Open Access Research article

The physical and mental health of a large military cohort: baseline functional health status of the Millennium Cohort

Tyler C Smith1*, Mark Zamorski2, Besa Smith1, James R Riddle3, Cynthia A LeardMann1, Timothy S Wells3, Charles C Engel4, Charles W Hoge5, Joyce Adkins6, Dan Blaze7 and the Millennium Cohort Study Team

Author Affiliations

1 Department of Defense Center for Deployment Health Research, Naval Health Research Center, San Diego, CA, USA.

2 Deployment Health Section, Directorate of Medical Policy, Canadian Forces Health Services Group Headquarters and Department of Family Medicine, University of Ottawa, Ottawa, Ontario, Canada.

3 Air Force Research Laboratory, Wright-Patterson Air Force Base, OH, USA.

4 Deployment Health Clinical Center, Walter Reed Army Medical Center, Silver Spring, MD, USA.

5 Department of Psychiatry and Behavioral Sciences, Walter Reed Army Institute of Research, Silver Spring, MD, USA.

6 Office of the Assistant Secretary of Defense for Health Affairs, Force Health Protection, the Pentagon, Washington, DC, USA.

7 Duke University Medical Center, Durham, NC, USA.

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BMC Public Health 2007, 7:340  doi:10.1186/1471-2458-7-340

Published: 26 November 2007



The US military is currently involved in large, lengthy, and complex combat operations around the world. Effective military operations require optimal health of deployed service members, and both mental and physical health can be affected by military operations.


Baseline data were collected from 77,047 US service members during 2001–2003 as part of a large, longitudinal, population-based military health study (the Millennium Cohort Study). The authors calculated unadjusted, adjusted, and weighted means for the Medical Outcomes Study Short Form 36-item Survey for Veterans physical (PCS) and mental component summary (MCS) scores over a variety of demographic and military characteristics at baseline.


The unadjusted mean PCS and MCS scores for this study were 53.4 (95% confidence interval: 53.3–53.4) and 52.8 (95% confidence interval: 52.7–52.9). Average PCS and MCS scores were slightly more favorable in this military sample compared to those of the US general population of the same age and sex. Factors independently associated with more favorable health status included male gender, being married, higher educational attainment, higher military rank, and Air Force service. Combat specialists had similar health status compared to other military occupations. Having been deployed to Southwest Asia, Bosnia, or Kosovo between 1998 and 2000 was not associated with diminished health status.


The baseline health status of this large population-based military cohort is better than that of the US general population of the same age and sex distribution over the same time period, especially in older age groups. Deployment experiences during the period of 1998–2001 were not associated with decreased health status. These data will serve as a useful reference for other military health studies and for future longitudinal analyses.