Latency and exposure-health associations in Gulf War veterans with early fatigue onsets: a case-control study.

Purpose: To see if self-reported exposures were associated with health in early-onset Gulf War illnesses (GWIs) cases and healthy Gulf War veteran controls.

Methods: Forty-nine cases and 44 controls completed questionnaires about wartime exposures and symptoms experienced. Odds ratios were calculated using 2 x 2 tables and logistic regression. The incubation curve of fatigue onsets in cases was drawn to highlight exposure/health associations using Sartwell's method and tested with the Shapiro-Wilk test. The incubation period was defined as the time from arrival in the Persian Gulf to fatigue onset.

Results: The incubation curve was right skewed and lognormally distributed (p = 0.48; p > 0.05 indicates lognormality), suggesting an association between a wartime exposure and fatigue. Exposure to oil fire smoke, pesticides, contaminated food or water, dead animals, scud missile attacks, dead bodies, prisoners of war, artillery or small arms fire, and chemical suits was significantly associated with GWIs. Pyridostigmine bromide (PB) was the only continuous exposure significantly associated with GWIs. The odds of having GWIs increased by 1.3% for every PB pill taken (95% confidence interval 1.001-1.02). There were significant trends toward worse health with greater intake of PB.

Conclusions: These analyses suggest that wartime exposures, including exposure to PB, are associated with fatigue.