Deployment, Combat, and Risk of Multiple Physical Symptoms in the US Military

A Prospective Cohort Study

Published in: Annals of Epidemiology, v. 26, no. 2, Feb. 2016, p. 122-128

Posted on RAND.org on March 29, 2016

by Phoebe K. McCutchan, Xian Liu, Cynthia A. LeardMann, Tyler C. Smith, Edward J. Boyko, Kristie Gore, Michael C. Freed, Charles C. Engel

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Research Questions

  1. What is the likelihood that service members will report multiple physical symptoms (MPS) after deployment to a combat zone?
  2. Does combat experience affect the probability of reporting MPS?

PURPOSE: Multiple physical symptoms (MPS) have historically been observed after deployment to a combat zone and are often disabling in nature. This study examined longitudinal trends in MPS status and its relationship to deployment in U.S. military service members. METHODS: Using longitudinal data from panel 1 participants in the Millennium Cohort Study (n = 76,924), MPS status was assessed at three time points (2001–2008) using the 15-item Patient Health Questionnaire. Probability of reporting MPS was analyzed using mixed-effects multinomial logit regression, with time and deployment experience as main explanatory variables. RESULTS: After adjustment for demographic, military, and health characteristics, service members who deployed with combat were significantly more likely to report MPS at each time point compared with those not deployed (odds ratio [OR] and 95% confidence interval [CI] for wave 1 = 1.49 [1.47-1.52], wave 2 = 1.73 [1.69-1.78], wave 3 = 2.08 [2.03–2.12]), and those who deployed without combat (OR and CI for wave 1 = 2.66 [2.59-2.74], wave 2 = 1.81 [1.75-1.87]; wave 3 = 1.68 [1.63-1.74]). CONCLUSIONS: Longitudinal trends indicate that the probability of reporting MPS has increased consistently over time only for those deployed, regardless of combat experience.

Key Findings

  • The probability of reporting MPS increases over time for those who were deployed, whether they experienced combat or not.
  • Service members who were not deployed were not more likely to report MPS.
  • Those with combat experience were even more likely to report MPS than service members who were deployed but did not experience combat.
  • The increased risk of reporting MPS among those deployed suggests long-term effects not only on health and well-being of service members, but also force readiness and the civilian workforce after individuals leave active duty.

Recommendation

The military health system should consider developing models of care that address service members' health functionality as they return from deployment and develop symptoms, as opposed to focusing primarily on the causes of diseases as they become apparent.

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