Increased Postdeployment Use of Medication for Common Mental Disorders in Danish Gulf War Veterans

Gulf War veterans (GWVs) have an elevated risk of reporting symptoms of mental disorders as compared with nondeployed military controls. A difficulty in the Gulf War health research is that most health outcomes are self-reported; therefore, it is highly relevant to study objective outcomes in this line of research. The Danish National Prescription Registry provides an opportunity to use the prescription of drugs as an objective evaluation of the impact of mental health disorders at the individual level. In this study, we investigated the prescription of drugs and postdeployment hospitalizations for mental disorders among GWVs compared with a control population of nonveterans (NVs).

A prospective registry study including a cohort of 721 GWVs and a control cohort of 3,629 NVs. Main outcome measures were incidence of (1) use of antidepressants, (2) use of anxiolytic/hypnotic medication, and (3) number of postdeployment psychiatric contacts. The association between outcomes and GWVs status was studied by using time-to-event analysis. The index date was the return date from the last deployment to the Gulf. The follow-up period was the time from index date until December 31, 2014.

GWVs had an elevated average risk over time for use of both types of medication compared with NV. For use of antidepressants the average hazard rate (HR) was 2.56, with 95% confidence interval (CI) = 2.04-3.21 (p < 0.0001); for use of anxiolytic/hypnotic medication the corresponding results were HR = 1.78, CI = 1.37-2.31 (p < 0.0001). The interaction with time was statistically significant with HR increasing with time for both outcomes. Incident use of antidepressants in GWVs after 10 years was two times higher than among NV, after 20 years it was nearly four times higher than among NV. Incident use of anxiolytic/hypnotic medication was one and a half that of NV after 10 years, but nearly three times that of NV after 20 years. There was no difference in rate of postdeployment psychiatric contacts.

The findings of increased use of antidepressants and anxiolytic or hypnotic medicine among GWVs compared with NVs were rather surprising since we recently, by using the same study population, found that deployment to the Persian Gulf was not associated with increased sickness absence or reduced labor market attachment. However, our results indicate that the mental health of the Danish GWVs is worse than in NV, and that this unfavorable difference increased with time. A possible explanation is that veterans have a high motivation for being in work, and that the deployment-related mental problems they may have acquired do not impair their ability to work, when treated properly. Furthermore, registry-based research in GWVs could include other outcomes, e.g., the use of pain medication, and other military comparison groups, e.g., veterans deployed to other areas than the Persian Gulf in addition to NV. The method of surveillance of military personnel with register data pertinent to health and monitoring outcomes compared with suitable control populations is highly recommended as a tool in the prevention of deployment-related health problems.