The effect of a gearshift interlock on seat belt use by drivers who do not always use a belt and its acceptance among those who do

IntroductionSeat belts reduce the risk of fatal injury in a crash, yet in 2015, nearly 10,000 people killed in passenger vehicles were unrestrained. Enhanced seat belt reminders increase belt use, but a gearshift interlock that prevents the vehicle from being placed into gear unless the seat belt is used may prove more effective.MethodThirty-two people with a recent seat belt citation and who admitted to not always using a seat belt as a driver were recruited as part-time belt users and asked to evaluate two new vehicles. Sixteen drove two vehicles with an enhanced reminder for one week each, and 16 drove a vehicle with an enhanced reminder for one week and a vehicle with a gearshift interlock the following week. Sixteen full-time belt users who reported always using a seat belt drove a vehicle with a gearshift interlock for one week to evaluate acceptance.ResultsRelative to the enhanced reminder, the gearshift interlock significantly increased the likelihood that a part-time belt user used a belt during travel time in a trip by 21%, and increased the rate of belt use by 16%; this effect approached significance. Although every full-time belt user experienced the gearshift interlock, their acceptance of the technology reported in a post-study survey was fairly positive and not significantly different from part-time belt users. Six part-time belt users circumvented the gearshift interlock by sitting on a seat belt, waiting for the system to deactivate, or unbuckling during travel.ConclusionThe gearshift interlock increased the likelihood that part-time belt users buckled up and the rate of belt use during travel relative to the enhanced reminder but could be more effective if it prevented circumvention.Practical applicationsAn estimated 718–942 lives could be saved annually if the belt use of unbuckled drivers and front passengers increased 16–21%.     

Nighttime seat belt use among front seat passengers: Does the driver's belt use matter?

Introduction and Method: We explored the relationship between nighttime seat belt use of right-front passengers and their drivers using observational data from 33,310 vehicles in east Tennessee during March 2015 – May 2017. Results: Overall, nighttime passenger seat belt use varied by 50 percentage points from 92% when drivers were belted to 42% when drivers were not belted, suggesting that part-time seat belt users can be heavily influenced by the seat belt status of their traveling companions. When stratified by vehicle type and sex, passenger seat belt use by driver seat belt status varied as much as 74 percentage points from 96% to 22%. Passenger seat belt use was typically lower when riding with unbelted same-sex drivers than when riding with unbelted drivers of the opposite sex. Conclusions and Practical Applications: This finding suggests that the role of peer influence in decision-making about seat belt use may differ depending on the sex of a vehicle driver and his or her passengers. Further research is warranted to explore this finding as well as other social and cultural influences that have not been fully examined in seat belt research.     

Taxi driver seat belt wearing in Nanjing, China

Objective

To determine and validate patterns of seat belt use and attitudes of taxi drivers on wearing a seat belt following national and provincial seat belt legislation in 2004-2005. Design: Roadside daylight seat belt observation and interview survey methods were used, as well as observations from inside taxis during routine trips and a taxi driver focus group. The setting was Nanjing, Jiangsu Province, PR China in April of 2006 and 2007.

Main outcome measures

Prevalence of seat belt use and attitudes to wearing a seat belt were determined, as were vehicle and driver characteristics, and comparisons with other motor-vehicle driver's seat belt use and attitudes.

Results

Taxi drivers interviewed were predominantly male and aged 30-39 years. They spent more hours per week in their vehicles and had more driving experience than other drivers. Over half (56.2%) of taxi drivers interviewed reported that they always wore seat belts, while observation of taxi drivers showed lower wearing rates (i.e., roadside observation was 43.8%, and observation from inside taxis was 36.2%). Belt tampering was a practice of 12-15% of taxi drivers. “Fine avoidance, safety, high speed and long trips” were given as important reasons for wearing and “feeling trapped and uncomfortable” for not wearing. Seat belt reminder signs in taxis were common (82.6% of taxis), but did not appear to impact on driver seat belt use.

Conclusion

The four research methods found taxi drivers to have consistently low “correct wearing” rates.

Impact on industry

As in several other countries, taxi drivers are particularly resistant to seat belt use. Innovative strategies, including occupational health and safety approaches, may be required to achieve increased levels of seat belt use.     

Attitudes toward a primary seat belt law among adults in a rural state with a secondary seat belt law

Problem

Enforced primary seatbelt laws can reduce morbidity and mortality associated with motor-vehicle crashes. Constituent support is an important factor associated with legislator voting behavior toward injury prevention laws. Little is known about attitudes toward a primary seat belt law among adults in rural states without a primary seat belt law.

Methods

Data from the Behavioral Risk Factor Surveillance System (BRFSS) survey, a telephone survey of a representative sample of adults in Montana, were used to assess attitudes toward a primary seat belt law.

Results

Sixty-one percent of respondents supported a primary seat belt law. Using multiple logistic regression analyses, women (AOR 1.87; 95% CI 1.49-2.36), persons aged 65 years and older (1.45; 1.06-1.96), American Indians (2.71; 1.55-4.75), those with health insurance (1.51; 1.07-2.14), and those who reported always wearing their seat belt (4.05; 3.14-5.21) were more likely to support a primary seat belt law than respondents without these characteristics.

Conclusions

The majority of adults in a rural state support a primary seat belt law.     

Investigation of seat belt use among the drivers of different education levels

Seat belt use habit has been investigated according to the education level of drivers. Copies of a questionnaire were distributed to 1000 participants of four different education levels. Factors such as seat belt usage habit, restricting factors and crash data have been investigated. Data have been analyzed with SPSS 15.0 software. Increased level of education leads to increased seat belt usage, lower numbers of crashes and crash severities. The factors restricting seat belt use are lack of habit, discomfort and short distance driving. The use of precaution signal and increases in comfort can increase seat belt usage. The primary and high school education on traffic safety and seat belt usage has been serving the purpose.     

Effect of enhanced seat belt reminders on driver fatality risk

Objective

Enhanced seat belt reminders in automobiles have been shown to increase belt use rates by approximately 3 percentage points. The objective of this study was to estimate the effect of enhanced seat belt reminders on driver fatality risk.

Method

Data included all passenger vehicle driver deaths and vehicle registration counts in the United States for calendar years 2000-2007. Driver fatality rates per vehicle registration per year were compared for otherwise identical vehicle models with and without enhanced seat belt reminders.

Results

Driver fatality rates were 6% lower for vehicles with enhanced seat belt reminders compared with vehicles without enhanced belt reminders. After adjusting for vehicle age differences, the estimated effect of enhanced belt reminders on driver fatality risk ranged from a 9% reduction for General Motors vehicles to a 2% increase for Honda vehicles. Combining all manufacturers, enhanced belt reminders reduced fatality risk by approximately 2%. Although not statistically significant, the 2% reduction in fatality risk agrees with what should be expected from a 3 percentage point increase in seat belt use rates.

Conclusions

Enhanced seat belt reminders have raised driver belt use rates and reduced fatality rates, but more aggressive systems may be needed for some drivers. It can be inferred that nonfatal injury rates also have been reduced.

Impact on Industry

Manufacturers should be encouraged to put enhanced seat belt reminders on all vehicles as soon as possible.     

Belief about seat belt use and seat belt wearing behavior among front and rear seat passengers in the United States

Introduction: Unrestrained drivers and passengers represent almost half of all passenger vehicle occupant deaths in the United States. The current study assessed the relationship between the belief about importance of seat belt use and the behavior of always wearing a seat belt. Method: Data from 2012 ConsumerStyles were analyzed separately for front and rear passenger seating positions. Multivariable regression models were constructed to identify the association between seat belt belief and behavior (i.e., always wears seat belt) among adults. Models controlled for type of state seat belt law (primary, secondary, or none). Results: Seat belt use was higher in front passenger seats (86.1%) than in rear passenger seats (61.6%). Similarly, belief that seat belt use was very important was higher in reference to the front passenger seat (84.2%) versus the rear passenger seat (70.5%). For the front passenger seat, belief was significantly associated with seat belt use in states with both primary enforcement laws (adjPR 1.64) and secondary enforcement laws (adjPR 2.77). For the rear passenger seat, belief was also significantly associated with seat belt use, and two 2-way interactions were observed (belief by sex, belief by region). Conclusions: Despite overall high rates of seat belt use in the United States, certain groups are less likely to buckle up than others. The study findings suggest that efforts to increase seat belt use among high-risk populations, such as those who live in states with secondary or no seat belt laws and those who ride in rear seats (which include people who utilize taxis or ride-hailing vehicles) could benefit from interventions designed to strengthen beliefs related to the benefits of seat belt use. Practical applications: Future research that uses a theoretical framework to better understand the relationship between beliefs and behavior may inform interventions to improve seat belt use.     

Self-reported factors that influence rear seat belt use among adults

Introduction: While seat belt use among front seat occupants has significantly increased overtime a substantial usage gap still exists between front and back seat occupants. This study aims to identify factors that predict rear seat belt use among adult back seat passengers. Methods: We examined data from the 2016 Motor Vehicle Occupant Safety Survey, conducted by the National Highway Traffic Safety Administration, to determine the influence of front seat belt use, support of and belief of rear seat belt use laws, peer perception of seat belt use, nighttime belt use, and demographic factors on self-reported rear seat belt use. Rao-Scott chi-squared tests were used to determine significant associations between self-reported rear belt use and each predictor. Multivariate logistic regression was used to calculate adjusted odds ratios and determine the influence of significant predictors on rear seat belt use. Sampling weights were applied to produce nationally representative estimates; all statistical significance tests accounted for the complex survey design. Results: Among adults who reported riding in the back seat, 63% reported always using a rear seat belt. Front seat belt use, support and belief of state seat belt laws, nighttime seat belt use, age, and education were significantly associated with rear seat belt use. Multivariate regression results showed that adults who supported rear seat belt laws, reported front seat belt use and believed their state has a rear seat belt law were significantly more likely to report full-time use in the back seat. Conclusions: Seat belt laws and front seat belt use had the strongest association with reporting full-time use in the back seat. Practical Applications: Increasing familiarity with existing laws directed towards rear seat belt use as well as increasing awareness about the benefits of seat belts in all seating positions may help improve rear seat belt use.     

Seat belt use in the ambulance patient compartment by emergency medical services professionals is low regardless of patient presence,seating position,or patient acuity

Background: Inconsistent use of seat belts in an ambulance may increase the risk of injury for emergency medical services (EMS) professionals and their patients. Our objectives were to: (1) describe the prevalence of seat belt usage based on patient acuity and seat location, and (2) assess the association between EMS-related characteristics and consistent use of a seat belt. Methods: We administered a cross-sectional electronic questionnaire to a random sample of 20,000 nationally-certified EMS professionals, measuring seat belt use in each seating location of an ambulance during transport of stable, critical, or no patients. We included practicing, non-military, emergency medical technicians or higher who reported working in ambulances. We used multivariable logistic regression models to estimate the odds of consistent (≥50% of the time) use of seat belts for the rear-facing jump seat and right-sided crew bench during transport of stable and critical patients. Results: A total of 1431 respondents were included in the analysis. Patient compartment seat belt use varied with the highest use in forward-facing seats when no patient was being transported (59.8%) and lowest use in the left-side “CPR” seat with a critical patient (9.4%). Only 40.2% of respondents reported an agency policy regarding seat belt use while riding in the patient compartment. In all multivariable logistic regression models, advanced life support level certification and fewer years of experience were associated with decreased odds of consistent seat belt use. An agency seat belt policy was strongly associated with increased odds of seat belt use in the patient compartment. Conclusions: Seat belt use was low and varied by seating location and patient acuity in the patient compartment of an ambulance. Practical Applications: EMS organizations should consider primary prevention approaches of provider education, improved ambulance designs, enactment and enforcement of policies to improve seat belt compliance and provider safety.     

Effectiveness and driver acceptance of the Honda belt reminder system

OBJECTIVE: Prior research suggests that vehicle-based seat belt reminder systems can produce moderate increases in belt use rates. However, these findings were based on a limited set of Ford vehicles in one geographic location. As more vehicles with reminder systems enter the market, it is important to determine their effectiveness as well as acceptance by consumers. The present study investigated the effectiveness of Honda's belt reminder system. METHODS: Driver belt use was observed unobtrusively as drivers brought their Honda vehicles to dealerships for service. Drivers also were asked to complete a mail-in survey designed to elicit their experience with the system. RESULTS: Belt use was significantly higher among drivers of vehicles with belt reminders compared with drivers of vehicles without reminders (90 vs. 84 percent). Use rates in vehicles with reminders were higher among both male and female drivers and in all vehicle types observed. Drivers of the Honda vehicles with belt reminders viewed the system very favorably, and nearly 90 percent said they would want one in their next vehicle. The reminder was perceived to be most effective by part-time belt users; 81 percent of part-time users said they now use belts more often, compared with 32 percent of respondents who said they always use belts and 18 percent who use belts occasionally. CONCLUSION: Belt reminders in Honda as well as Ford vehicles are increasing. Although the increase is moderate (5.6 percentage points), on a national level it could have prevented at least 736 driver deaths in 2004.     

Passenger use of and attitudes toward rear seat belts

Objectives: This study sought to identify attitudes toward belt use in the rear seat and to gain insight into the experiences of rear-seat passengers. Method: A telephone survey conducted between June and August 2016 targeted adult passengers who had recently ridden in the rear and who did not always wear their seat belt when doing so. Respondents were questioned regarding their reasons for not buckling up and possible conditions under which they would be more likely to buckle up during rear-seat travel. Results: Of 1163 recent rear-seat passengers, 72% reported always using their seat belt in the rear. Full-time belt use was lower among passengers who primarily travel in the rear of hired vehicles compared with personal vehicles. The most common explanation for not buckling up was that the back seat is safer than the front. Four out of five agreed they do not buckle up because of type of trip; two-thirds forget or do not see the need; and two-thirds agreed with reasons related to design, comfort, or usability issues. Nearly 40% agreed that they sometimes do not buckle up in the rear because there is no law requiring it. Conclusion: Many reasons for not using belts in the rear are similar to reasons in the front, such as forgetfulness, inconvenience, or discomfort. One difference is that many rear-seat passengers perceive using the belt is unnecessary because the back seat is safer than the front. More than half of part-time belt users and nonusers reported interventions such as rear seat belt reminders, stronger belt-use laws, and more comfortable belts would make them more likely to use their seat belt in the rear seat. Practical applications: This study identifies barriers to rear seat belt use that point to the need for a multi-faceted approach to increase belt use.     

Predictors of rear seat belt use among U.S. adults, 2012

IntroductionSeat belt use reduces the risk of injuries and fatalities among motor vehicle occupants in a crash, but belt use in rear seating positions is consistently lower than front seating positions. Knowledge is limited concerning factors associated with seat belt use among adult rear seat passengers.MethodsData from the 2012 ConsumerStyles survey were used to calculate weighted percentages of self-reported rear seat belt use by demographic characteristics and type of rear seat belt use enforcement. Multivariable regression was used to calculate prevalence ratios for rear seat belt use, adjusting for person-, household- and geographic-level demographic variables as well as for type of seat belt law in place in the state.ResultsRear seat belt use varied by age, race, geographic region, metropolitan status, and type of enforcement. Multivariable regression showed that respondents living in states with primary (Adjusted Prevalence Ratio (APR): 1.23) and secondary (APR: 1.11) rear seat belt use enforcement laws were significantly more likely to report always wearing a seat belt in the rear seat compared with those living in a state with no rear seat belt use enforcement law.Conclusions and practical applicationsSeveral factors were associated with self-reported seat belt use in rear seating positions. Evidence suggests that primary enforcement covering all seating positions is an effective intervention that can be employed to increase seat belt use and in turn prevent motor vehicle injuries to rear-seated occupants.     

State-level seat belt use in the United States, 2011–2016: Comparison of self-reported with observed use and use by fatally injured occupants

Introduction: Despite 49 states and the District of Columbia having seat belt laws that permit either primary or secondary enforcement, nearly half of persons who die in passenger vehicle crashes in the United States are unbelted. Monitoring seat belt use is important for measuring the effectiveness of strategies to increase belt use. Objective: Document self-reported seat belt use by state seat belt enforcement type and compare 2016 self-reported belt use with observed use and use among passenger vehicle occupant (PVO) fatalities. Methods: We analyzed the Behavioral Risk Factor Surveillance System (BRFSS) self-reported seat belt use data during 2011–2016. The Pearson correlation coefficient (r) was used to compare the 2016 BRFSS state estimates with observed seat belt use from state-based surveys and with unrestrained PVO fatalities from the Fatality Analysis Reporting System. Results: During 2011–2016, national self-reported seat belt use ranged from 86–88%. In 2016, national self-reported use (87%) lagged observed use (90%) by 3 percentage points. By state, the 2016 self-reported use ranged from 64% in South Dakota to 93% in California, Hawaii, and Oregon. Seat belt use averaged 7 percentage points higher in primary enforcement states (89%) than in secondary states (82%). Self-reported state estimates were strongly positively correlated with state observational estimates (r = 0.80) and strongly negatively correlated with the proportion of unrestrained PVO fatalities (r = −0.77). Conclusion: National self-reported seat belt use remained essentially stable during 2011–2016 at around 87%, but large variations existed across states. Practical Applications: If seat belt use in secondary enforcement states matched use in primary enforcement states for 2016, an additional 3.98 million adults would have been belted. Renewed attention to increasing seat belt use will be needed to reduce motor-vehicle fatalities. Self-reported and observational seat belt data complement one another and can aid in designing targeted and multifaceted interventions.     

Factors related to seat belt use among fatally injured teenage drivers

PROBLEM: In the United States, teenage drivers have a higher crash risk and lower observed seat belt use than other age groups. METHOD: Seat belt use was examined for teenage (16-19 years) drivers who were fatally injured in traffic crashes occurring in the United States during the years 1995-2000. Vehicle, driver, and crash factors potentially related to belt use were examined. State differences in belt use rates among fatally injured teenage drivers were related to states' observed belt use rates for all ages and other state-level variables. RESULTS: During 1995-2000, mean belt use was 36% among fatally injured teenage drivers and 23% among fatally injured teenage passengers. One of the strongest predictors of higher belt use for both drivers and passengers was whether the crash occurred in a state with a primary seat belt law. Belt use rates for 1995-2000 for fatally injured teenage drivers ranged from 20% or less in six states to more than 60% in two states. States with the highest use rates were those with strong primary belt use laws and those with high rates of observed belt use for all ages. Lower belt use among fatally injured teenage drivers was associated with increasing age; male drivers; drivers of SUVs, vans, or pickup trucks rather than cars; older vehicles; crashes occurring late at night; crashes occurring on rural roadways; single vehicle crashes; and drivers with BACs of 0.10 or higher. Teenage driver belt use declined as the number of teenage passengers increased, but increased in the presence of at least one passenger 30 years or older. IMPACT ON TRAFFIC SAFETY: It is suggested that to increase teenage belt use, states should enact strong primary belt use laws and mount highly publicized efforts to enforce these laws. Graduated driver licensing systems should incorporate strong provisions that require seat belt use by teenage drivers and passengers.     

The role of enforcement programs in increasing seat belt use

Seat belt laws by themselves led to increased belt use in the United States and Canada, but initial effects were limited. Canadian provincial officials launched highly publicized enforcement campaigns in the early 1980s that resulted in substantially increased belt use. Canadian-style enforcement programs subsequently were adopted in the United States, and the use of such programs has grown in recent years. Lessons from these efforts include the importance of police leadership, focused publicity about enforcement, and sustained rather than single-shot efforts. What is needed in the United States to achieve a national belt use rate of 90% or greater is widespread, methodical, and sustained application of enforcement programs augmented by creative publicity. Enhanced penalties-in particular drivers license points-likely will be needed to reach hard-core nonusers.     

Ninety five percent: an evaluation of law, policy, and programs to promote seat belt use in Washington state

Seat belt use in Washington state was 83% in 2001. In 2002, a series of law, policy, and program initiatives coalesced to produce a dramatic increase in seat belt use. Washington enacted a primary enforcement seat belt, the Chief of the Washington State Patrol made safety belt enforcement one of the core missions of that agency, and Washington participated in the national Memorial Day Click It or Ticket program during May 2002 and continued the program into 2003. Evaluation of these initiatives was accomplished through observation surveys of seat belt use, analysis of seat belt violation data, and analysis of data on traffic deaths of motor vehicle occupants. The major findings were that there was a two- to three-fold increase in enforcement of the seat belt law, belt use rates increased to 93% in 2002 and again to 95% in 2003, and motor-vehicle occupant fatalities decreased by 13%. IMPACT ON PRACTICE AND POLICY: The primary seat belt law and Click It or Ticket program activities were critical factors in increasing belt use in Washington state. Media and enforcement programs targeting seat belt use can be very effective in raising the belt use rate, but a long-term commitment to continuation of these program activities is essential. Other states implementing new primary seat belt laws should consider delivering a Click It or Ticket campaign prior to the effective date of the primary law and continuing these activities during subsequent months and years.     

Seat belt use among car drivers in Iranian safe communities: An observational study

Objective: The number of road traffic injuries and fatalities in Iran is high. The aim of the present study was to investigate the rate of drivers' seat belt use and a number of related factors in Kashmar, Bardaskan, and Khalilabad (Iranian Safe Communities).Methods: In 2014, driver observations were made at 48 road sites on intercity roads, main streets, side streets, and rural roads in these 3 cities.Results: A total of 10,255 vehicles were observed, with the overall rate of seat belt use being 51.8%. The rates in Kashmar, Bardaskan, and Khalilabad were 51.4, 56.3, and 47.7%, respectively. In Kashmar, the odds of seat belt use were higher among drivers who were female, older, and taxi drivers. Higher use was also found during the afternoon, and lower use was observed on rural roads. In Khalilabad the odds of seat belt use were higher among females, older drivers, taxis, and private car drivers. Seat belt use was also higher on weekends and during the morning but was significantly lower on rural roads. Similarly, in Bardaskan the odds of using a seat belt were higher among females, older drivers, taxis, and private car drivers. Seat belt use was also higher during the afternoon but was significantly lower on rural roads, in comparison to main streets and intercity roads.Conclusions: The rate of seat belt use in these 3 cities was found to be low, despite these cities being designated as International Safe Communities. Therefore, seat belt promotion programs, tougher regulations, stronger enforcement, public awareness campaigns, and more research are needed to promote seat belt use in these Iranian cities.     

Seat belt use and fit among drivers aged 75 years and older in their own vehicles

Objective: This article aims to describe seat belt wearing patterns and quality of seat belt fit among drivers aged 75 years and older. A secondary aim is to explore associations between body shape, comfort, and seat belt use patterns.

Methods: This is an observation and survey study of a cohort of 380 drivers aged 75 years and over. During home visits, photographs were taken of the drivers in their vehicles for later analysis of belt fit and a short survey was also administered to collect demographic data and information about seat belt use and comfort. Seat belt fit and use of belt and seat accessories were analyzed from the photographs.

Results: Data from 367 participants with photographs were analyzed. Whereas 97% reported using a seat belt and 90% reported their seat belt to be comfortable, 21% reported repositioning their seat belt to improve comfort. Good sash and lap belt fit were achieved in 53 and 59% of participants, respectively, but only 35% achieved overall good fit. Both poor sash and lap belt fit were observed in 23% of participants. Drivers who were in the obese category had over twice the odds (95% confidence interval [CI], 1.2–4.1) of having a poor lap belt fit than those in the normal body mass index [BMI] range, and drivers who were overweight had 1.8 times the odds (95% CI, 1.1–2.9) of having poor lap belt fit. Older females also had twice the odds (95% CI, 1.3–3.5) of poor lap belt fit compared to older males, regardless of BMI. Sash belt fit did not vary significantly by BMI, stature, or gender. However older drivers who reported that they had not made any adjustments to the D-ring height had 1.7 times the odds of having poor sash belt fit than those who made adjustments (1.2–2.9). Females were 7.3 times more likely to report comfort problems than males (95% CI, 3.2, 16.3) but there was no association between reported comfort and BMI or seat belt fit. Drivers who reported comfort problems had 6 times the odds (3.2–13.6) of also reporting active repositioning of the belt.

Conclusions: The results suggest that older drivers face challenges in achieving comfortable and correct seat belt fit. This may have a negative impact on crash protection. Belt fit problems appear to be associated with body shape, particularly high BMI and gender. There is a need for further investigation of comfort accessories; in the interim, older drivers and occupants should be encouraged to use features such as D-ring adjusters to improve sash belt fit.     

Driver and front passenger injury in frontal crashes: Update on the effect of unbelted rear occupants

Purpose: This is a study of the influence of an unbelted rear occupant on the risk of severe injury to the front seat occupant ahead of them in frontal crashes. It provides an update to earlier studies.

Methods: 1997–2015 NASS-CDS data were used to investigate the risk for severe injury (Maximum Abbreviated Injury Score [MAIS] 4+F) to belted drivers and front passengers in frontal crashes by the presence of a belted or unbelted passenger seated directly behind them or without a rear passenger. Frontal crashes were identified with GAD1 = F without rollover (rollover ≤ 0). Front and rear outboard occupants were included without ejection (ejection = 0). Injury severity was defined by MAIS and fatality (F) by TREATMNT = 1 or INJSEV = 4. Weighted data were determined. The risk for MAIS 4+F was determined using the number of occupants with known injury status MAIS 0+F. Standard errors were determined.

Results: The risk for severe injury was 0.803 ± 0.263% for the driver with an unbelted left rear occupant and 0.100 ± 0.039% with a belted left rear occupant. The driver's risk was thus 8.01 times greater with an unbelted rear occupant than with a belted occupant (P <.001). With an unbelted right rear occupant behind the front passenger, the risk for severe injury was 0.277 ± 0.091% for the front passenger. The corresponding risk was 0.165 ± 0.075% when the right rear occupant was belted. The front passenger's risk was 1.68 times greater with an unbelted rear occupant behind them than a belted occupant (P <.001). The driver's risk for MAIS 4+F was highest when their seat was deformed forward. The risk was 9.94 times greater with an unbelted rear occupant than with a belted rear occupant when the driver's seat deformed forward. It was 13.4 ± 12.2% with an unbelted occupant behind them and 1.35 ± 0.95% with a belted occupant behind them.

Conclusions: Consistent with prior literature, seat belt use by a rear occupant significantly lowered the risk for severe injury to belted occupants seated in front of them. The reduction was greater for drivers than for front passengers. It was 87.5% for the driver and 40.6% for the front passenger. These results emphasize the need for belt reminders in all seating positions.