Symptom clustering. The VA study searched for potentially new syndromes through factor analysis. A separate article by Kang and colleagues (2002) found that 47 symptoms reported by veterans yielded six factors, only one of which contained a cluster of neurologic symptoms that did not load on any factors in the non-Gulf War deployed veterans. The symptoms in the cluster were 1) loss of balance/dizziness; 2) speech difficulty; 3) blurred vision; and 4) tremors/shaking. A group of 277 deployed veterans (2.4 percent) versus 43 non-deployed veterans (0.45 percent) met a case definition subsuming all four symptoms. The authors interpreted their findings as suggesting a possible unique syndrome related to Gulf War deployment that requires objective supporting clinical evidence.

TABLE A.5 Results of the VA Study

10 Most Common Self-Reported Symptomsa

Prevalence in Gulf War Veterans (%)

Prevalence in Non-Gulf War Veterans (%)

Runny nose

56

43

Headache

54

37

Unrefreshing sleep

47

24

Anxiety

45

28

Joint pain

45

27

Back pain

44

30

Fatigue

38

15

Ringing in ears

37

23

Heartburn

37

25

Difficulty sleeping

37

21

5 Most Common Self-Reported Chronic Medical Conditionsa

Prevalence in Gulf War Veterans (%)

Prevalence in Non-Gulf War Veterans (%)

Sinusitis

38.6

28.1

Gastritis

25.2

11.7

Dermatitis

25.1

12.0

Arthritis

22.5

16.7

Frequent diarrhea

21.2

5.9

SOURCE: Kang et al., 2000.

aFor symptoms, subjects were asked whether symptoms were recurring or persistent during the previous 12 months. The differences in prevalence all are statistically significant (p<0.05).

Exposure-symptom relationships. A nested case-control analysis was performed on those who met the case definition to determine which of 23 self-reported exposures were more common among cases versus controls (Kang et al., 2002). Of nine exposures that were at least three times higher among deployed cases, two were solvent-related: CARC paint (51.2 percent in cases vs 16.3 percent in controls) and chemically contaminated food (73.4 percent in cases vs 20.6 percent in controls). No pesticide-related exposures were reported three or more times more frequently in cases versus controls. Dose-response was not studied because of the nature of the dataset regarding self-reported exposure.

The article covering the large cohort (Kang et al., 2000) did not assess exposure-symptom relationships. It reported on exposures only by compiling the percentages of veterans who reported each of 23 environmental exposures and nine vaccine or prophylactic exposures (such as to pyridostigmine bromide). The five most common environmental exposures reported by more than 60% of survey participants were to diesel, kerosene, or other petrochemical fumes; to local food other than that provided by the armed forces; to chemical protective gear; to smoke from oil-well fires; and to burning trash or feces. Table



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