Impact of driving cessation on health-related quality of life trajectories.

BACKGROUND: Trajectories of health-related quality of life (HRQoL) after driving cessation (DC) are thought to decline steeply, but for some, HRQoL may improve after DC. Our objective is to examine trajectories of HRQoL for individuals before and after DC. We hypothesize that for urban drivers, volunteers and those who access alternative transportation participants' health may remain unchanged or improve. METHODS: This study uses data from the AAA Longitudinal Research on Aging Drivers (LongROAD) study, a prospective cohort of 2,990 older drivers (ages 65-79 at enrollment). The LongROAD study is a five-year multisite study and data collection ended October 31, 2022. Participants were recruited using a convenience sample from the health centers roster. The number of participants approached were 40,806 with 7.3% enrolling in the study. Sixty-one participants stopped driving permanently by year five and had data before and after DC. The PROMIS®-29 Adult Profile was utilized and includes: 1) Depression, 2) Anxiety, 3) Ability to Participate in Social Roles and Activities, 4) Physical Function, 5) Fatigue, 6) Pain Interference, 7) Sleep Disturbance, and 8) Numeric Pain Rating Scale. Adjusted (age, education and gender) individual growth models with 2989 participants with up to six observations from baseline to year 5 in the models (ranging from n = 15,041 to 15,300) were utilized. RESULTS: Ability to participate in social roles and activities after DC improved overall. For those who volunteered, social roles and activities declined not supporting our hypothesis. For those who accessed alternative transportation, fatigue had an initial large increase immediately following DC thus not supporting our hypothesis. Urban residents had worse function and more symptoms after DC compared to rural residents (not supporting our hypothesis) except for social roles and activities that declined steeply (supporting our hypothesis). CONCLUSIONS: Educating older adults that utilizing alternative transportation may cause initial fatigue after DC is recommended. Accessing alternative transportation to maintain social roles and activities is paramount for rural older adults after DC especially for older adults who like to volunteer.

Distraction "Hangover": Characterization of the Delayed Return to Baseline Driving Risk After Distracting Behaviors.

OBJECTIVE: We measured how long distraction by a smartphone affects simulated driving behaviors after the tasks are completed (i.e., the distraction hangover). BACKGROUND: Most drivers know that smartphones distract. Trying to limit distraction, drivers can use hands-free devices, where they only briefly glance at the smartphone. However, the cognitive cost of switching tasks from driving to communicating and back to driving adds an underappreciated, potentially long period to the total distraction time. METHOD: Ninety-seven 21- to 78-year-old individuals who self-identified as active drivers and smartphone users engaged in a simulated driving scenario that included smartphone distractions. Peripheral-cue and car-following tasks were used to assess driving behavior, along with synchronized eye tracking. RESULTS: The participants' lateral speed was larger than baseline for 15 s after the end of a voice distraction and for up to 25 s after a text distraction. Correct identification of peripheral cues dropped about 5% per decade of age, and participants from the 71+ age group missed seeing about 50% of peripheral cues within 4 s of the distraction. During distraction, coherence with the lead car in a following task dropped from 0.54 to 0.045, and seven participants rear-ended the lead car. Breadth of scanning contracted by 50% after distraction. CONCLUSION: Simulated driving performance drops dramatically after smartphone distraction for all ages and for both voice and texting. APPLICATION: Public education should include the dangers of any smartphone use during driving, including hands-free.

The Development and Implementation of Preventive Medicine Resident Rotations in a Shelter Serving Asylum-Seekers at the US-Mexico Border.

Asylum-seekers present to the US-Mexico border with a variety of acute health needs. In December 2018, the County of San Diego Health and Human Services Agency partnered with the University of California, San Diego to provide health screenings to asylum-seekers at a humanitarian shelter administered by Jewish Family Services. The assessments screened for communicable diseases and acute conditions. Preventive medicine residents in the HRSA-funded UCSD-SDSU (University of California, San Diego-San Diego State University) Residency were trained to become an integral part of the program. Training included cultural competency, public health interface, protocol development and implementation, interdisciplinary teamwork, and quality improvement. Over 18 months, nearly 20000 asylum-seekers were screened, which allowed for the detection of an imported influenza outbreak and prevented any major public health incidents or medical errors. This health screening program for asylum-seekers provided an important experience for preventive medicine trainees. In turn, preventive medicine and other trainees were valuable contributors to the program.

'Just Drive': An Employee-Based Intervention to Reduce Distracted Driving.

Distracted driving is a major danger on today's roadways. Employers play a critical role in developing distracted driving policies and promoting a culture of workplace driving safety. The purpose of this study was to evaluate the effectiveness of an in-person work-based class to reduce distracted driving in participating employees. The "Just Drive-Take Action Against Distraction" class was designed by the UC San Diego Training, Research and Education for Driving Safety (TREDS) program to increase awareness of the dangers of distracted driving and to encourage employees to be safe and responsible drivers, both on and off the job. Participants completed pre- and post-anonymous surveys and, in a subset of attendees, volunteers were contacted via email 3 months post-intervention to complete a driving-behavior survey on Surveymonkey.com. 115 classes for 6896 employees were delivered at 54 agencies in Southern California. A total of 4928 participants completed the pre- and post-survey; 2014 n = 2263 and 2015 n = 2665. The course was found useful (85%) and engaging (85.6%). For non-commercial drivers, 55.6% of participants reported an increase of 80-100% in awareness of the dangers of distracted driving, and 67.2% reported an increase of 80-100% in their motivation to change. For commercial drivers, 71.3% reported a motivation increase of 80-100%. There were significant increases in knowledge for both groups. In the three-month follow-up survey, participants identified multiple positive changes in distracted driving behavior. This 1-h employer-supported intervention demonstrated positive changes in short-term intention and medium-term behaviors.

Associations between reliable changes in depression and changes in BMI, total body fatness and visceral adiposity during a 12-month weight loss trial.

We investigated associations between changes in depression and body composition over a 12-month weight loss trial. Of the 298 adults (BMI > 27 m/kg2), 219 with complete depression and body composition data were included. A 10-item Center for Epidemiologic Studies Depression Scale measured depression; dual-energy X-ray absorptiometry measured body composition. Multinomial logistic regression predicted reliable changes in depression by BMI, body fat (BF) and visceral adiposity (VAT). Multiplicative interaction terms tested modification by sex and ethnicity. Participants with increases in body composition were less likely to experience improvements in depression (BMI: RRR = 0.79 (0.68-0.91), p < 0.01; BF: RRR = 0.97 (0.94 - 0.99), p = 0.01; VAT: RRR = 0.99 (0.98-1.00), p = 0.02), but not worsening of depression (BMI: RRR = 1.29 (0.96-1.73), p = 0.10; BF: RRR = 1.04 (0.99-1.09), p = 0.15; VAT: RRR = 1.01 (1.00-1.03), p = 0.18). Sex and ethnicity interaction terms were not significant. However, the relationship was only significant among females, among non-Latinos for BMI and BF, and among Latinos for VAT. Our study supports the association between depression and obesity and highlights the need for longitudinal studies investigating VAT and depression in diverse ethnic groups.

Prevalence of Potentially Inappropriate Medication use in older drivers.

BACKGROUND: Potentially Inappropriate Medication (PIM) use has been studied in a variety of older adult populations across the world. We sought to examine the prevalence and correlates of PIM use in older drivers. METHODS: We applied the American Geriatrics Society 2015 Beers Criteria to baseline data collected from the "brown-bag" review of medications for participants of the Longitudinal Research on Aging Drivers (LongROAD) study to examine the prevalence and correlates of PIM use in a geographically diverse, community-dwelling sample of older drivers (n = 2949). Proportions of participants who used one or more PIMs according to the American Geriatrics Society 2015 Beers Criteria, and estimated odds ratios (ORs) and 95% confidence intervals (CIs) of PIM use associated with participant characteristics were calculated. RESULTS: Overall, 18.5% of the older drivers studied used one or more PIM. The most commonly used therapeutic category of PIM was benzodiazepines (accounting for 16.6% of the total PIMs identified), followed by nonbenzodiazepine hypnotics (15.2%), antidepressants (15.2%), and first-generation antihistamines (10.5%). Compared to older drivers on four or fewer medications, the adjusted ORs of PIM use were 2.43 (95% CI 1.68-3.51) for those on 5-7 medications, 4.19 (95% CI 2.95-5.93) for those on 8-11 medications, and 8.01 (95% CI 5.71-11.23) for those on ≥12 medications. Older drivers who were female, white, or living in urban areas were at significantly heightened risk of PIM use. CONCLUSION: About one in five older drivers uses PIMs. Commonly used PIMs are medications known to impair driving ability and increase crash risk. Implementation of evidence-based interventions to reduce PIM use in older drivers may confer both health and safety benefits. TRIAL REGISTRATION: Not applicable.

Planned care for obesity and cardiovascular risk reduction using a stepped-down approach: A randomized-controlled trial.

Primary care-based approaches to address concurrent obesity and cardiovascular disease risk factors (CVDRFs) that begin with a high intensity intervention that is subsequently decreased (i.e., stepped-down) if weight loss is achieved have not been rigorously examined. Our study is a 20-month, single-blind randomized controlled trial at five primary care clinics in San Diego, CA, in 2013, where 262 obese adults (aged 25-70 years; 32.1% male; 59.2% white) with at least one CVDRF were enrolled into planned care for obesity and risk reduction (PCORR) using a stepped-down approach or enhanced usual care (EUC). All patients received physician recommendations for weight loss and CVDRFs. EUC patients (n = 132) received an individual session with a health educator every 4 months. PCORR patients (n = 130) received individual and group sessions (in-person, mail, telephone, and email) in three steps, characterized by less contact if success was achieved. At 20 months, 40.7%, 23.8%, and 15.4% of PCORR patients were in steps 1, 2, and 3, respectively (25.2% were lost to follow-up). PCORR resulted in a between-group difference in reduction in body weight of 6.1% [95% CI, 5.3 to 6.9] compared to EUC 2.8% [95% CI, 2.0 to 3.6] p = 0.007, with a greater reduction in BMI (35.2 [95% CI, 34.4 to 35.9] to 33.7 [95% CI, 32.9 to 34.5] kg/m2) than EUC (36.0 [95% CI, 35.3 to 36.8] to 35.1 [95% CI, 34.3 to 35.9] kg/m2), as indicated by a significant treatment by time interaction (p = 0.009). PCORR resulted in greater weight loss over 20 months than EUC. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01134029.

Self-reported health conditions and related driving reduction in older drivers.

We surveyed self-reported lifetime health conditions (using National Health and Aging Trends Study questions) and related driving reduction in a large multi-site older driver cohort (n = 2990) from the AAA Longitudinal Research on Aging Drivers (LongROAD) Study's baseline assessment. Those reporting reduced driving (n = 337) largely attributed reduction to musculoskeletal (29%), neurologic (13%), and ophthalmologic (10%) conditions. Women reported health condition-related driving reduction more often than men (14% versus 8%, p<.001). Mobility affects well-being; health professionals should consider that health conditions may cause older adults to reduce driving. Gender differences deserve attention in future research and education efforts.

Influence of specific individual and environmental variables on the relationship between body mass index and health-related quality of life in overweight and obese adolescents.

PURPOSE: Overweight and obese adolescents are at risk for low health-related quality of life (HRQOL). We examined the role of individual- and environmental-level variables on the relationship between body mass index (BMI kg/m(2)) and HRQOL in adolescents. METHODS: Linear regressions were performed to conduct mediation and moderation analyses on the relationship between BMI and HRQOL in overweight and obese adolescents (N = 205). HRQOL was measured by the Pediatric Quality of Life Inventory. Hypothesized mediators included depression, measured by the Center for Epidemiologic Studies Depression Scale; body image, measured by the gender-specific body dissatisfaction subscale of the Eating Disorder Inventory; and self-esteem, measured by the Rosenberg Self-Esteem Scale. Mediation was assessed using Baron and Kenny's approach and Sobel's test of indirect effects. Anglo-acculturation, measured by the Short Acculturation Scale for Hispanics-Youth, and environmental perception, measured by parent-proxy report of the Neighborhood Environment Walkability Scale, were hypothesized moderators. RESULTS: Body image mediated the relationship between BMI and HRQOL (b = -0.34, SE = 0.17, adj R (2) = 0.19, p = .051), and self-esteem was a partial mediator (b = -0.37, SE = 0.17, adj R (2) = 0.24, p = .027). Sobel's test confirmed these results (p < .05). No significant moderation effects were found. CONCLUSIONS: The finding that individual-level factors, such as body image and self-esteem, influence the relationship between BMI and HRQOL while environmental factors, such as neighborhood environment and acculturation, do not extends previous research. The finding that body image and self-esteem partially mediate this relationship presents new areas to investigate in interventions that address BMI in youth.

Collective genius.

How can leaders build an organization that is capable of innovating continually over time? By creating a community that is both willing and able to innovate. To be willing, the community must share a sense of purpose, values, and rules of engagement. When Luca de Meo was Volkswagen's head of marketing communication, he fostered a sense of purpose in his team by asking its members to reflect on what being part of VW meant to them; strengthened their shared values by encouraging them to use the brand's three components-innovation, responsibility, and value-to guide their work; and built significant responsibility and autonomy into their rules of engagement. To be able, companies must generate ideas through discourse and debate; experiment quickly, reflect, and adjust; and make decisions that combine disparate and even opposing ideas. Bill Coughran, an SVP of engineering at Google, employed these capabilities both to solve the company's near-term data storage needs and to make progress toward a next-generation solution.

A border health crisis at the United States-Mexico border: an urgent call to action.

In this Viewpoint, we provide an overview of the worsening trend of traumatic injuries across the United States-Mexico border after its recent fortification and height extension to 30-feet. We further characterize the international factors driving migration and the current U.S. policies and political climate that will allow this public health crisis to progress. Finally, we provide recommendations involving prevention efforts, effective resource allocation, and advocacy that will start addressing the humanitarian and economic consequences of current U.S. border policies and infrastructure.

Relationship of Decisional Conflict About Driving Habits Between Older Adult Drivers and Their Family Members and Close Friends.

This study examines the relationship of decisional conflict about driving habits between older adult drivers (≥70 years old) and their family members and close friends. This secondary analysis utilizes data originating from a multi-site randomized controlled trial assessing the effect of a driving decision aid (DDA) intervention. Decisional conflict about stopping or changing driving habits for drivers was measured with the Decisional Conflict Scale (DCS). Dyadic associations between drivers' and study partners' (SPs') DCS scores were analyzed using an actor-partner interdependence model. Among 228 driver-SP dyads, Dyadic DCS was correlated at baseline (r = .18, p < .01), and pre-intervention DCS was associated with post-intervention DCS (p < .001 for SPs [ß = .73] and drivers [ß = .73]). Drivers' baseline DCS and SPs' post-intervention DCS were slighly correlated (ß = .10; p = .036). Higher decisional conflict about driving among older drivers is frequently shared by their SPs. Shared decisional conflict may persist beyond intervening to support decision-making about driving cessation.

Distribution of COVID-19 Home Testing Through Community Health Centers: Results of the COVID CoNOce MÁS Study.

OBJECTIVE: To assess acceptability and feasibility of rapid at-home COVID-19 testing and reporting of test results among individuals seeking care at community health centers (CHCs) and their household members. METHODS: Participants were recruited from 2 Community Health Centers during a clinic visit or a community event. Over-the-counter COVID-19 tests were distributed to participants for self-testing and to offer testing to household members. Separate surveys were administered to collect baseline information on the study participant and to collect test results on the study participant and household members. We calculated the proportion of individuals who agreed to complete COVID home testing, those who reported test results, and the test positivity. For household members, we calculated the proportion who completed and reported results and the positivity rate. We assessed reasons for undergoing COVID-19 testing and the action taken by participants who reported positive tests. RESULTS: A total of 2189 individuals were approached by CHC staff for participation and 1013 (46.3%) agreed to participate. Among the 959 participants with complete sociodemographic data, 88% were Hispanic and 82.6% were female. The proportion providing test results was 36.2% and the test positivity was 4.2%. Among the 1927 test reports, 35.3% for the index participant and 64.4% were for household members. The largest proportion of test results were for index participants (35.3%) and the second largest was for the participant's children (32.1%), followed by parents (16.9%), and spouse/partner (13.2%). The 2 most common reasons for testing were symptoms (29%) and attending family gatherings (26%). Among test-positive individuals (n = 80), most (83.3%) noted that they isolated but only 16.3% called their provider and 1.3% visited a clinic. CONCLUSION: Our results show interest in at-home COVID-19 testing of multiple household members, as we headed into the endemic phase of the pandemic. However, reporting of test results was modest and among test-positive individuals, reporting results to a provider was very low. These results underscore the challenges with reporting and following guidelines among people undergoing home testing for COVID-19, which may have implications for future pandemics.

Frailty and poor physical functioning as risk factors for driving cessation.

Introduction: Frailty and low physical performance are modifiable factors and, therefore, targets for interventions aimed at delaying driving cessation (DC). The objective was to determine the impact of frailty and physical performance on DC. Methods: Multisite prospective cohort of older drivers. The key inclusion criteria are as follows: active driver age 65-79 years, possessing a valid driver's license, without significant cognitive impairment, and driving a 1996 car or a newer model car. Of the 2,990 enrolled participants, 2,986 (99.9%) had at least one frailty or Short Physical Performance Battery (SPPB) measure and were included in this study. In total, 42% of participants were aged 65-69 years, 86% were non-Hispanic white, 53% were female, 63% were married, and 41% had a high degree of education. The Fried Frailty Phenotype and the Expanded Short Physical Performance Battery (SPPB) from the National Health and Aging Trends Study were utilized. At each annual visit, DC was assessed by the participant notifying the study team or self-reporting after no driving activity for at least 30 days, verified via GPS. Cox proportional hazard models, including time-varying covariates, were used to examine the impact of the SPPB and frailty scores on time to DC. This assessment included examining interactions by sex. Results: Seventy-three participants (2.4%) stopped driving by the end of year 5. Among women with a fair SPPB score, the adjusted hazard ratio (HR) of DC was 0.26 (95% confidence interval (CI) 0.10-0.65) compared to those with a poor SPPB score. For those with a good SPPB score, the adjusted HR of DC had a p-value of <0.001. Among men with a fair SPPB score, the adjusted hazard ratio (HR) of DC was 0.45 (95% CI 0.25-0.81) compared to those with a poor SPPB score. For men with a good SPPB score, the adjusted HR of DC was 0.19 (95% CI 0.10-0.36). Sex was not an effect modifier between frailty and DC. For those who were categorized into pre-frail or frail, the adjusted ratio of HR to DC was 6.1 (95% CI 2.7-13.8) compared to those who were not frail. Conclusion and relevance: Frailty and poor physical functioning are major risk factors for driving cessation. Staying physically active may help older adults to extend their driving life expectancy and mobility.

Dietary supplement use is common in older adult drivers: an analysis from the AAA LongROAD study.

BACKGROUND: Dietary supplement (DS) use is common and increasing among older adults, though much data available on use frequencies are from surveys and performed cross-sectionally. This paper sought to assess the frequency and pattern of dietary supplement use among older adults over time. METHODS: A secondary analysis of data from the AAA LongROAD study, a longitudinal prospective cohort study of older adult drivers, using data from baseline and the first two years of follow up included a total of 2990 drivers aged 65-79 years recruited at five study sites across the US from July 2015 to March 2017. Participants underwent baseline and annual evaluations, which included a "brown bag" medication review. DS were identified and categorized according to type and key components. Prevalence and pattern of DS use over time and relationship to demographics were measured with frequency and Chi squared analyses. RESULTS: 84% of participants took at least one dietary supplement during the 2-year study period, and 55% of participants continually reported use. DS accounted for approximately 30% of the total pharmacologic-pill burden in all years. Participants who were White non-Hispanic, female, 75-79 years of age at baseline, and on more non-supplement medications took significantly more dietary supplements (P < 0.05). Vitamin D, multivitamins, calcium, and omega-3 formulations were the most common supplements, with stable use over time. Use of individual herbal supplements and cannabis products was uncommon (< 1% participants per year). CONCLUSIONS: DS use among older adults is common and relatively stable over time and contributes to polypharmacy. In clinical settings, providers should consider the influence of DS formulations on polypharmacy, and the associated cost, risk of medication interactions, and effect on medication compliance.

Association of Depression and Antidepressant Use With Driving Behaviors in Older Adults: A LongROAD Study.

Older adults aged 70 and older who drive have higher crash death rates per mile driven compared to middle aged (35-54 years) adults who drive in the US. Prior studies have found that depression and or antidepressant medication use in older adults are associated with an increase in the vehicular crash rate. Using data from the prospective multi-site AAA Longitudinal Research on Aging Drivers Study, this analysis examined the independent and interdependent associations of self-reported depression and antidepressant use with driving behaviors that can increase motor vehicle crash risk such as hard braking, speeding, and night-time driving in adults over age 65. Of the 2951 participants, 6.4% reported having depression and 21.9% were on an antidepressant medication. Correcting for age, race, gender, and education level, participants on an antidepressant had increased hard braking events (1.22 [1.10-1.34]) but self-reported depression alone was not associated with changes in driving behaviors.

Migraine headaches are associated with motor vehicle crashes and driving habits among older drivers: Prospective cohort study.

BACKGROUND: Migraine headache is common in older adults, often causing symptoms that may affect driving safety. This study examined associations of migraine with motor vehicle crashes (MVCs) and driving habits in older drivers and assessed modification of associations by medication use. METHODS: In a multi-site, prospective cohort study of active drivers aged 65-79 (53% female), we assessed prevalent migraine (i.e., ever had migraine, reported at enrollment), incident migraine (diagnosis first reported at a follow-up visit), and medications typically used for migraine prophylaxis and treatment. During 2-year follow-up, we recorded self-reported MVCs and measured driving habits using in-vehicle GPS devices. Associations of prevalent migraine with driving outcomes were estimated in multivariable mixed models. Using a matched design, associations of incident migraine with MVCs in the subsequent year were estimated with conditional logistic regression. Interactions between migraine and medications were tested in all models. RESULTS: Of 2589 drivers, 324 (12.5%) reported prevalent migraine and 34 (1.3%) incident migraine. Interactions between migraine and medications were not statistically significant in any models. Prevalent migraine was not associated with MVCs in the subsequent 2 years (adjusted OR [aOR] = 0.98; 95% CI: 0.72, 1.35), whereas incident migraine significantly increased the odds of having an MVC within 1 year (aOR = 3.27; 1.21, 8.82). Prevalent migraine was associated with small reductions in driving days and trips per month and increases in hard braking events in adjusted models. CONCLUSION: Our results suggest substantially increased likelihood of MVCs in the year after newly diagnosed migraine, indicating a potential need for driving safety interventions in these patients. We found little evidence for MVC risk or substantial changes in driving habits associated with prevalent migraine. Future research should examine timing, frequency, and severity of migraine diagnosis and symptoms, and use of medications specifically prescribed for migraine, in relation to driving outcomes.

Diabetes mellitus and hard braking events in older adult drivers.

BACKGROUND: Diabetes mellitus (DM) can impair driving safety due to hypoglycemia, hyperglycemia, diabetic peripheral neuropathy, and diabetic eye diseases. However, few studies have examined the association between DM and driving safety in older adults based on naturalistic driving data. METHODS: Data for this study came from a multisite naturalistic driving study of drivers aged 65-79 years at baseline. Driving data for the study participants were recorded by in-vehicle recording devices for up to 44 months. We used multivariable negative binomial modeling to estimate adjusted incidence rate ratios (aIRRs) and 95% confidence intervals (CIs) of hard braking events (HBEs, defined as maneuvers with deceleration rates ≥ 0.4 g) associated with DM. RESULTS: Of the 2856 study participants eligible for this analysis, 482 (16.9%) reported having DM at baseline, including 354 (12.4%) insulin non-users and 128 (4.5%) insulin users. The incidence rates of HBEs per 1000 miles were 1.13 for drivers without DM, 1.15 for drivers with DM not using insulin, and 1.77 for drivers with DM using insulin. Compared to drivers without DM, the risk of HBEs was 48% higher for drivers with DM using insulin (aIRR 1.48; 95% CI: 1.43, 1.53). CONCLUSION: Older adult drivers with DM using insulin appear to be at increased proneness to vehicular crashes. Driving safety should be taken into consideration in DM care and management.

Association between polypharmacy and hard braking events in older adult drivers.

BACKGROUND: Polypharmacy (i.e., simultaneous use of two or more medications) poses a serious safety concern for older drivers. This study assesses the association between polypharmacy and hard braking events in older adult drivers. METHODS: Data for this study came from a naturalistic driving study of 2990 older adults. Information about medications was collected through the "brown-bag review" method. Primary vehicles of the study participants were instrumented with data recording devices for up to 44 months. Multivariable negative binomial model was used to estimate the adjusted incidence rate ratios (aIRRs) and 95 % confidence intervals (CIs) of hard-braking events (i.e., maneuvers with linear deceleration rates ≥0.4 g) associated with polypharmacy. RESULTS: Of the 2990 participants, 2872 (96.1 %) were eligible for this analysis. At the time of enrollment, 157 (5.5 %) drivers were taking fewer than two medications, 904 (31.5 %) were taking 2-5 medications, 895 (31.2 %) were taking 6-9 medications, 571 (19.9 %) were taking 10-13 medications, and 345 (12.0 %) were taking 14 or more medications. Compared to drivers using fewer than two medications, the risk of hard-braking events increased 8 % (aIRR 1.08, 95 % CI 1.04, 1.13) for users of 2-5 medications, 12 % (aIRR 1.12, 95 % CI 1.08, 1.16) for users of 6-9 medications, 19 % (aIRR 1.19, 95 % CI 1.15, 1.24) for users of 10-13 medications, and 34 % (aIRR 1.34, 95 % CI 1.29, 1.40) for users of 14 or more medications. CONCLUSIONS: Polypharmacy in older adult drivers is associated with significantly increased incidence of hard-braking events in a dose-response fashion. Effective interventions to reduce polypharmacy use may help improve driving safety in older adults.