title: Amyotrophic Lateral Sclerosis and the Military: A Population-based Study in the Danish Registries.
abstract: BACKGROUND
  Prior studies have suggested that military service may be associated with the development of amyotrophic lateral sclerosis (ALS). We conducted a population-based case-control study in Denmark to assess whether occupation in the Danish military is associated with an increased risk of developing ALS.
  
  
  METHODS
  There were 3,650 incident cases of ALS recorded in the Danish National Patient Registry between 1982 and 2009. Each case was matched to 100 age- and sex-matched population controls alive and free of ALS on the date of the case diagnosis. Comprehensive occupational history was obtained from the Danish Pension Fund database, which began in 1964.
  
  
  RESULTS
  2.4% (n = 8,922) of controls had a history of employment in the military before the index date. Military employees overall had an elevated rate of ALS (odds ratio [OR] = 1.3; 95% confidence interval [CI]: 1.1, 1.6). A 10-year increase in years employed by the military was associated with an OR of 1.2 (95% CI: 1.0, 1.4), and all quartiles of time employed were elevated. There was little suggestion of a pattern across calendar year of first employment, but there was some evidence that increasing age at first employment was associated with increased ALS rates. Rates were highest in the decade immediately following the end of employment (OR = 1.6; 95% CI: 1.2, 2.2).
  
  
  CONCLUSIONS
  In this large population-based case-control study, employment by the military is associated with increased rates of ALS. These findings are consistent with earlier findings that military service or employment may entail exposure to risk factors for ALS.
authors.affiliation: From the aDepartment of Epidemiology, bDepartment of Environmental Health, Harvard School of Public Health, Boston, MA; cCenter for Cancer Research, The Danish Cancer Society, Copenhagen, Denmark; and dRehabilitation Centre for Neuromuscular Diseases, Copenhagen, Denmark.
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Seals
authors.forename: Marianthi-Anna
authors.initials: MA
authors.lastname: Kioumourtzoglou
authors.forename: Johnni
authors.initials: J
authors.lastname: Hansen
authors.forename: Ole
authors.initials: O
authors.lastname: Gredal
authors.forename: Marc G
authors.initials: MG
authors.lastname: Weisskopf
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000690:Amyotrophic Lateral Sclerosis / Q000453:epidemiology*; D016022:Case-Control Studies; D003718:Denmark / Q000453:epidemiology; D004651:Employment; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008889:Military Personnel / Q000706:statistics & numerical data*; D016273:Occupational Exposure / Q000706:statistics & numerical data*; D016017:Odds Ratio; D012042:Registries; D012307:Risk Factors