Military Service, Deployments, And Exposures in Relation to Amyotrophic Lateral Sclerosis Etiology and Survival Public Deposited

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  • March 19, 2019
Creator
  • Beard, John
    • Affiliation: Gillings School of Global Public Health, Department of Epidemiology
Abstract
  • Amyotrophic lateral sclerosis (ALS) is a debilitating neurodegenerative disease. Its importance as a public health problem lies in its generally rapid progression and often fatal outcome. ALS rates have been reported to be higher among U.S. military veterans, of which there are currently more than 21 million, but the causal agents related to military service have not been identified. Previous studies were limited by reliance on mortality as a surrogate for incidence, a dearth of survival analyses, lack of clinical data, low statistical power, and limited exposure assessment. We used information from Genes and Environmental Exposures in Veterans with Amyotrophic Lateral Sclerosis, a study of 630 veteran ALS cases and 975 frequency-matched veteran controls to 1) evaluate associations between aspects of military service, deployments, and 40 exposures and ALS etiology; and 2) evaluate associations between aspects of military service, deployments, and 40 exposures and ALS survival. We used inverse probability weighting to evaluate and adjust for potential selection bias resulting from studying cases who likely represent long survivors and controls who may be different from U.S. military veterans at large. We observed several inverse associations between ALS and military service and deployment variables, but these may be because the control group was comprised of many career military veterans. We found lower odds of ALS among officers and higher odds among veterans whose longest deployment was World War II or the Korean War. There was no difference in the odds of ALS among veterans of the Air Force, Army, Marines, and Navy. ALS was more common among veterans who had direct contact with eight exposures incurred during deployment to four major wars. We did not find strong evidence that military-related factors were associated with shorter ALS survival. While we cannot exclude the effects of uncontrolled selection bias or confounding by non-military exposures on our results, they provide clues to potential causal factors underlying the apparent increase of ALS among military veterans and, therefore, require replication and further study. Furthermore, the null association we found between military-related factors and ALS survival may be comforting to ALS cases who are military veterans.
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  • In Copyright
Advisor
  • Gammon, Marilie D.
  • Kamel, Freya
  • Baird, Coleen
  • Richardson, David
  • Engel, Lawrence
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2015
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  • Chapel Hill, NC
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