title: Bicycle helmets are highly protective against traumatic brain injury within a dense urban setting.
abstract: BACKGROUND
  New York City (NYC) has made significant roadway infrastructure improvements, initiated a bicycle share program, and enacted Vision Zero, an action plan to reduce traffic deaths and serious injuries. The objective of this study was to examine whether bicycle helmets offer a protective advantage against traumatic brain injury (TBI) within a contemporary dense urban setting with a commitment to road safety.
  
  
  METHODS
  A prospective observational study of injured bicyclists presenting to a Level I trauma centre was performed. All bicyclists arriving within 24 h of injury were included. Data were collected between February, 2012 and August, 2014 and included demographics, imaging studies (e.g. computed tomography (CT)), injury patterns, and outcomes including Glasgow Coma Scale (GCS) and Injury Severity Score.
  
  
  RESULTS
  Of 699 patients, 273 (39.1%) were wearing helmets at the time of injury. Helmeted bicyclists were more likely to have a GCS of 15 (96.3% [95% Confidence Interval (CI), 93.3-98.2] vs. 87.6 [95% CI, 84.1-90.6]) at presentation. Helmeted bicyclists underwent fewer head CTs (40.3% [95% CI, 34.4-46.4] vs. 52.8% [95% CI, 48.0-57.6]) and were less likely to sustain intracranial injury (6.3% [95% CI, 2.6-12.5] vs. 19.7% [14.7-25.6]), including skull fracture (0.9% [95% CI, 0.0-4.9] vs. 15.3% [95% CI, 10.8-20.7]) and subdural hematoma (0.0% [95% CI, 0.0-3.2] vs. 8.1% [95% CI, 4.9-12.5]). Helmeted bicyclists were significantly less likely to sustain significant TBI, i.e. Head AIS ≥3 (2.6% [95% CI: 0.7-4.5] vs.10.6% [7.6-12.5]). Four patients underwent craniotomy while three died; all were un-helmeted. A multivariable logistic regression model showed that helmeted bicyclists were 72% less likely to sustain TBI compared with un-helmeted bicyclists (Adjusted Odds Ratio 0.28, 95% CI 0.12-0.61).
  
  
  CONCLUSIONS
  Despite substantial road safety measures in NYC, the protective impact of simple bicycle helmets in the event of a crash remains significant. A re-assessment of helmet laws for urban bicyclists is advisable to most effectively translate Vision Zero from a political action plan to public safety reality.
authors.affiliation: New York University School of Medicine, Bellevue Hospital Center, Department of Surgery, New York, New York, USA.
authors.forename: Monica
authors.initials: M
authors.lastname: Sethi
authors.affiliation: New York University School of Medicine, Bellevue Hospital Center, Department of Surgery, New York, New York, USA.
authors.forename: Jessica
authors.initials: J
authors.lastname: Heidenberg
authors.affiliation: New York University School of Medicine, Bellevue Hospital Center, Department of Emergency Medicine, New York, New York, USA.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Wall
authors.affiliation: New York University School of Medicine, Bellevue Hospital Center, Department of Surgery, New York, New York, USA.
authors.forename: Patricia
authors.initials: P
authors.lastname: Ayoung-Chee
authors.affiliation: New York University School of Medicine, Bellevue Hospital Center, Department of Surgery, New York, New York, USA.
authors.forename: Dekeya
authors.initials: D
authors.lastname: Slaughter
authors.affiliation: New York University School of Medicine, Bellevue Hospital Center, Department of Emergency Medicine and Pediatrics, New York, New York, USA.
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Levine
authors.affiliation: New York University School of Medicine, Bellevue Hospital Center, Department of Surgery, New York, New York, USA.
authors.forename: Sally
authors.initials: S
authors.lastname: Jacko
authors.affiliation: New York University School of Medicine, Bellevue Hospital Center, Department of Surgery, New York, New York, USA.
authors.forename: Chad
authors.initials: C
authors.lastname: Wilson
authors.affiliation: New York University School of Medicine, Bellevue Hospital Center, Department of Surgery, New York, New York, USA.
authors.forename: Gary
authors.initials: G
authors.lastname: Marshall
authors.affiliation: New York University School of Medicine, Bellevue Hospital Center, Department of Surgery, New York, New York, USA.
authors.forename: H Leon
authors.initials: HL
authors.lastname: Pachter
authors.affiliation: New York University School of Medicine, Bellevue Hospital Center, Department of Surgery, New York, New York, USA. Electronic address: Spiros.frangos@nyumc.org.
authors.forename: Spiros G
authors.initials: SG
authors.lastname: Frangos
mesh_terms: D000063:Accidents, Traffic / Q000706:statistics & numerical data*; D000293:Adolescent; D000328:Adult; D001642:Bicycling / Q000293:injuries / Q000331:legislation & jurisprudence; D000070642:Brain Injuries, Traumatic / Q000453:epidemiology / Q000517:prevention & control*; D002648:Child; D006259:Craniocerebral Trauma / Q000453:epidemiology / Q000517:prevention & control*; D005260:Female; D015600:Glasgow Coma Scale; D006260:Head Protective Devices / Q000706:statistics & numerical data*; D006801:Humans; D015601:Injury Severity Score; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009518:New York / Q000453:epidemiology; D011446:Prospective Studies; D011634:Public Health; D014193:Trauma Centers; D014504:Urban Health
keywords: Bicycle; Bike share; Head injury; Helmet; Trauma; Traumatic brain injury; Urban