Abstract

In 1990, military forces from Iraq invaded and occupiedKuwait and massed at the Saudi Arabia border. Early in 1991, an international alliance led by the United States attacked Iraqi forces and rapidly drove them back into Iraq. More than 500 000 U.S. personnel were involved in the Gulf War military action. Approximately 300 were killed and 500 were wounded—remarkably low numbers for a force of that size. But the end of hostilities was not the end of the story. By the end of 1991, many Gulf War veterans felt unwell. They reported various persistent and debilitating symp-toms. Both the U.S. Department of Defense and the U.S. Department of Veterans Affairs created registries of ailing combatants from the Gulf War. The most commonly re-ported symptoms were fatigue, rashes, headache, muscle and joint pain, and memory impairment (1, 2). Disability claims mounted. By 2001, nearly 20 % of personnel de-ployed to the Gulf War were receiving some form of dis-ability compensation (3). Was the Gulf War, in fact, associated with an unusual burden of chronic multisymptom reports? Data from the registries could not answer that question, since the individ-uals in the registries were self-selected. Therefore, the U.S. Department of Veterans Affairs initiated several large pop-ulation-based studies. The studies—conducted in the United States (4, 5),