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Williams S, Whitlock E, Smith P, et al. Primary Care Interventions to Prevent Motor Vehicle Occupant Injuries [Internet]. Rockville (MD): Agency for Healthcare Research and Quality (US); 2007 Aug. (Evidence Syntheses, No. 51.)

Cover of Primary Care Interventions to Prevent Motor Vehicle Occupant Injuries

Primary Care Interventions to Prevent Motor Vehicle Occupant Injuries [Internet].

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Scope and Purpose

This systematic review examines the evidence for the benefits and harms of counseling primary care patients to use age- and weight-appropriate motor vehicle occupant restraints for themselves and their children. We also examine evidence about primary care counseling to reduce alcohol-related drinking and driving behavior. Our review includes studies conducted in primary care, inpatient maternity wards, and settings that are feasible for referral from primary care. We defined behavioral counseling interventions as any intervention that included behavioral counseling among its components. This review's purpose is to summarize the current state of the evidence relevant to primary care clinicians and identify key gaps in this scientific literature.


Burden of Illness

Motor vehicle-related injuries are the single leading cause of death for children, adolescents, and young adults between the ages of 3 to 33 years in the United States, 1 and the leading cause of unintentional injury-related deaths for all ages. 2 During 2004, 42,636 people were killed in motor vehicle traffic crashes, and over 8,000 of those killed were infants, children, or adolescents. 3 Among these fatalities, 39% percent were in alcohol-related crashes, and 30% of drivers and 50% of occupants were unrestrained. Due to their premature nature, motor vehicle-related deaths are the third leading cause of years of life lost (1,766,854 years) for all ages, surpassed only by cancer and diseases of the heart. 1 An additional 2,788,000 people sustained non-fatal injuries. 3 In 2000, motor vehicle crashes are estimated to have cost $230.6 billion, representing $820 for every man, woman and child in the US. 4 In the same year, the total costs to society were $50.9 billion from alcohol-related crashes and $26.0 billion from safety belt non-use. In 2000, $32.6 billion was spent on medical care to treat injuries caused by motor vehicle crashes.

Mortality rates are highest among new drivers and young adults (16 to 24 years of age). These rates are two to three times higher in males than females in these groups, with the gender differential particularly among fatally injured drivers. 3 Male drivers may take more risks and male occupants are less likely to be restrained. Even when controlling for vehicle miles traveled, young adults have the highest fatality rate, closely followed by drivers greater than 85 years. Older drivers are more fragile and less likely to survive crashes, but drive a fewer total number of miles annually, 5 thus reducing their exposure. Fatally-injured older motor vehicle occupants are also more likely to have been wearing occupant restraints and older drivers are less likely to have a crash involving alcohol. 3 Occupants of passenger vehicles accounted for 78% of all of the traffic fatalities, with the remainder occurring among motorcycle riders, pedestrians, bicyclists, and other nonoccupants. Increasing the use of occupant restraint devices (child safety seats and lap/shoulder safety belts) and reducing alcohol-impaired driving are among the most important behavioral methods to reduce motor vehicle-related fatalities. 6 An additional 5,839 lives could have been saved if 100% of occupants used their restraints. 3

Factors that influence the proportion of deaths per trip traveled among adults (25–64 years) in decreasing order are gender, SES as measured by educational level, and race/ethnicity. 7 Women have half the death rate for trips traveled compared to males. Individuals with less than a high school education have a three-fold increased risk of death, and also have the greatest alcohol use. The influence of race/ethnicity varies with SES, seat belt use, and alcohol use. Caucasian males have the highest fatality rate among those with less than a high school education, but Blacks have the highest fatality rate as educational level increases. A greater proportion of Hispanics have elevated blood alcohol levels (BAC 0.10), and a greater proportion of Blacks are unrestrained. Finally, a greater proportion of Hispanics are both unrestrained and have elevated BAC, compared to Caucasians and Blacks.

Occupant restraint devices

Occupant restraint devices, specifically lap/shoulder belts, hold passengers in place during crashes and prevent contact with the vehicle's interior components and ejection from the vehicle. Child safety seats and booster seats are tailored to a child's anatomy so that they restrain without applying dangerous forces to vulnerable regions of the body. Optimal restraint use for children less than nine years of age entails the proper use of age- and weight-appropriate child safety seats or booster seats and children under 13 years should ride in the rear of the vehicle. 8 Traffic safety organizations make specific recommendations about the type of restraint systems that should be used, as well as seating position based on the occupant's age, weight, and height (Table 1). 8 When used correctly, child safety seats reduce risk of fatal injury by over 70% and risk of hospitalization by 67% for infants up to one year old and they reduce fatality risk by 54% for children 1 to 4 years old. 9, 10 Misuse of safety seats, which is reported as high as over 80%, can partially or completely nullify this effect. 11 14 Compared to seat belts, the use of belt positioning booster seats among four to seven year olds decreases the odds of injury by 59%. 12 Depending on seating position (front or rear), crash characteristics, and vehicle type, lap/shoulder belts use has been shown to reduce risk of fatal injury by 45%–70% and are 15–25% more effective than lap belts alone. 15, 16

Table 1. Recommendations for child safety seats (CSS) based on age and weight.

Table 1

Recommendations for child safety seats (CSS) based on age and weight.

Regulation by states plays a large role in increasing occupant restraint use. While all 50 states have laws requiring safety seats for infants and children and 49 states and the District of Columbia have adult seat belt use laws, large variation exists in the legislation. 17 For example, 34 states allow for children to travel unrestrained for circumstances such as nursing mothers, non-state residents, and overcrowding in vehicles. In 28 States, the laws specify secondary enforcement meaning that police officers may write a citation only after a vehicle is stopped for another traffic violation. 18 Data show that states with primary enforcement have absolute increases in the prevalence of observed restraint use of 12–23% and decreases in motor-vehicle-related fatality rates of 3–14%, compared to states with secondary enforcement. 19

Overall, restraint use has been rising and is considered a public health success. 20 Variation in restraint use depends on the individual's gender; age, seating position, economic status and race/ethnicity of the occupant. At the population-level, drivers and front seat adult passengers have an average observed restraint use of 82% (range 60–95%). Among these types of occupants, individuals from racial/ethnic minorities or of lower social economic status have 9–15% less restraint use. 7, 21, 22 Across all these groups, females have a higher restraint use than males. 23, 24 Among children, infants and toddlers have the highest restraint use followed by school-age children and adolescents (Figure 1). 25 Restraint use for children less than 8 years of age is complicated by the additional need to correctly use the age-appropriate car safety seat or belt-positioning booster seat. Misuse severe enough to theoretically compromise the effectiveness of the child safety seat or booster seat is common (range 20% – 84%), varies by type of seat (Figure 2), and is most commonly due to loosely attaching the seat to the vehicle by the seat belt or loose harness straps securing the child to the safety seat. 14 Among children who were involved in motor vehicle crashes in three large US regions in 2002, only 17 – 23% of children four to six years old, and 3% of those seven to eight years old were reported to have been restrained in belt-positioning booster seats. 26 Crash data show that 55% of fatalities were among unrestrained occupants, even with the increasing observed restraint use. 3

Figure 1. Restraint use among children, adolescents, and young adults in 2004 .


Figure 1. Restraint use among children, adolescents, and young adults in 2004 . * Any restraint use, without specifying correct use.

Figure 2. Child restraint system (CRS) misuse.


Figure 2. Child restraint system (CRS) misuse. * of the 3,442 CRSs observed in this study, 72.6 percent displayed one or more types of critical misuse. Critical misuse is defined as forms of misuse identified by a panel of experts that could reasonably (more...)

Alcohol-related driving

In 2004, 16,694 of all motor vehicle-related fatalities involved alcohol, representing 39% of all traffic-related deaths. 3 Of these deaths, 14,409 (86%) occurred in crashes in which at least one driver had a blood alcohol concentration (BAC) above the legal limit in most states (0.08 gram per deciliter (g/dL) or higher). 3 It is important to note, however, that driving skill impairment begins at even lower BAC levels. 27 Observational data from controlled studies demonstrate that drivers involved or injured in crashes are more likely to have a BAC of at least 0.10 than are other drivers. 28 Evidence from multiple time-series studies demonstrates that raising the legal drinking age or lowering legal blood concentration limits can significantly reduce alcohol-related fatal crashes. 28, 29

Currently, all 50 States, the District of Columbia, and Puerto Rico have laws making it illegal to drive with a BAC of 0.08 g/dL or higher, 30, 31 and rates of alcohol-involvement among fatal crashes have decreased in the last two decades. 32 Based on self-reported data from nationally representative population-based surveys, the prevalence of drinking and driving among drivers 18 and older was 2% during the previous month and, among drivers 16 and older, was 22% during the previous year (Table 2). 33 34 Reported prevalence is higher among males, younger adults (ages 18–34), and among those also who report binge drinking or heavy alcohol intake. 33 Among persons ages 16–64 years, 12% reported having ridden with someone during the past year who they thought may have had too much alcohol to drive safely. 34 High school students are more likely to report both driving after drinking alcohol during the previous 30 days (range 5–26%) and riding with a driver who had been drinking alcohol during the previous 30 days (27 – 40%). 35 Safety belt use among alcohol-impaired drivers is lower compared to other drivers. 30 Among children who died in alcohol-related crashes in which the drivers were drinking, the majority of children are unrestrained. 36

Table 2. Prevalence of driving or riding with drivers under the influence of alcohol.

Table 2

Prevalence of driving or riding with drivers under the influence of alcohol.

Current Clinical Practice

In 2000, 57% of primary caregivers (i.e., parents or other caregivers) of infants and toddlers ages 4–35 months answering a nationally representative survey indicated that their providers had talked with them about car seats during the previous 12 months (Table 3). 37 In a multiple-state survey of primary caregivers of children younger than 13 years, 38% of caregivers reported that their child's doctor had “talked with them about transporting their child safely.” 38 Caucasian respondents who had a higher income were most likely to report receiving counseling (51%), compared to African Americans and Hispanics from any income level and lower- income Caucasians (33–38%). These subgroup differences may have been confounded by the source of clinical care, as higher-income Caucasians were more likely to be seen by a pediatrician and counseling was higher among respondents who received care by pediatricians (45%) compared with other sources. Only 4%–5% said their physician actually spoke with them about car safety, while the rest received education materials, videos, or information from non-physicians.

Table 3. Current clinical practice for counseling on motor vehicle restraints and alcohol use.

Table 3

Current clinical practice for counseling on motor vehicle restraints and alcohol use.

In a recent survey, 60 academically-affiliated Canadian pediatricians self-reported their assessment of, and education about, child safety restraint use among their pediatric patients “most of the time” or “always.” 39 Between 29%–31% reported that they asked if a rear-facing car seat was used and educated parents to secure the car seat harness correctly at the first well-child visit. Fifty-five percent reported instructing parents to graduate their child from a forward-facing car seat to a booster seats and 36% educated parents about the risk associated with premature graduation to a lap and shoulder seatbelt. A higher proportion reported advising parent that the rear vehicle seat is the safest place (69% reported counseling “most of the time” or “always”).

In a nationally-representative survey assessing injury prevention counseling during 1997 to 2000, office-based physicians reported counseling adolescents during 10–15% of visits and adults during 2% of visits (Table 3). 40 42 In another recent survey, pediatricians and family practice physicians reported that they screened or educated 37–68% of adolescents about alcohol use and screened 17–40% about riding with a driver under the influence of alcohol, with higher rates of counseling among older adolescents. 43

Previous USPSTF Recommendations

In 1996, the USPSTF made recommendations for primary care clinicians regarding motor vehicle safety. 28 These USPSTF recommendations reviewed the effectiveness of the behavior in reducing morbidity and mortality, as well as the effectiveness of clinician counseling to increase safe behaviors. The USPSTF found that the correct use of federally approved child safety seats and lap/shoulder belts was effective in preventing morbidity and mortality (A recommendation for child safety seat use and lap/shoulder belt use). The USPSTF recommended that clinicians regularly counsel patients and their families to use age- and weight-appropriate restraint system (B recommendation for child safety seat use and lap/shoulder belt use).

The USPSTF made multiple recommendations regarding counseling about alcohol and drug use, which are major risk factors for motor vehicle collisions. The USPSTF recommended that clinicians counsel all patients regarding the risks of driving under, or riding with someone under the influence of, alcohol or other drugs, based on the proven efficacy of risk reduction (A recommendation). The USPSTF cited the effectiveness of counseling problem-drinkers to reduce alcohol consumption (B recommendations) and determined that no evidence was available regarding the effectiveness of clinicians counseling all patients to avoid drinking and driving (C recommendation).


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