Aging without injury in the United States requires action today

Introduction: In 2017, unintentional injuries were the seventh leading cause of death among older adults (age ≥ 65), resulting in over 55,000 deaths. Falls accounted for more than half of these deaths. Given that older adults are the fastest growing age group in the United States, we can anticipate that injuries will become an even greater health concern in the near future. Methods: Aging without injury is possible. There are evidence-based strategies that can reduce falls. However, older adults may not realize that falls can be prevented or they may be afraid to admit their fear of falling or difficulty with walking as these issues may signal their inability to live independently. Results: In this commentary, we will highlight what the Centers for Disease Control and Prevention is doing to prevent older adult falls. We also highlight the importance of broadening older adults' awareness about falls to successfully empower them to begin contemplating and preparing to adopt fall prevention strategies that can help them age in place. Conclusions: Older adult falls are common and can result in severe injury and death but they can be prevented. Broadening older adults' awareness about falls can empower them to take the actions necessary to reduce their fall risk. Practical applications: Increasing awareness about falls can help older adults, healthcare providers, and local and state health departments take steps to reduce fall risk.     

Seasonal variation in fall-related emergency department visits by location of fall – United States, 2015

Introduction: In the United States, fall-related emergency department (ED) visits among older adults (age 65 and older) have increased over the past decade. Studies document seasonal variation in fall injuries in other countries, while research in the United States is inconclusive. The objectives of this study were to examine seasonal variation in older adult fall-related ED visits and explore if seasonal variation differs by the location of the fall (indoors vs. outdoors), age group, and sex of the faller. Methods: Fall-related ED visit data from the National Electronic Injury Surveillance System-All Injury Program were analyzed by season of the ED visit, location of the fall, and demographics for adults aged 65 years and older. Results: Total fall-related ED visits were higher during winter compared with other seasons. This seasonal variation was found only for falls occurring outdoors. Among outdoor falls, the variation was found among males and adults aged 65 to 74 years. The percentages of visits for weather-related outdoor falls were also higher among males and the 65–74 year age group. Conclusions: In 2015, there was a seasonal variation in fall-related ED visits in the United States. Weather-related slips and trips in winter may partially account for the seasonal variation. Practical Implications: These results can inform healthcare providers about the importance of screening all older adults for fall risk and help to identify specific patients at increased risk during winter. They may encourage community-based organizations serving older adults to increase fall prevention messaging during winter.     

Geospatial distribution of fall-related hospitalization incidence in Texas

IntroductionWith the rapid growth of the aging U.S. population, the incidence of falls and fall-related injuries is expected to rise. We examined incidence and characteristics of fall-related hospitalizations (falls) among Texans aged 50 and older, by geography and across time.MethodWe calculated fall-related hospitalization incidence rates (65 and older), identified fall ‘hot spots,’ and examined availability of fall-prevention programming.ResultsThe incidence of fall-related hospitalizations for older adults increased by nearly 20% from 2007 to 2011. There were clusters of ‘hot spot’ counties throughout the state, many of which lack fall prevention programs.ConclusionsIncreased efforts are needed to identify older adults at elevated risk for falling and develop referral systems for promoting evidence-based fall prevention programs at multiple levels accounting for geographic settings.Practical applicationsGeospatial investigations can inform strategic planning efforts to develop clinical-community partnerships to offer fall prevention programming in high risk areas.     

Fall-related emergency department visits involving alcohol among older adults

Problem: Falls are the leading cause of injury deaths among adults aged 65 years and older. Characteristics of these falls may vary with alcohol use. Objective: Describe and compare characteristics of older adult fall-related emergency department (ED) visits with indication of alcohol to visits with no indication. Methods: Using nationally-representative 2015 National Electronic Injury Surveillance System-All Injury Program data, we compared demographic characteristics for fall-related ED visits by indication of alcohol consumption. Alcohol-indicated ED visits were matched on age group, sex, treatment month, and treatment day to ED visits with no alcohol indication using a 1:4 ratio and injury characteristics (i.e., diagnosis, body part injured, disposition) were compared. Results and discussion: Of 38,640 ED records, 906 (1.9%) indicated use of alcohol. Fall-related ED visits among women were less likely to indicate alcohol (1.0%) compared to ED visits among men (3.8%). ED visits indicating alcohol decreased with age from 4.1% for those 65–74 years to 1.5% for those 75–84 and <1% for those 85+. After controlling for age-group, sex, and month and day of treatment, 17.0% of ED visits with no alcohol indication had a traumatic brain injury compared to 34.8% of alcohol-indicated ED visits. Practical applications: Alcohol-indicated fall ED visits resulted in more severe head injury than those that did not indicate alcohol. To determine whether alcohol use should be part of clinical risk assessment for older adult falls, more routinely collected data and detailed information on the amount of alcohol consumed at the time of the fall are needed.     

A case control study of falling incidents among the hospitalized elderly

Falling incidents among the hospitalized elderly were investigated using a case/control methodology to identify high-risk individuals. The medical records of all patients who had a reported fall (N = 173) in 1978 in one geriatric facility were compared with the records of a random sample of patients without a reported fall (N = 339). The significant risk factors were male sex, urinary incontinence within 48 hours prior to the fall, and psychoactive medication 12 hours prior to the fall. It was concluded that some patients may have a greater tendency to fall than others and suggestions for exploring future means of prevention are presented.     

The direct costs of fatal and non-fatal falls among older adults — United States

IntroductionThis study sought to estimate the incidence, average cost, and total direct medical costs for fatal and non-fatal fall injuries in hospital, ED, and out-patient settings among U.S. adults aged 65 or older in 2012, by sex and age group and to report total direct medical costs for falls inflated to 2015 dollars.MethodIncidence data came from the 2012 National Vital Statistics System, 2012 Healthcare Cost and Utilization Project-Nationwide Inpatient Sample, 2012 Health Care Utilization Program National Emergency Department Sample, and 2007 Medical Expenditure Panel Survey. Costs for fatal falls were derived from the Centers for Disease Control and Prevention's Web-based Injury Statistics Query and Reporting System; costs for non-fatal falls were based on claims from the 1998/1999 Medicare fee-for-service 5% Standard Analytical Files. Costs were inflated to 2015 estimates using the health care component of the Personal Consumption Expenditure index.ResultsIn 2012, there were 24,190 fatal and 3.2 million medically treated non-fatal fall related injuries. Direct medical costs totaled $616.5 million for fatal and $30.3 billion for non-fatal injuries in 2012 and rose to $637.5 million and $31.3 billion, respectively, in 2015. Fall incidence as well as total cost increased with age and were higher among women.ConclusionMedically treated falls among older adults, especially among older women, are associated with substantial economic costs.Practical applicationWidely implementing evidence-based interventions for fall prevention is essential to decrease the incidence and healthcare costs associated with these injuries.     

Self-reported falls and fall-related injuries among persons aged>or=65 years--United States, 2006

PROBLEM: In 2005, 15,802 persons aged>or=65 years died from fall injuries. How many older adults seek outpatient treatment for minor or moderate fall injuries is unknown. METHOD: To estimate the percentage of older adults who fell during the preceding three months, the Centers for Disease Control and Prevention (CDC) analyzed data from two questions about falls included in the 2006 Behavioral Risk Factor Surveillance System (BRFSS) survey. RESULTS: Approximately 5.8 million (15.9%) persons aged>or=65 years reported falling at least once during the preceding three months, and 1.8 million (31.3%) of those who fell sustained an injury that resulted in a doctor visit or restricted activity for at least one day. DISCUSSION: This report presents the first national estimates of the number and proportion of persons reporting fall-related injuries associated with either doctor visits or restricted activity. SUMMARY: The prevalence of falls reinforces the need for broader use of scientifically proven fall-prevention interventions. IMPACT ON INDUSTRY: Falls and fall-related injuries represent an enormous burden to individuals, society, and to our health care system. Because the U.S. population is aging, this problem will increase unless we take preventive action by broadly implementing evidence-based fall prevention programs. Such programs could appreciably decrease the incidence and health care costs of fall injuries, as well as greatly improve the quality of life for older adults.     

Driver licensing,motor-vehicle crashes,and moving violations among older adults

IntroductionDriving is important for well-being among older adults, but age-related conditions are associated with driving reduction or cessation and increased crash risk for older drivers. Our objectives were to describe population-based rates of older drivers’ licensing and per-driver rates of crashes and moving violations.Methods: We examined individual-level statewide driver licensing, crash, and traffic citation data among all New Jersey drivers aged ≥ 65 and a 35- to 54-year-old comparison group during 2010–2014. Rate ratios (RR) of crashes and moving violations were estimated using Poisson regression.Results: Overall, 86% of males and 71% of females aged ≥ 65 held a valid driver’s license. Older drivers had 27% lower per-driver crash rates than middle-aged drivers (RR: 0.73, 95% CI: 0.73, 0.74)—with appreciable differences by sex—but 40% higher fatal crash rates (RR: 1.40 [1.24, 1.58]). Moving violation rates among older drivers were 72% lower than middle-aged drivers (RR: 0.28 [0.28, 0.28]).Conclusion: The majority of older adults are licensed, with substantial variation by age and sex. Older drivers have higher rates of fatal crashes but lower rates of moving violations compared with middle-aged drivers.Practical applications: Future research is needed to understand the extent to which older adults drive and to identify opportunities to further reduce risk of crashes and resultant injuries among older adults.     

Validating an evidence-based, self-rated fall risk questionnaire (FRQ) for older adults

Background

Falls are a common, serious, and often unrecognized problem facing older adults. The objective of this study was to provide an initial clinical and statistical validation for a public health strategy of fall risk self-assessment by older adults using a Fall Risk Questionnaire (FRQ).

Methods

Adults age 65 + (n = 40) were recruited at a Los Angeles Veterans Affairs (VA) medical facility and at a local assisted living facility. Participants completed the FRQ self-assessment and results were compared to a “gold standard” of a clinical evaluation of risks using the American/British Geriatrics Society guidelines to assess independent predictors of falls: history of previous falls, fear of falling, gait/balance, muscle weakness, incontinence, sensation and proprioception, depression, vision, and medications. For the comparison, we used an iterative statistical approach, weighing items based on relative risk.

Results

There was strong agreement between the FRQ and clinical evaluation (kappa = .875, p < .0001). Individual item kappa values ranged from .305-.832. After dropping one FRQ item (vision risk) because of inadequate agreement with the clinical evaluation (kappa = .139, p = .321), the final FRQ had good concurrent validity.

Conclusions

The FRQ goes beyond existing screening tools in that it is based on both evidence and clinical acceptability and has been initially validated with clinical examination data. A larger validation with longitudinal follow-up should determine the actual strength of the FRQ in predicting future falls.     

The National Falls Free™ Initiative, working collaboratively to affect change

Introduction

Since 2004 the National Council on Aging (NCOA) has been working in collaboration with a growing number of national, state, and local organizations through the Falls Free^© Initiative to address the growing public health issue of falls and fall-related injuries among older adults. Through collaborative leadership, evidence-based interventions, practical lifestyle adjustments, and community partnerships we are working to reduce the number of older adult falls.

Impact on industry

The many activities of the national and state coalitions have brought recognition to the issue of fall prevention, education, and training to providers and greater investment in programs and services resulting in tremendous momentum and community activism. While we have yet to realize an impact on rates of falls, this strategic investment in building the infrastructure needed to affect change is the first step toward reducing the growing number of falls among older adults.     

Assistive device use and mobility-related factors among adults aged ≥ 65 years

IntroductionExamining how assistive device (cane, walker) use relates to other mobility factors can provide insight into older adults' future mobility needs.MethodsData come from the Second Injury Control and Risk Survey, Phase 2 (ICARIS2-P2), conducted from March 2007 to May 2008. Prevalence estimates were calculated for older adults (aged ≥ 65) and multivariable logistic regression was used to explore associations between assistive device use and mobility-related characteristics.ResultCompared with non-users, assistive device users were more likely to report a recent fall (AOR 12.0; 95% CI 4.9–29.3), limit walking outside due to concerns about falling (AOR 7.1; 95% CI 2.6–19.1), be unable to walk outside for 10 min without resting (AOR 3.3; 95% CI 1.1–9.3), and be no longer driving (AOR 6.7; 95% CI 2.0–22.3).ConclusionAssistive device users have limited mobility and an increased risk for fall injury compared with non-users.Practical ApplicationEffective fall prevention interventions, and innovative transportation options, are needed to protect the mobility of this high-risk group.     

Unintentional injuries treated in hospital emergency departments among persons aged 65 years and older,United States, 2006–2011

IntroductionWith the aging of the United States population, unintentional injuries among older adults, and especially falls-related injuries, are an increasing public health concern.MethodsWe analyzed emergency department (ED) data from the Nationwide Emergency Department Sample, 2006–2011. We examined unintentional injury trends by 5-year age groups, sex, mechanism, body region, discharge disposition, and primary payer. For 2011, we estimated the medical costs of unintentional injury and the distribution of primary payers, plus rates by injury mechanisms and body regions injured by 5-year age groups.ResultsFrom 2006 to 2011, the age-adjusted annual rate of unintentional injury-related ED visits among persons aged ≥ 65 years increased significantly from 7987 to 8163, per 100,000 population. In 2011, 65% of injuries were due to falls. Rates for fall-related injury ED visits increased with age and the highest rate was among those aged ≥ 100. Each year, about 85% of unintentional injury-related ED visits in this population were expected to be paid by Medicare. In 2011, the estimated lifetime medical cost of unintentional injury-related ED visits among those aged ≥ 65 years was $40 billion.ConclusionIncreasing rates of ED-treated unintentional injuries, driven mainly by falls among older adults, will challenge our health care system and increase the economic burden on our society. Prevention efforts to reduce falls and resulting injuries among adults aged ≥ 65 years have the potential to increase well-being and reduce health care spending, especially the costs covered by Medicare.Practical applicationsWith the aging of the U.S. population, unintentional injuries, and especially fall-related injuries, will present a growing challenge to our health care system as well as an increasing economic burden. To counteract this trend, we must implement effective public health strategies, such as increasing knowledge about fall risk factors and broadly disseminating evidence-based injury and fall prevention programs in both clinical and community settings.     

CDC's research portfolio in older adult fall prevention: a review of progress, 1985-2005, and future research directions

PROBLEM: Falls are a leading cause of mortality and morbidity among adults age 65 and older. Population models predict steep increases in the 65 and older population bands in the next 10-15 years and in turn, public health is bracing for increased fall rates and the strain they place on health care systems and society. To assess progress in fall prevention, the Centers for Disease Control and Prevention conducted a research portfolio review to examine the quality, relevance, outcomes and successes of the CDC fall prevention program and its impact on public health. METHODS: A peer review panel was charged with reviewing 20 years of funded research and conducting a SWOT (strengths, weaknesses, opportunities, and threats) analysis for extramural and intramural research activities. Information was collected from grantees (via a survey instrument), staff were interviewed, and progress reports and products were reviewed and analyzed. RESULTS: CDC has invested over $24,900,000 in fall-related research and programs over 20 years. The portfolio has had positive impacts on research, policies and programs, increasing the public health injury prevention workforce, and delivering effective fall prevention programs. DISCUSSION: Public health agencies, practitioners, and policy makers recognize that while there are some evidence-based older adult fall prevention interventions available, many remain unused or are infeasible to implement. Specific recommendations across the public health model, include: additional research in gathering robust epidemiologic data on trends and patterns of fall-related injuries at all levels; researching risk factors by setting or sub-population; developing and testing innovative interventions; and engaging in translation and dissemination research on best practices to increase uptake and adoption of fall prevention strategies. CDC has responded to a number of suggestions from the portfolio review including: funding translation research of a proven Tai Chi fall intervention; beginning to address gaps in gender, ethnic, and racial differences in falls; and collaborating with partner organizations who share in CDC's mission to improve public health by preventing falls and reducing fall-related injuries. IMPACT ON INDUSTRY: Industry has an opportunity to develop more accessible and usable devices to reduce injury from falls (for example, hip protectors and force reducing flooring). By implementing effective, evidence-based interventions to prevent falls and reduce injuries from falls, significant decreases in health care costs can be expected.     

Preventing falls among seniors: the way forward

There is a growing body of research about the etiology and prevention of falls. However, the persistently high incidence of falls among seniors calls for renewed efforts to develop, test, implement, and scale-up fall prevention strategies for older adults. This paper considers advances in the field and describes three priority areas for generating research and translating knowledge on fall prevention. Clinical practice guidelines, systems change approaches and environmental risk factors are discussed. Recommendations include transcending our health sector view of the fall prevention problem, supporting comparative research on system-oriented approaches to fall prevention, and examining ways to sustain and scale-up fall prevention efforts.     

A systematic review of falls in hospital for patients with communication disability: Highlighting an invisible population

Background: Patients with communication disability, associated with impairments of speech, language, or voice, have a three-fold increased risk of adverse events in hospital. However, little research yet examines the causal relationship between communication disability and risk for specific adverse events in hospital. Objective: To examine the impact of a patient's communication disability on their falls risk in hospital. Methods: This systematic review examined 61 studies on falls of adult hospital patients with communication disability, and patients at high risk of communication disability, to determine whether or not communication disability increased risk for falls, and the nature of and reasons for any increased risk. Results: In total, 46 of the included studies (75%) reported on participants with communication disability, and the remainder included patients with health conditions placing them at high risk for communication disability. Two thirds of the studies examining falls risk identified communication disability as contributing to falls. Commonly, patients with communication disability were actively excluded from participation; measures of communication or cognition were not reported; and reasons for any increased risk of falls were not discussed. Conclusions: There is some evidence that communication disability is associated with increased risk of falls. However, the role of communication disability in falls is under-researched, and reasons for the increased risk remain unclear. Practical applications: Including patients with communication disability in falls research is necessary to determine reasons for their increased risk of adverse events in hospital. Their inclusion might be helped by the involvement of speech-language pathologists in falls research teams.     

Continued trends in older driver crash involvement rates in the United States: Data through 2017–2018

Introduction: With the growing older adult population due to the aging baby-boom cohort, there was concern that increases in fatal motor-vehicle crashes would follow. Yet, previous analyses showed this to be untrue. The purpose of this study was to examine current trends to determine if previous declines have persisted or risen with the recent increase in fatalities nationwide. Methods: Trends among drivers ages 70 and older were compared with drivers 35–54 for U.S. passenger vehicle fatal crash involvements per 100,000 licensed drivers from 1997 to 2018, fatal and all police-reported crash involvements per vehicle miles traveled using the 1995, 2001, 2009, and 2017 National Household Travel Surveys, and driver deaths per 1,000 crashes. Results: Since the mid-1990s, fatal crashes per licensed driver trended downward, with greater declines for drivers ages 70 and older than for middle-aged drivers (43% vs. 21%). Fatal crash rates per 100,000 licensed drivers and police-reported crash rates per mile traveled for drivers ages 70–79 are now less than those for drivers ages 35–54, but their fatal crash rates per mile traveled and risk of dying in a crash remain higher as they drive fewer miles. As the economy improved over the past decade, fatal crash rates increased substantially for middle-aged drivers but decreased or remained stable among older driver age groups. Conclusions: Fatal crash involvements for adults ages 70 and older has recently increased, but they remain down from their 1997 peak, even as the number of licensed older drivers and the miles they drive have increased. Health improvements likely contributed to long-term reductions in fatal crash rates. As older drivers adopt vehicles with improved crashworthiness and safety features, crash survivability will improve. Practical Application: Older adults should feel confident that their independent mobility needs pose less risk than previously expected.     

Fall-related traumatic brain injury deaths and hospitalizations among older adults--United States, 2005

PROBLEM: Among older adults, both unintentional falls and traumatic brain injuries (TBI) result in significant morbidity and mortality; however, only limited national data on fall-related TBI are available. METHOD: To examine the relationship between older adult falls and TBI deaths and hospitalizations, CDC analyzed 2005 data from the National Center for Health Statistics' National Vital Statistics System and the Agency for Healthcare Research and Quality's Nationwide Inpatient Sample. RESULTS: In 2005, among adults>or=65 years, there were 7946 fall-related TBI deaths and an estimated 56,423 hospitalizations for nonfatal fall-related TBI in the United States. Fall-related TBI accounted for 50.3% of unintentional fall deaths and 8.0% of nonfatal fall-related hospitalizations. SUMMARY: These findings underscore the need for greater dissemination and implementation of evidence-based fall prevention interventions.     

A cost–benefit analysis of three older adult fall prevention interventions

IntroductionOne out of three persons aged 65 and older falls annually and 20% to 30% of falls result in injury. The purpose of this cost–benefit analysis was to identify community-based fall interventions that were feasible, effective, and provided a positive return on investment (ROI).MethodsA third-party payer perspective was used to determine the costs and benefits of three effective fall interventions. Intervention effectiveness was based on randomized controlled trial results. National data were used to estimate the average annual benefits from averting the direct medical costs of a fall. The net benefit and ROI were estimated for each of the interventions.ResultsFor the Otago Exercise Program delivered to persons aged 65 and older, the net benefit was $121.85 per participant and the ROI was 36% for each dollar invested. For Otago delivered to persons aged 80 and older, the net benefit was $429.18 and the ROI was 127%. Tai chi: Moving for Better Balance had a net benefit of $529.86 and an ROI of 509% and Stepping On had a net benefit of $134.37 and an ROI of 64%.ConclusionsAll three fall interventions provided positive net benefits. The ROIs showed that the benefits not only covered the implementation costs but also exceeded the expected direct program delivery costs. These results can help health care funders and other community organizations select appropriate and effective fall interventions that also can provide positive returns on investment.     

Fall-related injuries for three ages groups – Analysis of Swedish registry data 1999–2013

Introduction: The objective of this study was to analyze which factors (including factors pertaining to the individual, the household, and the local area) increase the risk of fall injuries for the three age groups with the highest risk for fall injuries in Sweden. Method: The study combined longitudinal data covering the period 1999–2013 from several different official registries from Statistics Sweden as well as from the Swedish health care system and fitted the models to data using mixed model regressions. Results: Three age groups had a markedly heightened risk for fall injuries: 1–3-year olds, 12–14 year olds, and the elderly (65+). The home was the most common location for fall injuries, as about 40% of all fall injuries occur in the home. Only for the elderly strong predictors for fall injuries were found, and these were: age, single household, and special housing. Conclusions: There is preventive potential in the special residences for the elderly and disabled. People living in these special residences make up a strongly selected group that needs extra safe environments. Our findings indicate that their needs are currently not meet. Practical applications: Design of special residences for the elderly and disabled should aim at reducing the consequences of falling.     

Older Adults at Increased Risk as Pedestrians in Victoria,Australia: An Examination of Crash Characteristics and Injury Outcomes

Objectives: Engaging in active transport modes (especially walking) is a healthy and environmentally friendly alternative to driving and may be particularly beneficial for older adults. However, older adults are a vulnerable group: they are at higher risk of injury compared with younger adults, mainly due to frailty and may be at increased risk of collision due to the effects of age on sensory, cognitive, and motor abilities. Moreover, our population is aging, and there is a trend for the current cohort of older adults to maintain mobility later in life compared with previous cohorts. Though these trends have serious implications for transport policy and safety, little is known about the contributing factors and injury outcomes of pedestrian collision. Further, previous research generally considers the older population as a homogeneous group and rarely considers the increased risks associated with continued ageing.

Method: Collision characteristics and injury outcomes for 2 subgroups of older pedestrians (65–74 years and 75+ years) were examined by extracting data from the state police–reported crash dataset and hospital admission/emergency department presentation data over the 10-year period between 2003 and 2012. Variables identified for analysis included pedestrian characteristics (age, gender, activity, etc.), crash location and type, injury characteristics and severity, and duration of hospital stay. A spatial analysis of crash locations was also undertaken to identify collision clusters and the contribution of environmental features on collision and injury risk.

Results: Adults over 65 years were involved in 21% of all pedestrian collisions. A high fatality rate was found among older adults, particularly for those aged 75 years and older: this group had 3.2 deaths per 100,000 population, compared to a rate of 1.3 for 65- to 74-year-olds and 0.7 for adults below 65 years of age. Older pedestrian injuries were most likely to occur while crossing the carriageway; they were also more likely to be injured in parking lots, at driveway intersections, and on sidewalks compared to younger cohorts. Spatial analyses revealed older pedestrian crash clusters on arterial roads in urban shopping precincts. Significantly higher rates of hospital admissions were found for pedestrians over the age of 75 years and for abdominal, head, and neck injuries; conversely, older adults were underrepresented in emergency department presentations (mainly lower and upper extremity injuries), suggesting an increased severity associated with older pedestrian injuries. Average length of hospital stay also increased with increasing age.

Conclusion: This analysis revealed age differences in collision risk and injury outcomes among older adults and that aggregate analysis of older pedestrians can distort the significance of risk factors associated with older pedestrian injuries. These findings have implications that extend to the development of engineering, behavioral, and enforcement countermeasures to address the problems faced by the oldest pedestrians and reduce collision risk and improve injury outcomes.