| The purpose of this case-control study was to characterize Gulf War Illnesses (GWI), focusing on whether cases had Neurally Mediated Hypotension (NMH). Cases were defined as fatigued Gulf War veterans whose onsets occurred by July 31, 1992, and were matched to healthy Gulf War veterans and Era veterans. Forty-nine cases, 44 Gulf controls, and 45 Era controls were recruited nationally from all branches and types of military service and underwent laboratory blood testing, a blinded physical examination, and tilt table test at Johns Hopkins Hospital. The prevalence of NMH did not differ significantly by case or control status. GWI was characterized by nonspecific neurological abnormalities, with the odds of being a case = 3.45 (95% CI 1.49--8.04).; An incubation curve of case fatigue onsets revealed a log-normal distribution, suggesting that a Gulf exposure was associated with GWI. Exposures were examined in three separate case-control studies, with cases defined by having GWI, by having NMH, and by having an abnormal neurological examination. Pyridostigmine bromide was significantly associated with GWI and NMH; the odds of being a GWI case were 3.02 (95% CI 1.13--8.10), given a mean PB intake of 84 pills. A dose response relationship was observed in GWI cases, with higher PB intakes associated with higher symptom counts, lower sense of wellness, greater fatigue, and lower scores on the SF-36 physical component. Those who ingested food contaminated with oil well fire smoke, oil, or other chemicals were 5.6 times more likely to have neurological abnormalities (95% exact CI 1.15--30.17).; Fainting history data were collected from first-degree relatives of cases and controls to determine if those with NMH were more likely to have a family history of fainting. In contrast to the findings of other investigators, NMH was not associated with having a family history of fainting.; In conclusion, rapid-onset GWI was characterized by neurological abnormalities. The incubation curve suggested that a Gulf exposure was associated with ill health, and exposure analyses implicated PB and ingestion of contaminated food as sources of illness. The lack of a familial association with NMH further supports an environmental cause for GWI. |
