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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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Despite marked progress in reducing the motor vehicle-related mortality rate in the United States during recent decades, these injuries remain the leading cause of death for children, adolescents, and adults up to age 33. 1 The evidence for reducing the risk of injury and death when using child safety seats has been previously demonstrated to be strong and the current prevalence of restraint use is near the HP 2010 goal of 100% use for infants and is over 90% for children ages 1–3 years. 25 Incorrect use, however, remains common in these age groups and diminishes the level of protection provided. Restraint use is less prevalent among children ages four to -seven, among whom premature advancement to seat belts causes in increased risk of injuries, and among adolescents and adults (20–25% non-use in all these age groups). 24

The available scientific literature provides fair evidence that among infants and children up to age four, behavioral counseling interventions are effective in increasing short-term correct use of infant and child safety seats at the time of hospital discharge or within two months after initially delivering the intervention. Effects appear to diminish at later time points, in many cases because use picks up over time in groups without intervention. But, because correct use changes with age and growth (from rear facing to forward facing, from infant seats to toddler seats), messages may need to be delivered at multiple time points to educate parents about the next appropriate position or device to use. Many of the successful interventions included a demonstration of correct safety seat use as one component. The largest effect sizes were seen among the trials that included a safety seat distribution program through a reduced-cost loan or giveaway program. Several interventions that did not include distribution programs, however, were also effective, at least in the short-term. Some of the better quality trials were non-randomized controlled trials conducted during the late 1970's to 1980's, when many states were first starting to pass child seat restraint laws. No good-quality RCTs have been conducted for behavioral counseling among infants and children up to age four years. Experts in the field, including authors of previous evidence reviews, have expressed concern about the limited quality and lack of recency in this body of evidence, 46, 47, 72 especially given the magnitude of public health burden for this age group.

Child safety seat laws and other community-wide educational strategies are effective methods for increasing child safety seat use. 73 Due to recently revised safety recommendations, however, only 28 states currently have laws that apply to children in booster seats and most of these do no cover all children up to age eight years. 31 We identified one recently-conducted trial targeting booster seat use for four to seven year olds that demonstrated a large increase in self-reported use among previously non-using families that received education and a free booster seat. This trial was conducted among low-income families who presented to an emergency department for any chief complaint and were therefore similar to a low-income primary care population. The intervention, however, was delivered by certified car seat technicians who had undergone intensive training that is not routine for primary care clinicians. In addition, the distribution of a free booster seat was required in order to be effective. Translation of these findings to the primary care setting might be possible if new health care systems were developed to provide education by certified car seat technicians and free booster seats to patients in conjunction with primary care clinics.

Community-based interventions may be worth reviewing for their generalizability to the primary care setting. The Cochrane Collaboration recently reviewed effective interventions for the promotion of booster seat use that were set in non-primary care settings. 74 Interventions included education-only, distribution and education, incentive and education and enforcement. Meta-analysis of five studies demonstrated a two-fold increase in booster seat use, with interventions incorporating both incentives and education demonstrating the largest increases. Education-only interventions also demonstrated a small beneficial effect. Furthermore, because the current regulatory and cultural context for child booster seat use is similar to that for child safety seat use in the 1970s and 1980s, findings from older behavioral counseling trials included in our review that address child safety seat use among infants and toddlers may be considered for generalizing to primary care counseling for booster seat usage in current practice, if one assumes that the barriers to use among young children four to eight years are the same as among infants and toddlers.

Even in the absence of evidence for clinical counseling's effectiveness, clinicians can play an active role in advocating for evidence-based policies to create laws requiring booster seat usage for children ages four to eight years old. The professional role of physicians as public advocates for solutions to high-priority community health problems has recently been explored 75, 76 and appears to be particularly appropriate in this arena of injury prevention.

Few trials have evaluated counseling to increase seat belt use among older children and adolescents. Individuals in these age groups may be seen less often by primary care clinicians than younger children. 40 Hence, fewer opportunities exist to deliver or reinforce counseling messages. Evidence from the infants and young children suggests that short-term improvements are possible and findings could be applicable to older age groups to the extent that the motivations for use, barriers to use, and receptivity to counseling are similar. However, one relatively recent trials that we identified that targeted seat belt use among older children 70 reported no difference in seat belt use between the intervention and control groups one to three years later. It is possible that short-term effects occurred but were not measured or that the effects of counseling are different for older children. In addition, baseline seat belt usage in both groups was quite high (72 – 74%) and so it is possible that counseling may be less effective among higher use populations.

Data describing effects of counseling adults to use seat belts are lacking. Relatively high rates of current usage, supported by laws regulating seat belt use in most states may indicate that primary care clinicians' efforts to counsel all adults about seat-belt use should not be a high priority area for clinical preventive action. Strong evidence exists demonstrating that safety belt laws, primary enforcement strategies, and enhanced enforcement strategies (e.g., increasing the number of police officers on patrol) are all effective for increasing seat belt use. 19 Clinicians should advocate for these types of legislative measures if they are not already in place in their communities.

We found no research that addressed the impact of behavioral counseling interventions delivered to unselected patients in primary care to reduce alcohol-driving or riding with an impaired driver. However, the USPSTF has recommended screening and brief interventions for alcohol misuse in primary care, 55 and these interventions may also improve alcohol-related MVOIs. In the systematic review on primary care screening and interventions for risky and harmful alcohol prepared to support the USPSTF recommendation process, 49 only one randomized controlled trial (of the 12 controlled trials addressing brief primary care interventions for risky/harmful alcohol use) included self-reported driving after drinking—as well as binge or high chronic drinking patterns—when identifying alcohol misusers. 77 Fifty-five percent of all primary care patients who were defined as risky or harmful drinkers and eligible for brief intervention reported driving after drinking greater than two drinks; patients reporting alcohol-impaired driving represented less than 5% of all primary care patients. At 12 months after brief intervention, self-reported rates of driving after drinking were nearly half as great in the intervention group of risky/harmful drinkers (18%), compared with controls (34%) (p=.006). In a different randomized controlled trial of a brief primary care intervention to reduce binge drinking (more than five drinks of a single occasion) and heavy usual alcohol intake, 78 a sub-analysis of young adults aged 18–30 years in the trial found significant reductions in the proportion drinking heavily or binge drinking, with significant reductions after four years in total motor vehicle events (114 vs. 149, p<.05) and in motor vehicle crashes with non-fatal injuries (9 vs. 20, p<.05). 79 Emergency department visits were also reduced (103 vs. 177, p<.01). MVOI is the leading cause of death in the U.S. for people aged 3 to 33 years, with 39% of these deaths related to alcohol and with over 80% of alcohol-impaired driving episodes reported by people who also report binge drinking. 33 Thus, screening and brief interventions to reduce alcohol misuse, particularly among young adults, may be the best evidence-based approach currently available for primary care clinicians.

The absence of primary-care-based intervention evidence addressing MVOI safety behaviors in adolescents in particularly disturbing. Adolescent and young adult drivers have the highest MVOI mortality rates, even when controlling for vehicle miles traveled. Pediatricians may be able to influence the awareness and choices around MVOI safety behaviors of young drivers and their choices about riding with other young drivers, particularly under the influence of alcohol. Additional research in this area is very important.

Limitations of the Literature

Most of the studies included in this review had multiple methodological flaws and no single study was good quality by USPSTF criteria. Among RCTs, randomization methods were often unclear and allocation concealment unclear or inadequate. Many studies did not report any baseline characteristics for intervention and control groups, thereby making it impossible to determine if groups were similar before intervention. Most studies did not adequately measure or describe adherence in delivering the intervention, cross-over or contamination between groups. Many studies measured outcomes using data from self-reported use by parents and several studies that used parking lot observations did not specify whether these were blinded or not. Many studies had attrition over 20%, and all studies analyzed only those for whom they had complete follow-up data. Only two studies adjusted for possible confounding exposures in analyses of results.

The majority of these studies were conducted when prevalence of restraint use was much less common than it currently is. Some studies reported observed prevalence of correct use in fewer than 10% of the study population. Child safety seat restraint legislation was enacted during the late 1970's to 1980's and many studies measuring use at baseline and follow-up found that use increased in both intervention and control groups to some degree. Awareness and attitudes about restraint use were very different than they are currently. For example, several studies describe the practice of discharge staff commonly telling mothers that the safest place for their infant on the first ride home from the hospital was in their mother's arms. Among the studies that reported 60% or higher use at baseline or in a usual care control group, 60 65 67, 69, 70 most did not find a significant difference between the intervention and control groups, although these studies differed in terms of other important elements of the interventions from trials that found increases in use.

The definitions of correct use were variable across these studies. In several studies, only gross misuse (e.g., not securing the device to the car with a seat belt) was defined as incorrect. Other forms of misuse, such as seat orientation or placement of straps/harnesses, were not consistently categorized and may differ from more current standards of correct use.

The other major limitations of this body of evidence are the lack of adequately conducted studies evaluating either counseling to increase seat belt use or to reduce drinking/driving behaviors among adolescents and adults, or to counsel parents of children to increase use of booster seats.

Future Research

Individual behaviors continue to play an important role in decreasing morbidity and mortality associated with motor vehicle occupant injuries. Approaches needed to target occupant restraint use and risky behaviors, such as alcohol use before driving or riding, may need to vary depending on the age group at risk as well the type of research to evaluate their effectiveness. Among children four to eight years of age, appropriate restraint use is among the lowest of all age groups. While the effectiveness of booster seats and effects of community-based interventions have been established, gaps exist in the effectiveness of clinician counseling to promote booster seat use. Priorities for this target population include research on clinician counseling and may need to focus on understanding the generalizablity of previously demonstrated effective interventions in the clinical setting for promotion of child safety seats for the 0–4 year age groups, in which restraint use is approaching 100%, or on the adaptability of effective community interventions to the clinical setting.

The majority of adolescent fatalities are single-vehicle events and are primarily due to driver error. Adolescent drivers' risks are intertwined with their normal developmental process of emerging independence, and identifying youth at high-risk for risky driving may be possible. 80 Driving with distractions (multiple passengers, cell phones), over-estimating newly developed driving abilities (speeding, poor hazard assessment), and alcohol and drug experimentation contribute to poorer driving and lack of restraint use in young drivers. Behavioral counseling interventions by primary care clinical staff to improve MVOI-related safety behaviors in young drivers are urgently needed. Unless contributing factors particular to this age group are addressed in these future interventions, however, the ability to increase restraint use and safe-driving behavior may be limited.

Among adults in the general population, restraint use continues to increase due to multi-faceted interventions including regulatory changes. Among those involved in collisions, however, alcohol use and lack of restraint use remains high. Interventions to identify alcohol misuse (binge drinking and heavy drinking) and to counsel alcohol misusing patients to change their alcohol behaviors are an evidence-based method for reducing MVOI and may reach a large proportion of those who drive after drinking. However, it is important to understand the epidemiology of drinking and driving in the general adult population and the effectiveness of counseling all adults to avoid driving while alcohol-impaired (and riding with an impaired driver) as this approach may be required to decrease motor-vehicle related morbidity and mortality among adults.

In contrast to the general adult population, restraint use among the elderly is high. Fewer miles are driven, but when the elderly are involved in a collision they suffer more severe injuries. There is a paucity of evidence about effective clinician screening for determining an elderly individual's continued ability to drive. Factors such as the ability to quickly respond to events, declining cognitive ability (medication use, dementia), and physical impairment (visual impairment) are the primary factors impairing driving. In contrast to other age groups, the goal for this group may be to limit or cease driving.


Behavioral counseling interventions to increase correct age- and weight-appropriate restraint use may increase short-term use, or correct use, of restraints but effects may diminish by longer term follow-up. Effective interventions targeting infants or children included education, demonstration of correct use, and child safety seat distribution programs and were tested during a time of growing cultural support and increasing regulatory requirements for child safety restraint use. Data from primary care studies were lacking for interventions to increase use of belt-positioning booster seats for children ages four to eight years, an area where interventions are needed due to lower use and gaps in current child safety seat legislation. Similarly, no interventions targeting young drivers aged 16–24 years, a known high-risk group, were available. Data to address behavioral counseling interventions for adults was quite limited, although current data suggests usage rates are quite high and supported by a strong regulatory environment. Across age-groups addressed, there was a lack of recent or good-quality trials for any MVOI-related safety behaviors. Many of the available studies were conducted when restraint use was less common and the studies in populations with higher baseline use did not show improvements in restraint use, suggesting a possible ceiling effect. Misuse of child safety restraints remains common and diminishes their effectiveness.


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