Jaime L. Horton

Trajectories of trauma symptoms and resilience in deployed US military service members: prospective cohort study

BACKGROUND Most previous attempts to determine the psychological cost of military deployment have been limited by reliance on convenience samples, lack of pre-deployment data or confidentiality and cross-sectional designs. AIMS This study addressed these limitations using a population-based, prospective cohort of U.S. military personnel deployed in support of the operations in Iraq and Afghanistan. METHOD The sample consisted of U.S. military service members in all branches including active duty, reserve and national guard who deployed once (n = 3393) or multiple times (n = 4394). Self-reported symptoms of post-traumatic stress were obtained prior to deployment and at two follow-ups spaced 3 years apart. Data were examined for longitudinal trajectories using latent growth mixture modelling. RESULTS Each analysis revealed remarkably similar post-traumatic stress trajectories across time. The most common pattern was low-stable post-traumatic stress or resilience (83.1% single deployers, 84.9% multiple deployers), moderate-improving (8.0%, 8.5%), then worsening-chronic post-traumatic stress (6.7%, 4.5%), high-stable (2.2% single deployers only) and high-improving (2.2% multiple deployers only). Covariates associated with each trajectory were identified. CONCLUSIONS The final models exhibited similar types of trajectories for single and multiple deployers; most notably, the stable trajectory of low post-traumatic stress preto post-deployment, or resilience, was exceptionally high. Several factors predicting trajectories were identified, which we hope will assist in future research aimed at decreasing the risk of post-traumatic stress disorder among deployers.

Assessing nonresponse bias at follow-up in a large prospective cohort of relatively young and mobile military service members

BackgroundNonresponse bias in a longitudinal study could affect the magnitude and direction of measures of association. We identified sociodemographic, behavioral, military, and health-related predictors of response to the first follow-up questionnaire in a large military cohort and assessed the extent to which nonresponse biased measures of association.MethodsData are from the baseline and first follow-up survey of the Millennium Cohort Study. Seventy-six thousand, seven hundred and seventy-five eligible individuals completed the baseline survey and were presumed alive at the time of follow-up; of these, 54,960 (71.6%) completed the first follow-up survey. Logistic regression models were used to calculate inverse probability weights using propensity scores.ResultsCharacteristics associated with a greater probability of response included female gender, older age, higher education level, officer rank, active-duty status, and a self-reported history of military exposures. Ever smokers, those with a history of chronic alcohol consumption or a major depressive disorder, and those separated from the military at follow-up had a lower probability of response. Nonresponse to the follow-up questionnaire did not result in appreciable bias; bias was greatest in subgroups with small numbers.ConclusionsThese findings suggest that prospective analyses from this cohort are not substantially biased by non-response at the first follow-up assessment.

Bodybuilding, Energy, and Weight-Loss Supplements Are Associated With Deployment and Physical Activity in U.S. Military Personnel

PURPOSE The characteristics of U.S. military personnel who use dietary supplements have not been well described. This study aimed to determine whether deployment experience and physical activity were associated with the use of bodybuilding, energy, or weight-loss supplement among U.S. military personnel. METHODS Self-reported data from active-duty, Reserve, and National Guard participants of the Millennium Cohort Study collected from 2007-2008 (n = 106,698) on supplement use, physical activity, and other behavioral data were linked with deployment and demographic data. We used multivariable logistic regression sex-stratified models to compare the adjusted odds of each type of supplement use among those with deployment experience in support of operations in Iraq or Afghanistan and those engaged in aerobic or strength-training activities. RESULTS Overall, 46.7% of participants reported using at least one type of supplement, and 22.0% reported using multiple supplements. Male deployers were more likely to use bodybuilding supplements, whereas female deployers were more likely to use weight-loss supplements. Physically active and younger subjects reported all types of supplement use. Men and women reporting 5 or less hours of sleep per night were more likely to use energy supplements. CONCLUSIONS The high prevalence of supplement use and important characteristics found to be associated with their use, including deployment, physical activity, and suboptimal sleep, suggest focus areas for future research and adverse event monitoring.

A comparison of the PRIME-MD PHQ-9 and PHQ-8 in a large military prospective study, the Millennium Cohort Study

BACKGROUND In light of increased concerns about suicide in the military, institutional review boards have mandated increased scrutiny of the final item on the depression screening tool, the PHQ-9, which asks about suicidal thoughts. Since real-time monitoring of all individual responses in most observational studies is not feasible, many investigators have adopted the PHQ-8, choosing to remove the ninth item. This study compares the performance of the PHQ-8 with the PHQ-9 in a population-based sample of military or nonmilitary subjects. METHODS The Millennium Cohort Study administers a self-reported questionnaire that includes the PHQ-9 at 3-year intervals to current and former U.S. military personnel. PHQ-9 responses of 143,705 Millennium Cohort members were investigated. Cross-sectional comparisons of the PHQ-9 and PHQ-8 and prospective analyses to detect a 5-unit change in these measures were performed. RESULTS Greater than substantial agreement was found between the PHQ-8 and 9 instruments (kappas, 0.966-0.974 depending on survey cycle). There was similarly high agreement between the PHQ-8 and 9 in detecting a 5-point increase (κ=0.987) or decrease (κ=0.984) in score. LIMITATIONS One potential limitation of this study is that participants completed the PHQ-9, and PHQ-8 scores were extrapolated from the PHQ-9. In addition, the Millennium Cohort may not fully represent the U.S. military; though previous evaluations have shown the cohort to be a well-representative sample. CONCLUSIONS Since excellent agreement was detected between the PHQ-8 and PHQ-9 instruments, the PHQ-8 would capture nearly all the same cases of depression as the PHQ-9 in populations similar to the one in this study.

The impact of prior deployment experience on civilian employment after military service

Objective To determine if deployment to recent military operations or other health, demographic, or military-related characteristics were associated with employment after military service. Methods Former US active duty military service members participating in the Millennium Cohort Study, a population-based sample of US military personnel that began in July of 2001, were prospectively followed from the time of baseline health reporting to self-reported employment status after military separation. Results Of the 9099 separated personnel meeting inclusion criteria, 17% reported unemployment after military service. In multivariable modelling, prior deployment experiences, with or without reported combat, and post-traumatic stress disorder (PTSD) were not significantly associated with employment status postservice. Among those who routinely retired from service with a pension, positive screens for depression (OR, 1.67; 95% CI, 1.05 to 2.63) and panic/anxiety (OR, 1.63; 95% CI, 1.10 to 2.43) were significantly associated with subsequent unemployment. Poor physical health, female sex, black race, lower education and disabling illnesses/injuries were also predictive of postservice unemployment. Conclusions After stratifying for reason for military separation, mental disorders like depression or panic/anxiety and poor physical health may have greater impact than prior deployment experiences or PTSD on the ability to find or maintain employment postservice. These findings may guide support for veterans most in need of job placement services after military service.

Posttraumatic stress disorder and depression among U.S. military health care professionals deployed in support of operations in Iraq and Afghanistan.

Limited prospective studies exist that evaluate the mental health status of military health care professionals who have deployed. This study used prospective data from the Millennium Cohort Study with longitudinal analysis techniques to examine whether health care professionals deployed in support of the operations in Iraq and Afghanistan were more likely to screen positive for new-onset posttraumatic stress disorder (PTSD) or depression after deployment than individuals from other occupations. Of 65,108 subjects included, 9,371 (14.4%) reported working as health care professionals. The rates of new positive screens for PTSD or depression were similar for those in health care occupations (4.7% and 4.3%) compared with those in other occupations (4.6% and 3.9%) for the first and second follow-up, respectively. Among military personnel deployed with combat experience, health care professionals did not have increased odds for new-onset PTSD or depression over time. Among deployed health care professionals, combat experience significantly increased the odds: adjusted odds ratio = 2.01; 95% confidence interval [1.06, 3.83] for new-onset PTSD or depression. These results suggest that combat experience, not features specific to being a health care professional, was the key exposure explaining the development of these outcomes.

Trends in New U.S. Marine Corps Accessions During the Recent Conflicts in Iraq and Afghanistan

The objective of this study was to analyze trends in preservice characteristics among Marine Corps recruits during the recent operations in Iraq and Afghanistan. Recruits completed a confidential survey during their first week of training at the Marine Corps Recruit Depot in San Diego, California. Demographics, behaviors, and health information were analyzed for trends from 2001 to 2010 using the Cochran-Armitage trend test and F statistic. Data from 131,961 male recruits with a mean age of 19.8 years were analyzed. Overall, entry characteristics remained stable exhibiting only modest changes over the study period. Favorable trends included recent (2009-2010) improvements in body mass index and physical activity levels. Unfavorable trends included increases in smokeless tobacco and caffeine use, and angry outbursts. Although many recruit characteristics remained similar over the past decade, both favorable and unfavorable trends in sociobehavioral characteristics were noted. The ongoing assessment of preservice characteristics is important for detecting emerging trends over time. Findings may guide leaderships understanding of changes to help develop early-service trainings promoting a healthier force and potentially reducing future adverse outcomes.

The impact of deployment experience and prior healthcare utilization on enrollment in a large military cohort study

BackgroundLongitudinal cohort studies are highly valued in epidemiologic research for their ability to establish exposure-disease associations through known temporal sequences. A major challenge in cohort studies is recruiting individuals representative of the targeted sample population to ensure the generalizability of the study’s findings.MethodsWe evaluated nearly 350,000 invited subjects (from 2004-2008) of the Millennium Cohort Study, a prospective cohort study of the health of US military personnel, for factors prior to invitation associated with study enrollment. Multivariable logistic regression was utilized, adjusting for demographic and other confounders, to determine the associations between both deployment experience and prior healthcare utilization with enrollment into the study.ResultsStudy enrollment was significantly greater among those who deployed prior to and/or during the enrollment cycles or had at least one outpatient visit in the 12 months prior to invitation. Mental disorders and hospitalization for more than two days within the past year were associated with reduced odds of enrollment.ConclusionsThese findings suggest differential enrollment by deployment experience and health status, and may help guide recruitment efforts in future studies.

Prescription Stimulants and PTSD Among U.S. Military Service Members.

Posttraumatic stress disorder (PTSD) is a prevalent condition among military service members and civilians who have experienced traumatic events. Stimulant use has been postulated to increase the risk of incident PTSD; however, research in this area is lacking. In this study, the association between receipt of prescription stimulants and PTSD was examined in a secondary analysis among active duty U.S. military members (n = 25,971), participating in the Millennium Cohort Study, who completed a baseline (2001-2003) and two follow-up surveys (between 2004-2008). Prescription stimulant data were obtained from the military Pharmacy Data Transaction Service. PTSD was assessed using the PTSD Checklist-Civilian Version and incident PTSD was defined as meeting the criteria at follow-up among those who did not have a history of PTSD at baseline. Overall, 1,215 (4.7%) persons developed new-onset PTSD during follow-up. Receipt of prescription stimulants were significantly associated with incident PTSD, hazard ratio = 5.09, 95% confidence interval [3.05, 8.50], after adjusting for sociodemographic factors, military characteristics, attention-deficit/hyperactivity disorder, baseline mental and physical health status, deployment experiences, and physical/sexual trauma. Findings suggested that prescription stimulants are associated with incident PTSD among military personnel; these data may inform the underlying pathogenesis of and preventive strategies for PTSD.