Analysis Reporting System Research Articles

Association between legalization of recreational cannabis and fatal motor vehicle collisions in the United States: an ecologic study.

Background:With the recent legalization of recreational cannabis in Canada, cannabis-impaired driving is an important public safety concern. Our aim was to examine the association between recreational cannabis legalization and fatal motor vehicle collisions using data from the United States, which present a timely natural experiment of cannabis legalization.Methods:We conducted an ecologic study using the number of fatal motor vehicle collisions and the associated number of deaths for US jurisdictions with legalized recreational cannabis (2007–2018) retrieved from the US Fatality Analysis Reporting System. We examined jurisdiction-specific rates of fatal motor vehicle collisions and associated deaths before and after recreational cannabis legalization using Poisson regression and meta-analyzed estimates across jurisdictions using DerSimonian and Laird random-effects models.Results:After adjustment for calendar year, legalization was associated with increases in rates of fatal motor vehicle collisions (incidence rate ratio [IRR] 1.15, 95% confidence interval [CI] 1.06–1.26) and associated deaths (IRR 1.16, 95% CI 1.06–1.27). Differences between the first 12 months after legalization relative to subsequent months were inconclusive for rates of fatal motor vehicle collisions (IRR 0.92, 95% CI 0.84–1.02) and associated deaths (IRR 0.92, 95% CI 0.84–1.01).Interpretation:Recreational cannabis legalization in the US was associated with a relative increased risk of fatal motor vehicle collisions of 15% and a relative increase in associated deaths of 16%, with no conclusive difference between the first and subsequent years after legalization. These findings raise concern that there could be a similar increase in fatal motor vehicle collisions and associated deaths in Canada following recreational cannabis legalization.

A penalized-likelihood approach to characterizing bridge-related crashes in New Jersey

Objective A roadway departure crash is one in which a vehicle crosses an edge line, a centerline, or otherwise leaves the traveled way. These crashes that involve run-off-road and cross-median/centerline head-on collisions tend to be more severe than other crash types. According to the NHTSA Fatality Analysis Reporting System database, a total of 7,833 people perished in crashes involving fixed roadside objects in 2017, accounting for 21 percent of the total number of fatalities in the United States. Several previous studies have reported that rural bridge-related crashes result in more fatalities due to their being mostly the fixed-object crash type. As such, further in-depth investigation of this type of crash is necessary. Due to the lack of a comprehensive database that includes bridge-related crashes and bridge characteristics, identifying the key factors contributing to this type of crash is a challenging task that is addressed in this paper. Method Study team gathered and compiled five years (2011–2015) of crash data from the New Jersey crash database and the characteristics of bridges from the Long-Term Bridge Performance portal. A Firth’s penalized-likelihood logistic regression model was developed to examine the impact of explanatory variables on crash severity. Results Based on the five years (2011–2015) of crash data, significant factors (i.e., driver age, weather conditions, surface conditions, lighting conditions, speed limit, roadway characteristics, and direction of traffic) were identified that affect the severity of bridge-related crashes in Middlesex County, New Jersey. Conclusion This model is an appropriate tool for predicting the impact of all the confounding variables on the probability of bridge-related crashes while also considering the rareness of the event. Based on the obtained odds ratio, the various effects of the identified variables are discussed, and recommendations made regarding countermeasures policymakers can establish to reduce the number of these crashes in New Jersey.

Lipid levels and major adverse cardiovascular events in patients initiated on statins for primary prevention: an international population-based cohort study protocol.

BackgroundClinical guidelines recommend specific targets for low-density lipoprotein cholesterol (LDL-C) and non-high-density lipoprotein cholesterol (non-HDL-C) for primary prevention of cardiovascular disease (CVD). Furthermore, individual variability in lipid response to statin therapy requires assessment of the association in diverse populations.AimTo assess whether lower concentrations of LDL-C and non-HDL-C are associated with a reduced risk of major adverse cardiovascular events (MACE) in primary prevention of CVD.Design & settingAn international, new-user, cohort study will be undertaken. It will use data from three electronic health record databases from three global regions: Clinical Practice Research Datalink, UK; PREDICT-CVD, New Zealand (NZ); and the Clinical Data and Analysis Reporting System, Hong Kong (HK).MethodNew statin users without a history of atherosclerotic CVD, heart failure, or chronic kidney disease, with baseline and follow-up lipid levels will be eligible for inclusion. Patients will be classified according to LDL-C (<1.4, 1.4–1.7, 1.8–2.5, and ≥2.6 mmol/l) and non-HDL-C (<2.2, 2.2–2.5, 2.6–3.3, and ≥3.4 mmol/l) concentrations 24 months after initiating statin therapy. The primary outcome of interest is MACE, defined as the first occurrence of coronary heart disease, stroke, or cardiovascular death. Secondary outcomes include all-cause mortality and the individual components of MACE. Sensitivity analyses will be conducted using lipid levels at 3 and 12 months after starting statin therapy.ConclusionResults will inform clinicians about the benefits of achieving guideline recommended concentrations of LDL-C for primary prevention of CVD.

MiR-709 inhibits GHRP6 induced GH synthesis by targeting PRKCA in pituitary

Pituitary growth hormone (GH) plays an essential role in processes of organism growth and metabolism. MicroRNA (miRNA) could also participate in diverse biological processes. However, the role of miRNA in the regulation of pituitary GH during the growth process remains unclear. In this study, we firstly confirmed that the second highly expressed pituitary miRNA (miR-709) significantly inhibited the GH synthesis and suppressed the viability of GH3 cells. The bioinformatics analysis and dual luciferase report system were used to ascertain the PRKCA is the direct target gene of miR-709, which is the coding gene of PKCα. Then the transcription and translation levels of Prkca were obvious reduced by the over-expression of miR-709 in GH3 cells, followed by the inhibition of the transcription factor (CREB1) of Gh1 gene and the ERK1/2 signaling pathway or the possible cross-talk signaling pathway (cAMP/PKA signaling pathway) detected by western blot, suggesting that ERK1/2 maybe an important factor involved in the GH3 cell viability mediated by PKCα. At last, GHRP6 increased PKCα and GH expression but reduced miR-709 expression in vitro and vivo assays, and this conclusion was further confirmed by the result of GHRP6 attenuated the inhibition of miR-709 on GH expression. These findings will provide new molecular mechanism on the regulation of pituitary GH.

Risk and protective factors contributing to homelessness among foster care youth: An analysis of the National Youth in Transition Database

Homelessness is a pervasive problem among youth aging out of the foster care system. Many of these youth exit the system without any concrete plans for their future and wind up suffering bouts of homelessness. Although a growing body of literature has begun to look at the factors that contribute to homelessness among this population, less has been written about the factors that guard against homelessness. Furthermore, most of the studies have been confined to a particular geographic area. Using data from the National Youth in Transition Database (NYTD), combined with the Adoption and Foster Care Analysis Reporting System (AFCARS), the present study provides an analysis of the risk and protective factors contributing to homelessness among a nationwide sample of foster care youth at age 21, 29% of whom had experienced homelessness. The findings indicate that the strongest protective factors against homelessness were having a connection to an adult and remaining in foster care until age 21. Other protective factors included having at least a high school education, being currently enrolled in school, and having a full-time job. On the other hand, the strongest risk factors contributing to homelessness were having been incarcerated, as well as having been referred for substance abuse. Other significant risk factors were having a runaway history, having received public food assistance, and being emotionally disturbed. Given these findings, child welfare agencies should make greater efforts to ensure that youth have an adult in their life whom they can trust and turn to for help, as well as encourage youth to remain in care until they are better prepared for life on their own.

A thermostable flavin-based fluorescent protein from Chloroflexus aggregans: a framework for ultra-high resolution structural studies.

Light-Oxygen-Voltage (LOV) domains are conserved parts of photoreceptors in plants, bacteria and fungi that bind flavins as chromophores and detect blue light. In the past, LOV domain variants have been developed as fluorescent reporter proteins (called flavin-based fluorescent proteins; FbFPs), which due to their ability to fluoresce under anaerobic conditions, fast folding kinetics and a small size of ∼12-16 kDa are a promising reporter system for quantitative real-time analysis of biological processes. Here, we present a small thermostable flavin-based fluorescent protein CagFbFP derived from a soluble LOV domain-containing histidine kinase from the thermophilic bacterium Chloroflexus aggregans. CagFbFP is composed of 107 amino acids with a molecular weight of 11.6 kDa and consists only of the conserved LOV core domain. The protein is thermostable with a melting point of about 68 °C. It crystallizes easily and its crystals diffract to 1.07 Å. Both the crystal structure and small angle scattering data show that the protein is a dimer. Unexpectedly, glutamine 148, which in LOV photoreceptor proteins is the key residue responsible for signal transduction, occupies two conformations. Molecular dynamics simulations show that the two conformations interconvert rapidly. The crystal structure of the wild-type Chloroflexus aggregans LOV domain determined at 1.22 Å resolution confirmed the presence of two alternative conformations of the glutamine 148 side chain. Overall, this protein, due to its stability and ease of crystallization, appears to be a promising model for ultra-high resolution structural studies of LOV domains and for application as a fluorescent reporter.

Drivers with child passengers: distracted but cautious?

ObjectiveA remarkable portion of children’s traffic-related deaths occurred when travelling in as passengers in vehicles, but so far, few studies have focused on crash characteristics and crash risks of drivers with child passengers. It has been assumed that drivers with child passengers drive responsibly, but on the contrary, children in vehicles can distract drivers, increasing crash risks. In this study, we examined fatal crash characteristics and fatal crash risks of drivers with child passengers. MethodsFatal crash data from the U.S. Fatality Analysis Reporting System (FARS) for 1996–2015 were used. Only passenger-vehicle drivers aged 23–46 years old were included in the analysis because they represent the typical age of drivers with 0–9-year-old child passengers in the database. Prevalence of crash characteristics and the odds of being at fault were examined for drivers with only child passengers and compared to drivers with only adult passengers, with no passengers and with both adult and child passengers. Analyses were done separately for intersection crashes and non-junction crashes. ResultsFemale drivers were involved in twice as many fatal crashes alone with child passengers compared to male drivers. Drivers with only child passengers were more often reported as being inattentive, but for them, risk-taking behaviours were less typical than for drivers without child passengers. Our results showed that these differences were more evident in non-junction crashes than in intersection crashes. When risk-taking behaviours were controlled, both male and female drivers with only child passengers had higher odds of being at fault than drivers with adult passengers (with or without children) in non-junction crashes, but these differences were not significant in intersection crashes. ConclusionsDrivers with child passengers represent a specific driver population. They have a higher tendency to engage in distractions while driving, but they have fewer risk-taking behaviour-related fatal crashes compared to drivers with no child passengers. Our results indicate that the effects of child-passenger-related distractions on fatal crash risks are more relevant outside intersections, presumably because drivers may try to self-regulate their interactions with child passengers and focus on driving in more demanding traffic situations.

Wreck on the Highway: Intersectionality of Driver Culpability, Tetrahydrocannabinols, Other Intoxicants and Fatalities in Washington State

Given the legalization of recreational cannabis in 2012 in Washington State and recent mixed results regarding the effects of cannabis on driver safety, the paper examines the link between delta-9-tetrahydrocannabinols (THC) and driver behavior, including speeding and driver errors which may have contributed to a particular fatal crash. The current study utilized data from the Washington State Fatality Analysis Reporting System Analytical File (WA FARS) from 2008 to 2016. A series of logistic regressions were employed to compare THC-positive and -negative drivers, as well as drivers who tested positive for other intoxicants. The results of the study were mixed; it was found that delta-9-THC positively predicted speeding, but not other driver errors. Interestingly, carboxy-THC, a non-psychoactive chemical which can be detected for a longer period of time, was a significant predictor of both speeding and driver errors. This research further demonstrates that cannabis is predictive of risky behavior by drivers in fatal crashes, though it is not nearly as strong a predictor as alcohol. Additional research is needed to understand better why carboxy-THC is a stronger and more robust predictor of poor driving behavior than delta-9-THC.

Using Approximation Algorithms to Build Evidence Factors and Related Designs for Observational Studies

Observational or nonrandomized studies of treatment effects are often constructed with the aid of polynomial-time algorithms that optimally form matched treatment-control pairs or matched sets. Because each observational comparison may potentially be affected by bias, investigators often reinforce a single comparison with an additional comparison that is unlikely to be affected by the same biases, for instance using multiple control groups or evidence factors or control + instrument designs. Use of two comparisons affected by different biases may detect bias if the two comparisons disagree, or may show that two comparisons with different weakness concur in their conclusions. Even this simplest addition—a second comparison—creates design problems without polynomial-time solutions. Faced with a problem that no polynomial-time algorithm can solve, a so-called approximation algorithm is a type of compromise: it provides a solution in polynomial time that is provably not much worse than the unattainable optimal solution. Building upon existing techniques for related problems in operations research, we develop an approximation algorithm for minimum distance matching with near-fine balance for three comparison groups. This algorithm is a practical approach to most observational designs that add a second comparison. The method is applied to an observational study of the effects of side airbags on injury severity in the U.S. Fatality Analysis Reporting System. For many car makes and models, side airbags were initially unavailable, then later available as optional equipment for an additional fee, then still later provided as standard equipment. Within sets matched for make and model of car, for safety belt use, for direction of impact, and other covariates, we compare crashes in these three periods, where each comparison has different limitations. The method is implemented in the R package approxmatch, whose example reproduces some of the calculations. Supplementary materials for this article are available online.

Construction and characterization of broad-host-range reporter plasmid suitable for on-line analysis of bacterial host responses related to recombinant protein production

BackgroundBacteria are widely used as hosts for recombinant protein production due to their rapid growth, simple media requirement and ability to produce high yields of correctly folded proteins. Overproduction of recombinant proteins may impose metabolic burden to host cells, triggering various stress responses, and the ability of the cells to cope with such stresses is an important factor affecting both cell growth and product yield.ResultsHere, we present a versatile plasmid-based reporter system for efficient analysis of metabolic responses associated with availability of cellular resources utilized for recombinant protein production and host capacity to synthesize correctly folded proteins. The reporter plasmid is based on the broad-host range RK2 minimal replicon and harbors the strong and inducible XylS/Pm regulator/promoter system, the ppGpp-regulated ribosomal protein promoter PrpsJ, and the σ32-dependent synthetic tandem promoter Pibpfxs, each controlling expression of one distinguishable fluorescent protein. We characterized the responsiveness of all three reporters in Escherichia coli by quantitative fluorescence measurements in cell cultures cultivated under different growth and stress conditions. We also validated the broad-host range application potential of the reporter plasmid by using Pseudomonas putida and Azotobacter vinelandii as hosts.ConclusionsThe plasmid-based reporter system can be used for analysis of the total inducible recombinant protein production, the translational capacity measured as transcription level of ribosomal protein genes and the heat shock-like response revealing aberrant protein folding in all studied Gram-negative bacterial strains.

Miss-and-run: Factors contributing to two-vehicle phantom vehicle crashes in Florida

Objective: Phantom vehicle crashes (PVCs), or miss-and-run crashes, are a topical issue in car insurance coverage because of controversies over testimony and compensation. However, no peer-reviewed literature has examined the perceptions and deliberations involved in this infrequent type of car crash. A novel taxonomy of roadway traffic crashes is proposed in this study on the basis of whether physical collisions did occur (hit or miss) and whether the perpetrators stayed at the crash scene (stay or run). In this way, this study poses the issue of PVCs within the scope of traffic safety research and aims to investigate the statistically significant factors that are likely to induce PVCs.Methods: A binary logistic regression method was adopted to model the probability and occurrence of 2-vehicle PVCs (TV-PVCs) in Florida. Data derived from the Crash Analysis Reporting system in 2012–2014 consisted of 45,319 2-vehicle crashes, of which 1,376 (3.04%) were confirmed as positive TV-PVCs. Sixteen factors with 50 variables on crash information, roadway characteristics, and environmental conditions were included in the original consideration of the TV-PVC model.Results: The results indicated that a 2-vehicle crash is more likely to be a PVC when the crash happens on weekends, on roadways with no traffic control or speed control, full access control; on curving and sloping roadways; on roadways of National Highway System; and in low-density and other areas. A TV-PVC is less likely to occur on dry roads, in daylight, or at intersections or driveways. Moreover, alcohol involvement in a 2-vehicle crash is associated with hit-and-stay crashes than PVCs, and uninsured motorists are more likely to be the victims of PVCs because they tend to avoid physical collisions due to the potential self-paid loss.Conclusions: Several conclusions for better understanding the occurrence of PVCs are proposed for traffic management departments and car insurers. Cautious driving behavior including concentrated attention and deliberate lane changes should be encouraged for motorists to engage in appropriate levels of driving freedom, and drunk driving should be strictly supervised to keep motorists behind the wheel conscious. Car insurance is encouraged to compensate for economic loss resulting from roadway crashes. Road monitoring systems with well-performing illumination devices are recommended to help drivers provide potent testimony for compensation claims.

Multiple imputation of missing marijuana data in the Fatality Analysis Reporting System using a Bayesian multilevel model

BackgroundThe Fatality Analysis Reporting System (FARS) provides important data for studying the role of marijuana in motor vehicle crashes. However, marijuana testing data are available for only 34% of drivers in the FARS, which represents a major barrier in the use of the data. MethodsWe developed a multiple imputation (MI) procedure for estimating marijuana positivity among drivers with missing marijuana test results, using a Bayesian multilevel model that allows a nonlinear association with blood alcohol concentrations (BACs), accounts for correlations among drivers in the same states, and includes both individual-level and state-level covariates. We generated 10 imputations for the missing marijuana-testing data using Markov chain Monte Carlo simulations and estimated positivity rates of marijuana in the nation and each state. ResultsDrivers who were at older age, female, using seatbelt at the time of crash, having valid license, or operating median/heavy trucks were less likely to test positive for marijuana. There was a reverse U-shaped association between BACs and positivity of marijuana, with lower positivity when BACs < 0.01 g/dL or ≥0.15 g/dL. The MI data estimated a lower positivity rate of marijuana in the nation and each of the state than the observed data, with a national positivity rate of 11.7% (95% CI: 11.1, 12.4) versus 14.8% using the observed data in 2013. ConclusionsOur MI procedure appears to be a valid approach to addressing missing marijuana data in the FARS and may help strengthen the capacity of the FARS for monitoring the epidemic of drugged driving and understanding the role of marijuana in fatal motor vehicle crashes in the United States.

Smooth associations between the emergency medical services response time and the risk of death in road traffic crashes

BackgroundUnderstanding the impact of emergency medical services (EMS) response times on the likelihood of death has received repeated attention in the literature. However, the current literature lacks definite and detailed results. This study seeks to contribute by revealing a smoothed conditional association between EMS response times and the odds of fatality, also allowing this association to be heterogeneous with respect to the statuses of other influential variables. MethodsThe 2015 Fatality Analysis Reporting System (FARS) national dataset of the United States was adopted as it was large enough to support the sample-size requirement for exhibiting heterogeneous smooth link functions of EMS response times, with higher confidence levels. An additive logistic regression model with smooth interaction terms was introduced. Two ordinary logistic models with different settings for the EMS response time were developed for comparison with the additive logistic model. ResultsThe overall impact of the EMS response time, as well as age, gender, seating position and manner of collision, on the odds of death, was statistically significant. For the first time, the marginal smooth influential pattern of the EMS response time was found to be non-monotonic, such that, for cases with long EMS response times, it could be negatively associated with the odds of death. Similar phenomena were also found when the EMS response time interacted with several other factors. ConclusionTwo critical values (5.5 minutes and 17 minutes respectively) of the EMS response time were found. The former represents the fastest decline in the chance of survival and the latter is just the “gold time” for operating rescues. Overestimation of the urgency level of certain types of crashes at the very early stages of rescues could be the main reason for observing a negative influential pattern of the EMS response time on the odds of death.

Exploring crash characteristics and injury outcomes among older truck drivers: An analysis of truck-involved crash data in the United States

Road freight transportation represents a long-standing public health and transportation safety problem in the United States. Despite the United States’ aging population, and predictions of an aging road freight transportation workforce, there is little information about the unique safety issues faced by older truck drivers, whether they pose an increased safety risk or how to inform the development of new evidence-based preventive strategies. This study represents the starting point for addressing these issues by exploring differences in crash characteristics and injury outcomes in older and middle aged driver groups. Two sets of data in the United States (i.e., Fatality Analysis Reporting System and the National Automotive Sampling System General Estimates System) were used to analyze trends and compare truck drivers aged 60 years and older to their younger counterparts (i.e., 27–50 year olds). The results of this study both support and refute previous research. No differences were identified in crash outcomes and characteristics between older and middle aged truck drivers, representing a departure from previous research conducted with non-professional drivers. Furthermore, older drivers were found to display some safer driver behaviors (i.e., safety belt and alcohol use) compared with middle aged drivers. The results support the need for future research in this area and countermeasures that leverage the knowledge and experience of older truck drivers in managing safety in the transportation industry.

A broad-host range dual-fluorescence reporter system for gene expression analysis in Gram-negative bacteria

Fluorescence-based reporter systems are valuable tools for studying gene expression dynamics in living cells. Here we describe a dual-fluorescence reporter system carrying the red fluorescent marker mCherry and the blue fluorescent protein EBFP2 enabling the simultaneous analysis of two promoters in broad-host range autofluorescent Gram-negative bacteria.

Molecular Genetic Characterization of Mutagenesis Using a Highly Sensitive Single-Stranded DNA Reporter System in Budding Yeast.

Mutations are permanent alterations to the coding content of DNA. They are starting material for the Darwinian evolution of species by natural selection, which has yielded an amazing diversity of life on Earth. Mutations can also be the fundamental basis of serious human maladies, most notably cancers. In this chapter, I describe a highly sensitive reporter system for the molecular genetic analysis of mutagenesis, featuring controlled generation of long stretches of single-stranded DNA in budding yeast cells. This system is ~100- to ~1000-fold more susceptible to mutation than conventional double-stranded DNA reporters, and is well suited for generating large mutational datasets to investigate the properties of mutagens.

Young females at risk while driving with a small child

IntroductionPrevious research suggests that young mothers with little driving experience are at risk when driving with a small child passenger. In this study we examined the prevalence, characteristics and risk of fatal motor vehicle crashes involving an infant passenger under the age of one among female drivers of different ages. MethodsWe used crash data from the US Fatality Analysis Reporting System for 1994–2013. The prevalence of fatal crashes involving infants was examined by age of female drivers and compared to the number of births among mothers of a similar age. The essential characteristics of the crashes were described, and the odds of being at fault were determined for young (16–24-year-olds) and older female drivers (25–39-year-olds) with an infant passenger or with no passengers. ResultsThe prevalence of fatal crashes involving infant passengers was higher among young female drivers in relation to the number of births among mothers of a similar age than among older females. Young female drivers with an infant passenger were more often at fault than older drivers (aOR=1.83, 95%, CI=1.52, 2.20). Their vehicles were older and smaller and they used proper safety seats for infants less often than the older drivers. In addition, young female drivers with an infant passenger but with no adult passenger in the vehicle were more often at fault than young female drivers with no passengers (aOR=1.27, 95% CI=1.06, 1.51).Both young and older female drivers’ crashes involving an infant passenger typically occurred in ordinary driving conditions, but these drivers with infant passengers were more often reported as having fallen asleep or inattentive than those with no passengers. The presence of an adult passenger in addition to an infant passenger lowered female drivers’ odds of being at fault, regardless of the driver’s age. ConclusionsYoung females driving with an infant passenger, probably most often mothers, are at an elevated risk of a fatal crash, especially when they drive alone with an infant. The protective effect of an adult passenger suggests that another adult in the vehicle can assist the driver by taking care of the infant and enabling the driver to focus on driving.

Effect of mobile phone proliferation on crash notification times and fatality rates

IntroductionThe purpose of this study was to evaluate whether increased proliferation of mobile telephones has been associated with decreased MVC notification times and/or decreased MVC fatality rates in the United States (US). MethodsWe used World Bank annual mobile phone market penetration data and US Fatality Analysis Reporting System (FARS) fatal MVC data for 1994–2014. For each year, phone proliferation was measured as mobile phones per 100 population. FARS data were used to calculate MVC notification time (time EMS notified – time MVC occurred) in minutes, and to determine the MVC fatality rate per billion vehicle miles traveled (BVMT). We used basic vector auto-regression modeling to explore relationships between changes in phone proliferation and subsequent changes in median and 90th percentile MVC notification times, as well as MVC fatality rates. ResultsFrom 1994 to 2014, larger year-over-year increases in phone proliferation were associated with larger decreases in 90th percentile notification times for MVCs occurring during daylight hours (p=0.004) and on the national highway system (p=0.046) two years subsequent, and crashes off the national highway system three years subsequent (p=0.023). There were no significant associations between changes in phone proliferation and subsequent changes in median crash notification times, nor with subsequent changes in MVC fatality rates. ConclusionBetween 1994 and 2014 increased mobile phone proliferation in the U.S. was associated with shorter 90th percentile EMS notification times for some subgroups of fatal MVCs, but not with decreases in median notification times or overall MVC fatality rates.

Crash Fatality Rates After Recreational Marijuana Legalization in Washington and Colorado.

To evaluate motor vehicle crash fatality rates in the first 2 states with recreational marijuana legalization and compare them with motor vehicle crash fatality rates in similar states without recreational marijuana legalization. We used the US Fatality Analysis Reporting System to determine the annual numbers of motor vehicle crash fatalities between 2009 and 2015 in Washington, Colorado, and 8 control states. We compared year-over-year changes in motor vehicle crash fatality rates (per billion vehicle miles traveled) before and after recreational marijuana legalization with a difference-in-differences approach that controlled for underlying time trends and state-specific population, economic, and traffic characteristics. Pre-recreational marijuana legalization annual changes in motor vehicle crash fatality rates for Washington and Colorado were similar to those for the control states. Post-recreational marijuana legalization changes in motor vehicle crash fatality rates for Washington and Colorado also did not significantly differ from those for the control states (adjusted difference-in-differences coefficient = +0.2 fatalities/billion vehicle miles traveled; 95% confidence interval = -0.4, +0.9). Three years after recreational marijuana legalization, changes in motor vehicle crash fatality rates for Washington and Colorado were not statistically different from those in similar states without recreational marijuana legalization. Future studies over a longer time remain warranted.

Urban street structure and traffic safety

IntroductionThis paper reports the influence of road type and junction density on road traffic fatality rates in U.S. cities. MethodThe Fatality Analysis Reporting System (FARS) files were used to obtain fatality rates for all cities for the years 2005–2010. A stratified random sample of 16 U.S. cities was taken, and cities with high and low road traffic fatality rates were compared on their road layout details (TIGER maps were used). Statistical analysis was done to determine the effect of junction density and road type on road traffic fatality rates. ResultsThe analysis of road network and road traffic crash fatality rates in these randomly selected U.S. cities shows that, (a) higher number of junctions per road length was significantly associated with a lower motor- vehicle crash and pedestrian mortality rates, and, (b) increased number of kilometers of roads of any kind was associated with higher fatality rates, but an additional kilometer of main arterial road was associated with a significantly higher increase in total fatalities. When compared to non-arterial roads, the higher the ratio of highways and main arterial roads, there was an association with higher fatality rates. ConclusionsThese results have important implications for road safety professionals. They suggest that once the road and street structure is put in place, that will influence whether a city has low or high traffic fatality rates. A city with higher proportion of wider roads and large city blocks will tend to have higher traffic fatality rates, and therefore in turn require much more efforts in police enforcement and other road safety measures. Practical applicationsUrban planners need to know that smaller block size with relatively less wide roads will result in lower traffic fatality rates and this needs to be incorporated at the planning stage.