deployed and 39% of eligible nondeployed) and the number of years that had passed since the war. Blanchard et al. (2006) re-examined the same data as those of Eisen et al. to determine the prevalence of chronic multisymptom illness and came to a similar conclusion: hypertension was not higher in Gulf War-deployed veterans than in their nondeployed counterparts, whether or not the veterans had multisymptom illness.
The VES, conducted by CDC in 1985-1986, looked at cardiorespiratory conditions in 2490 Vietnam-theater Army veterans and 1972 Vietnam-era veterans. In Phase 1 conducted about 15-20 years after the war, a telephone interview was used to assess whether the veterans had any one of a number of health effects; in Phase 2, participants received physical examinations to screen for health status. A diagnosis of hypertension was based on a measured blood pressure above 140/90 mmHg or by patients reporting that they were taking antihypertensive medication. The prevalence of hypertension was not significantly higher in the theater veterans (33.5%) than in the era veterans (31.4%) (OR 1.1, 95% CI 0.9-1.2) after adjustment for age at enlistment, race, year of enlistment, enlistment status, score on a general technical test, and primary military occupation. About 5% of the veterans in each group reported using antihypertensive medication at the time of the study (CDC 1988b).
Secondary studies are defined as those in which the diagnosis of hypertension was based only on self-reports. A cross-sectional study of 1456 Australian Gulf War veterans and 1588 nondeployed veterans, surveyed 10 years after the war, found no increase in the prevalence of self-reports of physician diagnoses or of treatment of hypertension after the war in the deployed veterans (OR 1.2, 95% CI 0.9-1.6) after adjustment for service type, rank, age, education, and marital status (Kelsall et al. 2004a). The strength of this study is that a physician assessed and rated the likelihood of each self-reported medical condition during a followup face-to-face interview although a physical examination was not conducted.
Several other cross-sectional studies relied exclusively on self-reports. The largest, conducted by VA (Kang et al. 2000b), was a mailed survey with followup telephone interviews of a population-based sample of 11,441 Gulf War veterans and a stratified random sample of 9476 nondeployed veterans. The study was the first phase of the National Health Survey of Gulf War Era Veterans and Their Families conducted in 1995, which surveyed 30,000 deployed and nondeployed Gulf War veterans for health problems, and was used by Eisen et al. (2005). A slightly higher (but significant because of the large numbers) prevalence of hypertension was reported in the Gulf War veterans than in the nondeployed veterans (11.4% vs 7.6%, rate difference 3.84, 95% CI 3.75-3.93) in the preceding 12 months.
In a cross-sectional study by Hotopf et al. (2003a), a stratified random sample of 2049 UK veterans of the Bosnia peacekeeping mission, 570 veterans who had served in both the Gulf War and Bosnia, and 1785 nondeployed veterans completed a mail questionnaire that asked about a variety of health effects. No difference in the frequency of self-reported hypertension was seen between the groups (6.1% in both the deployed and the nondeployed and 4.2% in those deployed only to Bosnia).
Three other studies reported a statistically significant increase in self-reported hypertension. The Seabee Health Study (Gray et al. 2002), a survey of 3831 Gulf War-deployed Navy Seabees and 3104 nondeployed Seabees in which questionnaires were mailed to the participants 7 years after the Gulf War (1997-1999), found a significantly higher rate of self-reported hypertension in the Seabees who had been deployed than in those who had not (OR