How would increasing seat belt use affect the number of killed or seriously injured light vehicle occupants?

The expected effects of increasing seat belt use on the number of killed or seriously injured (KSI) light vehicle occupants have been estimated for three scenarios of increased seat belt use in Norway, taking into account current seat belt use, the effects of seat belts and differences in crash risk between belted and unbelted drivers. The effects of seat belts on fatality and injury risk were investigated in a meta-analysis that is based on 24 studies from 2000 or later. The results indicate that seat belts reduce both fatal and non-fatal injuries by 60% among front seat occupants and by 44% among rear seat occupants. Both results are statistically significant. Seat belt use among rear seat occupants was additionally found to about halve fatality risk among belted front seat occupants in a meta-analysis that is based on six studies. Based on an analysis of seat belt wearing rates among crash involved and non-crash involved drivers in Norway it is estimated that unbelted drivers have 8.3 times the fatal crash risk and 5.2 times the serious injury crash risk of belted drivers. The large differences in crash risk are likely to be due to other risk factors that are common among unbelted drivers such as drunk driving and speeding. Without taking into account differences in crash risk between belted and unbelted drivers, the estimated effects of increasing seat belt use are likely to be biased. When differences in crash risk are taken into account, it is estimated that the annual numbers of KSI front seat occupants in light vehicles in Norway could be reduced by 11.3% if all vehicles had seat belt reminders (assumed seat belt wearing rate 98.9%), by 17.5% if all light vehicles had seat belt interlocks (assumed seat belt wearing rate 99.7%) and by 19.9% if all front seat occupants of light vehicles were belted. Currently 96.6% of all (non-crash involved) front seat occupants are belted. The effect on KSI per percentage increase of seat belt use increases with increasing initial levels of seat belt use. Had all rear seat occupants been belted, the number of KSI front seat occupants could additionally be reduced by about 0.6%. The reduction of the number of KSI rear seat occupants would be about the same in terms of numbers of prevented KSI.     

Method to evaluate the effect of safety belt use by rear seat passengers on the injury severity of front seat occupants

Although the effectiveness of seat belts for reducing injury to rear seat passengers in traffic accidents has been well documented, the ratio of rear-seat passengers restrained by seatbelts remains lower than that of drivers or passengers in front seats. If passengers in rear seats do not wear seat belts, they may sustain unexpected injury to themselves when involved in accidents, and also endanger front occupants (drivers or front seat passengers). This paper focuses on the tendency of front seat occupants to sustain severer injuries due to forward movement of passengers in rear seats at the moment of frontal collisions, and evaluates the effectiveness of rear passengers' wearing seat belts in reducing injuries of front seat occupants. Since the occurrence of occupant injuries depends considerably on the crash severity, we proposed to use pseudo-delta V in regression analysis to represent velocity change during a collision when analyzing statistical accident data. As the crash severity can be estimated from pseudo-delta V, it becomes possible to make appropriate estimations even when the crash severity differs in data. The binary model derived from the ordered response model was used to evaluate the influence on the injury level based on pseudo-delta V, belted or unbelted status, gender and age. Occupants in cars with a hood in the case of car-to-car frontal collisions were extracted from the statistical data on accidents in Japan. Among 81,817 cars, where at least one passenger was present, a total of 6847 cars in which all passengers sustained injuries and which had at least one rear seat passenger aboard were analyzed. The number of killed or seriously injured drivers is estimated to decrease by around 25% if rear seat occupants come to wear seat belts. Also, the number of killed or seriously injured passengers in front seats is estimated to decrease by 28% if unbelted rear seat occupants come to wear seat belts. Thus, wearing of seat belts by previously unbelted rear seat passengers is considered effective in reducing not only injuries to the rear seat passengers themselves but also injuries to front seat occupants.     

What can we learn about North Dakota's youngest drivers from their crashes?

For North Dakota teens, three of every four deaths are from motor vehicle crashes. Injury crash records for teen drivers were studied to gain insight regarding driver, vehicle, and road factors for public safety policy and program discussions. Results show 14-year-old drivers are three times more likely to die or be disabled in an injury crash than 17-year-old drivers, and that male drivers are 30% less likely to incur severe injury. As expected, seat belt use is a critical factor in severe injury avoidance. The likelihood for death or disablement is 165% greater for unbelted teen drivers than for those who are properly belted. In addition, rural and gravel roads pose a risk. Teens are six times more likely to be severely injured in crashes on rural roads than on urban roads. Findings suggest that an increased licensing age and seat belt emphasis may reduce teen traffic injuries in the state. In addition, more information on exposure should be attained to better understand rural and gravel road as risks.     

Fatality risk for belted drivers versus car mass

This study was performed to determine how the likelihood of a belted driver being killed in a single car crash depends on the mass of the car. This was done by applying the pedestrian fatality exposure approach to the subset of fatalities in the Fatal Accident Reporting System (FARS) for which the driver was coded as using a shoulder belt and/or a lap belt. Combining the 1975 through 1982 data provided a sufficiently large population of belted drivers to perform the analysis. In the exposure approach used, the number of car drivers killed in single car crashes is divided by the number of nonoccupant fatalities (pedestrians or motorcyclists) associated with the same group of cars. The ratio is interpreted to reflect the physical effect of car mass, essentially independent of driver behavior effects. In the present application, car mass effects for belted drivers were determined by considering the number of belted drivers killed divided by the number of nonoccupants killed in crashes involving cars whose drivers were coded in the FARS files as being belted. Because the belt use of surviving drivers is, to some extent, self-reported, it is considered that the data given in the report should be not used to estimate the effectiveness of seat belts in preventing fatalities. The results are presented as graphical and analytical comparisons of fatality likelihood versus car mass for belted and unbelted drivers. It is concluded that the effect of car mass on relative driver fatality likelihood is essentially the same for belted and unbelted drivers (for example, the present analysis gives that a belted driver in a 900 kg car is 2.3 times as likely to be killed in a single car crash as is the belted driver in an 1800 kg car. The corresponding ratio determined here for unbelted drivers is 2.4). As a consequence of this conclusion, the relative effectiveness of seat belts in preventing driver fatalities is similar for cars of different masses.     

Mathematical models assuming selective recruitment fitted to data for driver mortality and seat belt use in Japan

Previous research has indicated that unbelted drivers are at higher risk of involvement in fatal crashes than belted drivers, suggesting selective recruitment that high-risk drivers are unlikely to become belt users. However, how the risk of involvement in fatal crashes among unbelted drivers varies according to the level of seat belt use among general drivers has yet to be clearly quantified. We, therefore, developed mathematical models describing the risk of fatal crashes in relation to seat belt use among the general public, and explored how these models fitted to changes in driver mortality and changes in observed seat belt use using Japanese data. Mortality data between 1979 and 1994 were obtained from vital statistics, and mortality data in the daytime and nighttime between 1980 and 2001 and belt use data between 1979 and 2001 were obtained from the National Police Agency. Regardless of the data set analyzed, exponential models, assuming that high-risk drivers would gradually become belt users in order of increasing risk as seat belt use among general motorists reached high levels, showed the best fit. Our models provide an insight into behavioral changes among high-risk drivers and support the selective recruitment hypothesis.     

Compulsory seatbelt use: Further inferences

On 1 June 1972, the wearing of available seatbelts by front seat occupants (drivers and front seat passengers) became compulsory in New Zealand. A comparison of fatality rates for front seat occupants during the two years preceding and following the law has been made by Toomath and Laurenson (1976). The fatality rate per million gallons of taxable petrol consumption shows a drop of about 7% for such occupants, accompanied by a surveyed usage rate increase from 25% to 67%. Considering the well established value of seatbelts in reducing road trauma, the size of the fatality reduction is rather disappointing For clarification, fatality rates crudely adjusted for exposure were separately calculated for belted and unbelted front seat occupants. Comparative rates before and after the law were somewhat surprising, so a model was constructed in which the after-law use rate could be treated as an unknown. Principal findings were: Based on surveyed use data, the fatality rate for belted front seat occupants increased after the law; likewise so did the fatality rate for unbelted front seat occupants. Since the fatality rate for all front seat occupants (aggregate of belted and unbelted) decreased, there is an apparent paradox that can be resolved by assuming a qualitative shift in the user population. Inferential analysis suggests that belt use reduced the probability of fatal injury, in a given crash, by about 40%. Similar analysis suggests that the effects of the law, when added to those of voluntary use, were to save only about 40% as many lives as could have been saved by universal belt usage among front seat occupants. Apparently those still unbelted after the law represent a particularly high-risk group, by whom increased belt use would result in disproportionate savings.     

Comparison of reporting of seat belt use by police and crash investigators: variation in agreement by injury severity

Purpose: To evaluate agreement between police and trained investigators regarding seat belt use by crash victims, according to injury severity. Methods: We used data from the National Accident Sampling System Crashworthiness Data System (CDS) for front seat occupants, 16 years and older, in crashes during 1993–2000. Crashworthiness Data System investigators determined belt use from vehicle inspection, interviews, and medical record information; their assessment was considered the gold standard for this analysis. Occupant severity of injury was categorized in five levels from no injuries to death. We estimated the sensitivity, specificity, and area under receiver operating characteristic curves for police reports of belt use. Results: Among 48,858 occupants, sensitivity of a police report that a belt was used was 95.8% overall and varied only modestly by injury severity. Specificity of a police report that a belt was not used was 69.1% overall; it was the lowest among the uninjured (53.2%) and greatest among the dead (90.4%). The area under the curve was 0.82 (95% confidence interval 0.82–0.83) overall; this was lowest among those not injured (0.75, 95% confidence interval 0.74–0.76) and increased with injury severity to 0.91 (95% confidence interval 0.90–0.93) among those who died. Conclusion: Police usually classify belted crash victims as belted, regardless of injury severity. But they often classify unbelted survivors as belted when they were not. This misclassification may result in exaggerated estimates of seat belt effectiveness in some studies.     

Estimating seat belt effectiveness using matched-pair cohort methods

Using US data for 1986-1998 fatal crashes, we employed matched-pair analysis methods to estimate that the relative risk of death among belted compared with unbelted occupants was 0.39 (95% confidence interval (CI) 0.37-0.41). This differs from relative risk estimates of about 0.55 in studies that used crash data collected prior to 1986. Using 1975-1998 data, we examined and rejected three theories that might explain the difference between our estimate and older estimates: (1) differences in the analysis methods; (2) changes related to car model year; (3) changes in crash characteristics over time. A fourth theory, that the introduction of seat belt laws would induce some survivors to claim belt use when they were not restrained, could explain part of the difference in our estimate and older estimates; but even in states without seat belt laws, from 1986 through 1998, the relative risk estimate was 0.45 (95% CI 0.39-0.52). All of the difference between our estimate and older estimates could be explained by some misclassification of seat belt use. Relative risk estimates would move away from 1, toward their true value, if misclassification of both the belted and unbelted decreased over time, or if the degree of misclassification remained constant, as the prevalence of belt use increased. We conclude that estimates of seat belt effects based upon data prior to 1986 may be biased toward 1 by misclassification.     

Shoulder belts in motor vehicle crashes: a statewide analysis of restraint efficacy

The purpose of our study was to evaluate the impact of shoulder belt use on motor vehicle crash ejection, morbidity and mortality. We analyzed motor vehicle crash records linked to hospital inpatient data for front seat occupants of passenger cars in Utah between 1994 and 1996 (n = 103,035). Stochastic simulations were used to adjust for possible seatbelt misclassification. There were 276 (0.3%) occupants coded as using only a shoulder belt. The adjusted odds of ejection for shoulder only belted occupants was higher compared to lap-shoulder belted (odds ratio (OR) = 18.9; 95% confidence interval (CI) = 15.1, 25.1) and lap only belted occupants (OR = 4.3; 95% Cl = 2.9, 7.7). There was no difference in the odds of ejection for an occupant using a shoulder belt only and an occupant using no seatbelt (OR = 1.1; 95% CI = 1.0, 1.3). Occupants using a shoulder belt only were more likely to sustain a fatal or hospitalizing injury than lap-shoulder belted (OR = 2.3; 95% Cl = 1.9, 3.0), and lap only belted occupants (OR = 1.8; 95% CI = 1.3, 2.7), while controlling for other covariates. Occupants using only a shoulder belt had the same odds of a fatal or hospitalizing injury as unbelted occupants (OR = 1.1; 95% Cl = 0.9, 1.4). Average hospital inpatient length of stay, charges and injury severity scores were similar for all restraint types. These results stress the need for the use of a lap belt in conjunction with the shoulder belt.     

Increased risk of driver fatality due to unrestrained rear-seat passengers in severe frontal crashes

While belt usage among rear-seat passengers is disproportionately lower than their front-seat counterpart, this may have serious consequences in the event of a crash not only for the unbelted rear-seat passenger but also for the front-seat passengers as well. To quantify that effect, the objective of the study is to evaluate the increased likelihood of driver fatality in the presence of unrestrained rear-seat passengers in a severe frontal collision. U.S.-based census data from 2001 to 2009 fatal motor vehicle crashes was used to enroll frontal crashes which involved 1998 or later year vehicle models with belted drivers and at least one adult passenger in the rear left seat behind the driver. Results using multivariate logistic regression analysis indicated that the odds of a belt restrained driver sustaining a fatal injury was 137% (95% CI = 95%, 189%) higher when the passenger behind the driver was unbelted in comparison to a belted case while the effects of driver age, sex, speed limit, vehicle body type, airbag deployment and driver ejection were controlled in the model. The likelihood of driver fatality due to an unrestrained rear left passenger increased further (119–197%) in the presence of additional unrestrained rear seat passengers in the rear middle or right seats. The results from the study highlight the fact that future advances to front row passive safety systems (e.g. multi-stage airbag deployment) must be adapted to take into account the effect of unrestrained rear-seat passengers.     

Deaths of teenagers as passengers in motor vehicles

Teenagers far exceed all other ages in fatalities per capita both as drivers and as passengers in motor vehicles. Most studies of vehicle crashes involving teenagers focus on teenage drivers, despite the fact that the numbers of teenage deaths as passengers and as drivers are about equal. In 1978, 63% of all fatally injured teenage passengers sustained their injuries in vehicles driven by teenage drivers: 72% of the passengers fatally injured in vehicles driven by teenage drivers were teenagers. Half of the teenage passenger deaths occurred in nighttime crashes. Possible ways to reduce the crash deaths of teenagers are discussed. These include restricting the driving of teenagers; prohibiting teenage drivers from transporting teenage passengers; greater implementation of crash packaging technologies; cleaning up highway and roadside hazards, and laws requiring seat belt use by teenagers.     

The effect of seat belts on minor and severe injuries measured on the abbreviated injury scale

Following the implementation of seat belt wearing legislation in Victoria in December 1970, the Royal Australasian College of Surgeons established a survey to collect detailed injury and crash data from car accidents in that State. An analysis of the effect of seat belt wearing on severe injuries sustained by car occupants during the first two years of the survey was reported by Cameron and Nelson[1977]. Minor injuries were ignored in that analysis. Further work extended the file to cover 8537 occupants injured during the first three years of the survey and the injuries (including minor injuries) were coded on the Abbreviated Injury Scale. This paper examines the effect of seat belt wearing on both minor and severe injuries. Some comparisons of injury severity distributions in the Victorian data and in data collected by North American MDAI teams are also made. The paper concludes that the wearing of static three-point lap/sash belts by front outboard seat occupants of cars and car derivatives is associated with: (a) Reduced likelihood of severe-to-fatal injury to the head-face, thorax, lower torso and lower extremities when injured and not ejected in crashes in built-up areas and, for some body regions, in open road crashes, (b) Increased likelihood of minor injury to the thorax and lower torso when injured and not ejected in crashes in all locations and of minor injury to the neck (i.e. whiplash) when injured and not ejected in crashes in built-up areas. There are suggestions that the increased likelihoods of the minor injuries are not artefacts of the injury criterion for inclusion, nor of the reduced likelihood of severe injury to the trunk when seat belts are worn, but are due to the wearing of the seat belt.     

Rollover crashes: predicting serious injury based on occupant, vehicle, and crash characteristics

The purpose of this research was to determine occupant, vehicle, and crash characteristics predicting serious injury during rollover crashes. We compared 27 case occupants with serious or greater severity injuries with 606 control occupants without injury or with only minor or moderate injury. Odds ratios (OR) for individual variables and logistic regression were used to identify predictive variables for serious injury associated with rollovers. Cases more often had thorax, spine, or head injury compared to controls that more often had extremity injuries. Intrusion (especially roof rail or B-pillar intrusion) at the occupant's position, the vehicle interior side and roof as sources of injury, and improper safety belt use were significantly associated with serious injury. Even when safety belt use or proper use was controlled for, occupants with greater magnitude of intrusion at their seat position were about 10 times more likely to receive serious injury. Although prevention of rollover crashes is the ultimate goal, it is important to develop safer vehicles and safety systems to better protect occupants who are involved in rollover crashes. This also requires improvement in data collection systems documenting these types of crashes.     

The effectiveness of safety belts in preventing fatalities

The effectiveness of safety belts in preventing fatalities to drivers and right front passengers is estimated by applying the double pair comparison method to 1974 or later model year cars coded in the Fatal Accident Reporting System. The method focuses on "subject" occupants (drivers or right front passengers) and "other" occupants (any except the subject occupant). Fatality risks to belted and unbelted subject occupants are compared using the other occupant to estimate exposure. In this study, drivers and right front passengers are subject occupants; choosing other occupants differing in age, seating positions, and belt use, generated 46 essentially independent estimates of safety belt effectiveness. The weighted average and standard error of these is (41 +/- 4)%. This finding agrees with the 40%-50% range reported in a recent major review and synthesis by the National Highway Traffic Safety Administration. Combining this with the present determination gives (43 +/- 3)%; that is, if all presently unbelted drivers and right front passengers were to use the provided three point lap/shoulder belt, but not otherwise change their behavior, fatalities to this group would decline by (43 +/- 3)%.     

Characteristics of belted and unbelted drivers

Drivers who had been observed wearing or not wearing shoulder belts were compared using vehicle registration data, driver records, and telephone interviews. The observations were made on the New York Thruway during a special seat belt publicity and enforcement program, which achieved a 75% overall belt use. The results showed that those drivers who still did not wear a shoulder belt despite New York law and the special Thruway program were more likely to be male, to be driving older vehicles, to have more prior traffic convictions, to have more prior injury crash involvements, and to say they are more likely to take risks than others. Although drivers reported that assessing points against the drivers license for belt law violations could increase belt use, citations for belt use law violations were very rare, and enforcement would probably have to increase before any new penalty could be effective.     

Predicting seat belt use in fatal motor vehicle crashes from observation surveys of belt use

There is a large difference between the rates of observed seat belt use by the general public and belt use by motor vehicle occupants who are fatally injured in crashes. Seat belt use rates of fatally injured occupants, as reported in the Fatality Analysis Reporting System (FARS), are much lower than the use rates found in observation surveys conducted by the states. A series of mathematical models describing the empirical relationship between FARS and observed rates were explored. The initial model was a 'straw man' and used two simplifying assumptions: (a) belt users and nonusers are equally likely to be involved in 'potentially fatal collisions', and (b) belts are 45% effective in preventing deaths. The model was examined by comparing each state's FARS use rate with the predicted rate. The model did not fit the state data points even when possible biases in the data were controlled. We next examined the assumptions in the model. Changing the seat belt effectiveness parameter provided a reasonable fit, but required an assumption that seat belts are 67% effective in preventing fatalities. The inclusion of a risk coefficient for non-belted occupants also provided a reasonable fit between the model and data. A variable risk model produced the best fit with the data. The major finding was that a model consistent with the data can be obtained by incorporating the assumption that nonusers of seat belts have a higher risk of involvement in potentially fatal collisions than do seat belt users. It was concluded that unbelted occupants are over-represented in fatal collisions for two reasons: (a) because of a greater chance of involvement in potentially fatal collisions in the first place, and (b) because they are not afforded the protection of seat belts when a collision does occur.     

Assessing the relative risk of severe injury in automotive crashes for older female occupants

A logistic regression model was used in the prediction of injury severity for individuals who are involved in a vehicular crash. The model identified females and older occupants (segmented by age 55-74, and 75 and older) as having a significantly higher risk of severe injuries in a crash. Further, interactions of older females with other factors, such as occupant seat position, crash type, and environmental factors were also shown to significantly impact the relative risk of a severe injury. This study revealed that females 75 years and older had the lowest odds of injury among all female occupants studied (OR=1.16) while females between 55 and 74 years old have higher risk of severe injuries (OR=1.74). All older females (55 and older) were at greater risk for head-on, side-impact and rear-end collisions. Seatbelt use reduced severe injuries for females in this age group, but not to the same extent as the rest of the population studied. Additionally, crashes in severe weather, which were less likely to result in severe injuries for the general population, increased the risk of severe injuries to females that were 55 and older. Among occupants of light trucks, sport utility vehicles and vans, older females were less likely than others to be severely injured. In this case, older females appear better off in vehicles which are larger and protect better in severe crashes. This research demonstrates that circumstances surrounding a crash greatly impact the severity of injuries sustained by older female occupants.     

Burst fractures of the lumbar spine in frontal crashes

Background

In the United States, major compression and burst type fractures (>20% height loss) of the lumbar spine occur as a result of motor vehicle crashes, despite the improvements in restraint technologies. Lumbar burst fractures typically require an axial compressive load and have been known to occur during a non-horizontal crash event that involve high vertical components of loading. Recently these fracture patterns have also been observed in pure horizontal frontal crashes. This study sought to examine the contributing factors that would induce an axial compressive force to the lumbar spine in frontal motor vehicle crashes.

Methods

We searched the National Automotive Sampling System (NASS, 1993–2011) and Crash Injury Research and Engineering Network (CIREN, 1996–2012) databases to identify all patients with major compression lumbar spine (MCLS) fractures and then specifically examined those involved in frontal crashes. National trends were assessed based on weighted NASS estimates. Using a case–control study design, NASS and CIREN cases were utilized and a conditional logistic regression was performed to assess driver and vehicle characteristics. CIREN case studies and biomechanical data were used to illustrate the kinematics and define the mechanism of injury.

Results

During the study period 132 NASS cases involved major compression lumbar spine fractures for all crash directions. Nationally weighted, this accounted for 800 cases annually with 44% of these in horizontal frontal crashes. The proportion of frontal crashes resulting in MCLS fractures was 2.5 times greater in late model vehicles (since 2000) as compared to 1990s models. Belted occupants in frontal crashes had a 5 times greater odds of a MCLS fracture than those not belted, and an increase in age also greatly increased the odds. In CIREN, 19 cases were isolated as horizontal frontal crashes and 12 of these involved a major compression lumbar burst fracture primarily at L1. All were belted and almost all occurred in late model vehicles with belt pretensioners and buckets seats.

Conclusion

Major compression burst fractures of the lumbar spine in frontal crashes were induced via a dynamic axial force transmitted to the pelvis/buttocks into the seat cushion/pan involving belted occupants in late model vehicles with increasing age as a significant factor.     

Injuries to belted older children in motor vehicle crashes

Context

The American Academy of Pediatrics and the National Highway Traffic Safety Administration currently recommend that, unless they are under 57 in. in height, 8–12-year-old children use seat belts and all should ride in the rear seats of vehicles. These recommendations assume that the vehicle seat belt should provide adequate protection for these older children in the event of a crash.

Objectives

To describe characteristics of older children in the rear seat using seat belts in crashes, to estimate their risk and body region distribution of injury, and to identify risk factors for injury.

Methods

A representative sample of 6680 seat belt-restrained occupants, 8–12 years of age, seated in the rear seat during crashes involving insured vehicles in 16 US states between December 1998 and December 2007. A telephone interview was conducted with the driver of each vehicle. The main outcome was the parent-reported injury defined as Abbreviated Injury Scale (AIS) 2 or greater injuries.

Results

The risk of injury for belted 8–12 year olds in the rear seat was 1.3%. Head injury was the most common injury (60%), followed by injuries to the face (9%), upper extremity (9%) and abdomen (9%). One out of five (21%) 8–12 year olds either did not use the shoulder portion of the vehicle seat belt or placed it incorrectly behind their back or under their arm. Bivariate analyses indicated a higher risk of injury for these children (1.8%) as compared to children using both the lap and shoulder portions of the seat belt (1.1%). However, this difference was not statistically significant when other risk factors such as crash severity and characteristics of the driver were considered.

Conclusions

Injuries to the head, face, abdomen and upper extremity are the most common injuries to target for improved protection among 8–12 year olds in seat belts. Driver and crash characteristics are important risk factors for injury. A recent federal motor vehicle safety standard requiring lap and shoulder belts in all rear seat positions has the potential to further decrease the risk of injury to older children using seat belts.     

Risk factors for pelvic fractures in lateral impact motor vehicle crashes

Lateral impact motor vehicle crashes account for over 10% of all crashes and are more likely to result in pelvic fractures than frontal crashes. We performed a case control study of lateral impact motor vehicle crashes using the 1995-2004 National Accident Sampling System Crashworthiness Data System to determine occupant and vehicle risk factors for pelvic fractures. Cases (N=728) were occupants involved in a near-side lateral impact crash who experienced a pelvic fracture and controls were occupants (N=5710) who did not experience a pelvic fracture. Occupant risk factors evaluated were age, body mass index (BMI), gender including pregnancy status, and seat belt use. Vehicle risk factors evaluated were vehicle body type, weight of striking and struck vehicles, and magnitude of intrusion of side or door panel. Using multivariate logistic regression analysis, we found that age 65 years or older, female gender, underweight body mass index, and increasing magnitude of intrusion of the door or side panel of the vehicle were associated with an increased risk of a pelvic fracture. Injury prevention strategies should focus on decreasing the magnitude of side or door panel intrusion to decrease the risk of pelvic fracture in the event of a lateral impact crash.