The health effects of deployment frequency and duration in United States military service members supporting the global war on terrorism

In response to the threat of global terrorism, operational units deploy more quickly world-wide than in military conflicts of the past. As a result, service members are deploying multiple times to Iraq and Afghanistan in support of the Global War on Terrorism (GWOT). Stress of deployment may prompt coping mechanisms such as smoking, and may affect mental and functional health. The purpose of this dissertation was to investigate the effects of multiple deployments and other extreme deployment experiences on the postdeployment health of service members supporting GWOT. Analyses in this dissertation utilized data from the Millennium Cohort Study, which enrolled over 77,000 service members between July 2001 and June 2003. Self-reported deployment history was compared with military electronic records for over 55,000 participants who completed a follow-up questionnaire between June 2004 and February 2006. Agreement was substantial for deployment status, frequency, and number of deployments (kappa = 0.81, 0.71, and 0.61 respectively). No clinically meaningful differences in functional health for the small proportion with inconsistent deployment information were observed. Based on these findings, electronic military deployment data were used for the prospective evaluations of deployment and smoking and deployment and functional health. Smoking increased 43.8% among nondeployers and 55.6% among deployers. In multivariable logistic regression, past smokers were 35 times more likely to smoke at follow-up than never-smokers (odds ratio, 35.3; 95% confidence interval, 31.8-39.3). Those who deployed multiple times, >9 months, or deployed with combat exposures were at greater risk for smoking uptake. On average, mental and physical functioning scores decreased significantly among participants who deployed >9 months or were deployed with combat exposures. Extreme deployments, including multiple deployments, deploying longer than 9 months, and deploying with combat exposures were consistently associated with smoking uptake, smoking relapse, and small decrements in mental and physical functioning, though functional health scores were remarkably consistent. Service members, however, may manage the stress of deployment by using various coping mechanisms which may have detrimental health consequences. Increased smoking rates unquestionably imply future long-term morbidity, underscoring the importance of smoking prevention and cessation programs targeted towards deployed military personnel.