5.17
Alcohol and other substance use
5.17.1
Alcohol disorders at follow up
A number of data sources were used to determine whether or not a participant was likely to
have had alcohol or other substance abuse or dependency disorders in the 12 months prior
to the follow up study. These sources comprised the CIDI, AUDIT questionnaire and selfreported doctor diagnosis and treatment from the postal questionnaire. Only five (0.8%) Gulf
War veterans and two (0.3%) comparison group participants met DSM-IV diagnostic criteria
for drug disorders using the CIDI, while only four (0.6%) Gulf War veterans and none (0%) of
the comparison group participants reported doctor diagnosed and treated substance
disorders. As the substance disorder figures were too small for valid statistical analyses,
only alcohol disorders are examined further.
Figure 1 shows the percentages of participants who possibly have a current alcohol disorder
based on the above measures.
Figure 1 Percentage of participants with possible alcohol disorder in the past 12 months based
on CIDI, AUDIT and self-report doctor-diagnosis data
CIDI defined 12 month Alcohol disorders at follow up
Forty (6.2%) Gulf War veterans and 17 (2.8%) comparison group participants met DSM-IV
diagnostic criteria for 12 month alcohol disorders using the CIDI. This difference between
groups at follow up was statistically significant, with the risk of alcohol disorders in Gulf War
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veterans estimated to be almost twice as high as the risk in the comparison group (RR 2.21,
adj RR = 1.93, 95% CI 1.10 – 3.38).
AUDIT caseness at follow up
One hundred and ninety-nine (28.8%) Gulf War veterans and 138 (21.1%) comparison group
participants met past year AUDIT caseness criteria for possible harmful or hazardous
drinking. The difference in levels of AUDIT caseness between the groups at follow up was
statistically significant, with the risk of caseness in Gulf War veterans estimated to be around
26% higher than the risk in the comparison group (RR 1.36, adj RR = 1.26, 95% CI 1.05 –
1.52).
The relative risk for Gulf War veterans compared with the comparison group was higher for
CIDI alcohol disorders than for AUDIT caseness. The AUDIT is a self-report screening
instrument for harmful or hazardous levels of drinking or drinking-related behaviour, rather
than an actual diagnosis, and so prevalence would be expected to be higher for this
measure, rather than for the more comprehensive CIDI DSM-IV diagnosis of alcohol
disorders.
Self-reported doctor-diagnosis and treatment for alcohol abuse or dependence
Twenty (2.9%) Gulf War veterans and eight (1.2%) comparison group participants reported
that a medical doctor had diagnosed them with, or treated them for, alcohol abuse or
dependency in the period since January 2001, and that they had been treated by a doctor
for that condition in the past 12 months. Although the risk of doctor diagnosed alcohol
disorders treated in the past 12 months was estimated to be almost one and a half times as
high as the risk in the comparison group, this difference between groups at follow up was not
statistically significant, (RR 1.45, adj RR = 1.55, 95% CI 0.64 – 2.81), as numbers were
small. Similar results were obtained for exact Poisson regression, performed due to small
cell sizes.
The overall levels of doctor diagnosed and treated alcohol disorder was far lower than that of
either CIDI-defined alcohol disorders or AUDIT caseness in both groups, suggesting the
possibility of a response bias in not self-reporting diagnoses of alcohol disorder at interview,
or not reporting alcohol symptoms to medical doctors in the first place, or doctors missing
these diagnoses.
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5.17.2
Association between Gulf War-deployment characteristics
and alcohol disorders in veterans at follow up
The associations between Gulf War deployment characteristics and occurrence of CIDIdefined 12 month alcohol disorders at follow up in male Gulf War veterans are shown in
Table 1. Alcohol disorders at follow up were associated with lower ranks, with the highest
risks being observed for other rank – non supervisory, followed by other rank – supervisory,
when compared with Officers. The overall differences in risk associated with each rank were
statistically significant (p < 0.01). There were not any apparent differences in risk of alcohol
disorders between age category (p = 0.21), and service branch (p = 0.93).
Table 1 Association between Gulf War-deployment characteristics and 12 month alcohol
disorders at follow up in Gulf War veterans
Gulf War deployment
characteristic
Veterans with 12-month alcohol disorders at follow up
N
n (%)
RR
Adj RR (95% CI)
< 20
58
6 (10.3)
1.0
1.0
20-24
156
13 (8.3)
0.8
1.1 (0.4-2.8)
25-34
336
14 (4.2)
0.4
0.9 (0.3-2.3)
>=35
97
7 (7.2)
0.7
2.1 (0.7-6.1)
Navy
552
35 (6.3)
1.0
1.0
Army
45
3 (6.7)
1.0
1.2 (0.4-3.7)
Air Force
50
2 (4.0)
0.6
0.9 (0.2-3.6)
Officer
139
2 (1.4)
1.0
1.0
Other rank-supervisory
330
19 (5.8)
4.0
5.0 (1.3-19.4)
Other rank - non supervisory
177
19 (10.7)
7.4
9.7 (2.5-37.4)
Age at deployment
Service branch
Rank category
5.17.3
Change in prevalence, also persistence, remittance and
incidence of 12 month alcohol disorder since baseline
For male participants who completed the CIDI Alcohol module at both baseline and follow up
(n=637 Gulf War veterans and n=555 comparison group), Table 2 shows the change in
prevalence of 12 month alcohol disorder, from baseline to follow up, in both study groups.
These results indicate that, in the decade or so since the baseline study, the risk of 12 month
alcohol disorder in Gulf War veterans approximately doubled, and this was a statistically
significant increase. In contrast the risk of alcohol disorder in the comparison group has
increased since the baseline study, but not significantly so. Additional analysis showed,
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however, that any difference in risk of developing alcohol disorder across time between Gulf
War veterans and the comparison group was not statistically significant (RR 1.13; 95% CI
0.46 – 2.72).
Table 2 Prevalence of 12 month alcohol disorders at baseline and follow up for male
participants who completed the CIDI at both time points
Gulf War veterans (n=637)
12 month
Alcohol
Comparison group (n=555)
Baseline
prevalence
(%)*
Follow up
prevalence
(%)
RR (95% CI)
Baseline
prevalence
(%)*
Follow up
prevalence
(%)
RR (95% CI)
20 (3.1)
40 (6.3)
2.0 (1.25-3.20)
9 (1.6)
16 (2.9)
1.78 (0.84-3.76)
*Includes only those participants who also completed the CIDI at follow up
Table 3 shows the proportions of Gulf War veterans and comparison group participants with
a diagnosis (present) or without a diagnosis (absent) of 12 month alcohol disorders at
baseline and at follow up. Due to the small cell sizes, exact Poisson regressions were
performed. Relatively few of the large proportion (>94%) of Gulf War veterans and
comparison group participants who had no diagnosis of 12 month alcohol disorders at
baseline, then had this diagnosis at follow up. Incident cases are shown in the first row of
data in Table 3, and consist of those participants for whom 12 month alcohol disorders were
absent at baseline and present at follow up. The percentage of incident alcohol disorder
cases in the Gulf War group (5.3%) was higher than that in the comparison group (2.6%).
The adjusted difference between the groups narrowly missed statistical significance,
although the unadjusted difference between groups was significant (unadjusted 95% CI 1.09
– 4.22), suggesting that differences were due to possible confounders such as age and
military rank when included in the exact Poisson regression model.
Persistent cases are shown in the second row of data Table 3, and consist of those
participants for whom 12 month alcohol disorders were present at baseline and present at
follow up, while remitted cases are those for whom 12 month alcohol disorders were present
at baseline but absent at follow up. Of the 20 Gulf War veterans and 9 comparison group
members who had a 12 month diagnosis of alcohol disorder at baseline, 35% and 22.2%
respectively were persistent cases who met this criteria at follow up, whereas 65% and 77.8%
remitted. These differences between groups in persistence and remittance were not
statistically significant, but numbers were small and these analyses had limited statistical
power.
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Table 3 Persistent and incident cases of 12 month Alcohol disorders among Gulf War veterans
and comparison group members who completed the CIDI at baseline and follow up
12-month Alcohol
Gulf War veterans
Comparison group
Follow up
n (%)
absent
n (%)
present
absent (n = 617)
584 (94.7)
present (n = 20)
13 (65.0)‡
Baseline
Follow up
Baseline
n (%)
absent
n (%)
present
33 (5.3)*
absent (n = 546)
532 (97.4)
14 (2.6)*
7 (35.0)†
present (n = 9)
7 (77.8)‡
2 (22.2)†
Between groups
RR
Adj RR§ (95% CI)
Incidence
2.09
1.85 (0.96–3.77)
Remittance
0.84
0.81 (0.28–2.51)
Persistence
1.58
1.66 (0.29–16.96)
*Incident cases
†Persistent cases
‡Remitted cases
§These RRs are adjusted for binary age category (<25, >=25), service type (Navy, Army/Air Force) and rank (Officer, nonOfficer) category at August 1990 , using exact Poisson regression due to small cell sizes.
5.17.4
Key findings
The risk of current alcohol disorders in Gulf War veterans was significantly higher than that
in the comparison group, as ascertained using both DSM-IV CIDI-defined 12-month
diagnosis and AUDIT caseness, but not doctor diagnosed and treated alcohol disorders. In
addition, Gulf War veterans were twice as likely to have a CIDI diagnosis at follow-up
compared with baseline.
Among Gulf War veterans, risk of CIDI-defined 12 month alcohol disorders was highest for
lower ranks. Since the time of the baseline study, CIDI-defined 12 month alcohol disorders
in Gulf War veterans are suggestive of being more persistent, less likely to remit and new
cases of alcohol disorders have been more likely to occur relative to the comparison group,
although numbers were small and these differences were not statistically significant.
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