Crash-involved Drivers Research Articles

Driver health and crash involvement: A case-control study

The study investigates the relative crash involvement risk associated with diagnosed medical conditions, subjective symptoms and the use of some medicines based on self-report questionnaires from 4448 crash-involved drivers. Whereas many previous studies of medical conditions and crash risk have focussed exclusively on elderly drivers, this study included drivers of all ages. Relative risk for each health condition was estimated by comparing drivers with and without the condition, regarding the odds of being at fault for the crash. Statistical significance was tested by a logistic regression analysis for each condition with crash culpability as the dependent variable. Relative risks were expressed as odds ratios (OR) adjusted for age and annual driving distance. The analyses identified the following significant risk factors: non-medicated diabetes (OR = 3.08), a history of myocardial infarction (OR = 1.77), using glasses when driving (OR = 1.26), myopia (OR = 1.22), sleep onset insomnia (OR = 1.87), frequent tiredness (OR = 1.36), anxiety (OR = 3.15), feeling depressed (OR = 2.43) and taking antidepressants (OR = 1.70). In addition, there was a relatively large and nearly significant relative risk for drivers who had suffered a stroke (OR = 1.93). For some additional conditions the crude odds ratios were significant, but failed to reach significance after correction for age and annual driving distance.

A method for estimating crash risk associated with driver BAC

A method is presented for estimating the risk of driver involvement in injury crashes for case-control data where control drivers have reliable measures of BAC (blood alcohol concentration) and other driver characteristics, but crash-involved drivers do not have BAC measures. The usual estimates of risk associated with BAC derived from case-control studies depend on the provision of driver BAC for virtually all case (crash-involved drivers) and control (drivers on the road) samples. The method described here makes use of the case-control study design but requires only the total numbers of case drivers within groups of drivers defined by variables common to both samples. The risk associated with BAC of New Zealand driver night-time involvement in injury crashes is estimated to illustrate the application of this method.

Potential Crash Involvement of Young Novice Drivers with Previous Crash and Citation Records

A goal for any licensing agency is the ability to identify crash-prone drivers. Thus, the objective of this study is the development of a crash prediction model that can be used to estimate the likelihood of a young novice driver's involvement in a crash occurrence. Multiple logistic regression techniques were employed with available Kentucky data. This study considers as crash predictors the driver's total number of previous crashes, citations accumulated, and demographic factors. The driver's total number of previous crashes was further disaggregated into the driver's total number of previous at-fault and not-at-fault crashes. Sensitivity analysis was used to select an optimal cut-point for the model. The overall efficiency of the model is 77.82%, and it can be used to classify correctly more than one-third of potential crash-prone drivers if a cut-point of 0.247 is selected. The total number of previous at-fault and not-at-fault crash involvements and the accumulation of speeding citations are strongly associated with a driver's being at risk. In addition, a driver's risk is increased by being young and being male. Although the statistical nature of driver crash involvements makes them difficult to predict accurately, the model presented here enables agencies to identify correctly 49.4% of crash-involved drivers from the top 500 high-risk drivers. Moreover, the model can be used for driver control programs aimed at road crash prevention that may range from issuance of warning letters to license suspension.

License Suspension Revisited: A 3-Year Follow-Up Study of Older Drivers

This 3-year follow-up study addressed changes in health, cognitive functioning, and driving status among 37 older drivers and 37 individually matched controls. Initially, the study group had suspended driver’s licenses due to traffic violations. The in-person follow-up medical and neuropsychological examinations concerned 20 case participants and 22 controls. Mortality tended to be higher with case participants than with controls (p = .085), and there was more dementia or cognitive impairment with case participants (5/37) than with controls (0/37,p = .027). Initially, crash-involved case participants performed consistently worse on measures of cognitive functioning than did controls and noncrashed case participants and showed greater deterioration over time. Compared to controls, more crash-involved drivers had died (p = .019) or had stopped driving (p = .040). Because some older drivers with unsafe driving behavior may be in early phases of dementing processes or serious medical conditions, they should be medically and cognitively assessed.

Trends of behavioral risk factors in motor vehicle crashes in Utah, 1992–1997

Objective: Measure changes in the prevalence of behavioral factors including police-reported fatigue and alcohol intoxication, as well as self-reported seatbelt use, and assess their effect on hospitalization or death after a motor vehicle crash. Methods: Probabilistic linkage was used to match drivers in motor vehicle crashes with hospital discharge records for the years 1992–1997. Frequencies of specific behavioral factors were evaluated using the Cochran–Armitage test for trend. Odds ratios and corresponding 95% confidence intervals were calculated using generalized estimating equations (GEEs) with crash and driver characteristics as independent variables and hospitalization or death as the dependent variable. Results: The analysis database consisted of 450,286 crash driver records, which linked to 4219 (0.9%) hospitalizations or deaths. There was an increasing trend for self-reported seatbelt use among crash-involved drivers from 80.5% in 1992 to 89.3% in 1997 ( P<0.001). Police-reported alcohol intoxication among crash-involved drivers showed a decreasing trend from 2.4% in 1992 to 1.5% in 1997 ( P<0.001). There was no trend for police-reported fatigue-related crashes. Odds ratios of hospitalization or death for seatbelt use, alcohol involvement, and fatigue were significant and did not fluctuate considerably between 1992 and 1997. Seatbelt use offered a protective effect from hospitalization or death, while alcohol intoxication and fatigue contributed to increased likelihood of hospitalization or death. Conclusions: These results suggest that while some improvement has been made in decreasing seatbelt non-use and driver alcohol intoxication among crash-involved drivers, no improvement has been made in reducing fatigue-related crashes.

Mobility impairments in crash-involved older drivers.

To evaluate potential associations of impairments in physical function with motor vehicle crash involvement in older drivers. Case participants were randomly selected residents of Mobile County, Alabama, greater or less than 65 years old who had sustained an at-fault motor vehicle crash in 1996. Similarly selected crash-free controls were frequency matched to cases on gender and age. Self-report data on demographic variables, medical conditions, medications, driving exposure, and function were collected by telephone interviewers. Relative to crash-free subjects, crash-involved drivers were significantly more likely to report difficulty walking one fourth mile and moving outdoors. Marginally significant associations were observed for trouble carrying a heavy object 100 yards and for the occurrence of falls in the prior year. Increasing numbers of functional limitations were directly related to the odds of crash involvement. In comparison to crash-free controls, crash-involved older drivers are more likely to report other mobility-related impairments, possibly including falls.

Visual risk factors for crash involvement in older drivers with cataract.

The Impact of Cataracts on Mobility project has previously demonstrated that older drivers with cataract have an elevated risk of motor vehicle collision. To examine what types of visual impairment serve as a basis of the increased crash risk of older drivers with cataract. A cross-sectional analysis was performed on 274 older drivers with cataract and 103 older drivers free of cataract recruited through 12 eye care clinics for the purposes of the Impact of Cataracts on Mobility project, a prospective study on driving mobility in older adults with cataract. Tests measured visual acuity, contrast sensitivity, and disability glare for each eye separately using habitual distance correction. The dependent variable was involvement in at least 1 state-recorded, at-fault vehicle crash during the 5 years prior to study enrollment. Logistic regression evaluated associations (odds ratios [ORs]) between visual function and crash involvement. Better and worse eye models defined on the basis of visual acuity were developed. Associations between each type of visual function and crash involvement were adjusted for age, sex, driving exposure, cognitive status, and other types of visual function. For both the better and worse eye models, contrast sensitivity was independently associated with crash involvement, whereas visual acuity and disability glare were not. Drivers with a history of crash involvement were 8 times more likely to have a serious contrast sensitivity deficit in the worse eye (defined as a Pelli-Robson score of 1.25 or less) than those who were crash-free (OR = 7.86; 95% confidence interval [CI], 1.55-39.79); this association was weaker for the better eye but still statistically significant (OR = 3.78; 95% CI, 1.15-12.48). Crash-involved drivers were 6 times more likely to have severe contrast sensitivity impairment in both eyes (OR = 5.78; 95% CI, 1.87-17.86) than crash-free drivers. A severe contrast sensitivity deficit in only 1 eye was still significantly associated with crash involvement (OR = 2.70; 95% CI, 1.16-6.51). Severe contrast sensitivity impairment due to cataract elevates at-fault crash risk among older drivers, even when present in only 1 eye.

Predictors of safety belt use among crash-involved drivers and front seat passengers: adjusting for over-reporting

Police-reported crash data are rarely used to investigate safety belt use and its predictors, even though these data have a number of advantages over data collected in roadside surveys. It has been widely recognized that motorists tend to over-report their safety belt use to police when mandatory belt use becomes law. In this paper, we use a logistic regression model that allows for misclassification errors in outcome variable to examine predictors of safety belt use among crash-involved drivers and front seat passengers. Our analysis shows significant associations between occupant characteristics, driving circumstances, and safety belt use. Alcohol involvement has the strongest negative association with safety belt use, but this association would be considerably underestimated without adjusting for the over-reporting of safety belt use in police-reported crash data. The adjusted belt use rate among front seat occupants with at least nonincapacitating injuries is about 81%, compared to 90% in police-reported crash data.

Identifying crash involvement among older drivers: agreement between self-report and state records

Older drivers have a high crash rate per vehicle mile of travel. Coupled with the growth of the number of older drivers on the road, this has generated interest in the identification of factors which place older drivers at increased risk. However, much of the existing research on medical and functional risk factors for crash involvement has generally been inconsistent. Methodological differences between studies have been hypothesized as being partly responsible for such inconsistencies. The source of information used to identify crash-involved drivers has been identified as one such difference. This paper reports on the agreement between self-report and state record for identifying crash involved-older drivers. We also sought to determine whether the prevalence of visual and cognitive impairment differs across crash-involved drivers identified by either or both sources. Finally, we assessed whether risk factors for crash involvement differed when crash-involved drivers were identified by either self-report or state records. Results indicated that there was a moderate level of agreement between self-reported and state-recorded crash involvement (kappa=0.45). However, we did find significant differences between crash-involved drivers identified via state records and/or self-report with respect to demographic (age, race), driving (annual mileage, days per week driven), and vision impairment (acuity, contrast sensitivity, peripheral visual field sensitivity, useful field of view). We also found that the possibility for biased measures of association is real. Useful field of view impairment was associated with both self-reported and state-recorded crash involvement; however, the magnitude of the associations was disparate. Moreover, glaucoma was identified as a significant risk factor when considering state-recorded crashes but not self-reported crashes. While validation of these findings is required, research designed to identify risk factors for crash involvement among older drivers should carefully consider the issue of case definition, particularly if self-report is used to identify crash-involved older drivers.

Impairments of some cognitive functions are common in crash-involved older drivers

The relationship between limitations in different cognitive functions, measured with a neuropsychological test battery, and moving traffic violations among older drivers was investigated. Thirty-seven drivers aged 65 years or more, with temporarily suspended driving licenses (suspended drivers) were identified 23 were crash-involved and 14 were not. When compared to 31 controls with clean driving records, crash-involved suspended drivers performed less well on tests of visuoconstructive ability ( p = 0.008), psychomotor speed ( p = 0.019) and visuospatial memory ( p = 0.036). Non-crash-involved suspended drivers did not differ from controls. A combination of three tests (of visuoconstructive ability, visuospatial memory and verbal episodic memory) succeeded in correctly classifying 65.2% of the crash-involved suspended drivers. The results support the idea of cognitive decrements as an important causal factor in crashes of older drivers.

The effect of teenage passengers on the fatal crash risk of teenage drivers

Fatal crash-involved drivers of passenger vehicles were identified in the Fatality Analysis Reporting System for the period 1990 through 1995. Each driver was categorized as being alone in the vehicle at the time of the crash or with one or more passengers. Drivers at fault or responsible for crash occurrence were defined as all drivers involved in a single-vehicle crash, or drivers in multiple-vehicle crashes who were coded in the Fatality Analysis Reporting System as committing one or more driver errors. The results indicated that passenger presence was associated with proportionately more at-fault fatal crashes for drivers aged 24 and younger, were a neutral factor for drivers aged 25–29, and were associated with fewer at-fault involvements for drivers aged 30 and older. Relative risk of fatal crash involvement was particularly high for teenage drivers traveling, day or night, with two or more teenage passengers. Additional research is needed to determine how the added risk associated with teenage passengers riding with teenage drivers can be reduced or eliminated.

Demographic characteristics, drinking patterns and drink-driving behavior of injured male drivers and motorcycle riders.

The demographic characteristics, usual drinking and drink-driving patterns, incidence of problem drinking, precrash drinking behavior and attitudes towards drink-driving of crash-involved male drivers and riders are described and related to blood alcohol concentration (BAC) on admission to hospital. A better understanding of these issues will enable drink-driving countermeasures to target more specifically those individuals who are most at risk of being killed or injured in alcohol-related road crashes. Between June 1985 and April 1987 interviews were conducted with a sample of 302 male drivers and motorcycle riders admitted to the Royal Adelaide Hospital in Adelaide, South Australia. With one exception, the likelihood of having a high BAC (i.e., 80 mg/dl or above) did not differ with demographic profile. As BAC increased, there was a significant increase in: various indices of quantity and frequency of drinking; beer being the preferred beverage; percentages drinking alone, in a hotel, in a vehicle and for various less socially acceptable reasons; frequency of drink-driving; likelihood of previous drink-driving suspension; and, more liberal attitudes towards drink-driving. About 25% of those with a BAC of at least 150 mg/dl were probably experiencing alcohol-related problems prior to the crash, compared with only a very small proportion of those with lower BACs. Precrash drinking most commonly involved drinking in a hotel, drinking with friends and drinking beer, with no significant differences between BAC groups. The results suggest that usual drinking and drink-driving patterns, as well as attitudes to drink-driving, become more extreme as the BAC of male crash-involved drivers and riders increases.

Psychosocial characteristics of alcohol-involved and nonalcohol-involved seriously injured drivers

This study compared two groups of alcohol-positive and alcohol-negative, seriousiy injured, crash-involved drivers on demographics, personality characteristics, driving-related attitudes, prior driving history, lifestyle, substance use, and antecedent driver condition. The study sample was drawn from motor vehicle accident admissions to the Sunnybrook Health Science Centre Regional Trauma Unit. One hundred and six interviews were completed between August 1986 and November 1989, with blood alcohol concentration (BAC) data available for 96 drivers. These data suggest no driving-related attitude differences between the two groups. Self-reported driving histories indicated significantly fewer graduates of driving schools and more licence suspensions for the BAC-positive group. The only consistently significant differences were found for the drinking-related variables, with a greater percentage of the BAC-positive group reporting: lower age of first intoxication; a greater self-perceived drinking problem; a greater frequency of intoxication in the month before the accident; and greater self-reported drinking-driving in the month before the accident. Principal-components factor analysis revealed a four-factor solution labelled: Alcohol Use, Deviant/Illicit Drug Use, Aggression, and Neuroticism. Alcohol Use was the only factor found to contribute substantially to the discriminant function, together with the job-related stress item. These data suggest that seriously injured, alcohol-positive and alcohol-negative crashed drivers are similar except that the alcohol-positive drivers show more signs of an alcohol problem.

Psychoactive drugs and the risk of injurious motor vehicle crashes in elderly drivers.

To determine whether commonly used psychoactive drugs increase the risk of involvement in motor vehicle crashes for drivers > or = 65 years of age, the authors conducted a retrospective cohort study. Data were obtained from computerized files from the Tennessee Medicaid program, driver's license files, and police reports of injurious crashes. Cohort members were Medicaid enrollees 65-84 years of age who had a valid driver's license during the study period 1984-1988 and who met other criteria designed to exclude persons unlikely to be drivers and to ensure availability of necessary study data. There were 16,262 persons in the study cohort with 38,701 person-years of follow-up and involvement in 495 injurious crashes. For four groups of psychoactive drugs (benzodiazepines, cyclic antidepressants, oral opioid analgesics, and antihistamines), the risk of crash involvement was calculated with Poisson regression models that controlled for demographic characteristics and use of medical care as an indicator of health status. The relative risk of injurious crash involvement for current users of any psychoactive drug was 1.5 (95% confidence interval (CI) 1.2-1.9). This increased risk was confined to benzodiazepines (relative risk = 1.5; 95% CI 1.2-1.9) and cyclic antidepressants (relative risk = 2.2; 95% CI 1.3-3.5). For these drugs, the relative risk increased with dose and was substantial for high doses: 2.4 (95% CI 1.3-4.4) for > or = 20 mg of diazepam and 5.5 (95% CI 2.6-11.6) for > or = 125 mg of amitriptyline. Analysis of data for the crash-involved drivers suggested that these findings were not due to confounding by alcohol use or driving frequency.

The Driver's Role in Fatal Two-Car Crashes: A Paired “Case-Control” Study

This population-based study examines drivers' characteristics associated with driving errors that resulted in fatal motor vehicle crashes. Routinely collected data from the Fatal Accident Reporting System were used to assess whether a driver initiated the crash (case) or was passively involved (control) in 6,506 two-car collisions (81% of 7,993 eligible events). A paired comparison of cases and controls avoided confounding by environmental factors, exposure to traffic, and differences in case fatality. The strongest predictor of crash initiation is alcohol (odds ratio (OR) = 11.5; 95% confidence interval (CI) 9.57-13.9). Odds ratios are elevated even at the lowest blood alcohol concentration levels and increase dramatically as alcohol levels rise. Drivers aged 40-49 years are least likely to initiate crashes; odds ratios rise in a U-shaped manner to 3.35 in teenagers (95% CI 2.72-4.13) and to 22.1 in drivers over 80 years (95% CI 14.2-34.5). Other risk factors for initiating a fatal crash are the following: not wearing a seat belt (OR = 1.54; 95% CI 1.35-1.75), driving without a valid driver's license (OR = 2.16; 95% CI 1.72-2.73), and having had a crash within the last year (OR = 1.21; 95% CI 1.07-1.38). Driving errors leading to fatal crashes do not occur at random, but are associated with specific driver characteristics. The risk factors for crash initiation among crash-involved drivers are similar to risk factors for crash involvement found in other studies. These findings suggest that driving errors often explain high rates of crash involvement, invite further use of crash initiation in traffic injury research, and underscore the value of population-based registries for analytic epidemiology.

Motorcycle licensure, ownership, and injury crash involvement.

The interrelationships among motorcycle licensure, ownership, and injury crash involvement were investigated in a sample of 2,723 motorcycle drivers severely or fatally injured in California in 1985-86. Owners of motorcycles in such crashes ("driver-owners") were less likely to have valid licenses than a random sample of motorcycle owners who had not been in crashes (42 vs. 57 percent). Thirty-three percent of the crash-involved drivers had valid motorcycle driver's licenses; 39 percent were operating motorcycles they did not own ("driver-nonowners"). Driver-nonowners were less likely to be validly licensed than driver-owners (20 percent vs. 44 percent). The licensing rate of crash-involved driver-nonowners was 15 percent if the owner was also unlicensed. Rates of valid licensure were lowest among the youngest drivers. Virtually no crash-involved driver-nonowners under age 21 were licensed in cases in which the owner was also young and unlicensed.

Estimating the effects over time of alcohol on injury severity

Estimates of the effect of blood alcohol on injury severity obtained through studies of patients at clinical facilities have been found to be quite different from those estimated through the analysis of highway accident data. Several factors have been suggested to account for these differences, including consideration of the relative frequencies of alcohol-involved and alcohol free drivers who were killed at the scene or who died before reaching a treatment facility. More generally, the nature of the way that the effect of alcohol varies as a function of time from injury may play a important role. In this paper information from highway accident data was combined with time of death information from state medical examiner files to yield estimates of the function P( T), the probability that an injured driver dies at the time T or later from an injury occurring at T = 0, for classes of crash-involved drivers with differing blood alcohol concentrations. Other factors also considered in the analyses included measures of crash severity, driver age, and restraint use. Elevated blood alcohol was consistently found to be associated with shorter survival times.