Gulf War-deployed regular military and reserve/National Guard veterans, respectively, and 12.2% and 16.8% in nondeployed regular military and reserve controls, respectively, for a statistically significant prevalence difference of 2.4 (95% CI 0.4-4.5, p ≤ 0.05) (Iowa Persian Gulf Study Group 1997). The response rate for the telephone interview (76%) was relatively high.
The CIDI was administered in Australia as part of a two-phase study of 1381 Gulf War veterans and 1377 nondeployed controls (Ikin et al. 2004). Health professionals conducted interviews in clinics throughout the country. The prevalence of alcohol and drug abuse or dependence before the Gulf War was similar in the deployed and nondeployed groups (23.7% and 27.9%, respectively, for alcohol dependence or abuse and 2.8% and 2.3%, respectively, for drug dependence or abuse). The incidence rates for the disorder being first present after the war were significantly higher in deployed veterans than nondeployed veterans for both alcohol disorders (19.8% vs 12.6%, p = 0.001) and drug disorders (3.7% vs 1.8%, p = 0.015) for ORs of 1.5 (95% CI 1.2-2.0) for alcohol and 1.9 (95% CI 1.1-3.2) for drugs adjusted for service type, rank, age, education, and marital status. Significantly more deployed than nondeployed veterans also met criteria for alcoholism in the year before the interview (4.3% vs 2.5%, p = 0.011) for an adjusted OR of 1.8 (95% CI 1.1-2.8) but not the criteria for drug dependence or abuse (0.7% vs 0.6%, p = 0.863, OR 0.8, 95% CI 0.3-2.5).
Fiedler et al. (2006) conducted telephone interviews 10 years after the Gulf War with a national sample of 967 U.S. military personnel deployed to the Gulf and 784 nondeployed controls using the 12-month version of the CIDI. They found similar rates of alcohol disorder in the two groups (4.6% in deployed and 3.1% in nondeployed veterans), but the deployed had significantly higher rates of drug dependence (1.2% vs 0.1%, p < 0.05) and “any dependence” (5.1% vs 3.2%, p < 0.05) than the nondeployed.
Thus, the preponderance of the evidence from the six primary studies suggests that deployed Vietnam and Gulf War veterans, particularly personnel exposed to greater war-zone stress, have higher rates of alcohol or drug disorders than nondeployed controls.
Secondary studies are those with inadequate or no comparison groups, studies of treated populations or nonmilitary populations, and studies that used alcohol or drug measures of unknown reliability and validity. Four studies of Vietnam veterans are in this category. Helzer (1984) interviewed 943 Vietnam veterans in 1972, of whom 605 were eligible for a 2-year followup; at the time of followup, 571 were reinterviewed (94% response rate). The original sample included 470 respondents chosen at random from all enlisted personnel who returned from Vietnam in September 1971 and 495 others identified as illicit drug users on the basis of a urine screening test at the time of departure from Vietnam. The interview schedule was not described in detail, but problem use of alcohol was defined as having regular use of alcohol plus one or two alcohol-abuse symptoms; alcoholism was defined having regular use of alcohol plus three or more alcohol-abuse symptoms or at least one hospitalization because of drinking. At the first interview, 42% of combatants (those who were on combat patrols or dangerous duties, were under enemy fire, or were surrounded by the enemy) were problem drinkers or alcoholics compared with 28% of noncombatants (p < 0.001); a similar pattern was found at followup (45% vs 29%, p < 0.001). In the subsample of 297 veterans with no preservice alcohol problems, 24% of combat veterans and 19% of noncombat veterans were problem drinkers at the first interview, and 31% and 21% at the followup (p < 0.05 for both comparisons). After additional analyses,