The epidemiology of mountain bike park injuries at the Whistler Bike Park, British Columbia (BC), Canada.

OBJECTIVE: To describe the epidemiology of injuries sustained during the 2009 season at Whistler Mountain Bike Park. METHODS: A retrospective chart review was performed of injured bike park cyclists presenting to the Whistler Health Clinic between May 16 and October 12, 2009. RESULTS: Of 898 cases, 86% were male (median age, 26 years), 68.7% were Canadian, 19.4% required transport by the Whistler Bike Patrol, and 8.4% arrived by emergency medical services. Identification of 1759 specific injury diagnoses was made, including 420 fractures in 382 patients (42.5%). Upper extremity fractures predominated (75.4%), 11.2% had a traumatic brain injury, and 8.5% were transferred to a higher level of care: 7 by helicopter, 62 by ground, and 5 by personal vehicle. Two patients refused transfer. CONCLUSIONS: Mountain bikers incurred many injuries with significant morbidity while riding in the Whistler Mountain Bike Park in 2009. Although exposure information is unavailable, these findings demonstrate serious risks associated with this sport and highlight the need for continued research into appropriate safety equipment and risk avoidance measures.

Safe cycling: how do risk perceptions compare with observed risk?

OBJECTIVE: Safety concerns deter cycling. The Bicyclists' Injuries and the Cycling Environment (BICE) study quantified the injury risk associated with 14 route types, from off-road paths to major streets. However, when it comes to injury risk, there may be discordance between empirical evidence and perceptions. If so, even if protective infrastructure is built people may not feel safe enough to cycle. This paper reports on the relationship between perceived and observed injury risk. METHODS: The BICE study is a case-crossover study that recruited 690 injured adult cyclists who visited emergency departments in Toronto and Vancouver. Observed risk was calculated by comparing route types at the injury sites with those at randomly selected control sites along the same route. The perceived risk was the mean response of study participants to the question "How safe do you think this site was for cyclists on that trip?", with responses scored from +1 (very safe) to -1 (very dangerous). Perceived risk scores were only calculated for non-injury control sites, to reduce bias by the injury event. RESULTS: The route type with the greatest perceived risk was major streets with shared lanes and no parked cars (mean score = -0.21, 95% confidence interval [CI]: -0.54-0.11), followed by major streets without bicycle infrastructure (-0.07, CI -0.14-0.00). The safest perceived routes were paved multi-use paths (0.66, CI 0.43-0.89), residential streets (0.44, CI 0.37-0.51), bike paths (0.42, CI 0.25-0.60) and residential streets marked as bike routes with traffic calming (0.41, CI 0.32-0.51). Most route types that were perceived as higher risk were found to be so in our injury study; similarly, most route types perceived as safer were also found to be so. Discrepancies were observed for cycle tracks (perceived as less safe than observed) and for multiuse paths (perceived as safer than observed). CONCLUSIONS: Route choices and decisions to cycle are affected by perceptions of safety, and we found that perceptions usually corresponded with observed safety. However, perceptions about certain separated route types did not align well. Education programs and social media may be ways to ensure that public perceptions of route safety reflect the evidence.

Proportion of injured drivers presenting to a tertiary care emergency department who engage in future impaired driving activities.

OBJECTIVE: We determined the rate of, and predictive factors for, subsequent impaired driving activity (IDA) by injured drivers treated in a Canadian tertiary care emergency department (ED) following a motor vehicle crash (MVC). METHODS: We retrospectively identified all drivers injured in a MVC who presented to our tertiary care, urban ED (1999-2003) and had their blood alcohol content (BAC) measured. Injured drivers were categorized by BAC: group 1, BAC = 0; group 2, 0 < BAC < or = 17.3 mM (80 mg/dL, legal limit); and group 3, BAC > 17.3 mM. IDA was defined as any of the following: a conviction for impaired driving; a 24-h or 90-day license suspension for impaired driving; involvement in alcohol-related MVC. Time to IDA following the index event between groups was compared with Kaplan-Meier survival analyses. Effects of covariates on time to IDA were analyzed using Cox proportional hazards models. RESULTS: During the study period, 1489 injured drivers met study criteria: 1171 in group 1, 51 in group 2, and 267 in group 3. During an average follow-up of 52.4 months, 82 (30.7%) group 3 drivers engaged in subsequent IDA, compared with 80 (6.8%) group 1 drivers (p < 0.0001). Youth, male gender, history of previous IDA, and the number of previous IDA events were all associated with a significant increase in subsequent IDA. A history of IDA was the strongest predictor of future IDA in group 1 (440% increase risk) and in group 3 (80% increased risk). The magnitude of BAC elevation above the legal limit was not predictive of future IDA. CONCLUSIONS: A high portion of injured impaired drivers who present to hospital engage in repeat IDA following discharge. Besides impairment at time of hospital visit, the best predictor of future IDA is a history of IDA prior to the index event.

An evaluation of the osmole gap as a screening test for toxic alcohol poisoning.

BACKGROUND: The osmole gap is used routinely as a screening test for the presence of exogenous osmotically active substances, such as the toxic alcohols ethylene glycol and methanol, particularly when the ability to measure serum concentrations of the substances is not available. The objectives of this study were: 1) to measure the diagnostic accuracy of the osmole gap for screening for ethylene glycol and methanol exposure, and 2) to identify whether a recently proposed modification of the ethanol coefficient affects the diagnostic accuracy. METHODS: Electronic laboratory records from two tertiary-care hospitals were searched to identify all patients for whom a serum ethylene glycol and methanol measurement was ordered between January 1, 1996 and March 31, 2002. Cases were eligible for analysis if serum sodium, blood urea nitrogen, glucose, ethanol, ethylene glycol, methanol, and osmolality were measured simultaneously. Serum molarity was calculated using the Smithline and Gardner equation and ethanol coefficients of 1 and 1.25 mOsm/mM. The diagnostic accuracy of the osmole gap was evaluated for identifying patients with toxic alcohol levels above the recommended threshold for antidotal therapy and hemodialysis using receiver-operator characteristic curves, likelihood ratios, and positive and negative predictive values. RESULTS: One hundred and thirty-one patients were included in the analysis, 20 of whom had ethylene glycol or methanol serum concentrations above the threshold for antidotal therapy. The use of an ethanol coefficient of 1.25 mOsm/mM yielded higher specificities and positive predictive values, without affecting sensitivity and negative predictive values. Employing an osmole gap threshold of 10 for the identification of patients requiring antidotal therapy resulted in a sensitivity of 0.9 and 0.85, and a specificity of 0.22 and 0. 5, with equations 1 and 2 respectively. The sensitivity increased to 1 for both equations for the identification of patients requiring dialysis. CONCLUSION: In this sample, an osmole gap threshold of 10 has a sensitivity and negative predictive value of 1 for identifying patients for whom hemodialysis is recommended, independent of the ethanol coefficient applied. In patients potentially requiring antidotal therapy, applying an ethanol coefficient of 1.25 resulted in a higher specificity and positive predictive value without compromising the sensitivity.