title: Motorcycle helmet effectiveness in reducing head, face and brain injuries by state and helmet law.
abstract: BACKGROUND
  Despite evidence that motorcycle helmets reduce morbidity and mortality, helmet laws and rates of helmet use vary by state in the U.S.
  
  
  METHODS
  We pooled data from eleven states: five with universal laws requiring all motorcyclists to wear a helmet, and six with partial laws requiring only a subset of motorcyclists to wear a helmet. Data were combined in the Crash Outcome Data Evaluation System's General Use Model and included motorcycle crash records probabilistically linked to emergency department and inpatient discharges for years 2005-2008. Medical outcomes were compared between partial and universal helmet law settings. We estimated adjusted relative risks (RR) and 95 % confidence intervals (CIs) for head, facial, traumatic brain, and moderate to severe head/facial injuries associated with helmet use within each helmet law setting using generalized log-binomial regression.
  
  
  RESULTS
  Reported helmet use was higher in universal law states (88 % vs. 42 %). Median charges, adjusted for inflation and differences in state-incomes, were higher in partial law states (emergency department $1987 vs. $1443; inpatient $31,506 vs. $25,949). Injuries to the head and face, including traumatic brain injuries, were more common in partial law states. Effectiveness estimates of helmet use were higher in partial law states (adjusted-RR (CI) of head injury: 2.1 (1.9-2.2) partial law single vehicle; 1.4 (1.2, 1.6) universal law single vehicle; 1.8 (1.6-2.0) partial law multi-vehicle; 1.2 (1.1-1.4) universal law multi-vehicle).
  
  
  CONCLUSIONS
  Medical charges and rates of head, facial, and brain injuries among motorcyclists were lower in universal law states. Helmets were effective in reducing injury in both helmet law settings; lower effectiveness estimates were observed in universal law states.
authors.affiliation: Department of Pediatrics, Division of Critical Care, University of Utah School of Medicine, 295 Chipeta Way, Salt Lake City, UT, 84108, USA. cody.olsen@hsc.utah.edu.
authors.forename: Cody S
authors.initials: CS
authors.lastname: Olsen
authors.affiliation: Department of Pediatrics, Division of Critical Care, University of Utah School of Medicine, 295 Chipeta Way, Salt Lake City, UT, 84108, USA.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Thomas
authors.affiliation: Department of Biostatistics and Kentucky Injury Prevention and Research Center, University of Kentucky College of Public Health, 333 Waller Ave., Suite 206, Lexington, KY, 40504, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Singleton
authors.affiliation: Minnesota Department of Health, 85 East Seventh Place, Suite 220, St. Paul, MN, 55164, USA.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Gaichas
authors.affiliation: Health and Demographics Section, South Carolina Revenue and Fiscal Affairs Office, Rembert C. Dennis Building, 1000 Assembly Street, Suite 240, Columbia, SC, 29201, USA.
authors.forename: Tracy J
authors.initials: TJ
authors.lastname: Smith
authors.affiliation: Center for Injury Research and Policy, The Research Institute at Nationwide Children's Hospital, The Ohio State University College of Medicine, 700 Children's Drive, Columbus, OH, 43205, USA.
authors.forename: Gary A
authors.initials: GA
authors.lastname: Smith
authors.affiliation: Connecticut Department of Public Health, Community, Family and Health Equity Section, Public Health Initiatives Branch, 410 Capitol Avenue, MS# 11-HLS, Hartford, CT, 06134, USA.
authors.forename: Justin
authors.initials: J
authors.lastname: Peng
authors.affiliation: New York State Department of Health, Bureau of Occupational Health and Injury Prevention, Empire State Plaza, Corning Tower, Room 1325, Albany, NY, 12237, USA.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Bauer
authors.affiliation: Division of Public Health, Nebraska Department of Health and Human Services, Epidemiology and Health Informatics Unit, PO Box 95026, Lincoln, NE, 68509, USA.
authors.forename: Ming
authors.initials: M
authors.lastname: Qu
authors.affiliation: Georgia Department of Public Health, Injury Prevention Program, 2 Peachtree Street NW, 10.414, Atlanta, GA, 30303, USA.
authors.forename: Denise
authors.initials: D
authors.lastname: Yeager
authors.affiliation: National Study Center for Trauma and EMS, University of Maryland Baltimore, 110 South Paca Street, Baltimore, MD, 21201, USA.
authors.forename: Timothy
authors.initials: T
authors.lastname: Kerns
authors.affiliation: National Study Center for Trauma and EMS, University of Maryland Baltimore, 110 South Paca Street, Baltimore, MD, 21201, USA.
authors.forename: Cynthia
authors.initials: C
authors.lastname: Burch
authors.affiliation: Department of Pediatrics, Division of Critical Care, University of Utah School of Medicine, 295 Chipeta Way, Salt Lake City, UT, 84108, USA.
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Cook
keywords: Charges; Hospital charges; Injury; Legislation; Log-binomial regression; Motor vehicle crash; Motorcycle helmet; Motorcycle helmet law; Probabilistic linkage; Traumatic brain injury