nearly 2-fold increase in risk. A secondary study that used general population estimates as the comparison group found a slightly higher relative risk.
Peripheral neuropathy has been studied in Gulf War veterans. One large, well-designed study conducted by VA which used a thorough and objective evaluation and a stringent case definition, did not find evidence of excess peripheral neuropathy. Several other secondary studies supported no excess risk. Thus, there does not appear to be an increase in the prevalence of peripheral neuropathy in deployed vs nondeployed veterans, as defined by history, physical examination, and electrophysiologic studies.
With regard to cardiovascular disease, primary studies found no significant differences between deployed and nondeployed veterans in rates of hypertension. One study did report a small but significant increase in hospitalizations due to cardiovascular disease among a subset of deployed veterans who were possibly exposed to the Khamisiyah plume compared with Gulf War-deployed veterans who were not in the suspected exposure area. The increased hospitalizations were due entirely to an increase in cardiac dysrhythmias. In secondary studies, deployed veterans were generally more likely to report hypertension and palpitations, but those reports were not confirmed with medical evaluations. Thus, it does not appear that there is a difference in the prevalence of cardiovascular disease or diabetes between deployed Gulf War veterans and nondeployed.
Many veterans are understandably concerned about the possibility of birth defects in their offspring. Two primary studies yielded some evidence of increased risk of birth defects among offspring of Gulf War veterans. However, the specific defects with increased prevalence (cardiac, kidney, urinary tract, and musculoskeletal abnormalities) in the two studies were not consistent. Overall, the studies are difficult to interpret because of the relative rarity of specific birth defects, use of small sample, timing of exposure (before or after conception), and whether the mother or the father was exposed. There was no consistent pattern of one of more birth defects with a higher prevalence in the offspring of male or female Gulf War veterans. Only one set of defects (that is, urinary tract abnormalities) has been found to be increased in more than one well-designed study. With regard to other adverse reproductive outcomes, the results of one primary study, which had hospital discharge data available, were suggestive of an increased risk of spontaneous abortions and ectopic pregnancies in Gulf War veterans.
Numerous studies in several countries examined respiratory outcomes related to deployment to the Gulf War Theater. The overwhelming majority of studies conducted among Gulf War veterans, whether from the United States, the UK, Canada, Australia, or Denmark, have found that several years after deployment, those deployed report higher rates of respiratory symptoms and respiratory illnesses than nondeployed troops. However, in all five studies, representing four distinct cohorts from three countries (the United States, Australia, and Denmark) that examined associations of Gulf War deployment with pulmonary-function measures or respiratory disease diagnoses based in part on such measures, such associations were not found. The uniformity of the findings is striking, especially given that the same five studies found that Gulf War deployment status was significantly associated with self-reports of respiratory symptoms among three of the four cohorts.
Whereas the studies discussed above examined respiratory outcomes associated simply with deployment vs nondeployment, other studies examined respiratory outcomes associated with specific environmental exposures experienced by Gulf War veterans, including exposure to oil-well fires and nerve agents. The methodologically strongest such study used objective exposure measures and methods and found significant associations between exposure to oil-well