clinical entity distinct from all other established diagnoses, while not clearcut, does have several recognized steps. Generally, the process begins with the identification of patients who are experiencing symptoms that do not coincide with established recognizable diagnoses. An attempt is then made to determine whether there are patterns or clusters of symptoms that are common to a wide group of patients. If such patterns are detected, experts are able to develop a “case definition.” A case definition strives to contain not only common symptoms but a mix of clinical, laboratory, and epidemiological criteria. This case definition is used to identify a new patient population that is distinct from other patient populations with recognized syndromes, conditions, or diagnoses (IOM 2000).
Much of the published literature on the health of Gulf War veterans has searched for an etiology or tried to prove causality in defining a specific disease or syndrome in ill Gulf War veterans. A disease can be characterized as having (1) common symptoms or signs and/or laboratory findings and (2) a defined etiology or pathophysiology with identifiable abnormalities in body structure or function. Syndromes or conditions also have common symptoms and signs, but the etiology and pathophysiology of the syndrome are often unknown. The patient's illness is defined by common symptoms or physical findings and therapy becomes symptom based. Therapy is standardized to that group of patients with common symptoms, and treatment effectiveness is often measured by improvement in quality of life indicators. For patients who have symptoms or groups of symptoms that cannot be linked to a specific syndrome or disease, and where no group of patients has the same group of symptoms (medically unexplained physical symptoms or medically unexplained illness), approaches to treatment are more difficult.
Because there has been no single identifiable disease to treat, it has not been possible to develop a uniform approach to health interventions in the Gulf War veteran population. The Department of Defense (DoD) is implementing a longitudinal study of health status that may yield useful information in planning for the future care of veterans of conflict; however, physicians treating Gulf War veterans need guidance now on treatment, and patients need to feel there is an approach to treatment that results in improved health.
The committee was asked to identify illnesses and conditions present among Gulf War veterans, to identify valid models of treatment for such illnesses to the extent they exist, and to identify new approaches, theories, or research on management of these conditions if validated treatment models are not available. To accomplish this, the committee examined the most common symptoms reported by Gulf War veterans and grouped them into established and accepted symptom-based conditions. This approach is supported by a number of well-done population studies (Iowa Persian Gulf Study Group 1997; Goss Gilroy 1998; Unwin et al. 1999).