Limited but Suggestive Evidence of an Association

Evidence from available studies is suggestive of an association between deployment to a war zone and a specific health outcome, but the body of evidence is limited by the inability to rule out chance and bias, including confounding, with confidence. For example, at least one high-quality study reports a positive association that is sufficiently free of bias, including adequate control for confounding, and other corroborating studies provide support for the association (corroborating studies might not be sufficiently free of bias, including confounding). Alternatively, several studies of lower quality show consistent positive associations, and the results are probably not due to bias, including confounding.

  • Drug abuse.

  • Chronic fatigue syndrome.

  • Gastrointestinal symptoms consistent with functional gastrointestinal disorders, such as irritable bowel syndrome or functional dyspepsia.

  • Skin disorders.

  • Fibromyalgia and chronic widespread pain.

  • Increased symptom reporting, unexplained illness, and chronic pain.

  • Incarceration.

Inadequate/Insufficient Evidence to Determine Whether an Association Exists

Evidence from available studies is of insufficient quantity, quality, or consistency to permit a conclusion regarding the existence of an association between deployment to a war zone and a specific health outcome in humans.

  • Cancer.

  • Diabetes mellitus.

  • Thyroid disease.

  • Neurocognitive and neurobehavioral effects.

  • Sleep disorders or objective measures of sleep disturbance.

  • Hypertension.

  • Coronary heart disease.

  • Chronic respiratory effects.

  • Structural gastrointestinal diseases.

  • Reproductive effects.

  • Homelessness.

  • Adverse employment outcomes.

Limited/Suggestive Evidence of No Association

Evidence from well-conducted studies is consistent in not showing a positive association between exposure to a specific agent and a specific health effect after exposure of any magnitude. A conclusion of no association is inevitably limited to the conditions, magnitudes of exposure, and length of observation in the available studies. The possibility of a very small increase in risk after exposure studied cannot be excluded.

  • No effects.

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