Winston FK, Kallan MJ, Elliott MR, Menon RA, Durbin DR. Risk of Injury to Child Passengers in Compact Extended-Cab Pickup Trucks. JAMA. 2002;287(9):1147-1152. doi:10.1001/jama.287.9.1147
Author Affiliations: Department of Pediatrics, Division of General Pediatrics (Dr Winston), Center for Clinical Epidemiology and Biostatistics (Drs Elliott and Durbin and Mr Kallan), and Department of Pediatrics, Division of Emergency Medicine (Dr Durbin), University of Pennsylvania School of Medicine, and TraumaLink: the Interdisciplinary Pediatric Trauma Research Center, Children's Hospital of Philadelphia (Drs Winston, Menon, and Durbin), Philadelphia, Pa.
Context An increasing number of compact pickup trucks can accommodate restrained
rear occupants. Rear seats in these pickup trucks are exempt from regulatory
safety testing though their relative safety has not been determined.
Objectives To evaluate the risk of injury to children in compact extended-cab pickup
trucks compared with children in other vehicles and to determine if any unique
Design Cross-sectional study of children aged 15 years or younger in crashes
of insured vehicles, with data collected via insurance claim records and a
Setting and Participants Probability sample of 7192 multirow vehicles involved in crashes, with
11 335 child occupants, in 3 large US regions from December 1, 1998,
to November 30, 2000.
Main Outcome Measure Relative risk of injury, defined as concussions and more serious brain
injuries, spinal cord injuries, internal organ injuries, extremity fractures,
and facial lacerations, estimated by odds ratios (ORs) adjusting for age,
restraint use, point of impact, vehicle weight, and crash severity.
Results Injuries were reported for 1356 children, representing 1.6% of the population.
Children in compact extended-cab pickup trucks were at greater risk of injury
than children in other vehicles (adjusted OR, 2.96; 95% confidence interval
[CI], 1.68-5.21). Children in the rear seats of compact pickup trucks were
at substantially greater risk of injury than rear-seated children in other
vehicles (adjusted OR, 4.75; 95% CI, 2.39-9.43). Children seated in the front
seat of compact extended-cab pickup trucks were at greater risk of injury
than children in the front seats of other vehicles, but this risk was not
statistically significant (adjusted OR, 1.70; 95% CI, 0.78-3.69).
Conclusions Children in compact extended-cab pickup trucks are not as safe as children
in other vehicles, primarily due to the increased relative risk of injury
in the back seat. For families with another choice of vehicle, clinicians
should advise parents against transporting children in compact pickup trucks.
The current exemption for regulatory testing for occupant protection in the
rear seats of compact pickup trucks should be reconsidered.
Despite the popularity of compact pickup trucks, many only have a single
row, thereby limiting seating capacity.1 Manufacturers
now produce extended-cab models that can accommodate at least 2 restrained
rear-seated occupants.2 These extended-cab
models may be viewed as family vehicles by parents who want to follow safety
recommendations that children be placed in the rear seat.3,4
However, little is known about the relative safety of pickup trucks for rear-seated
occupants, particularly children.
Current compact extended-cab pickup trucks typically have small rear
occupant compartments and most have side-facing, fold-down, or "jump" seats
that are considered auxiliary, nonstandard seats by manufacturers and by the
National Highway Traffic Safety Administration. In contrast, current full-size
extended-cab pickup trucks, similar to other vehicles, typically have larger
rear-occupant compartments and standard bench seats. Manufacturers' instructions
recommend that children be seated in the front seat of compact extended-cab
pickup trucks in appropriate child restraints rather than in the auxiliary
seats. The National Highway Traffic Safety Administration exempts these auxiliary
jump seats from regulatory testing, and, as such, the relative safety of these
seats has not been determined.
The purposes of this study were to evaluate the risk of injury to children
in compact extended-cab pickup trucks compared with children in other vehicles
and to determine if any unique hazards exist with the rear seating compartment
of compact extended-cab pickup trucks.
Data were collected from December 1, 1998, to November 30, 2000. A description
of the study methods has been published previously.5,6
The project consists of a large-scale, child-specific crash surveillance system.
Insurance claims from State Farm Insurance Co (Bloomington, Ill) function
as the source of subjects, with telephone survey and on-site crash investigations
serving as the primary sources of data.
Vehicles eligible for inclusion were State Farm insured, model year
1990 or newer, and involved in a crash with at least 1 child occupant aged
15 years or younger. Eligible crashes were limited to those that occurred
in 15 states and the District of Columbia, representing 3 large regions of
the United States (East: New York, New Jersey, Pennsylvania, Delaware, Maryland,
Virginia, West Virginia, North Carolina, and the District of Columbia; Midwest:
Ohio, Michigan, Indiana, and Illinois; and West: California, Nevada, and Arizona).
After policyholders consented to participate in the study, limited data were
transferred electronically to researchers at the Children's Hospital of Philadelphia
and University of Pennsylvania. Data in this initial transfer included contact
information for the insured driver, the age and sex of all child occupants,
and a coded variable describing the level of medical treatment received by
all child occupants (ie, no treatment, physician's office or emergency department
only, admitted to the hospital, or death).
A stratified cluster sample was designed to select vehicles (the unit
of sampling) for conducting a telephone survey with the driver. In the first
stage of sampling, vehicles were stratified on the basis of whether they were
towed from the scene, and a probability sample of both towed and nontowed
vehicles was selected at random, with a higher probability of selection for
towed vehicles. In the second stage of sampling, vehicles were stratified
on the basis of the level of medical treatment received by child occupants.
A probability sample from each tow status/medical treatment stratum was selected
at random. Probabilities of selection ranged from 0.025 for vehicles for which
no child received medical treatment to 1.0 for vehicles for which a child
died or was admitted to the hospital. In this way, the majority of injured
children would be selected while maintaining the representativeness of the
overall population. If a vehicle was sampled, the "cluster" of all child occupants
in that vehicle were included in the survey.
Drivers of sampled vehicles for which at least 1 child received medical
treatment were contacted by telephone (Ropen ASW, Princeton, NJ) and screened
via an abbreviated survey to verify the presence of at least 1 child occupant
with an injury. All vehicles with at least 1 child who screened positive for
injury and a 10% random sample of vehicles in which all child occupants screened
negative for injury were selected for a full interview. (The 2.5% of sampled
vehicles for which no children were treated were also selected for a full
interview.) The full interview involved a 30-minute telephone survey with
the driver of the vehicle and parents of the involved children. Only adult
drivers and parents were interviewed. The median length of time between the
date of the crash and the completion of the interview was 6 days.
The eligible study population consisted of 126 907 vehicles involving
189 962 children. Claim representatives correctly identified 93% of eligible
vehicles, and 77% of policyholders consented to participation in the study.
Of these, 22% were sampled for interview and an estimated 82% of these were
successfully interviewed (Figure 1).
Comparing the included sample with known population values from State Farm
claims, little difference exists; in both the sample and the population, 42%,
34%, and 24% of the vehicles were located in the East, Midwest, and West regions,
respectively; 52% of the sampled vehicles were model 1996 or newer, compared
with 51% of the population; 55% were passenger cars, 20% were passenger vans,
16% were sport utility vehicles, and 7% were pickup trucks, compared with
56%, 19%, 16%, and 7% in the population; and 33% were nondriveable, compared
with 32% of the population. The mean age of the child occupants in the sample
was 7.0 years, compared with 7.2 years in the population.
For cases in which child occupants were seriously injured or killed,
in-depth crash investigations were performed. Cases were screened via telephone
to confirm the details of the crash. Contact information from selected cases
was then forwarded to a crash investigation firm (Dynamic Science Inc, Annapolis,
Md), and a full-scale on-site crash investigation was conducted using custom
child-specific data collection forms. Among cases selected for investigation,
97% were completed. For the purposes of this analysis, these cases were used
to examine the validity of information obtained from the telephone survey.
Crashes involving passenger cars, vans, sport utility vehicles, and
pickup trucks were included in the study. Pickup trucks were defined as trucks
with an open cargo bed behind a closed cab.7
Pickup trucks were further classified as extended-cab (having 2 rows of seats)
or regular cab (1 passenger row only). Compact pickup trucks were defined
as those with a gross vehicle weight rating (truck weight plus carrying capacity)
of less than 6000 lb (2722 kg).7- 9
Compact pickup trucks weigh more than most passenger cars but are comparable
in weight with sport utility vehicles and minivans. For classification based
on cab type, the vehicle identification number was decoded using Vindicator
(Insurance Institute for Highway Safety/Highway Loss Data Institute, Arlington,
Va). Rear-seated children were believed to contribute to the excessive risk
of compact extended-cab pickup trucks, so we restricted our analysis to children
seated in vehicles with 2 or more rows of seats (97% of all children in the
sample). We have combined full-size extended-cab pickup trucks with other
vehicles, given that the rear seat of a full-size pickup truck is similar
in design to rear seats in other passenger vehicles and that preliminary analyses
indicated no significant difference in risk of injury among children in the
second row of these vehicles when compared with other vehicles.
Direction of first impact was derived from a series of questions regarding
the vehicle parts that were involved in the first collision. Crash severity
was categorized both by the tow status of the vehicle (ie, whether the vehicle
was towed from the crash scene) as indicated in the insurance claims data,
as well as by driver report via the telephone survey of intrusion into the
occupant compartment of the vehicle (ie, the integrity of the vehicle structure
was lost and the interior space was reduced).
Seating location of each child was determined from the telephone survey.
Among the 170 children for whom paired information on seating position (front
vs rear) was available from both the telephone survey and crash investigations,
agreement was 99% between the driver report and the crash investigator (κ
= 0.99; P<.001).
Restraint status of children was classified as either restrained or
unrestrained as determined from the telephone survey. Among the 164 children
for whom paired information on restraint use was available from both the telephone
survey and the crash investigation, agreement was 89% between the driver report
and the crash investigator (κ = 0.38; P<.001).
Survey questions regarding injuries to children were designed to provide
responses that were classified by body region and severity based on the Abbreviated
Injury Scale score,10 and have been previously
validated.11 For the purposes of this study,
children were classified as injured if they had an injury likely to require
medical attention, including any injury with an Abbreviated Injury Scale score
of 2 or greater (ie, concussions and more serious brain injuries, all internal
organ injuries, spinal cord injuries, and extremity fractures) and facial
Separate oral consent was obtained from eligible participants for the
transfer of claim information from State Farm to the Children's Hospital of
Philadelphia/University of Pennsylvania School of Medicine for the conduct
of the telephone survey and for the conduct of the crash investigation. The
study protocol was reviewed and approved by the institutional review boards
of both the Children's Hospital of Philadelphia and the University of Pennsylvania
School of Medicine.
The primary purpose of these analyses was to compute the relative risk
of injury for children in compact extended-cab pickup trucks compared with
children in other vehicles. Statistical significance was set at P<.05.
Because sampling was based on the likelihood of an injury, subjects
least likely to be injured were underrepresented in the study sample in a
manner potentially associated with the predictors of interest.12
To account for this potential bias, analytical methods were used to account
for sampling weights, sampling strata, and sampling units.
To compute P values and 95% confidence intervals
(CIs) to account for the stratification of subjects by medical treatment,
clustering of subjects by vehicle, and the disproportional probability of
selection, Taylor Series linearization estimates of the logistic regression
parameter variance were calculated using SAS-callable SUDAAN: Software for
the Statistical Analysis of Correlated Data, version 7.5 (Research Triangle
Institute, Research Triangle Park, NC). Results of logistic regression modeling
are expressed as unadjusted and adjusted odds ratios (ORs) with corresponding
95% CIs. Adjustments included seating position (front vs rear), age of the
child, restraint use, point of first impact, crash severity, and vehicle weight.
Complete interview data were obtained for 7192 vehicles with 2 or more
seating rows involving 11 335 children, representing an estimated 110 423
children in 71 229 vehicles in the study population. Injuries were reported
for 1356 of the sampled children, representing an estimated 1756 children
or 1.6% of the population.
Child occupant characteristics and crash characteristics associated
with each child occupant are given in Table
1. Children in compact extended-cab pickup trucks comprised 1.1%
of the estimated overall population of children in crashes. On average, children
in compact extended-cab pickup truck crashes were older, more likely to be
restrained and seated in the front row, and more likely to contact the interior
of the vehicle during impact than children in other vehicles. The crashes
in which they were involved were more likely to be frontal-impact crashes
and less likely to be multiple-impact crashes, although there was no significant
difference in crash severity as measured by intrusion or tow status and virtually
no difference in mean vehicle weight when comparing crashes involving compact
pickup trucks with those involving all other vehicles.
Injuries occurred in 7.5% of the children in compact extended-cab pickup
truck crashes compared with 1.6% of the children in other vehicle crashes.
One compact extended-cab pickup truck crash involved a child with an injury
(concussion) who had not initially received medical treatment and, as per
our sampling algorithm, this crash had an unusually large sample weight compared
with other children with injuries. Excluding this crash would result in an
estimated risk of injury in compact extended-cab pickup trucks of 3.8%. To
produce more conservative estimates of injury risks, we excluded this crash
from further analyses.
The distribution of the injuries among the 32 (unweighted number) injured
children in compact pickup trucks was as follows (note that some children
had multiple injuries): 23 head injuries, 8 facial lacerations, 3 pulmonary
contusions, 1 hemopneumothorax, 3 internal abdominal organ injuries (2 kidney
and 1 spleen), 1 spinal cord injury, 5 upper-extremity fractures (3 forearm,
1 clavicle, and 1 unknown type), and 2 lower-extremity fractures (1 femur
and 1 unknown type). All of these children underwent medical treatment: 11
were admitted to the hospital (6 to the intensive care unit), 18 were treated
and released from the emergency department, and 3 visited an urgent care center
or physician's office. Children in compact extended-cab pickup trucks were
more than 4 times as likely to be hospitalized as children in other vehicles
(OR, 4.43; 95% CI, 1.68-11.68).
Children in compact extended-cab pickup trucks were at nearly 3 times
the risk of injury (OR, 2.96; 95% CI, 1.68-5.21) compared with children in
other vehicles after adjusting for age, restraint use, point of impact, vehicle
weight, and crash severity (Table 2).
There was a significant interaction (P = .047) between
seating position (front vs rear) and risk of injury for children in compact
extended-cab pickup trucks (Table 3).
Children in the rear seat of compact extended-cab pickup trucks were more
than 4 times as likely to be injured (adjusted OR, 4.75; 95% CI, 2.39-9.43)
as rear row–seated children in other vehicles; front row–seated
children also appeared to be at greater risk, although this difference was
not statistically significant (adjusted OR, 1.70; 95% CI, 0.78-3.69). Put
another way, the protective effect of rear-row seating vs front-row seating
for children in other vehicles (adjusted OR, 0.71; 95% CI, 0.57-0.89) was
not observed for children in compact extended-cab pickup trucks (adjusted
OR, 1.99; 95% CI, 0.75-5.30) (Table 4).
A substantial portion of the increase in risk of injury to children
in compact extended-cab pickup trucks appears to be mediated by contact with
the vehicle interior during the crash. Adjusting for interior contact reduced
the OR for injury in compact extended-cab pickup trucks vs other vehicles
to 2.10 (95% CI, 1.26-3.51) (Table 2).
In addition, the effect of contact (ie, the risk of injury given contact)
appeared stronger in compact pickup trucks than in other vehicles (adjusted
OR, 13.82; 95% CI, 4.42-43.19 in compact pickup trucks vs adjusted OR, 4.81;
95% CI, 3.77-6.13 in other vehicles; P value for
difference = .08).
When limiting analysis to children in pickup trucks, children in the
rear seat of compact pickup trucks were at more than twice the risk of injury
(4.9%) than children in the rear seat of full-size pickup trucks (2.1%; adjusted
OR, 2.99; 95% CI, 0.72-12.33). The risk of injury to children in the front
seat of compact pickup trucks is greater than that to those in the front seat
of full-size pickup trucks, although this difference is less pronounced than
in the rear seat (3.0% vs 1.8%; adjusted OR, 1.45; 95% CI, 0.41-5.16).
On average, children seated in compact extended-cab pickup trucks are
not as safe as children seated in other vehicles, primarily because the protective
effect of rear seating is not present in compact extended-cab pickup trucks.
Therefore, parents with a choice of vehicles available to transport their
children should not use compact pickup trucks. The hazards of riding in the
front seats of vehicles for children are well known,13,14
and, in the current study, it was found that children in the front seats of
compact extended-cab pickup trucks are at even higher risk of injury than
children in the front seats of other vehicles, although this result did not
reach statistical significance. Furthermore, children in the rear seats of
compact pickup trucks are at substantially increased risk of injury compared
with children in the rear seats of other vehicles. This increase in risk appears
to be caused at least in part by contact with the interior of the vehicle
These results point to unique hazards of compact extended-cab pickup
trucks that put children at risk. The rear occupant compartment of compact
pickup trucks is smaller than that of most other vehicles. In addition, these
rear seats provide only 2-point (ie, lap-only) restraints that allow for excessive
upper body movement in the event of a crash. These factors may contribute
to excess vehicle interior contact for occupants of compact pickup trucks.
Furthermore, the trend toward increased risk of injury given vehicle interior
contact in compact pickup trucks suggests that inadequate vehicle padding
may contribute to the injuries sustained by child occupants in these vehicles.
For example, the unpadded rear wall of most compact trucks may be struck by
occupants either directly, in rear collisions, or on rebound, in frontal collisions,
with children seated sideways.
For all vehicles sold in the United States, Federal Motor Vehicle Safety
Standard (FMVSS) 201, Occupant Protection in Interior Impact (49 CFR 571.201)
Section S5.2 requires that the portion of the seat back that is within the
head impact area be tested by a prescribed procedure except in the case of
side-facing, folding auxiliary jump seats. Section S5.2.1 of Standard 201
states that the testing requirements do not apply to such temporary seats.
Therefore, testing for occupant protection in interior impact is not required
for the rear seats in most compact pickup trucks. Results from this study
suggest that this exemption should be reconsidered and that testing is needed
to ensure sufficient rear occupant space to allow for head excursion in the
event of a crash, as well as adequate padding in the rear occupant compartment
For more than 20 years, rear seating has been associated with reductions
in risk of serious injury and fatality to children.13,14
Recognizing the safety advantages of rear seat occupancy, multiple national
organizations, including the National Highway Traffic Safety Administration4 and the American Academy of Pediatrics,3
have promoted rear seating for children. In the current study, 46% of children
in compact extended-cab pickup trucks were in the rear seat, suggesting that
many parents are attempting to follow these recommendations, even in compact
pickup trucks. These data suggest that the rear seats in compact pickup trucks
are not being used as auxiliary seats (ie, ones that are not intended for
regular use) as they were designed, but rather as common seating positions
for child passengers. This provides further justification for removing the
exemption for testing in FMVSS 201.
This study relied on parent report of restraint use by children, which,
if differentially reported by vehicle type, might have biased the results.
To determine some potential effects of restraint misclassification, we assumed
that those identified as unrestrained were indeed unrestrained and that the
observed risk of injury among the unrestrained correctly estimates their risk.
If we further assume that all of those classified as restrained in other vehicles
were correctly classified, 42% of those classified as restrained in compact
extended-cab pickup trucks would have to be unrestrained for the risk differences
between those restrained in compact pickup trucks and those restrained in
other vehicles to be eliminated. Since the maximum misclassification rate
among compact extended-cab pickups (which requires the risk of injury among
the restrained to be 0) is 49%, this is highly unlikely. Assuming a 20% misclassification
rate among other vehicles (the maximum possible is 31%) would require a misclassification
rate of 46% among compact extended-cab pickup trucks to nullify risk differences.
It is highly unlikely that this large of a differential misclassification
Ongoing comparisons of driver-reported child restraint use and seating
position to evidence from crash investigations have demonstrated a high degree
of agreement. In addition, our results on age-specific restraint use and seating
position are similar to those of other recently reported population-based
studies of child occupants.15,16
We have used ORs as an approximation to risk ratios; for unusual strata
that are at very high risk of injury, such as unrestrained children in high-velocity
crashes, this approximation fails and use of the OR will overstate the true
increase in risk.
Surveillance data of the nature presented in this study cannot elucidate
precise injury mechanisms. More detailed information on the nature and severity
of the injuries, occupant kinematics, and the occupant compartment space and
configuration is needed to inform regulations for testing.
For families who have a choice of vehicles available for transporting
children, clinicians should advise parents against transporting children in
compact pickup trucks. When an alternative vehicle is not available, it is
not clear whether front vs rear seating is optimal for children in compact
extended-cab pickup trucks, though either is clearly preferred to riding in
the cargo area, which has a well-described fatality risk.2,17,18
In this case, clinicians should advise parents either to consult the vehicle
owner's manual or contact the vehicle manufacturer to obtain recommendations
regarding optimal protection of children in the pickup truck.