Comparing veterans deployed in the first Persian Gulf War with veterans deployed elsewhere at the same time has revealed veterans who served in the Persian Gulf have nearly twice the prevalence of chronic multisymptom illness (CMI), a cluster of symptoms similar to a set of conditions often called Gulf War Syndrome.
To be diagnosed with CMI, veterans must have had symptoms for more than six months in at least two of the following categories: fatigue; mood symptoms or difficulty thinking; and muscle or joint pain.
However, the study also found CMI in veterans who did not serve in the Gulf, suggesting that the Persian Gulf conflict isn't the only trigger for CMI.
"We're still not sure whether CMI is due to a single disease or pathological process," said the study's lead author, Melvin Blanchard, M.D., assistant professor of medicine and associate chief of medicine at the St. Louis Veterans Affairs (VA) Medical Center. "But this study has identified an intriguing association between CMI risk and diagnosis of depression and anxiety disorders prior to military service."
Other findings from the study include:
• Having CMI doubles the risk of developing metabolic syndrome, which is associated with increased risk of coronary heart disease, diabetes and cirrhosis of the liver;
• Veterans with CMI report much poorer quality of life and poorer mental and physical functioning than unaffected veterans; and
• Veterans with CMI use more health-care services.
Also, although CMI is still much more common among deployed Gulf War veterans, veterans may be recovering, because the illness' prevalence appears to be declining as time passes.
Blanchard's study, published online by the Journal of Epidemiology, is part of the continuing analysis of data collected in a large VA-sponsored study, the "National Health Survey of Gulf War-Era Veterans and Their Families."
The data comes from physical evaluations of more than 2,000 veterans and their families conducted from 1999-2001. The study divided veterans into two groups: those who served in the Persian Gulf War, referred to as "deployed veterans," and those who served elsewhere during the war, referred to as "nondeployed veterans."
Among deployed veterans, CMI incidence was 28.9 percent; in nondeployed veterans, it was 15.8 percent.
"A key point is that 10 years after the first Gulf War, CMI was still much more prevalent among deployed than nondeployed veterans," Blanchard said. "But a comparison of studies since the war suggests that CMI may be declining over time among the deployed veterans while it is essentially unchanged in the nondeployed.
"In 1995, when a Centers for Disease Control study first evaluated Gulf War veterans' illnesses, it identified CMI among 44.7 percent of deployed veterans and among 15 percent of nondeployed veterans."
To help understand the nature of CMI, Blanchard and his colleagues reviewed the data looking for associations between CMI and a variety of other medical conditions. Of the conditions associated with CMI, all were based on symptoms rather than examination and laboratory test findings (fibromyalgia syndrome, chronic fatigue syndrome, upset stomach), except metabolic syndrome.
Fibromyalgia syndrome afflicts sufferers with persistent, widespread pain. Chronic fatigue syndrome leaves sufferers with a disabling loss of energy.
While acknowledging that these conditions have serious effects on veterans' health and quality of life, Blanchard notes that they are both based on subjective symptom reports from the patient.
Diagnosis of metabolic syndrome, in contrast, is based on patients meeting at least three of five objective criteria:
• elevated blood pressure;
• high levels of triglycerides in the blood;
• low levels of HDL, also known as good cholesterol;
• elevated levels of blood glucose after fasting; and
• a large waist size.
In both deployed and nondeployed veterans diagnosed with CMI, the prevalence of metabolic syndrome was twice that of veterans not suffering from CMI. Metabolic syndrome is associated with several-fold risk of death from coronary artery disease.
"Physicians need to be aware of the potential manifestations of CMI and the need to treat them, and metabolic syndrome is a key example," Blanchard said. "There's quite a bit of literature on this condition, and there are steps physicians can encourage their patients to take — such as increased exercise, stress management and dieting to reduce abdominal fat — that can lessen its effects."
In addition, some of the individual health risk components of the metabolic syndrome can be treated with currently available medications.
Researchers also screened for factors prior to time in the service that affected CMI risk, looking at age, race and other demographic factors, military characteristics, as well as medical and psychiatric history.
"History of psychiatric conditions prior to service appears to place veterans at a significantly increased risk of CMI," Blanchard said.
"This should not be taken as an indication that CMI is all in the veteran's head; the condition has physical manifestations that are very real, including objectively defined conditions such as metabolic syndrome."
Blanchard and others suspect CMI may be connected to malfunctions in the body systems that respond to stress, such as the nervous system. Battlefield stress may help trigger the disorder in deployed veterans. Veterans who develop CMI without serving in the field of combat may be responding to other sources of stress.
Blanchard is conducting a follow-up study of 100 individuals with CMI and 100 without. The study includes an extensive evaluation of participants' stress response systems.