GULF-WAR VETERANS ILLNESSES - A CASE-STUDY IN CAUSAL INFERENCE

The objective of this study was to determine from the published epidem iological literature whether there is evidence for a causal associatio n between service in the Gulf War and illness in U.S. veterans. Eleven published studies were analyzed using standardized epidemiologic crit eria for assessing causality. A consistent association was found betwe en deployment to the Gulf and self-reports of symptoms. No consistency was seen in physical findings or laboratory results. Strength of asso ciation varied with different study designs. Dose-response information is limited, because of lack of quantitative data on exposures. Biolog ical plausibility varies for different risk factors. Specificity of as sociation is not seen. Frequency of self-reported symptoms is increase d in U.S. Gulf War veterans compared to other veterans of the same era , but specific causes of illnesses cannot be ascertained. Major gaps i n data that impeded this analysis include (1) lack of objective data o n specific environmental exposures (2) lack of baseline health assessm ents, and (3) lack of objective measures of post deployment health sta tus. In future deployment of U.S. troops, accurate exposure and health data will be needed if the causes of subsequent illnesses are to be a ccurately assessed. (C0 1998 Academic Press.