veterans was 3.4% and 1.4% for those who had participated in combat and for those who did not, respectively. The study is limited by the inclusion of both deployed and nondeployed veterans in the PTSD-positive group and the lack of specific data on the prevalence of various health outcomes.

A study of posttraumatic stress symptomatology (PTSS) and unexplained illness was conducted by Ford et al. (2001). They sought to determine whether there was an association between war-zone trauma or PTSS and illnesses reported by Gulf War veterans. Participants were randomly selected from a DoD database of 8603 eligible Gulf War veterans from Oregon or Washington who were deployed from August 1, 1990, through July 31, 1991. Of those deemed eligible and who completed questionnaires, 237 cases and 113 controls were identified by medical examination. A 4-hour test battery of 19 tests was administered to assess psychologic status and neurobehavioral function. Findings indicate that 13 of the 14 psychologic variables were significantly associated with case (vs control) status in unadjusted univariate logistic regression analyses. Case subjects reported significantly higher levels of somatic distress; health problems, fatigue, pain, and deterioration in physical health; global and specific psychiatric distress; negative effects of recent life events; and war-zone trauma exposure than controls. The study is limited by its retrospective analysis of war trauma and its lack of representativeness of the entire Gulf War veteran population.

Chronic Pain

Chronic pain, defined as “an unpleasant sensory and emotional experience, associated with actual or potential tissue damage or described in terms of such damage” that persists for 6 months or longer (Otis et al. 2003), is one of the most frequently reported symptoms in veteran populations. Such unexplained pain does not help the body to prevent injury. It can persist for weeks to years as pain signals continue to stimulate the nervous system. Common chronic pain complaints include headache, low-back pain, joint pain, neurogenic pain (pain resulting from damage to the peripheral nerves or to the central nervous system), and psychogenic pain (pain not due to disease, injury, or any visible sign of damage inside or outside the nervous system). Chronic pain is different from CWP (discussed earlier in the chapter with fibromyalgia) because it does not meet the ACR criteria necessary for a diagnosis of CWP. It has been estimated that 50 million Americans have serious chronic pain annually (American Pain Foundation 2007).

Studies of various types of unspecified and unexplained pain in deployed and nondeployed veteran groups invariably find that deployed veterans report significantly more pain symptoms—including joint pain, backache, chronic back pain, muscular pain, neck ache, neuralgia, and headache—than nondeployed troops (Gray et al. 1999; Kang et al. 2000b; Kelsall et al. 2006; Kuzma and Black 2006; Proctor et al. 1998, 2001; Simmons et al. 2004; Unwin et al. 1999). In a study of 970 OEF and OIF veterans seeking treatment at a VA medical center, 38% reported some level of pain; of those, 59% had pain that was clinically significant and likely to interfere with functional activities (Gironda et al. 2006). In over half the patients with chronic pain, the pain could not be attributed to any type of injury.

Thomas et al. (2006) conducted a meta-analysis of 20 studies that compared self-reports of pain in Gulf War-deployed veterans with era veterans. They found that deployment was most strongly associated with abdominal pain (six studies, OR 3.23, 95% CI 2.31-4.51), but deployment was also associated with reports of other pain, including muscle pain (eight studies, OR 3.06, 95% CI 2.18-4.30), joint pain (12 studies, OR 2.81, 95% CI 2.31-3.42), chest pain (seven studies, OR 2.52, 95% CI 2.23-2.85), and back pain (six studies, OR 1.58, 95% CI 1.23-



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