To drive or not to drive? A study of travel behavior for a recent drinking occasion.

Despite decades of education and enforcement campaigns, alcohol-impaired driving persists as a social problem in the U.S. Are there other factors influencing decisions to drive after alcohol consumption that may be amenable to change? We conducted a roadside survey in California in 2012 to assess whether residential accessibility, travel attitudes (indicated by ratings of convenience and safety for travel options), and perceptions of arrest risk affect travel choices made subsequent to alcohol consumption. We conducted hybrid choice modeling for 580 participants. Mode-specific travel attitudes were valid constructs and predictive of travel behavior. Perceived level of service (speed) increased the utility for taxi and getting a ride. Perceiving high risk of arrest affected mode choice through travel attitudes. Not everyone assessed their mode options in the same way. For example, frequent binge drinkers appear to be more willing to consider taxis, men had stronger preferences towards active modes, and younger drivers were less pro-driving in this context. Past drinking and driving behavior affected one's attitude towards driving, while the number of drinks was related to mode choice. While our accessibility measure was not significantly related to attitudes or choice, decreasing urbanicity corresponded with stronger preferences for driving. This pilot study suggests that improving level of service (speed), convenience, and overall safety are considerations for public health in terms of promoting alternatives to drinking and driving. This line of research also has implications for emerging options, such as ride hailing, and how these might be optimized for specific segments of the population.

Latent analysis of Complete Streets and traffic safety along an urban corridor.

BACKGROUND: To evaluate Complete Street implementations that covary, the present paper aims to: 1) explore the development of typologies of intersections; and 2) examine how these typologies relate to traffic safety. METHODS: The study site is a five-mile segment in Los Angeles County, California. Multiple indicators of environmental features were collected in 2012 and were included in a latent analysis. Latent classes were then analyzed as a predictor of the number of pedestrian injuries/fatalities and injuries/fatalities for all modes in separate models using negative binomial regression and controlling for exposures. Injuries/fatalities represent the most recent 3 years of crash data available surrounding the environmental data collection (2009-2014). We also examined the role of alcohol. RESULTS: For a relatively short segment of an urban corridor, we identified two distinct classes of intersections. One class was more complete with respect to pedestrian features but was also associated with indicators of increased potential conflict and was predictive of higher overall injuries/fatalities for all modes. This class also had higher pedestrian volumes but was not predictive of higher pedestrian injuries/fatalities in the final models. The alcohol involvement in crash injuries at these locations did not differ by intersection class but was positively associated with injuries/fatalities for all modes and with severe/fatal injuries for pedestrians in the final models. CONCLUSIONS: Identifying typologies can be used to understand the combination of features and prioritize locations for treatment. While Complete Streets may help counter pedestrian injury trends, the efforts captured in this data are insufficient for municipalities aiming for Vision Zero. Ideally, future research can examine these intersections after the implementation of additional improvements in order to isolate treatment effects. These findings suggest additional intersection countermeasures are needed, in addition to efforts to address social problems such as alcohol use and traffic safety.

Non-Emergency Medical Transportation Needs of Middle-Aged and Older Adults: A Rural-Urban Comparison in Delaware, USA.

Background: Older adults in rural areas have unique transportation barriers to accessing medical care, which include a lack of mass transit options and considerable distances to health-related services. This study contrasts non-emergency medical transportation (NEMT) service utilization patterns and associated costs for Medicaid middle-aged and older adults in rural versus urban areas. Methods: Data were analyzed from 39,194 NEMT users of LogistiCare-brokered services in Delaware residing in rural (68.3%) and urban (30.9%) areas. Multivariable logistic analyses compared trip characteristics by rurality designation. Results: Rural (37.2%) and urban (41.2%) participants used services more frequently for dialysis than for any other medical concern. Older age and personal accompaniment were more common and wheel chair use was less common for rural trips. The mean cost per trip was greater for rural users (difference of $2910 per trip), which was attributed to the greater distance per trip in rural areas. Conclusions: Among a sample who were eligible for subsidized NEMT and who utilized this service, rural trips tended to be longer and, therefore, higher in cost. Over 50% of trips were made for dialysis highlighting the need to address prevention and, potentially, health service improvements for rural dialysis patients.

Drinking and driving and perceptions of arrest risk among California drivers: Relationships with DUI arrests in their city of residence.

OBJECTIVE: Addressing drinking and driving remains a challenge in the United States. The present study aims to provide feedback on driving under the influence (DUI) in California by assessing whether drinking and driving behavior is associated with the DUI arrest rates in the city in which the driver lives; whether this is due to perceptions that one can get arrested for this behavior; and whether this differed by those drivers who would be most affected by deterrence efforts (those most likely to drink outside the home). METHODS: This study consisted of a 2012 roadside survey of 1,147 weekend nighttime drivers in California. City DUI arrest rates for 2009-2011 were used as an indicator of local enforcement efforts. Population average logistic modeling was conducted modeling the odds of perceived high arrest likelihood for DUI and drinking and driving behavior within the past year. RESULTS: As the DUI arrest rates for the city in which the driver lives increased, perceived high risk of DUI arrest increased. There was no significant relationship between either city DUI arrest rates or perceived high risk of DUI arrest with self-reported drinking and driving behavior in the full sample. Among a much smaller sample of those most likely to drink outside the home, self-reported drinking and driving behavior was negatively associated with DUI arrests rates in their city of residence but this was not mediated by perceptions. CONCLUSION: The results of the present study suggest that perceptions are correlated with one aspect of DUI efforts in one's community. Those who were more likely to drink outside the home could be behaviorally influenced by these efforts.

The role of Ugandan District Hospital orthopedic units in the care of vulnerable road users: a cross-sectional study.

BACKGROUND: Musculoskeletal injuries are a common cause of morbidity after road traffic injury (RTI) in motorizing countries. District hospitals provide front-line orthopedic care in Uganda and other sub-Saharan African nations. Improving care at the district hospital level is an important component of the World Health Organization's strategy for surgical and trauma systems strengthening, but the data necessary to inform RTI safety and care initiatives has previously been insufficient at the district hospital level. The objective of this study was to provide data on the patient population and patterns of musculoskeletal injury caused by RTI at Ugandan district hospitals. METHODS: In this cross-sectional study, all patients with musculoskeletal injuries identified on x-ray presenting to three Ugandan district hospitals from October 2013 to January 2014 were interviewed and examined to obtain data on patient demographics and injury context by road user category. This manuscript is a sub-group analysis of RTI victims from a broader dataset of all musculoskeletal injuries. RESULTS: Vulnerable road users comprised 92 % of musculoskeletal RTI patients, with 49 % (95 % CI 41-57 %) pedestrians, 41 % (95 % CI 33-49 %) motorcyclists, and 2 % (95 % CI 0-4 %) cyclists. Commonly injured subgroups included student pedestrians (33 % (95 % CI 22-44 %) of pedestrians) and motorcyclists with less than a post-secondary education (74 % (95 % CI 63-85 %) of motorcyclists). The morning hours were the most common time of injury for all RTI patients (37 %%; 95 % CI 30-44 %) and motorcyclists (46 %; 95 % CI 34-58 %), while pedestrians were most commonly injured in the evening (32 %; 95 % CI 21-43 %). CONCLUSIONS: By demonstrating commonly injured demographic groups and high frequency times of day for injury, this surveillance study of musculoskeletal RTI suggests targeted avenues for future road safety research in the districts of Uganda. Compared with previous studies from the capital of Uganda, these results suggest that Ugandan district hospitals care for a disproportionate share of vulnerable road users, a discrepancy which may pertain to other sub-Saharan African nations, as well. Strengthening district hospital orthopedic care should be considered a priority of strategies aimed at improving outcomes for these vulnerable groups.

Utilizing the eigenvectors of freeway loop data spatiotemporal schematic for real time crash prediction.

The concept of crash precursor identification is gaining more practicality due to the recent advancements in Advanced Transportation Management and Information Systems. Investigating the shortcomings of the existing models, this paper proposes a new method to model the real time crash likelihood based on loop data through schematic eigenvectors. Firstly, traffic volume, occupancy and density spatiotemporal schematics in certain duration before an accident occurrence were constructed to describe the traffic flow status. Secondly, eigenvectors and eigenvalues of the spatiotemporal schematics were extracted to represent traffic volume, occupancy and density situation before the crash occurrence. Thirdly, by setting the vectors in crash time as case and those at crash free time as control, a logistic model is constructed to identify the crash precursors. Results show that both the eigenvectors and eigenvalues can significantly impact the accident likelihood compared to the previous study, the proposed model has the advantage of avoiding multicollinearity, better reflection of the overall traffic flow status before the crash, and improving missing data problem of loop detectors.

Modeling secondary accidents identified by traffic shock waves.

The high potential for occurrence and the negative consequences of secondary accidents make them an issue of great concern affecting freeway safety. Using accident records from a three-year period together with California interstate freeway loop data, a dynamic method for more accurate classification based on the traffic shock wave detecting method was used to identify secondary accidents. Spatio-temporal gaps between the primary and secondary accident were proven be fit via a mixture of Weibull and normal distribution. A logistic regression model was developed to investigate major factors contributing to secondary accident occurrence. Traffic shock wave speed and volume at the occurrence of a primary accident were explicitly considered in the model, as a secondary accident is defined as an accident that occurs within the spatio-temporal impact scope of the primary accident. Results show that the shock waves originating in the wake of a primary accident have a more significant impact on the likelihood of a secondary accident occurrence than the effects of traffic volume. Primary accidents with long durations can significantly increase the possibility of secondary accidents. Unsafe speed and weather are other factors contributing to secondary crash occurrence. It is strongly suggested that when police or rescue personnel arrive at the scene of an accident, they should not suddenly block, decrease, or unblock the traffic flow, but instead endeavor to control traffic in a smooth and controlled manner. Also it is important to reduce accident processing time to reduce the risk of secondary accident.

Acceptance of drinking and driving and alcohol-involved driving crashes in California.

BACKGROUND: Alcohol-impaired driving accounts for substantial proportion of traffic-related fatalities in the U.S. Risk perceptions for drinking and driving have been associated with various measures of drinking and driving behavior. In an effort to understand how to intervene and to better understand how risk perceptions may be shaped, this study explored whether an objective environmental-level measure (proportion of alcohol-involved driving crashes in one's residential city) were related to individual-level perceptions and behavior. METHODS: Using data from a 2012 cross-sectional roadside survey of 1147 weekend nighttime drivers in California, individual-level self-reported acceptance of drinking and driving and past-year drinking and driving were merged with traffic crash data using respondent ZIP codes. Population average logistic regression modeling was conducted for the odds of acceptance of drinking and driving and self-reported, past-year drinking and driving. RESULTS: A non-linear relationship between city-level alcohol-involved traffic crashes and individual-level acceptance of drinking and driving was found. Acceptance of drinking and driving did not mediate the relationship between the proportion of alcohol-involved traffic crashes and self-reported drinking and driving behavior. However, it was directly related to behavior among those most likely to drink outside the home. DISCUSSION: The present study surveys a particularly relevant population and is one of few drinking and driving studies to evaluate the relationship between an objective environmental-level crash risk measure and individual-level risk perceptions. In communities with both low and high proportions of alcohol-involved traffic crashes there was low acceptance of drinking and driving. This may mean that in communities with low proportions of crashes, citizens have less permissive norms around drinking and driving, whereas in communities with a high proportion of crashes, the incidence of these crashes may serve as an environmental cue which informs drinking and driving perceptions. Perceptual information on traffic safety can be used to identify places where people may be at greater risk for drinking and driving. Community-level traffic fatalities may be a salient cue for tailoring risk communication.

Missed or Delayed Medical Care Appointments by Older Users of Nonemergency Medical Transportation.

PURPOSE OF THE STUDY: This study identified factors associated with canceling nonemergency medical transportation appointments among older adult Medicaid patients. DESIGN AND METHODS: Data from 125,913 trips for 2,913 Delaware clients were examined. Mediation analyses, as well as, multivariate logistic regressions were conducted. RESULTS: Over half of canceled trips were attributed to client reasons (e.g., no show, refusal). Client characteristics (e.g., race, sex, functional status) were associated with cancelations; however, these differed based on the cancelation reason. Regularly scheduled trips were less likely to be canceled. IMPLICATIONS: The evolving American health care system may increase service availability. Additional policies can improve service accessibility and overcome utilization barriers.

Surrogate safety measure for evaluating rear-end collision risk related to kinematic waves near freeway recurrent bottlenecks.

This study presents a surrogate safety measure for evaluating the rear-end collision risk related to kinematic waves near freeway recurrent bottlenecks using aggregated traffic data from ordinary loop detectors. The attributes of kinematic waves that accompany rear-end collisions and the traffic conditions at detector stations spanning the collision locations were examined to develop the rear-end collision risk index (RCRI). Together with RCRI, standard deviations in occupancy were used to develop a logistic regression model for estimating rear-end collision likelihood near freeway recurrent bottlenecks in real-time. The parameters in the logistic regression models were calibrated using collision data gathered from the 6-mile study site between 2006 and 2007. Findings indicated that an additional unit increase in RCRI results in increasing the odds of rear-end collision by 21.1%, a unit increase in standard deviation of upstream occupancy increases the odds by 19.5%, and a unit increase in standard deviation of downstream occupancy increases the odds by 18.7%. The likelihood of rear-end collisions is highest when the traffic approaching from upstream is near capacity state while downstream traffic is highly congested. The paper also reports on the findings from comparing the predicted number of rear-end collisions at the study site using the proposed model with the observed traffic collision data from 2008. The proposed model's true positive rates were higher than those of existing real-time crash prediction models.

The Impact of Health Problems on Driving Status among Older Adults.

OBJECTIVE: This study assesses the impact of health problems on driving status (current driver vs. ex-driver) among older adults to identify which of those health problems have the greatest individual and population impact on driving cessation. METHODS: Data were from baseline and 5 year follow-up waves of a longitudinal survey of adults age 55 years and older (N=1,279). The impact of several health problems on driving status was assessed using a relative risk ratio and a population attributable risk percent. Analyses controlled for age, gender, and the presence of additional baseline health problems. RESULTS: Many health conditions were not associated with driving cessation. Functional limitations, cognitive function, and measures of vision were significant predictors of driving cessation. Self-care functional limitations were associated with the highest risk for driving cessation, while visual function was associated with the highest attributable risks. DISCUSSION: In order to effectively address healthy aging and mobility transitions, it is important to consider the implications of targeting individuals or populations who are most at risk for driving cessation. The risk ratio is relevant for evaluating individuals; the attributable risk is relevant for developing interventions in populations.

Factors associated with hit-and-run pedestrian fatalities and driver identification.

As hit-and-run crashes account for a significant proportion of pedestrian fatalities, a better understanding of these crash types will assist efforts to reduce these fatalities. Of the more than 48,000 pedestrian deaths that were recorded in the United States between 1998 and 2007, 18.1% of them were caused by hit-and-run drivers. Using national data on single pedestrian-motor vehicle fatal crashes (1998-2007), logistic regression analyses were conducted to identify factors related to hit-and-run and to identify factors related to the identification of the hit-and-run driver. Results indicate an increased risk of hit-and-run in the early morning, poor light conditions, and on the weekend. There may also be an association between the type of victim and the likelihood of the driver leaving and being identified. Results also indicate that certain driver characteristics, behavior, and driving history are associated with hit-and-run. Alcohol use and invalid license were among the leading driver factor associated with an increased risk of hit-and-run. Prevention efforts that address such issues could substantially reduce pedestrian fatalities as a result of hit-and-run. However, more information about this driver population may be necessary.

Visual assessment of pedestrian crashes.

Of the numerous factors that play a role in fatal pedestrian collisions, the time of day, day of the week, and time of year can be significant determinants. More than 60% of all pedestrian collisions in 2007 occurred at night, despite the presumed decrease in both pedestrian and automobile exposure during the night. Although this trend is partially explained by factors such as fatigue and alcohol consumption, prior analysis of the Fatality Analysis Reporting System database suggests that pedestrian fatalities increase as light decreases after controlling for other factors. This study applies graphical cross-tabulation, a novel visual assessment approach, to explore the relationships among collision variables. The results reveal that twilight and the first hour of darkness typically observe the greatest frequency of pedestrian fatal collisions. These hours are not necessarily the most risky on a per mile travelled basis, however, because pedestrian volumes are often still high. Additional analysis is needed to quantify the extent to which pedestrian exposure (walking/crossing activity) in these time periods plays a role in pedestrian crash involvement. Weekly patterns of pedestrian fatal collisions vary by time of year due to the seasonal changes in sunset time. In December, collisions are concentrated around twilight and the first hour of darkness throughout the week while, in June, collisions are most heavily concentrated around twilight and the first hours of darkness on Friday and Saturday. Friday and Saturday nights in June may be the most dangerous times for pedestrians. Knowing when pedestrian risk is highest is critically important for formulating effective mitigation strategies and for efficiently investing safety funds. This applied visual approach is a helpful tool for researchers intending to communicate with policy-makers and to identify relationships that can then be tested with more sophisticated statistical tools.

Geocoding police collision report data from California: a comprehensive approach.

BACKGROUND: Collision geocoding is the process of assigning geographic descriptors, usually latitude and longitude coordinates, to a traffic collision record. On California police reports, relative collision location is recorded using a highway postmile marker or a street intersection. The objective of this study was to create a geocoded database of all police-reported, fatal and severe injury collisions in the California Statewide Integrated Traffic Records System (SWITRS) for years 1997-2006 for use by public agencies. RESULTS: Geocoding was completed with a multi-step process. First, pre-processing was performed using a scripting language to clean and standardize street name information. A state highway network with postmile values was then created using a custom tool written in Visual Basic for Applications (VBA) in ArcGIS software. Custom VBA functionality was also used to incorporate the offset direction and distance. Intersection and address geocoding was performed using ArcGIS, StreetMap Pro 2003 digital street network, and Google Earth Pro. A total of 142,007 fatal and severe injury collisions were identified in SWITRS. The geocoding match rate was 99.8% for postmile-coded collisions and 86% for intersection-coded collisions. The overall match rate was 91%. CONCLUSIONS: The availability of geocoded collision data will be beneficial to clinicians, researchers, policymakers, and practitioners in the fields of traffic safety and public health. Potential uses of the data include studies of collision clustering on the highway system, examinations of the associations between collision occurrence and a variety of variables on environmental and social characteristics, including housing and personal demographics, alcohol outlets, schools, and parks. The ability to build maps may be useful in research planning and conduct and in the delivery of information to both technical and non-technical audiences.

Attribution of functional limitation to cancer decreases in the year following breast cancer diagnosis in older patients.

OBJECTIVES: To examine the prevalence of self-reported functional limitations in a breast cancer population, identify whether these reported limitations are attributed to breast cancer versus other coexisting illnesses, and examine how this attribution changes over time from early in treatment to 9 months later. DESIGN: Longitudinal, observational study. SETTING: Community dwelling adults in Detroit metropolitan area. PARTICIPANTS: 2033 participants (1011 breast cancer patients, 1022 controls) aged 40-84 years. MEASUREMENTS: Participants were asked about each of 23 possible coexisting illnesses in addition to breast cancer and whether or not each illness, including breast cancer, caused any activity limitation. RESULTS: Of the 933 cancer patients who completed both baseline and follow-up evaluations, 45% were aged 65 years and older. At baseline, 56% of patients 65 years and older reported functional limitation compared with 50% of patients younger than 65 years (p=0.005). Of those patients who reported limitation at baseline, 59% of older patients and 78% of younger patients attributed their limitation to breast cancer (p<0.001). At follow-up, 53% of older and 37% of younger patients reported functional limitation (p<0.001), with 27% of older patients compared with 57% of younger patients (p<0.001) attributing limitation to breast cancer. CONCLUSION: Self-reported functional limitations are common 3 months after breast cancer diagnosis, being attributed primarily to breast cancer. By 1 year after diagnosis, much of the limitation due to breast cancer resolves. Older women are less likely to have resolution of their limitations, which are most commonly due to other coexisting illnesses.

Driving cessation and increased depressive symptoms.

BACKGROUND: To understand the consequences of driving cessation in older adults, the authors evaluated depression in former drivers compared with active drivers. METHODS: Depression (as assessed using the Center for Epidemiological Studies Depression Scale), driving status, sociodemographic factors, health status, and cognitive function were evaluated for a cohort of 1953 residents of Sonoma County, California, aged 55 years and older, as part of a community-based study of aging and physical performance. The authors re-interviewed 1772 participants who were active drivers at baseline 3 years later. RESULTS: At baseline, former drivers reported higher levels of depression than did active drivers even after the authors controlled for age, sex, education, health, and marital status. In a longitudinal analysis, drivers who stopped driving during the 3-year interval (i.e., former drivers) reported higher levels of depressive symptoms than did those who remained active drivers, after the authors controlled for changes in health status and cognitive function. Increased depression for former drivers was substantially higher in men than in women. CONCLUSIONS: With increasing age, many older adults reduce and then stop driving. Increased depression may be among the consequences associated with driving reduction or cessation.

Alcohol, stress-related factors, and short-term absenteeism among urban transit operators.

Transit operators, relative to workers in many other occupations, experience high levels of work-related stress, as documented through neuroendocrine elevations on the job vis-a-vis resting states (J Occup Health Psychol. 1998;3:122-129). Previous research suggests that self-reported job stress is associated with higher levels of alcohol consumption among transit operators (Alcohol Clin Exp Res. 2000;24:1011-1019) and with absenteeism (Working Environment for Local Public Transport Personnel, Stockholm: Swedish Work Environmental Fund, 1982; Work Stress. 1990;4:83-89). The purpose of this study was to examine the interrelationships between alcohol use, stress-related factors (stressful life events, job stressors, and burnout), and short-term absenteeism among a multiethnic cohort of urban transit operators. Self-reported measures of alcohol, stress-related factors, and short-term absenteeism were obtained from a sample (n=1,446) of San Francisco municipal transit operators who participated in the 1993-1995 Municipal Railway Health and Safety Study. Multivariate logistic regression analyses showed that absenteeism among drinkers was associated with risk for alcohol dependence [odds ratio (OR)=2.46, heavy drinking (OR=1.87), alcohol-related harm (OR=2.17), increased drinking since becoming a transit operator (OR=1.74), and having any problem drinking indicator (OR=1.72). The association between absenteeism and stress-related factors varied by gender and drinking status. Final multivariate models among drinkers indicated that among males, problem drinking (OR=1.82), stressful life events (OR=1.62), and job burnout (OR=1.22) were independently associated with elevated odds of absenteeism. Among female drinkers, only stressful life events (OR=5.17) was significantly associated with elevated odds of absenteeism. Findings suggest that workplace interventions that address both individual and environmental stressors are most likely to have a positive impact on health-related outcomes, including problem drinking, thereby reducing absenteeism.

Physical workload, ergonomic problems, and incidence of low back injury: a 7.5-year prospective study of San Francisco transit operators.

BACKGROUND: The etiologic role of biomechanical factors for low back injury (LBI) needs to be confirmed in prospective studies that control for psychosocial factors. METHODS: Complete baseline information on 1,233 vehicle operators was gathered during medical examinations and by questionnaire. First LBI during 7.5 years of follow-up was ascertained from insurance records. Hazard ratios and etiologic fractions were analyzed with Cox regression models stratified by injury severity and controlling for age, sex, height, weight, ethnicity, and biomechanical and psychosocial job factors. Severe LBI was defined as medically diagnosed postlaminectomy syndrome, spinal stenosis, herniated lumbar disc, sciatica, or spinal instability. RESULTS: An exponential dose-response relationship was found between weekly driving hours and incidence of first LBI. Indicators of physical workload were more strongly associated with more severe low back injuries compared to less severe injuries. Rates of severe LBI increased 39% for every 10-hr increase in weekly driving (hazard ratio 1.39, 95% confidence interval 1.15-1.68). Higher risks of severe LBI were also found among operators performing heavy physical labor on cable cars (hazard ratio 2.76, 95% confidence intervals 1.24-6.14) or reporting more ergonomic problems at baseline (HR for upper quartile 1.65 (95% confidence interval 1.08-2.50). Estimates of etiologic fractions suggest that reduction of ergonomic problems to the low level currently experienced by 25% of drivers would result in a 19% reduction of severe LBI among all drivers. A change from full- (more than 30 hr) to part-time driving (20-30 hr) could reduce the number of severe LBI by 59%, although this gain would be reduced to 28% at the company level if injuries expected among additional employees, hired to maintain full service are included. CONCLUSIONS: Duration of professional driving and ergonomic problems are independent and preventable risk factors for LBI even after adjustment for psychosocial factors.

Problems with vision associated with limitations or avoidance of driving in older populations.

OBJECTIVES: This report examines the role of (a) disease processes affecting vision, (b) reported troubles with vision, (c) physical symptoms affecting the eyes, and (d) objective measures in reported driving limitation due to problems with eyesight among older drivers. METHODS: Data for this study (N = 1,840) were obtained from participants in a community-based study of aging and physical performance in people age 55 or older in the city of Sonoma, California. Each of 16 visual conditions was assessed for impact on reported driving limitation due to eyesight by calculating a "risk" ratio. Then, prevalence of the condition was combined with the ratio to generate an attributable risk for that condition for vision-related limitations in driving. RESULTS: Each condition was significantly associated with reported limitations in driving due to eyesight. "Avoiding physical activity due to vision" (ratio = 3.4) and "trouble seeing steps up/down stairs" (ratio = 2.9) had the strongest association. However, "glasses/contacts required for driving" and "trouble with glare from sun/lights" had the highest attributable risks (35.8 and 29.4). DISCUSSION: The risk ratio is relevant for evaluating individuals; the attributable risk is relevant to planning countermeasures in populations. Addressing specific problems related to vision should substantially reduce driving limitations due to eyesight.