DISEASES OF THE CIRCULATORY SYSTEM

Cardiovascular disease is a broad term for any disorder of the heart or the blood vessels, such as artherosclerosis and hypertension. Cardiovascular disease, which includes coronary heart disease and stroke, is the leading cause of death of both women and men in the United States. In 2005, 864,480 people (53% of them women) died of cardiovascular disease, accounting for 34% of all US deaths. The age-adjusted death rate was 262.9 per 100,000 of population. Over 40% of deaths in those aged 65 or older is the result of cardiovascular disease (Lakatta, 2002). Major risk factors for cardiovascular disease include hypercholesterolemia, diabetes, smoking, obesity, and physical inactivity. Primary studies for circulatory system diseases are presented in Table 4-7.

Summary of Volume 4

Primary Studies

Volume 4 included two primary studies considering cardiovascular outcomes. The first study (Eisen et al., 2005) examined the prevalence of different health outcomes in a group of 1061 Gulf War deployed veterans and 1128 nondeployed veterans between 1999 and 2001; veterans were part of the larger National Health Survey of Gulf War Era Veterans and Their Families, who had completed mailed questionnaires about their health status in 1995 (Kang et al., 2000). Hypertension, defined as systolic blood pressure greater or equal than 140, diastolic blood pressure greater or equal than 90 mmHg, or use of antihypertensive medication, was equally prevalent in deployed and nondeployed veterans (adjusted OR 0.90, 95% CI 0.60-1.33). The major limitation of this study was the differential, low response rate (53% in Gulf War veterans and 39% in nondeployed).

The second study examined hospitalizations in DoD hospitals among Gulf War veterans according to their exposure to the demolition of the Khamisiyah weapons depot. An initial report of this analysis, published in 1999 (Gray et al., 1999b), was updated in a later publication (Smith et al., 2003). Among those potentially exposed to sarin and cyclosarin the risk ratio of being hospitalized with a cardiovascular condition was 1.07 (95% CI 1.01-1.13) compared to nonexposed. The increased risk was specific for cardiac dysrhythmias (risk ratio 1.23, 95% CI 1.04-1.44). This study could not ascertain outpatient diagnoses as well as hospitalizations in those who did not remain in active duty after the war.

Secondary Studies

Several large epidemiologic studies examined self-reported cardiovascular outcomes occurring in Gulf War veterans. The committee classified studies relying on self-report of cardiovascular disease as secondary. In an Australian study, prevalence of self-reported physician-diagnosed high blood pressure was similar in 1456 veterans deployed to the Gulf War and 1588 nondeployed (OR 1.2, 95% CI 0.9-1.6) (Kelsall et al., 2004a). Similarly, Kansas veterans were as likely as their nondeployed counterparts to report physician-diagnosed high blood pressure (OR 1.24, 95% CI 0.82-1.89) or heart disease (OR 1.56, 95% CI 0.69-3.56) (Steele, 2000). In a study including 11,441 Gulf War veterans and 9476 nondeployed veterans, Kang and colleagues (2000) found an increased prevalence of self-reported high blood pressure in deployed versus nondeployed veterans (prevalence difference 3.84%, 95% CI 3.75-3.93) and a



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