Child Passenger Safety: An Evidence-Based Review

Authors

Child Passenger Safety Workgroup of the EAST Practice Management Guideline Committee

Robert D. Barraco MD, MPH, Chair, Lehigh Valley Health Network, Allentown, PA
Julius D. Cheng, MD, MPH, Vice Chair, University of Rochester Medical Center, Rochester, NY
William J. Bromberg, MD, Memorial Health University Medical Center, Savannah, GA
Richard A. Falcone, MD, Cinncinati Children’s Hospital Medical Center, Cincinnati, OH
Jeffrey S. Hammond, MD, MPH, University of Medicine and Dentistry of New Jersey, New Brunswick, NJ
Felix Y. Lui, MD, Yale School of Medicine, New Haven, CT
Rovinder S. Sandhu, MD, Lehigh Valley Health Network, Allentown, PA
David W. Scaff, DO, Lehigh Valley Health Network, Allentown, PA

Address for correspondence: 
Robert D. Barraco MD
Department of Surgery, Lehigh Valley Health Network
Cedar Crest & I-78, P.O. Box 689
Allentown, PA 18105-1556
phone: 610-402-1296
fax: 610-402-1667
sally.lutz@lvh.com

I. Statement of the Problem

Motor vehicle crashes are the number 1 cause of death in the United States in children age 14 and under. They are the number 2 cause of death in toddlers and the number one cause of death in the 5 to 14 year old age group.  

There is literature that shows that proper restraint use can reduce these injuries and fatalities. However, according to SAFE KIDS study, 81% of children are incorrectly restrained (Child Passengers at Risk in America: A National Study of Restraint Use, National SAFE KIDS Campaign, 2002).

Legislation has attempted to reduce these numbers. Two means to this end are primary and secondary laws. A primary law allows motorists to be pulled over and cited if noted to be in violation of that law. A secondary law does not allow motorists to be stopped for violating that law but instead mandates the motorists be stopped and cited for another violation before dealing with the one in question. All 50 states and the District of Columbia (http://www.iihs.org/laws/restraintoverview.aspx) have some form of child restraint laws, only half are primary and none have detention options. There are data in adults to show primary laws are more effective in increasing compliance.

Despite the above, passenger vehicle occupant deaths among children were only 16% lower in 2004 than in 1975 (http://images.businessweek.com/autos/pdfs/children.pdf). In 2004, five children died and 586 were injured each and every day in motor vehicle crashes in the United States. Of those killed, half were unrestrained. In 2005, 29% or almost one-third of children younger than age one who were killed in motor vehicle crashes were totally unrestrained. Fifty-six percent of children ages 9 -12 who were killed in motor vehicle crashes that same year were also totally unrestrained (http://www.iihs.org/research/fatality_facts_2005/children.html).

This is obviously a public health issue of the greatest magnitude. The safety of our children is paramount. Therefore, we in the Child Passenger Safety Workgroup of the EAST Practice Management Guideline Committee will examine the literature concerning the following questions to be answered

Questions to be addressed

1.  What is the effectiveness of child passenger restraints in reducing morbidity and mortality?
2.  What is the effectiveness of legislation in the reduction of injuries and/or mortality?

II. Process

We conducted a Medline search for human, English language literature from 1980 to 2006 on child passenger restraints. Child passenger restraints as keyword only yielded four results. Using “Protective Devices” or “Seat Belts” and combining that with “infant” over similar dates and restrictions, 491 references resulted, with toddler, six resulted, with “child,” 827 references resulted and with “adolescent,” 842 resulted. Studies from other countries that involved legislation were dropped due to issues of generalizability. Fifty-nine were deemed appropriate to answer the above questions, 55 of these were available for review. Fourteen articles examined legislation and 41 articles examined restraint effectiveness with relation to outcomes. We did not utilize technical reports or engineering literature, but felt these were not relevant to the endpoints of morbidity or mortality and many could not be subject to scientific review.

III. Scientific Foundation

Restraint effectiveness

Three class II and 21 class III articles demonstrate reduction of injury and/or injury severity with restraint use in children. Two class II and 10 class III articles demonstrated reduction of mortality with automotive restraint use in children as compared to unrestrained children. The risks of injury follow a continuum, with unrestrained children faring worse in a crash than improperly restrained children faring worse than restrained. Unrestrained 0-4 year olds had relative risks (RR) of 4.4 for broken bones, 2.7 for concussions, 2.5 for open wounds and 2.5 for hospitalization (O­30) compared to restrained children. In children aged 2-5 years, premature graduation of children to seat belts had a RR for injury of 2.5 compared to those still in child safety seats. The RR was 4.2 for head injury in this study. The RR of injury was higher for 2-3 years olds (4.0) than 4-5 years olds (2.4)^[40]. In children age 4 and above, restrained children fared better than unrestrained.^[2] Compared to children in proper restraints, unrestrained children had 3 times the risk of injury. Inappropriate restraints also increased the risk of injury, doubling that risk compared to appropriate restraints ^[20]. One large retrospective study of 5751 children showed that among those children age 0-4, 27% were unrestrained compared to 44% of children age 5-11 and 52% of children age 12-14. In the same study, overall figures showed that 38% of children were optimally restrained and 34% suboptimally restrained. Those with restraint devices were 2.7 times more likely not to have a serious injury ^[10]. Another study of 600 children showed that age-appropriately restrained children had a significant reduction in severe injuries in every anatomic site except the back. This study also showed a reduction in solid and hollow visceral injuries as well as mortality with age-appropriate restraints.^[39]

Other studies corroborated this risk reduction for age-appropriate, optimal restraints with a three-fold decrease in significant intra-abdominal injury and a 28% reduction in mortality risk^{[21] [29]}. Forward-facing restraint systems were found to reduce injury compared to seat belts in the 1-4 year age range^[7-8]. Lap belts only are associated with increased spinal cord injury^[25]. Facial fractures are also increased in inappropriately restrained and front seat children, RR 1.6 and 1.8, respectively^[6].   Suboptimal restraint use has a RR of hollow viscus injury of 4.4 compared to appropriate restraint use^[26]. Improper use is cited in a class II article comparing restrained to unrestrained children, showing that restrained children were less injured than unrestrained. Serious injuries in this study resulted from improper use, using seat belts at an inappropriate age or unavoidable circumstances such as intrusion or being struck by non-stationary objects^[1].

Belt-positioning booster seats reduce injury by 58 to 70% in children age 4-8 while mortality is also reduced by 61%^{[4] [17]}. Backless booster seats were found to be no different than seatbelts in risk^[4]. Only one class III article showed an increase in head and cervical spine injuries with restraint devices in children 0 to 8 years of age compared to those from 9-18^[41]. Many have explained this predisposition by the anatomic differences in the developing pediatric C-spine. However, their evaluation was limited in that they could not determine if the restraints systems were used properly or were appropriate to the weight and age of these younger children. Only one class III article addressed cost and showed a decrease in healthcare costs in Arizona with use of child passenger restraints^[15]. There were not enough articles to develop a recommendation on this topic.

Seven class III articles supported rear seat position for children 12 and under.  Risk of injury and/or mortality in the front seat was 40% to 70% higher than the rear seat.^{[6] [9-11] [14] [22] [36]} One article documented risk reductions for fatal injury with rear seat position of 41% from age 1-4, 30% from age 5-12, and 32% from age 13-18. The center rear seat was the safest with a 9-24% risk reduction for fatal injury compared to the outboard seats. Risk reductions applied to all but rear impact collisions. Restraints also reduced fatal injury risk in this study as well.^[11]  

Seven studies (1 class II, 6 class III) showed increased injuries and mortality from airbags in children up to 12 years old.^{[5] [9] [14] [18-19] [22] [36]} One class II study showed as high as 84% mortality for unrestrained children and 31% mortality for restrained children with airbag deployment.^[22] This is even higher for restrained infants who are at 254% increased risk of dying in the front seat with an airbag compared those without airbag. This was the only study not to find increased mortality in children 9-12 from airbags. Two class III articles suggested that second-generation airbags may result in less injury than first-generation airbags.^{[5] [9]}

Legislation Effectiveness

Seven articles, three Class II, and four Class III, demonstrated increased (perceived or observed) compliance with child restraint use.^{[42-43] [45] [50-53]} Four studies showed decrease in injury^{[42] [47-49]} and three a decrease in mortality^{[45] [48-49]} with enactment ofvchild restraint legislation. The magnitude of the decrease in injury and death ranged from 10% to 50%. Ages in the studies were not uniform and ranged from 0 to 15.

IV. Recommendations

Level 1 Standards

1. Child restraint and restraint systems reduce injury and injury severity in all ages reported and are recommended for use.
   1. The highest reductions come from age appropriate, properly used restraints, as per the American Academy of Pediatrics guidelines on selection and use of car safety seats.

Please note that these recommendations rose to Level 1 standards based on the preponderance of available literature, including well-done Class II data, that supports the age-appropriate use of child restraints and restraint systems as successful in the reduction of morbidity and mortality.

Level 2 Guidelines

1. Rear seat position reduces injury at all ages studied and is recommended especially for those less than or equal to 12 years of age.
2. Airbags can cause injury and/or death to children less than or equal to 12 years of age and thus seating position with exposure to airbags should be avoided in that age range.
3. Child restraint laws help reduce injury and mortality and increase compliance with restraint use.

V. Summary

Child restraints are clearly effective in injury prevention and reduction of injury severity at all ages examined. Rear seat position is also effective, especially when used in conjunction with child restraints. Legislation is also effective in improving compliance and even reducing injury. There are some data showing that primary laws are the most effective form of legislation. Further research is required on the effectiveness of legislation on injury and mortality. 

VI. References

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2. Agran PF. Comparison of Motor Vehicle Occupant Injuries in Restrained and Unrestrained 4- to 14-Year-Olds. Accid Anal Prev. 1992;24:349-355.
3. Anonymous. Child Passenger Restraint Use and Motor-Vehicle-Related Fatalities Among Children - United States, 1982-1990. MMWR Morb Mortal Wkly Rep. 1991;40:600-602.
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7. Arbogast KB. Evaluation of pediatric use patterns and performance of lap shoulder belt systems in the center rear. Annu Proc Assoc Adv Automot Med. 2004;48:57-72.
8. Arbogast KB. An evaluation of the effectiveness of forward facing child restraint systems.Accident Anal Prev. 2004;36:585-589.
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