The Volume 4 committee identified two large well-designed studies of Gulf War veterans that were considered secondary studies because they lacked a dermatologic examination or were imprecise regarding specific dermatologic diagnoses: Kang et al. (2000) and Proctor et al. (1998). In the first phase of the VA National Health Survey of Gulf War Era Veterans and Their Families, Kang et al. (2000) compared 11,441 deployed veterans with 9476 nondeployed veterans identified by the DMDC. Dermatitis other than eczema and psoriasis was among the five most frequently reported medical conditions diagnosed by a physician in the preceding 12 months. The skin conditions reported by the deployed and nondeployed veterans were eczema or psoriasis (7.7% vs 4.4%; rate difference 3.34, 95% CI 3.26-3.42), other dermatitis (25.1% vs 12.0%; rate difference 13.16, 95% CI 13.04-13.28), and diseases of the hair or scalp or hair loss (16.9% vs 7.2; rate difference 9.65, 95% CI 9.55-9.75). A sample of participants were later evaluated by clinical examination in the Eisen et al. study (2005). Proctor et al. (1998) assessed the prevalence of dermatologic conditions—such as rashes, eczema, and skin allergies—in US veterans. The estimated prevalence was 15.5% for the 186 Gulf War deployed veterans from the Fort Devens cohort, 11.7% for the 66 deployed veterans from the New Orleans cohort, and 1.9% for the 48 veterans deployed to Germany during the Gulf War.
The Update committee identified one new primary study: Ishoy et al. (1999b). This study reported on Danish peacekeepers deployed to the Persian Gulf area during 1990-1997. The 686 deployed veterans and 231 nondeployed age-, sex-, and profession-matched veterans each received a medical examination and were interviewed for a full medical history by a physician based on a previously administered questionnaire. Veterans indicated whether any medical condition had its onset before or after deployment to the gulf. The examinations found that the prevalence of the following conditions with onset during or after deployment or August 1990 was higher in deployed veterans than in nondeployed veterans: eczema (15.0% vs 3.0%, p < 0.001), retarded wound healing (6.0% vs 1.7%, p < 0.01), other skin problems (17.1% vs 5.2%, p < 0.001), hair loss or hair disease (4.2% vs 0.9%, p < 0.01), and sweaty, clammy, or damp hands (7.9% vs 3.9%, p < 0.05). There were no significant differences in the prevalence of psoriasis and nettle rash between deployed and nondeployed troops. Although the examination process used to verify the veteran’s actual skin conditions at the time of the interview by the physician is somewhat unclear in the report, the use of a physician to discuss the veterans’ responses to the questionnaire provides support for the designation of this report as primary.
The Update committee also reassessed the two primary studies from Volume 4 and determined that the Eisen study was a primary study based on a dermatologist’s diagnosis of two specific skin disorders: vulgaris (warts) and atopic dermatitis. However, for the Higgins et al. (2002) study, the committee also found that based on its study design that compared disabled deployed and disabled nondeployed veterans, as well as the lack of an appropriate comparison group (that is nondeployed nondisabled veterans serving in the same era), this study could not be considered a primary study.