continues to be no single “Gulf War syndrome” or any clearly established etiology for the symptoms or symptom clusters. Veterans who are experiencing severe fatigue, for example, may or may not meet criteria for a diagnosis of chronic fatigue syndrome (CFS). Studies of CFS, then, may or may not be generalizable to the entire population of veterans experiencing fatigue even if they are deemed generalizable to veterans with CFS. Similarly, results of studies of fibromyalgia, depression, or migraine may or may not be applicable to Gulf War veterans who are experiencing symptoms of these conditions but do not have all the characteristics that would justify a formal diagnosis. One should not assume that Gulf War veterans with medically unexplained symptoms have one of the diseases of unknown etiology discussed here. Results of studies on conditions with unknown etiology may not generalize directly to Gulf War veterans whose similar symptoms may have a different etiology. However, given currently available diagnostic information and the lack of effectiveness studies conducted on Gulf War veterans, identification of effective treatments for such conditions as these may offer the best opportunity for alleviating the health problems of Gulf War veterans.
Another complication is the current absence of criteria for defining the presence, duration, progression, or severity of Gulf War veterans' health problems that match similar criteria for diagnosable illnesses. Clinical trials may be done on conditions that are “acute” or “uncomplicated,” or “recurrent” or “severe.” The patients recruited for such trials must meet certain explicit criteria for being in that category. Although the specific symptoms experienced by veterans may be categorized in these ways, and future prospective studies may be conducted on groups defined in this way, it will be challenging in the near term (and in the context of this report) to draw conclusions from existing published literature about the possible effectiveness of treatments in Gulf War veterans. Development of a standard language for describing Gulf War veterans' health problems (including severity and temporal characteristics) would facilitate the conduct of treatment effectiveness trials.
The preceding discussion and analysis describes approaches used for assessing treatment effectiveness. Based on this analysis, to implement well-designed and valuable treatment effectiveness studies, the committee recommends that the VA:
use a hierarchy of evidence structure that includes effectiveness studies as well as efficacy studies for any future treatment guidelines it develops for symptoms or illnesses of Gulf War veterans;