Effect of frequency and duration of deployment on the functional health of service members deployed in support of the wars in Iraq and Afghanistan

Background Research from previous military conflicts have indicated that combat veterans may be at risk for anxiety disorders, cognitive dysfunction, lower health-related quality of life, and lower functional status. Recent reports suggest service members returning from Iraq and Afghanistan have significant mental health morbidity. Deployment length per se has been related to psychological distress, although it is unknown whether those who deploy multiple times are more likely to report lower functional status or mental health problems.

Objective To prospectively investigate the mental and physical health of a large, population-based US military cohort in relation to deployment.

Methods The Millennium Cohort Study is a 21-year longitudinal study launched in 2001. Participants in the current study submitted baseline (June 2001–July 2003) and follow-up (June 2004–February 2006) questionnaire data. Using the 36-item Short Form Health Survey for Veterans to measure functional health, analysis of covariance was used to assess changes in mental and physical functioning scores for personnel with multiple and extreme deployments (of long duration or with combat-related exposures).

Results On average, mental and physical functioning scores decreased significantly among participants who deployed >9 months, or were deployed with combat-related exposures. Overall scores changed, on average, by less than two points.

Conclusions Statistical differences in adjusted means of mental and physical functioning scores were small and may have little clinical significance. Results suggest a consistency in mental and physical functioning scores over almost 3 years, regardless of deployment, in this large military cohort.