Garth S. Hunte

Route Infrastructure and the Risk of Injuries to Bicyclists: A Case-Crossover Study

OBJECTIVES We compared cycling injury risks of 14 route types and other route infrastructure features. METHODS We recruited 690 city residents injured while cycling in Toronto or Vancouver, Canada. A case-crossover design compared route infrastructure at each injury site to that of a randomly selected control site from the same trip. RESULTS Of 14 route types, cycle tracks had the lowest risk (adjusted odds ratio [OR] = 0.11; 95% confidence interval [CI] = 0.02, 0.54), about one ninth the risk of the reference: major streets with parked cars and no bike infrastructure. Risks on major streets were lower without parked cars (adjusted OR = 0.63; 95% CI = 0.41, 0.96) and with bike lanes (adjusted OR = 0.54; 95% CI = 0.29, 1.01). Local streets also had lower risks (adjusted OR = 0.51; 95% CI = 0.31, 0.84). Other infrastructure characteristics were associated with increased risks: streetcar or train tracks (adjusted OR = 3.0; 95% CI = 1.8, 5.1), downhill grades (adjusted OR = 2.3; 95% CI = 1.7, 3.1), and construction (adjusted OR = 1.9; 95% CI = 1.3, 2.9). CONCLUSIONS The lower risks on quiet streets and with bike-specific infrastructure along busy streets support the route-design approach used in many northern European countries. Transportation infrastructure with lower bicycling injury risks merits public health support to reduce injuries and promote cycling.

Comparing the effects of infrastructure on bicycling injury at intersections and non-intersections using a case–crossover design

Background This study examined the impact of transportation infrastructure at intersection and non-intersection locations on bicycling injury risk. Methods In Vancouver and Toronto, we studied adult cyclists who were injured and treated at a hospital emergency department. A case–crossover design compared the infrastructure of injury and control sites within each injured bicyclists route. Intersection injury sites (N=210) were compared to randomly selected intersection control sites (N=272). Non-intersection injury sites (N=478) were compared to randomly selected non-intersection control sites (N=801). Results At intersections, the types of routes meeting and the intersection design influenced safety. Intersections of two local streets (no demarcated traffic lanes) had approximately one-fifth the risk (adjusted OR 0.19, 95% CI 0.05 to 0.66) of intersections of two major streets (more than two traffic lanes). Motor vehicle speeds less than 30 km/h also reduced risk (adjusted OR 0.52, 95% CI 0.29 to 0.92). Traffic circles (small roundabouts) on local streets increased the risk of these otherwise safe intersections (adjusted OR 7.98, 95% CI 1.79 to 35.6). At non-intersection locations, very low risks were found for cycle tracks (bike lanes physically separated from motor vehicle traffic; adjusted OR 0.05, 95% CI 0.01 to 0.59) and local streets with diverters that reduce motor vehicle traffic (adjusted OR 0.04, 95% CI 0.003 to 0.60). Downhill grades increased risks at both intersections and non-intersections. Conclusions These results provide guidance for transportation planners and engineers: at local street intersections, traditional stops are safer than traffic circles, and at non-intersections, cycle tracks alongside major streets and traffic diversion from local streets are safer than no bicycle infrastructure.

Clinical decision rules to improve the detection of adverse drug events in emergency department patients.

OBJECTIVES Adverse drug events (ADEs) are unintended and harmful consequences of medication use. They are associated with high health resource use and cost. Yet, high levels of inaccuracy exist in their identification in clinical practice, with over one-third remaining unidentified in the emergency department (ED). The study objective was to derive clinical decision rules (CDRs) that are sensitive for the detection of ADEs, allowing their systematic identification early in a patients hospital course. METHODS This was a prospective observational cohort study carried out in two Canadian tertiary care hospitals. Participants were adults presenting to the ED having ingested at least one prescription or over-the-counter medication within 2 weeks. Nurses and physicians evaluated patients for standardized clinical findings. A second evaluator performed interobserver assessments of predictor variables in a subset of patients. Pharmacists, who were blinded to the predictor variables, evaluated all patients for ADEs. An independent committee reviewed and adjudicated cases where the ADE assessment was uncertain or the pharmacists diagnosis differed from the physicians working diagnosis. The primary outcome was an ADE that required a change in medical therapy, diagnostic testing, consultation, or hospital admission. CDRs were derived using kappa coefficients, chi-square statistics, and recursive partitioning. RESULTS Among 1,591 patients, 131 (8.2%, 95% confidence interval [CI] = 7.0% to 9.7%) were diagnosed with the primary outcome. The following variables were associated with ADEs and were used to derive two CDRs: 1) presence of comorbid conditions, 2) antibiotic use within 7 days, 3) medication changes within 28 days, 4) age ≥ 80 years, 5) arrival by ambulance, 6) triage acuity, 7) recent hospital admission, 8) renal failure, and 9) use of three or more prescription medications. The more sensitive rule had a sensitivity of 96.7% (95% CI = 91.8% to 98.6%) and required 40.8% (95% CI = 37.7% to 42.9%) of patients to have medication review. The more specific rule had a sensitivity 90.8% (95% CI = 81.4% to 95.7%) and required 28.3% of patients to proceed to medication review. CONCLUSIONS The authors derived CDRs that identified patients with ADEs with high sensitivity. These rules may improve the identification of ADEs early in a patients hospital course while limiting the number of patients requiring a detailed medication review.

Public bicycle share programs and head injuries

OBJECTIVES We evaluated the effect of North American public bicycle share programs (PBSPs), which typically do not offer helmets with rentals, on the occurrence of bicycle-related head injuries. METHODS We analyzed trauma center data for bicycle-related injuries from 5 cities with PBSPs and 5 comparison cities. We used logistic regression models to compare the odds that admission for a bicycle-related injury would involve a head injury 24 months before PBSP implementation and 12 months afterward. RESULTS In PBSP cities, the proportion of head injuries among bicycle-related injuries increased from 42.3% before PBSP implementation to 50.1% after (P < .01). This proportion in comparison cities remained similar before (38.2%) and after (35.9%) implementation (P = .23). Odds ratios for head injury were 1.30 (95% confidence interval = 1.13, 1.67) in PBSP cities and 0.94 (95% confidence interval = 0.79, 1.11) in control cities (adjusted for age and city) when we compared the period after implementation to the period before. CONCLUSIONS Results suggest that steps should be taken to make helmets available with PBSPs. Helmet availability should be incorporated into PBSP planning and funding, not considered an afterthought following implementation.

Acute hypervolemia lengthens red cell pulmonary transit time during exercise in endurance athletes

The purpose was to determine if acute plasma volume expansion (PVE) changed red-cell pulmonary transit time (PTT) during severe exercise. Twelve endurance athletes performed 6.5 min of severe cycling exercise on different days. Pentaspan [(500 ml, infusion condition, I] or placebo [(60 ml saline), non-infusion condition, N] were infused prior to exercise. Blood gas tensions, PTT, multigated acquisition (MUGA) derived cardiac output, and oxygen uptake were measured during exercise. PTT was measured during minute 3 of exercise by radionuclide cardiography. Arterial P(O(2)) (Pa(O(2))), and alveolar-arterial oxygen pressure difference (AaD(O(2))) at minute 3 of exercise did not differ between conditions. Mean PTT at minute 3 of exercise was 0.3 sec longer in the I condition (P=0.002). However, the change in PTT between conditions was not correlated to the change in either Pa(O(2)) or AaD(O(2)). We conclude that PVE slows (lengthens) PTT without affecting pulmonary gas exchange. Therefore, rapid PTT may not be related to hypoxemia during exercise.

Bicycling crash circumstances vary by route type: a cross-sectional analysis

BackgroundWidely varying crash circumstances have been reported for bicycling injuries, likely because of differing bicycling populations and environments. We used data from the Bicyclists’ Injuries and the Cycling Environment Study in Vancouver and Toronto, Canada, to describe the crash circumstances of people injured while cycling for utilitarian and leisure purposes. We examined the association of crash circumstances with route type.MethodsAdult cyclists injured and treated in a hospital emergency department described their crash circumstances. These were classified into major categories (collision vs. fall, motor vehicle involved vs. not) and subcategories. The distribution of circumstances was tallied for each of 14 route types defined in an earlier analysis. Ratios of observed vs. expected were tallied for each circumstance and route type combination.ResultsOf 690 crashes, 683 could be characterized for this analysis. Most (74%) were collisions. Collisions included those with motor vehicles (34%), streetcar (tram) or train tracks (14%), other surface features (10%), infrastructure (10%), and pedestrians, cyclists, or animals (6%). The remainder of the crashes were falls (26%), many as a result of collision avoidance manoeuvres. Motor vehicles were involved directly or indirectly with 48% of crashes. Crash circumstances were distributed differently by route type, for example, collisions with motor vehicles, including “doorings”, were overrepresented on major streets with parked cars. Collisions involving streetcar tracks were overrepresented on major streets. Collisions involving infrastructure (curbs, posts, bollards, street furniture) were overrepresented on multiuse paths and bike paths.ConclusionsThese data supplement our previous analyses of relative risks by route type by indicating the types of crashes that occur on each route type. This information can guide municipal engineers and planners towards improvements that would make cycling safer.

Acute Hypervolaemia Improves Arterial Oxygen Pressure in Athletes with Exercise‐Induced Hypoxaemia

The aim of this study was to determine the effect of acute plasma volume expansion on arterial blood‐gas status during 6.5 min strenuous cycling exercise comparing six athletes with and six athletes without exercise‐induced arterial hypoxaemia (EIAH). We hypothesized that plasma volume expansion could improve arterial oxygen pressure in a homogeneous sample of athletes ‐ those with EIAH. In this paper we have extended the analysis and results of our recently published surprising findings that lengthening cardiopulmonary transit time did not improve arterial blood‐gas status in a heterogeneous sample of endurance cyclists. One 500 ml bag of 10% Pentastarch (infusion condition) or 60 ml 0.9% saline (placebo) was infused prior to exercise in a randomized, double‐blind fashion on two different days. Power output, cardiac output, oxygen consumption and arterial blood gases were measured during strenuous exercise. Cardiac output and oxygen consumption were not affected by acute hypervolaemia. There were group × condition interaction effects for arterial oxygen pressure and alveolar‐arterial oxygen pressure difference, suggesting that those with hypoxaemia experienced improved arterial oxygen pressure (+4 mmHg) and lower alveolar‐arterial oxygen pressure difference (‐2 mmHg) with infusion. In conclusion, acute hypervolaemia improves blood‐gas status in athletes with EIAH. The impairment of gas exchange occurs within the first minute of exercise, and is not impaired further throughout the remaining duration of exercise. This suggests that arterial oxygen pressure is only minimally mediated by cardiac output.

Engaging Pediatric Intensive Care Unit (PICU) clinical staff to lead practice improvement: the PICU Participatory Action Research Project (PICU-PAR)

BackgroundDespite considerable efforts, engaging staff to lead quality improvement activities in practice settings is a persistent challenge. At British Columbia Children’s Hospital (BCCH), the pediatric intensive care unit (PICU) undertook a new phase of quality improvement actions based on the Community of Practice (CoP) model with Participatory Action Research (PAR). This approach aims to mobilize the PICU ‘community’ as a whole with a focus on practice; namely, to create a ‘community of practice’ to support reflection, learning, and innovation in everyday work.MethodologyAn iterative two-stage PAR process using mixed methods has been developed among the PICU CoP to describe the environment (stage 1) and implement specific interventions (stage 2). Stage 1 is ethnographic description of the unit’s care practice. Surveys, interviews, focus groups, and direct observations describe the clinical staff’s experiences and perspectives around bedside care and quality endeavors in the PICU. Contrasts and comparisons across participants, time and activities help understanding the PICU culture and experience. Stage 2 is a succession of PAR spirals, using results from phase 1 to set up specific interventions aimed at building the staff’s capability to conduct QI projects while acquiring appropriate technical skills and leadership capacity (primary outcome). Team communication, information, and interaction will be enhanced through a knowledge exchange (KE) and a wireless network of iPADs.RelevanceLack of leadership at the staff level in order to improve daily practice is a recognized challenge that faces many hospitals. We believe that the PAR approach within a highly motivated CoP is a sound method to create the social dynamic and cultural context within which clinical teams can grow, reflect, innovate and feel proud to better serve patients.

Personal and trip characteristics associated with safety equipment use by injured adult bicyclists: a cross-sectional study

BackgroundThe aim of this study was to estimate use of helmets, lights, and visible clothing among cyclists and to examine trip and personal characteristics associated with their use.MethodsUsing data from a study of transportation infrastructure and injuries to 690 adult cyclists in Toronto and Vancouver, Canada, we examined the proportion who used bike lights, conspicuous clothing on the torso, and helmets on their injury trip. Multiple logistic regression was used to examine associations between personal and trip characteristics and each type of safety equipment.ResultsBike lights were the least frequently used (20% of all trips) although they were used on 77% of trips at night. Conspicuous clothing (white, yellow, orange, red) was worn on 33% of trips. Helmets were used on 69% of trips, 76% in Vancouver where adult helmet use is required by law and 59% in Toronto where it is not. Factors positively associated with bike light use included night, dawn and dusk trips, poor weather conditions, weekday trips, male sex, and helmet use. Factors positively associated with conspicuous clothing use included good weather conditions, older age, and more frequent cycling. Factors positively associated with helmet use included bike light use, longer trip distances, hybrid bike type, not using alcohol in the 6 hours prior to the trip, female sex, older age, higher income, and higher education.ConclusionsIn two of Canada’s largest cities, helmets were the most widely used safety equipment. Measures to increase use of visibility aids on both daytime and night-time cycling trips may help prevent crashes.

Injuries to Adult Cyclists in Toronto and Vancouver: Describing the Circumstances as a First Step towards Injury Prevention

Introduction Bicycling is a sustainable mode of transportation with health benefits, but the risk of injury deters many people. We studied injured cyclists from two urban areas to characterise injury severity and mechanism. Methods Multicentre case-crossover study. Adult cyclists who visit emergency departments in three Toronto and two Vancouver hospitals are being recruited. Canadian Trauma and Acuity Score (CTAS) data are retrieved from hospital records. Descriptive data and comparisons of the first 300 injury events, 150 in each city, are presented. Results The median CTAS score was 3 (IQR: 3–4; n=228). Of the 300 cyclists studied, 27 (9.0%; 95% CI 5.8 to 12.2%) were admitted to hospital. Injury mechanism was classified as a collision in 213 cases (70.9%; 65.9–76.1%) or fall in 87 (29.1%; 23.9–34.1%). Collisions involved motor vehicles in 102 cases (34.1% of all events; 28.6–39.4%), streetcar/train tracks in 46 (15.4%; 10.9–19.0%), curbs/fences/barriers in 38 (12.7%; 8.3–15.7%), pedestrians/other cyclists in 14 (4.7%; 2.3–7.1%), potholes in 9 (3%; 1.1–4.9%) and animals in 3 (1%; 0–2.1%). Manoeuvres to avoid collisions resulted in 28 falls (9.3% of all events). The proportions of injuries involving motor vehicles were almost identical in the two cities, but the odds of an event involving dooring were higher in Toronto than Vancouver (OR 2.83, 95% CI 1.13 to 7.02). Toronto events were more likely to involve streetcar tracks (OR 19.6, 5.9 to 65.0) and less likely to involve pedestrians or cyclists (OR 0.33, 0.13 to 0.83) than those in Vancouver. Conclusions Injury circumstances and differences between cities suggest that transportation infrastructure and interactions with motorised and non-motorised traffic are important factors in cycling injuries.