Baseline functional health predicts vulnerability to posttraumatic stress disorder following combat deployment

Background: It has been well established that posttraumatic stress disorder (PTSD) is associated with a variety of adverse health effects, including reduced functional health and quality of life, as well as an increased number of physical symptoms and comorbidities. Most previous studies have relied on cross-sectional or retrospective data, and therefore it has not been temporally established whether PTSD causes health status to deteriorate and quality of life to worsen, or conversely, whether those with poor mental and physical health status are more vulnerable to developing PTSD.

Objectives: To examine if baseline functional health status, as measured by the 36-item Short Form Health Survey for Veterans, predicts new-onset PTSD symptoms or diagnosis among deployed personnel with combat exposure.

Methods: Participants consisted of combat-deployed Millennium Cohort Study members who submitted baseline and follow-up questionnaires. Baseline Mental Component Summary (MCS) and Physical Component Summary (PCS) scores were categorized into three groups, with the highest and lowest group representing a total of 30% of the study population, while the remaining 70% represented the group in the middle. The PTSD Checklist, augmented by a self-reported question, was used to assess PTSD at follow-up. Descriptive statistics and univariate analyses were completed to compare characteristics and functional health of participants with and without new-onset PTSD. Multivariable modeling adjusting for potential confounders was conducted to investigate associations between predeployment functional health scores and new-onset PTSD at follow-up.

Results: Of the 5,410 eligible participants, 395 (7.3%) had new-onset PTSD symptoms and/or diagnosis at the time of follow-up. Study participants whose baseline MCS scores were in the lowest 15th percentile were proportionately more likely to be female, younger, less educated, current smokers, problem drinkers, and enlisted service members. Participants whose PCS scores were in the lowest 15th percentile were proportionately more likely to be less educated, past or current smokers, problem drinkers, and enlisted and active-duty service members. Individuals whose MCS or PCS scores were in the lowest 15th percentile at baseline were more than two times as likely to develop PTSD by follow-up compared with those with average MCS or PCS scores, and represented 58% of the post-combat-deployment PTSD burden.

Conclusions: The current study indicates that low physical or mental health status prior to combat exposure significantly increases the risk of developing PTSD after deployment and represents an identifiable subgroup that may benefit from targeted interventions to improve functional health prior to deployment.