85 74.1% 21.18% 4.71%
Sideways 40 80.0% 17.5% 2.5%
Backwards 44 65.9% 31.82% 2.27%
Forwards 21 85.7% 9.52% 4.76%
All non-
rollovers 155 74.0% 23.00% 3.00%
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17. Falls/Ejection to the Rear
 ATVs with passengers were over seven times more likely to result in
a Fall/Ejection to the rear than other types of ejections (p<0.01, OR 7.8
[2.6-23.3]).
– Falls/Ejection to the rear were more likely to have passengers than non-
ejections (p<0.01).
% Driver +
% Driver Passengers
Type of Ejection Total Alone Passengers % Other
Self Ejection 9 100% 0% 0%
Thrown over
Handlebars 46 89.1% 8.7% 2.2
Fall/ejected to Side 34 73.5% 26.5% 0%
Fall/Ejected from
Rear 17 35.3% 58.8% 5.9%
Unspecified
Ejection 68 75.0% 20.6% 4.4%
Not Reported as
Ejected 171 77.2% 19.3% 3.5%
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18. Ejections over Handlebars/Self Ejection
 Ejections over the handlebars (forward) and self ejections were less
likely if there were passengers than other types of ejections. (p=0.02,
OR = 0.2 [0.1-0.6])
– Thrown over handlebars (forward) were less likely to have passengers
than non-ejections. (p = 0.12)
% Driver +
% Driver Passengers
Type of Ejection Total Alone Passengers % Other
Self Ejection 9 100% 0% 0%
Thrown over
Handlebars 46 89.1% 8.7% 2.2
Fall/ejected to Side 34 73.5% 26.5% 0%
Fall/Ejected from
Rear 17 35.3% 58.8% 5.9%
Unspecified
Ejection 68 75.0% 20.6% 4.4%
Not Reported as
Ejected 171 77.2% 19.3% 3.5%
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19. Head Injury after Ejection
• Those ejected to the rear had the lowest GCS scores.
• Falls to the rear had lower GCS scores than Falls to the side
(p = 0.19).
Glasgow Coma Scale by Ejection Subtype
15
Average Glasgow Coma Scale
14.5
14
13.5
13
12.5
12
Ejection Thrown over Thrown/ Fall/ slip to Thrown/ Fall from Self ejection
Unspecified handlebars ejected to side ejected from rear
side rear
Ejection Subtype
19

20. Head Injury after Ejection
• Of those ejected, patients falling or ejected to the rear had the
worst head injury scores.
• Falls to the rear had higher head injury scores than Falls to the
side (p = 0.13).
MAX HEAD by Ejection Subtype
1.9
Average MAX HEAD
1.7
1.5
1.3
1.1
0.11
0.9
Ejection Thrown over Thrown/ Fall/ slip to Thrown/ Fall from rear Self ejection
Unspecified handlebars ejected to side ejected from
side rear
Ejection Subtype
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21. Extremity Injury after Ejection
• Patients who had self ejected or were thrown/fell to the side
experienced the worst extremity injuries (p=<.05).
– Those who had self ejected had significantly worse extremity injury scores
than all other types of ejection except Fall/slip to the side (p=<.05).
MAX Extremity Score by Ejection Subtype
2.2
Average MAX EXTREM
1.7
1.2
0.7
0.2
Ejection Thrown Thrown/ Fall/ slip to Thrown/ Fall from Self
Unspecified over ejected to side ejected rear ejection
handlebars side from rear
Ejection Subtype
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22. Conclusions
• Passengers on ATVs may be
at greater risk for rollovers
and fall/ejection to the rear.
• Rearward falls/ejections
appear to increase the risk of
severe head injuries.
• A strict and enforced “no
passenger” rule would help
decrease the likelihood of
some ATV crashes and injury
severity.
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23. Future Directions
 Improve crash and injury surveillance in the
emergency department:
• A multicenter ATV research network.
• Collect data prospectively.
• Standardized collection tool.
 Educational and training approaches to increase user
knowledge about the danger of riding with
passengers.
 Engineering approaches to limit seat length and
minimize likelihood of passengers.
 No passenger legislation for both private and public
lands in every state.
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24. Questions?
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