title: Military service, deployments, and exposures in relation to amyotrophic lateral sclerosis etiology.
abstract: BACKGROUND
  Factors underlying a possible excess of amyotrophic lateral sclerosis (ALS) among military veterans remain unidentified. Limitations of previous studies on this topic include reliance on ALS mortality as a surrogate for ALS incidence, low statistical power, and sparse information on military-related factors.
  
  
  OBJECTIVE
  We evaluated associations between military-related factors and ALS using data from a case-control study of U.S. military veterans.
  
  
  METHODS
  From 2005 to 2010, we identified medical record-confirmed ALS cases via the National Registry of Veterans with ALS and controls via the Veterans Benefits Administration's Beneficiary Identification and Records Locator System database. In total, we enrolled 621 cases and 958 frequency-matched controls in the Genes and Environmental Exposures in Veterans with Amyotrophic Lateral Sclerosis study. We collected information on military service and deployments and 39 related exposures. We used unconditional logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs). We used inverse probability weighting to adjust for potential bias from confounding, missing covariate data, and selection arising from a case group that disproportionately included long-term survivors and a control group that may or may not differ from U.S. military veterans at large.
  
  
  RESULTS
  The odds of ALS did not differ for veterans of the Air Force, Army, Marines, and Navy. We found higher odds of ALS for veterans whose longest deployment was World War II or the Korean War and a positive trend with total years of all deployments (OR=1.27; 95% CI: 1.06, 1.52). ALS was positively associated with exposure to herbicides for military purposes, nasopharyngeal radium, personal pesticides, exhaust from heaters or generators, high-intensity radar waves, contaminated food, explosions within one mile, herbicides in the field, mixing and application of burning agents, burning agents in the field, and Agent Orange in the field, with ORs between 1.50 and 7.75.
  
  
  CONCLUSIONS
  Although our results need confirmation, they are potentially important given the large number of U.S. military veterans, and they provide clues to potential factors underlying the apparent increase of ALS in veteran populations.
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA; Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA.
authors.forename: John D
authors.initials: JD
authors.lastname: Beard
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Lawrence S
authors.initials: LS
authors.lastname: Engel
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: David B
authors.initials: DB
authors.lastname: Richardson
authors.affiliation: Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Marilie D
authors.initials: MD
authors.lastname: Gammon
authors.affiliation: Environmental Medicine Program, US Army Public Health Command, Aberdeen Proving Ground, MD, USA.
authors.forename: Coleen
authors.initials: C
authors.lastname: Baird
authors.affiliation: Biostatistics and Computational Biology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Umbach
authors.affiliation: Durham VA Medical Center, Durham, NC, USA; Department of Medicine and Thurston Arthritis Research Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Kelli D
authors.initials: KD
authors.lastname: Allen
authors.affiliation: Durham VA Medical Center, Durham, NC, USA; Department of Medicine, Duke University Medical Center, Durham, NC, USA.
authors.forename: Catherine L
authors.initials: CL
authors.lastname: Stanwyck
authors.affiliation: Westat, Inc., Durham, NC, USA.
authors.forename: Jean
authors.initials: J
authors.lastname: Keller
authors.affiliation: Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA.
authors.forename: Dale P
authors.initials: DP
authors.lastname: Sandler
authors.affiliation: Department of Medicine, Duke University Medical Center, Durham, NC, USA.
authors.forename: Silke
authors.initials: S
authors.lastname: Schmidt
authors.affiliation: Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA. Electronic address: kamel@niehs.nih.gov.
authors.forename: Freya
authors.initials: F
authors.lastname: Kamel
mesh_terms: D015085:2,4,5-Trichlorophenoxyacetic Acid; D015084:2,4-Dichlorophenoxyacetic Acid; D000328:Adult; D000368:Aged; D000075182:Agent Orange; D000690:Amyotrophic Lateral Sclerosis / Q000453:epidemiology*; D016022:Case-Control Studies; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D008889:Military Personnel / Q000706:statistics & numerical data*; D016017:Odds Ratio; D010575:Pesticides; D000072317:Polychlorinated Dibenzodioxins; D011883:Radium; D014481:United States / Q000453:epidemiology; D014728:Veterans / Q000706:statistics & numerical data*
chemical_list: D010575:Pesticides; D000072317:Polychlorinated Dibenzodioxins; D015084:2,4-Dichlorophenoxyacetic Acid; D000075182:Agent Orange; D015085:2,4,5-Trichlorophenoxyacetic Acid; D011883:Radium
keywords: Amyotrophic lateral sclerosis; Case-control; Deployment; Etiology; Military