Bicycle helmets are highly protective against traumatic brain injury within a dense urban setting
Introduction
Bicycling is an increasingly popular mode of transportation and recreation for New Yorkers. Commuter ridership in New York City (NYC) jumped 262% from 2000 to 2010, and this accelerated growth is projected to continue in ensuing years [1]. In May 2013, NYC launched its bicycle share program, which significantly expanded bicycle accessibility and further increased ridership [2].
Bicycling, however, is not without risk. National statistics report that 500,000 people sustain bicycle-related injuries, including approximately 800 deaths, every year in the U.S. [3]. In 2013, there were nearly 4,300 reported bicycle-related injuries in NYC [4]. Head injury is the leading cause of death and permanent disability in bicycle-related crashes, with traumatic brain injury (TBI) accounting for more than one-third of bicycle-related emergency room visits, two-thirds of hospital admissions, and three-fourths of deaths [5].
With the goal of promoting safe bicycling, the NYC Department of Transportation (DOT) has made substantial improvements in roadway infrastructure, including the addition of over 300 miles of bicycle lanes and vehicle-protected bicycle paths in just the last six years [6]. In January 2014, NYC launched ‘Vision Zero,’ a multidisciplinary traffic safety action plan with a strong government commitment aimed at eliminating traffic-related deaths and serious injuries [7], [8], [9]. Vision Zero was first introduced by the Swedish government in the late 1990's as a sustained road safety campaign and has since been adopted in many cities and states internationally.
Currently, NYC mandates bicycle helmets for delivery cyclists and children under the age of 14 [10]; helmet use remains optional for the broader bicyclist population. Evidence that helmets protect against TBI derives from pivotal epidemiologic and case-controlled studies conducted in the 1980s and 90s [11,] [12]. The scientific literature has also focused on high-speed sporting injury [13], biomechanical laboratory data [14], and paediatric head injury before and after the passage of helmet legislation [15], [16], [17]. A major limitation of earlier studies is that they do not delineate collision-related brain injuries in a detailed systematic manner based on radiologic findings. Additionally, the effect of helmets in more contemporary urban traffic conditions within a presumed safer infrastructure requires examination. Despite a correlation between helmet non-use and bicycle share programs [2] [18], there is little data showing how this relationship might impact bicycle-related injuries.
The objective of this study was threefold: 1 – to examine whether bicycle helmet use offers a protective advantage in NYC's hub, a uniquely dense urban centre with significant motor-vehicular traffic congestion, an evolving cycling infrastructure, and a newly-implemented bicycle share program, 2 – to define patient demographics and risk-factors associated with helmet use and non-use, and 3 – to delineate the specific types of brain injuries which may be impacted by helmet use. Our primary hypothesis was that un-helmeted bicyclists sustain more severe TBI in the event of a crash regardless of bicycling infrastructure advances intended to make cycling safer.
Section snippets
Materials and methods
This was a prospective cohort study of injured bicyclists presenting to Bellevue Hospital Center (BHC)–a Level I regional trauma centre. Data collection was performed at BHC between February 1, 2012 and August 31, 2014, excluding a 14-week interruption (between October 29, 2012 and February 7, 2013) when clinical services were disrupted as a result of Superstorm Sandy. BHC's catchment area includes the lower half of Manhattan and western Brooklyn. The BHC emergency department (ED) evaluates
Results
Seven hundred and six bicyclists were enrolled. Of these, seven had unknown or indeterminate helmet status and were excluded from analysis. Of the remaining 699 patients, 273 (39.1%) were wearing helmets at the time of injury. Demographic data of the study population is listed in Table 1. The mean age was 34.6 years (range 3–82 years) and 79.9% were men. 36.9% of men wore helmets versus 47.8% of women. The helmeted group had a greater proportion of Caucasian (52.9% [95%CI, 46.6–58.8] vs. 42.9%
Discussion
Prior epidemiologic studies have demonstrated the protective effect of helmets among injured bicyclists [5] [11] [12] [19]; these studies however do not reflect the enhanced roadway infrastructure and major engineering changes (including hundreds of miles of new bike lanes) which define modern urban bicycling within traffic-congested settings including NYC. Our results show that the protective effect of helmets in the event of injury is maintained despite the many structural improvements
Appointments
Monica Sethi, MD- Resident Surgeon
Jessica Heidenberg, BA- Medical Student
Stephen Wall, MD, MSc, MAEd- Associate Professor
Patricia Ayoung-Chee, MD, MPH- Assistant Professor
Dekeya Slaughter, BSc- Research Coordinator
Deborah A. Levine, MD- Associate Professor
Sally Jacko, RN, MPH- Trauma Program Manager
Chad Wilson, MD- Assistant Professor
Gary Marshall, MD- Assistant Professor
H. Leon Pachter, MD- Chairman of the Department of Surgery
Spiros G. Frangos, MD, MPH- Associate Professor
Conflict of interests
The authors have no conflicts of interest regarding this research and have no financial disclosures to report.
Acknowledgements
The authors wish to acknowledge injury epidemiologist Dr. Charles DiMaggio, PhD, who advised us on the appropriateness of our statistical methods and analyses. This study was funded by a Highway Safety Grant from the State of New York Governor's Traffic Safety Committee (October, 2011- September, 2014; year 1: $48,000, year 2: $47,705, year 3: $48,206). The sponsor did not participate in the design and conduct of the study, in the collection, management, analysis, and interpretation of the
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