Intervenção comunitária para prevenção de acidentes de trânsito entre trabalhadores ciclistas

Studies of the effectiveness of transport sector interventions in low- and middle-income countries: An evidence and gap map

Background

There are great disparities in the quantity and quality of infrastructure. European countries such as Denmark, Germany, Switzerland, and the UK have close to 200 km of road per 100 km2, and the Netherlands over 300 km per 100 km2. By contrast, Kenya and Indonesia have <30, Laos and Morocco <20, Tanzania and Bolivia <10, and Mauritania only 1 km per 100 km2. As these figures show, there is a significant backlog of transport infrastructure investment in both rural and urban areas, especially in sub-Saharan Africa. This situation is often exacerbated by weak governance and an inadequate regulatory framework with poor enforcement which lead to high costs and defective construction.The wellbeing of many poor people is constrained by lack of transport, which is called "transport poverty". Lucas et al. suggest that up to 90% of the world's population are transport poor when defined as meeting at least one of the following criteria: (1) lack of available suitable transport, (2) lack of transport to necessary destinations, (3) cost of necessary transport puts household below the income poverty line, (4) excessive travel time, or (5) unsafe or unhealthy travel conditions.

Objectives

The aim of this evidence and gap map (EGM) is to identify, map, and describe existing evidence from studies reporting the quantitative effects of transport sector interventions related to all means of transport (roads, rail, trams and monorail, ports, shipping, and inland waterways, and air transport).

Methods

The intervention framework of this EGM reframes Berg et al's three categories (infrastructure, prices, and regulations) broadly as infrastructure, incentives, and institutions as subcategories for each intervention category which are each mode of transport (road, rail trams and monorail, ports, shipping, and inlands waterways, and air transport). This EGM identifies the area where intervention studies have been conducted as well as the current gaps in the evidence base.This EGM includes ongoing and completed impact evaluations and systematic reviews (SRs) of the effectiveness of transport sector interventions. This is a map of effectiveness studies (impact evaluations). The impact evaluations include experimental designs, nonexperimental designs, and regression designs. We have not included the before versus after studies and qualitative studies in this map. The search strategies included both academic and grey literature search on organisational websites, bibliographic searches and hand search of journals.An EGM is a table or matrix which provides a visual presentation of the evidence in a particular sector or a subsector. The map is presented as a matrix in which rows are intervention categories (e.g., roads) and subcategories (e.g., infrastructure) and the column outcome domains (e.g., environment) and subcategories as (e.g., air quality). Each cell contains studies of the corresponding intervention for the relevant outcome, with links to the available studies. Included studies were coded according to the intervention and outcomes assessed and additional filters as region, population, and study design. Critical appraisal of included SR was done using A Measurement Tool to Assess Systematic Reviews (AMSTAR -2) rating scale.

Selection Criteria

The search included both academic and grey literature available online. We included impact evaluations and SRs that assessed the effectiveness of transport sector interventions in low- and middle-income countries.

Results

This EGM on the transport sector includes 466 studies from low- and middle-income countries, of which 34 are SRs and 432 impact evaluations. There are many studies of the effects of roads intervention in all three subcategories-infrastructure, incentives, and institutions, with the most studies in the infrastructure subcategories. There are no or fewer studies on the interventions category ports, shipping, and waterways and for civil aviation (Air Transport).In the outcomes, the evidence is most concentrated on transport infrastructure, services, and use, with the greatest concentration of evidence on transport time and cost (193 studies) and transport modality (160 studies). There is also a concentration of evidence on economic development and health and education outcomes. There are 139 studies on economic development, 90 studies on household income and poverty, and 101 studies on health outcomes.The major gaps in evidence are from all sectors except roads in the intervention. And there is a lack of evidence on outcome categories such as cultural heritage and cultural diversity and very little evidence on displacement (three studies), noise pollution (four studies), and transport equity (2). There is a moderate amount of evidence on infrastructure quantity (32 studies), location, land use and prices (49 studies), market access (29 studies), access to education facilities (23 studies), air quality (50 studies), and cost analysis including ex post CBA (21 studies).The evidence is mostly from East Asia and the Pacific Region (223 studies (40%), then the evidence is from the sub-Saharan Africa (108 studies), South Asia (96 studies), Latin America & Caribbean (79 studies). The least evidence is from Middle East & North Africa (30 studies) and Europe & Central Asia (20 studies). The most used study design is other regression design in all regions, with largest number from East Asia and Pacific (274). There is total 33 completed SRs identified and one ongoing, around 85% of the SR are rated low confidence, and 12% rated as medium confidence. Only one review was rated as high confidence. This EGM contains the available evidence in English.

Conclusion

This map shows the available evidence and gaps on the effectiveness of transport sector intervention in low- and middle-income countries. The evidence is highly concentrated on the outcome of transport infrastructure (especially roads), service, and use (351 studies). It is also concentrated in a specific region-East Asia and Pacific (223 studies)-and more urban populations (261 studies). Sectors with great development potential, such as waterways, are under-examined reflecting also under-investment.The available evidence can guide the policymakers, and government-related to transport sector intervention and its effects on many outcomes across sectors. There is a need to conduct experimental studies and quality SRs in this area. Environment, gender equity, culture, and education in low- and middle-income countries are under-researched areas in the transport sector.

Sample size determination for stepped wedge cluster randomized trials in pragmatic settings

The stepped-wedge cluster randomized design has been increasingly employed by pragmatic trials in health services research. In this study, based on the GEE approach, we present closed-form sample size calculation that is applicable to both closed-cohort and cross-sectional stepped wedge trials. Importantly, the proposed method is flexible to accommodate design issues routinely encountered in pragmatic trials, such as different within- and between-subject correlation structures, irregular crossover schedules for the switch to intervention, and missing data due to repeated measurements over prolonged follow-up. The closed-form formulas allow researchers to analytically assess the impact of different design factors on sample size requirement. We also recognize the potential issue of limited numbers of clusters in pragmatic stepped wedge trials and present an adjustment approach for underestimated variance of the treatment effect. We conduct extensive simulation to assess the performance of the proposed sample size method. An application example to a real clinical trial is presented.

Explaining the variation in the attained power of a stepped-wedge trial with unequal cluster sizes

Background

In a cross-sectional stepped-wedge trial with unequal cluster sizes, attained power in the trial depends on the realized allocation of the clusters. This attained power may differ from the expected power calculated using standard formulae by averaging the attained powers over all allocations the randomization algorithm can generate. We investigated the effect of design factors and allocation characteristics on attained power and developed models to predict attained power based on allocation characteristics.

Method

Based on data simulated and analyzed using linear mixed-effects models, we evaluated the distribution of attained powers under different scenarios with varying intraclass correlation coefficient (ICC) of the responses, coefficient of variation (CV) of the cluster sizes, number of cluster-size groups, distributions of group sizes, and number of clusters. We explored the relationship between attained power and two allocation characteristics: the individual-level correlation between treatment status and time period, and the absolute treatment group imbalance. When computational time was excessive due to a scenario having a large number of possible allocations, we developed regression models to predict attained power using the treatment-vs-time period correlation and absolute treatment group imbalance as predictors.

Results

The risk of attained power falling more than 5% below the expected or nominal power decreased as the ICC or number of clusters increased and as the CV decreased. Attained power was strongly affected by the treatment-vs-time period correlation. The absolute treatment group imbalance had much less impact on attained power. The attained power for any allocation was predicted accurately using a logistic regression model with the treatment-vs-time period correlation and the absolute treatment group imbalance as predictors.

Conclusion

In a stepped-wedge trial with unequal cluster sizes, the risk that randomization yields an allocation with inadequate attained power depends on the ICC, the CV of the cluster sizes, and number of clusters. To reduce the computational burden of simulating attained power for allocations, the attained power can be predicted via regression modeling. Trial designers can reduce the risk of low attained power by restricting the randomization algorithm to avoid allocations with large treatment-vs-time period correlations.

Mapping global evidence on strategies and interventions in neurotrauma and road traffic collisions prevention: a scoping review

BACKGROUND

Neurotrauma is an important global health problem. The largest cause of neurotrauma worldwide is road traffic collisions (RTCs), particularly in low- and middle-income countries (LMICs). Neurotrauma and RTCs are preventable, and many preventative interventions have been implemented over the last decades, especially in high-income countries (HICs). However, it is uncertain if these strategies are applicable globally due to variations in environment, resources, population, culture and infrastructure. Given this issue, this scoping review aims to identify, quantify and describe the evidence on approaches in neurotrauma and RTCs prevention, and ascertain contextual factors that influence their implementation in LMICs and HICs.

METHODS

A systematic search was conducted using five electronic databases (MEDLINE, EMBASE, CINAHL, Global Health on EBSCO host, Cochrane Database of Systematic Reviews), grey literature databases, government and non-government websites, as well as bibliographic and citation searching of selected articles. The extracted data were presented using figures, tables, and accompanying narrative summaries. The results of this review were reported using the PRISMA Extension for Scoping Reviews (PRISMA-ScR).

RESULTS

A total of 411 publications met the inclusion criteria, including 349 primary studies and 62 reviews. More than 80% of the primary studies were from HICs and described all levels of neurotrauma prevention. Only 65 papers came from LMICs, which mostly described primary prevention, focussing on road safety. For the reviews, 41 papers (66.1%) reviewed primary, 18 tertiary (29.1%), and three secondary preventative approaches. Most of the primary papers in the reviews came from HICs (67.7%) with 5 reviews on only LMIC papers. Fifteen reviews (24.1%) included papers from both HICs and LMICs. Intervention settings ranged from nationwide to community-based but were not reported in 44 papers (10.8%), most of which were reviews. Contextual factors were described in 62 papers and varied depending on the interventions.

CONCLUSIONS

There is a large quantity of global evidence on strategies and interventions for neurotrauma and RTCs prevention. However, fewer papers were from LMICs, especially on secondary and tertiary prevention. More primary research needs to be done in these countries to determine what strategies and interventions exist and the applicability of HIC interventions in LMICs.

A systematic review of the effectiveness of interventions to reduce motor vehicle crashes and their injuries among the general and working populations

OBJECTIVE

To summarize the best available international scientific evidence on the effectiveness of interventions to reduce motor vehicle collisions and their consequences among the working and general populations.

METHODS

A broad and systematic review was conducted of the literature available in biomedical databases and grey literature. At least two investigators working in parallel performed data extraction, synthesis, and risk of bias analysis.

RESULTS

Forty-one studies with low to moderate risk of bias were included. Of these, 18 had an ecological design (time series), 10 were quasi-experimental, one was a population survey, one was a randomized clinical trial, and 11 were systematic reviews.

CONCLUSIONS

The interventions that most consistently show a positive effect on incidence, morbidity, and mortality due to motor vehicle collisions are national policies or programs that: regulate, enforce, and penalize driving under the influence of alcohol; improve driving safety and driver conditions; improve road infrastructure with the purpose of preventing collisions; and educate and penalize drivers with a history of road violations.

Analysis of factors associated with traffic accidents of cyclists attended in Brazilian state capitals

Introduction:

Brazil has the sixth largest bicycles fleet in the world and bicycle is the most used individual transport vehicle in the country. Few studies address the issue of cyclists' accidents and factors that contribute to or prevent this event.

Methodology:

VIVA is a cross-sectional survey and is part of the Violence and Accidents Surveillance System, Brazilian Ministry of Health. We used complex sampling and subsequent data review through multivariate logistic regression and calculation of the respective odds ratios.

Results:

Odds ratios showed greater likelihood of cyclists' accidents in males, people with less schooling and living in urban and periurban areas. People who were not using the bike to go to work were more likely to suffer an accident.

Discussion:

The profile found in this study corroborates findings of other studies. They claim that the coexistence of cyclists and other means of transportation in the same urban space increases the likelihood of accidents.

Conclusion:

The construction of bicycle-exclusive spaces and educational campaigns are required.

After 10 years, how do changes in asset ownership affect the Indicador Econômico Nacional?

OBJECTIVE

Our main objective was to analyse how the evolution of household assets ownership affected the Indicador Econômico Nacional (IEN - National Wealth index) and to point out the most stable assets and which lost importance more quickly.

METHODS

We analysed the trend of the ownership of each IEN variable and the distribution of the households' scores. We calculated the correlation coefficients of each variable separately with the IEN score and the household income. We also evaluated how the changes of the score distribution over time affected the validity of the published reference cut-points. We used data from consortium surveys conducted every two years from 2002 to 2014 in the city of Pelotas, Brazil.

RESULTS

An increase in the educational level of household heads and in the ownership of all IEN assets, except radio and telephone, was observed in the study period. In general, the correlation of the assets with the IEN scores decreased over time. There was an increase in the score, with a consequent increase in the quintiles cut-points, but the distance between these cut-points had no significant variation. Thus, the reference cut-points for Pelotas, quickly became outdated.

CONCLUSIONS

Some assets showed greatly reduction on its importance for the indicator, and the reference cut-points became obsolete very quickly. It is essential for a standardized wealth (or asset) index with research purposes to be updated frequently, especially the cut-points of reference distribution.

OBJETIVO

Analisar como a evolução temporal da posse de bens domésticos afetou o Indicador Econômico Nacional e como essas mudanças afetaram o poder discriminatório do indicador.

MÉTODOS

Analisou-se a evolução temporal da posse de cada uma das variáveis do Indicador Econômico Nacional, bem como da distribuição do escore dos domicílios. Utilizamos dados de inquéritos populacionais realizados bienalmente no município de Pelotas, RS, de 2002 a 2014. Foi calculado o coeficiente de correlação de cada variável isoladamente com o escore do Indicador Econômico Nacional e com a renda familiar. Avaliamos também como a variação da distribuição do escore ao longo do tempo afetou a validade da utilização dos pontos de corte de referência publicados.

RESULTADOS

Houve aumento da escolaridade dos chefes das famílias e da posse de todos os bens, exceto rádio e linha telefônica no período. A correlação dos bens com o Indicador Econômico Nacional reduziu com o tempo. O escore aumentou, com consequente incremento nos pontos de corte dos quintis, mas a distância entre os pontos não teve variação importante. Assim, os pontos de corte de referência publicados para Pelotas rapidamente ficaram desatualizados.

CONCLUSÕES

Alguns bens perderam a capacidade discriminatória e os pontos de corte ficaram obsoletos rapidamente. É essencial um indicador de bens padronizado para uso em pesquisa, que seja atualizado com frequência, em especial os pontos de corte da distribuição de referência.

Distracted Biking: An Observational Study

Commuting via bicycle is a very popular mode of transportation in the Northeastern United States. Boston, MA, has seen a rapid increase in bicycle ridership over the past decade, which has raised concerns and awareness about bicycle safety. An emerging topic in this field is distracted bicycle riding. This study was conducted to provide descriptive data on the prevalence and type of distracted bicycling in Boston at different times of day. This was a cross-sectional study in which observers tallied bicyclists at 4 high traffic intersections in Boston during various peak commuting hours for 2 types of distractions: auditory (earbuds/phones in or on ears), and visual/tactile (electronic device or other object in hand). Nineteen hundred seventy-four bicyclists were observed and 615 (31.2%), 95% CI [29, 33%], were distracted. Of those observed, auditory distractions were the most common (N = 349; 17.7%), 95% CI [16, 19], p = .0003, followed by visual/tactile distractions (N = 266; 13.5%), 95% CI [12, 15]. The highest proportion (40.7%), 95% CI [35, 46], of distracted bicyclists was observed during the midday commute (between 13:30 and 15:00). Distracted bicycling is a prevalent safety concern in the city of Boston, as almost a third of all bicyclists exhibited distracted behavior. Education and public awareness campaigns should be designed to decrease distracted bicycling behaviors and promote bicycle safety in Boston. An awareness of the prevalence of distracted biking can be utilized to promote bicycle safety campaigns dedicated to decreasing distracted bicycling and to provide a baseline against which improvements can be measured.

Stepped wedge cluster randomised trials: a review of the statistical methodology used and available

BACKGROUND

Previous reviews have focussed on the rationale for employing the stepped wedge design (SWD), the areas of research to which the design has been applied and the general characteristics of the design. However these did not focus on the statistical methods nor addressed the appropriateness of sample size methods used.This was a review of the literature of the statistical methodology used in stepped wedge cluster randomised trials.

METHODS

Literature Review. The Medline, Embase, PsycINFO, CINAHL and Cochrane databases were searched for methodological guides and RCTs which employed the stepped wedge design.

RESULTS

This review identified 102 trials which employed the stepped wedge design compared to 37 from the most recent review by Beard et al. 2015. Forty six trials were cohort designs and 45 % (n = 46) had fewer than 10 clusters. Of the 42 articles discussing the design methodology 10 covered analysis and seven covered sample size. For cohort stepped wedge designs there was only one paper considering analysis and one considering sample size methods. Most trials employed either a GEE or mixed model approach to analysis (n = 77) but only 22 trials (22 %) estimated sample size in a way which accounted for the stepped wedge design that was subsequently used.

CONCLUSIONS

Many studies which employ the stepped wedge design have few clusters but use methods of analysis which may require more clusters for unbiased and efficient intervention effect estimates. There is the need for research on the minimum number of clusters required for both types of stepped wedge design. Researchers should distinguish in the sample size calculation between cohort and cross sectional stepped wedge designs. Further research is needed on the effect of adjusting for the potential confounding of time on the study power.

Road Traffic Injury Prevention Initiatives: A Systematic Review and Metasummary of Effectiveness in Low and Middle Income Countries

Background

Road traffic injuries (RTIs) are a growing but neglected global health crisis, requiring effective prevention to promote sustainable safety. Low- and middle-income countries (LMICs) share a disproportionately high burden with 90% of the world’s road traffic deaths, and where RTIs are escalating due to rapid urbanization and motorization. Although several studies have assessed the effectiveness of a specific intervention, no systematic reviews have been conducted summarizing the effectiveness of RTI prevention initiatives specifically performed in LMIC settings; this study will help fill this gap.

Methods

In accordance with PRISMA guidelines we searched the electronic databases MEDLINE, EMBASE, Scopus, Web of Science, TRID, Lilacs, Scielo and Global Health. Articles were eligible if they considered RTI prevention in LMICs by evaluating a prevention-related intervention with outcome measures of crash, RTI, or death. In addition, a reference and citation analysis was conducted as well as a data quality assessment. A qualitative metasummary approach was used for data analysis and effect sizes were calculated to quantify the magnitude of emerging themes.

Results

Of the 8560 articles from the literature search, 18 articles from 11 LMICs fit the eligibility and inclusion criteria. Of these studies, four were from Sub-Saharan Africa, ten from Latin America and the Caribbean, one from the Middle East, and three from Asia. Half of the studies focused specifically on legislation, while the others focused on speed control measures, educational interventions, enforcement, road improvement, community programs, or a multifaceted intervention.

Conclusion

Legislation was the most common intervention evaluated with the best outcomes when combined with strong enforcement initiatives or as part of a multifaceted approach. Because speed control is crucial to crash and injury prevention, road improvement interventions in LMIC settings should carefully consider how the impact of improvements will affect speed and traffic flow. Further road traffic injury prevention interventions should be performed in LMICs with patient-centered outcomes in order to guide injury prevention in these complex settings.

Stepped wedge randomised controlled trials: systematic review of studies published between 2010 and 2014

BACKGROUND

In a stepped wedge, cluster randomised trial, clusters receive the intervention at different time points, and the order in which they received it is randomised. Previous systematic reviews of stepped wedge trials have documented a steady rise in their use between 1987 and 2010, which was attributed to the design's perceived logistical and analytical advantages. However, the interventions included in these systematic reviews were often poorly reported and did not adequately describe the analysis and/or methodology used. Since 2010, a number of additional stepped wedge trials have been published. This article aims to update previous systematic reviews, and consider what interventions were tested and the rationale given for using a stepped wedge design.

METHODS

We searched PubMed, PsychINFO, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), the Web of Science, the Cochrane Library and the Current Controlled Trials Register for articles published between January 2010 and May 2014. We considered stepped wedge randomised controlled trials in all fields of research. We independently extracted data from retrieved articles and reviewed them. Interventions were then coded using the functions specified by the Behaviour Change Wheel, and for behaviour change techniques using a validated taxonomy.

RESULTS

Our review identified 37 stepped wedge trials, reported in 10 articles presenting trial results, one conference abstract, 21 protocol or study design articles and five trial registrations. These were mostly conducted in developed countries (n = 30), and within healthcare organisations (n = 28). A total of 33 of the interventions were educationally based, with the most commonly used behaviour change techniques being 'instruction on how to perform a behaviour' (n = 32) and 'persuasive source' (n = 25). Authors gave a wide range of reasons for the use of the stepped wedge trial design, including ethical considerations, logistical, financial and methodological. The adequacy of reporting varied across studies: many did not provide sufficient detail regarding the methodology or calculation of the required sample size.

CONCLUSIONS

The popularity of stepped wedge trials has increased since 2010, predominantly in high-income countries. However, there is a need for further guidance on their reporting and analysis.

Analysis and reporting of stepped wedge randomised controlled trials: synthesis and critical appraisal of published studies, 2010 to 2014

Background

Stepped wedge cluster randomised trials introduce interventions to groups of clusters in a random order and have been used to evaluate interventions for health and wellbeing. Standardised guidance for reporting stepped wedge trials is currently absent, and a range of potential analytic approaches have been described.

Methods

We systematically identified and reviewed recently published (2010 to 2014) analyses of stepped wedge trials. We extracted data and described the range of reporting and analysis approaches taken across all studies. We critically appraised the strategy described by three trials chosen to reflect a range of design characteristics.

Results

Ten reports of completed analyses were identified. Reporting varied: seven of the studies included a CONSORT diagram, and only five also included a diagram of the intervention rollout. Seven assessed the balance achieved by randomisation, and there was considerable heterogeneity among the approaches used. Only six reported the trend in the outcome over time. All used both ‘horizontal’ and ‘vertical’ information to estimate the intervention effect: eight adjusted for time with a fixed effect, one used time as a condition using a Cox proportional hazards model, and one did not account for time trends. The majority used simple random effects to account for clustering and repeat measures, assuming a common intervention effect across clusters. Outcome data from before and after the rollout period were often included in the primary analysis. Potential lags in the outcome response to the intervention were rarely investigated. We use three case studies to illustrate different approaches to analysis and reporting.

Conclusions

There is considerable heterogeneity in the reporting of stepped wedge cluster randomised trials. Correct specification of the time-trend underlies the validity of the analytical approaches. The possibility that intervention effects vary by cluster or over time should be considered. Further work should be done to standardise the reporting of the design, attrition, balance, and time-trends in stepped wedge trials.

Sample size calculation for a stepped wedge trial

BACKGROUND

Stepped wedge trials (SWTs) can be considered as a variant of a clustered randomised trial, although in many ways they embed additional complications from the point of view of statistical design and analysis. While the literature is rich for standard parallel or clustered randomised clinical trials (CRTs), it is much less so for SWTs. The specific features of SWTs need to be addressed properly in the sample size calculations to ensure valid estimates of the intervention effect.

METHODS

We critically review the available literature on analytical methods to perform sample size and power calculations in a SWT. In particular, we highlight the specific assumptions underlying currently used methods and comment on their validity and potential for extensions. Finally, we propose the use of simulation-based methods to overcome some of the limitations of analytical formulae. We performed a simulation exercise in which we compared simulation-based sample size computations with analytical methods and assessed the impact of varying the basic parameters to the resulting sample size/power, in the case of continuous and binary outcomes and assuming both cross-sectional data and the closed cohort design.

RESULTS

We compared the sample size requirements for a SWT in comparison to CRTs based on comparable number of measurements in each cluster. In line with the existing literature, we found that when the level of correlation within the clusters is relatively high (for example, greater than 0.1), the SWT requires a smaller number of clusters. For low values of the intracluster correlation, the two designs produce more similar requirements in terms of total number of clusters. We validated our simulation-based approach and compared the results of sample size calculations to analytical methods; the simulation-based procedures perform well, producing results that are extremely similar to the analytical methods. We found that usually the SWT is relatively insensitive to variations in the intracluster correlation, and that failure to account for a potential time effect will artificially and grossly overestimate the power of a study.

CONCLUSIONS

We provide a framework for handling the sample size and power calculations of a SWT and suggest that simulation-based procedures may be more effective, especially in dealing with the specific features of the study at hand. In selected situations and depending on the level of intracluster correlation and the cluster size, SWTs may be more efficient than comparable CRTs. However, the decision about the design to be implemented will be based on a wide range of considerations, including the cost associated with the number of clusters, number of measurements and the trial duration.

Logistic, ethical, and political dimensions of stepped wedge trials: critical review and case studies

Background

Three arguments are usually invoked in favour of stepped wedge cluster randomised controlled trials: the logistic convenience of implementing an intervention in phases, the ethical benefit of providing the intervention to all clusters, and the potential to enhance the social acceptability of cluster randomised controlled trials. Are these alleged benefits real? We explored the logistic, ethical, and political dimensions of stepped wedge trials using case studies of six recent evaluations.

Methods

We identified completed or ongoing stepped wedge evaluations using two systematic reviews. We then purposively selected six with a focus on public health in high, middle, and low-income settings. We interviewed their authors about the logistic, ethical, and social issues faced by their teams. Two authors reviewed interview transcripts, identified emerging issues through qualitative thematic analysis, reflected upon them in the context of the literature, and invited all participants to co-author the manuscript.

Results

Our analysis raises three main points. First, the phased implementation of interventions can alleviate problems linked to simultaneous roll-out, but also brings new challenges. Issues to consider include the feasibility of organising intervention activities according to a randomised sequence, estimating time lags in implementation and effects, and accommodating policy changes during the trial period. Second, stepped wedge trials, like parallel cluster trials, require equipoise: without it, randomising participants to a control condition, even for a short time, remains problematic. In stepped wedge trials, equipoise is likely to lie in the degree of effect, effectiveness in a specific operational milieu, and the balance of benefit and harm, including the social value of better evaluation. Third, the strongest arguments for a stepped wedge design are logistic and political rather than ethical. The design is advantageous when simultaneous roll-out is impractical and when it increases the acceptability of using counterfactuals.

Conclusions

The logistic convenience of phased implementation is context-dependent, and may be vitiated by the additional requirements of phasing. The potential for stepped wedge trials to enhance the social acceptability of cluster randomised trials is real, but their ethical legitimacy still rests on demonstrating equipoise and its configuration for each research question and setting.

Accidents involving motorcyclists and cyclists in the municipality of São Paulo: characterization and trends

Objective

To describe the characteristics of motorcycle and bicycle accident victims, according to notifications of suspected and confirmed accidents that have occurred in the municipality of São Paulo.

Method

This was a descriptive epidemiological study. It covered all accidents (12,924) that occurred involving motorcycles (11,366) and bicycles (1558) between January 2011 and October 2013. Data in the Health Department's information system for surveillance of violence and accidents (SIVVA) was surveyed.

Results

Motorcycle accidents accounted for 52.1% of the cases notified and bicycles, 7.1%. Males predominated in both types of accidents: 81.6% and 80.6%, respectively. In the motorcycle accidents, the predominant age group among the victims was from 20 to 24 years. Both types of accidents occurred during the daytime (7:00–18:00 h): 37.4% and 27.0% respectively. Among the motorcycle accidents, the driver had been using alcohol in 3% and it was not possible to identify whether this had occurred in 67%.

Conclusions

Public policies prioritizing financial and human resources applied toward reducing these types of accidents need to be brought in.

The influence of bicycle oriented facilities on bicycle crashes within crash concentrated areas

OBJECTIVE

This study analyzes environmental features that influence bicycle crashes within crash concentrated areas. This study particularly provides a systemic approach to analyzing major bicycle oriented facilities contributing to bicycle crashes within crash concentrated areas.

METHODS

This study applies geographic information systems (GIS) to the identification of crash concentrated areas in Riverside County, California using five years of crash data as well as the development of environment feature data inventory. Based on the data inventory, a regression method was applied to discover whether there was a correlation between the presence of bicycle facilities and the occurrence of bicycle crashes.

RESULTS

This study identifies that longer distance between crosswalks and bus stops are positively associated with bicyclist crashes, while structured medians contribute to the reduction of bicycle crashes. This study also suggests that parking lot entrance ways and parking lots with no physical barrier from sidewalks cause bicycle crashes on sidewalks.

CONCLUSIONS

This study presents guidelines for local transportation planners to analyze the patterns of bicyclist crashes in order to improve roadway safety. This research also assists planners in effectively allocating scarce resources as they address issues of bicyclist safety.

Deaths of bicycle riders in Brazil: characteristics and trends during the period of 2000 - 2010

INTRODUCTION: In Brazil, bicycle use has been increasing. Accidents involving cyclists are important causes of morbidity and mortality. OBJECTIVE: To describe the mortality of cyclists injured in transport accidents in Brazil, the characteristics of the victims and of the occurrence, and to investigate its trends during the period between 2000 and 2010. METHODS: A descriptive study with data from the Mortality Information System (SIM) was conducted in the period of 2000 - 2010. Crude and age-standardized corrected mortality rates were calculated for Brazil, its macro-regions and states. Linear regression was used to study the trends. RESULTS: In the period of 2000 - 2010, 32,422 bicycle-related deaths were identified in Brazil. In 2010, there were, on average, 8.8 bicycle-related deaths per day. Age-standardized mortality rates for the country were 15.3 and 15.9 deaths per million inhabitants in 2000 and 2010, respectively (p = 0.725). During the whole period, the Center-Western region showed the highest rates, though stable, corresponding to 23.4 deaths per million inhabitants in 2010. Men accounted for 85.4% of deaths, with death risk 5 times higher than women. CONCLUSION: In spite of the stable rates for the country, there was an increase trend in the Northern and Northeastern regions, while a decreasing trend was observed in the Southern and Southeastern regions. The risk of death was higher among men, elderly, and people living in large cities and at the Center-Western region.

Projecting the health and economic impact of road safety initiatives: a case study of a multi-country project

OBJECTIVE

The Road Safety in 10 Countries (RS-10) project will implement 12 different road safety interventions at specific sites within 10 low- and middle-income countries (LMICs). This evaluation reports the number of lives that RS-10 is projected to save in those locations, the economic value of the risk reduction, and the maximum level of investment that a public health intervention of this magnitude would be able to incur before its costs outweigh its health benefits.

METHODS

We assumed a 5-year time implementation horizon corresponding to the duration of RS-10. Based on a preliminary literature review, we estimated the effectiveness for each of the RS-10 interventions. Applying these effectiveness estimates to the size of the population at risk at RS-10 sites, we calculated the number of lives and life years saved (LYS) by RS-10. We projected the value of a statistical life (VSL) in each RS-10 country based on gross national income (GNI) and estimated the value of the lives saved using each country's VSL. Sensitivity analysis addressed robustness to assumptions about elasticity, discount rates, and intervention effectiveness.

RESULTS

From the evidence base reviewed, only 13 studies met our selection criteria. Such a limited base presents uncertainties about the potential impact of the modeled interventions. We tried to account for these uncertainties by allowing effectiveness to vary ± 20 percent for each intervention. Despite this variability, RS-10 remains likely to be worth the investment. RS-10 is expected to save 10,310 lives over 5 years (discounted at 3%). VSL and $/LYS methods provide concordant results. Based on our estimates of each country's VSL, the respective countries would be willing to pay $2.45 billion to lower these fatality risks (varying intervention effectiveness by ± 20 percent, the corresponding range is $2.0-$2.9 billion). Analysis based on $/LYS shows that the RS-10 project will be cost-effective as long as its costs do not exceed $5.14 billion (under ± 20% intervention effectiveness, the range = $4.1-$6.2 billion). Even at low efficacy, these estimates are still several orders of magnitude above the $125 million projected investment.

CONCLUSION

RS-10 is likely to yield high returns for invested resources. The study's chief limitation was the reliance on the world's limited evidence base on how effective the road safety interventions will be. Planned evaluation of RS-10 will enhance planners' ability to conduct economic assessments of road safety in developing countries.

Acidentes de trânsito no Brasil de 1998 a 2010: muitas mudanças e poucos resultados

O artigo descreve a situação dos acidentes de trânsito no Brasil, desde a implementação do Código de Trânsito Brasileiro de 1998 até o ano de 2010. Foi realizada análise dos principais trabalhos científicos e publicações não acadêmicas nacionais. A revisão de literatura incluiu periódicos indexados, não indexados, relatórios técnicos, busca específica por autores, referências bibliográficas de artigos e contato com pesquisadores. Os principais problemas do trânsito brasileiro identificados foram aumento do número absoluto de mortos e das taxas de mortalidade, ampliação da frota de motocicletas e o uso de álcool. Foram identificados autores influentes e ilhas de produção de conhecimento nas áreas pesquisadas. Os autores apresentam algumas possíveis soluções e sugerem que o poder público não tem assumido a responsabilidade que lhe cabe no controle e redução dos acidentes de trânsito.