To the Editor.
—Although Dr Haley and coinvestigators1 have made a valiant attempt to define Gulf War-related syndromes among Gulf War veterans, a key methodological limitation of their study is the inability to support a link between service in the Gulf War and the syndromes that were uncovered.To conclude that syndromes are related to service in the Gulf War because they are found among Gulf War veterans is premature. The possibility that the same methods applied to a sample of nondeployed, Gulf War-era veterans would find a similar proportion of veterans reporting the same syndromes cannot be excluded. The authors note their sample consists of healthy and ill Gulf War veterans. However, to link syndromes to Gulf War service, this distribution of subjects cannot substitute for a non-Gulf War veteran control group. Similarly, observing relationships among exposures reported by veterans, clinically derived case criteria, or biological factors cannot substitute for an
Engel CC, Jing Z. Identification of Gulf War Syndrome: Methodological Issues and Medical Illnesses. JAMA. 1997;278(5):383-384. doi:10.1001/jama.1997.03550050045020