Epidemiology of Major Depressive Disorder Disability in the US Military: FY 2007-2012.

This study assesses the incidence of major depressive disorder (MDD) disability discharge and retirement in the Army, Navy, Marine Corps and Air Force and describes MDD comorbidity. Service members with a disability discharge for either MDD (n = 2,882) or any nonpsychiatric disability (n = 56,145), between fiscal years 2007 and 2012, were included in the study population. Those with MDD disability at first evaluation but not at last evaluation were excluded. The incidence of MDD disability discharge increased significantly in the Army and Air Force between fiscal years 2007 and 2012. MDD disability retirement significantly increased in the Army, Navy, and Air Force. Females, and those who experienced at least one deployment, had higher incidence rates of MDD disability discharge. All services included spinal diseases and posttraumatic stress disorder in their top five comorbid categories. Given the association between trauma and MDD, further research into the role of both combat exposure and injury on MDD is merited.

Preenlistment and Early Service Risk Factors for Traumatic Brain Injury in the Army and Marine Corps: FY 2002-2010.

OBJECTIVE: To determine the preenlistment and early service risk factors for traumatic brain injury (TBI)-related disability in Army and Marine Corps service members. DESIGN: Matched case-control design. MAIN OUTCOME: TBI disability discharges. SUBJECTS: Army and Marine Corps service members with an enlistment record and disability discharge for TBI were included as cases. Controls were selected from the enlisted population with no disability evaluation record and were matched on fiscal year of enlistment, sex, and service at a ratio of 5:1. RESULTS: Older age at enlistment resulted in a significantly increased risk for TBI disability in the crude and adjusted models (adjusted odds ratio [aOR] = 1.49; 95% confidence interval [CI], 1.16-1.91). An enlistment military occupational specialty (MOS) with a combat arms designation resulted in an almost 3-fold increased odds of TBI disability compared with other MOS categories (aOR = 2.75; 95% CI, 2.46-3.09). This remained a significant risk factor for TBI disability in the multivariate model (aOR = 2.74; 95% CI, 2.45-3.08). CONCLUSION: Results from this study help inform the existing body of military TBI research by highlighting the preenlistment demographic and early service risk factors for TBI disability. Further research into the role of age on TBI disability in the military is merited.

Towards a blood-based diagnostic panel for bipolar disorder.

BACKGROUND: Bipolar disorder (BD) is a costly, devastating and life shortening mental disorder that is often misdiagnosed, especially on initial presentation. Misdiagnosis frequently results in ineffective treatment. We investigated the utility of a biomarker panel as a diagnostic test for BD. METHODS AND FINDINGS: We performed a meta-analysis of eight case-control studies to define a diagnostic biomarker panel for BD. After validating the panel on established BD patients, we applied it to undiagnosed BD patients. We analysed 249 BD, 122 pre-diagnostic BD, 75 pre-diagnostic schizophrenia and 90 first onset major depression disorder (MDD) patients and 371 controls. The biomarker panel was identified using ten-fold cross-validation with lasso regression applied to the 87 analytes available across the meta-analysis studies. We identified 20 protein analytes with excellent predictive performance [area under the curve (AUC)⩾0.90]. Importantly, the panel had a good predictive performance (AUC 0.84) to differentiate 12 misdiagnosed BD patients from 90 first onset MDD patients, and a fair to good predictive performance (AUC 0.79) to differentiate between 110 pre-diagnostic BD patients and 184 controls. We also demonstrated the disease specificity of the panel. CONCLUSIONS: An early and accurate diagnosis has the potential to delay or even prevent the onset of BD. This study demonstrates the potential utility of a biomarker panel as a diagnostic test for BD.

Epidemiology of asthma-related disability in the U.S. Armed Forces: 2007-2012.

OBJECTIVE: To characterize the demographic, disability and deployment characteristics of U.S. Armed Forces personnel with an asthma-related disability discharge, which includes separation (without benefits) and retirement (with disability benefits). METHODS: Incidence rates for personnel evaluated for disability discharge and/or disability retired due to asthma and due to all other causes of disability discharge were calculated per 100,000 active duty enlisted service members by year. Multivariate logistical regression was used to examine the associations between disability retirement and several demographic and disability characteristics of service members evaluated for asthma-related disability discharge versus those evaluated for any other non-respiratory condition for each branch of military service. RESULTS: Service members evaluated for disability discharge related to asthma most often do not have comorbidity and are disability retired rather than separated, with rates of disability retirement increasing over time. Groups with a significantly higher incidence of evaluation for asthma-related disability include females, individuals who entered the military prior to the age of 20, non-Whites, and those with a history of deployment to Iraq or Afghanistan. The characteristic most associated with the odds of disability retirement was a history of deployment. CONCLUSIONS: New-onset asthma occurring after military entry often causes occupational impairment in service members, especially in those that have been deployed to Iraq or Afghanistan.

Predictors of the Onset of Schizophrenia in US Military Personnel.

Alterations in immune response may be an important component in the etiopathogenesis of schizophrenia and bipolar disorder. We examined the associations of pentraxin-3 (PTX3) with the onset of schizophrenia or bipolar disorder. We tested preonset serum specimens from 160 US military service members who were later diagnosed with schizophrenia or bipolar disorder and 160 matched controls without psychiatric disorders. Lower serum levels of PTX3 were predictive of schizophrenia but not of bipolar disorder. Subjects with below-median PTX3 levels had a 3.0 odds ratio (confidence interval, 1.6-5.7) for schizophrenia onset in the multivariable logistic regression model controlling for demographic and military variables. The test for trends was significant (p = 0.002), with the likelihood increasing as the levels of PTX3 decreased. Crude and adjusted categorized levels were not predictive of bipolar disorder. A lower level of inflammatory response indicated by PTX3 might be implicated in developing schizophrenia.

Trends in the epidemiology of disability related to traumatic brain injury in the US Army and Marine Corps: 2005 to 2010.

BACKGROUND: Traumatic brain injury (TBI) has been recognized as a major public health issue for several decades. Despite technological advancements in protective equipment and medical care available during recent military conflicts, TBI is the most common neurological condition among Soldiers and Marines evaluated for discharge from service. This study describes the demographic, service-related, and disability characteristics of Soldiers and Marines referred for combat-related TBI disability evaluation. METHODS: Cross-sectional analysis of Soldiers and Marines evaluated for combat-related disability between October 1, 2004 and September 30, 2010 was performed. Traumatic brain injury cases were identified using the Veterans Affairs Schedule for Rating Disabilities code for TBI and compared with other combat-related disabilities. RESULTS: Combat-related TBI disability rates have significantly increased in both the Army and the Marine Corps since 2005. Significantly more unfitting conditions are present on average in combat-related TBI cases than in other combat-related disability cases. Combat-related TBI disability cases are more likely to be medically retired than other types of combat-related disability. CONCLUSIONS: Because veterans with combat-related TBI disabilities are likely to require chronic care for TBI-associated medical conditions, disability evaluation policy and programs must ensure that combat-related TBI disabilities are accurately identified and compensated, and the potential long-term care needs are addressed.

Pre-enlistment hearing loss and hearing loss disability among US soldiers and marines.

Hearing loss is a common condition among US adults, with some evidence of increasing prevalence in young adults. Noise-induced hearing loss attributable to employment is a significant source of preventable morbidity world-wide. The US military population is largely comprised of young adult males serving in a wide variety of occupations, many in high noise-level conditions, at least episodically. To identify accession and service-related risk factors for hearing-related disability, matched case-control study of US military personnel was conducted. Individuals evaluated for hearing loss disability in the US Army and Marine Corps were frequency matched to controls without history of disability evaluation on service and enlistment year. Conditional logistic regression was used to examine the association between accession and service-related factors and hearing-related disability evaluations between October 2002 and September 2010. Individuals with medically disqualifying audiograms or hearing loss diagnoses at application for military service were 8 and 4 times more likely, respectively, to have a disability evaluation related to hearing loss, after controlling for relevant accession, demographic, and service-related factors. Conservative hearing loss thresholds on pre-enlistment audiograms, stricter hearing loss medical waiver policies or qualified baseline audiograms pre-enlistment are needed in the U.S military. Industrial corporations or labor unions may also benefit from identifying individuals with moderate hearing loss at the time of employment to ensure use of personal protective equipment and engineer controls of noise.

Temporal trends in the epidemiology of disabilities related to posttraumatic stress disorder in the U.S. Army and Marine Corps from 2005-2010.

Since the start of Operation Iraqi Freedom and Operation Enduring Freedom, over 2 million U.S. military members were deployed to Iraq and Afghanistan. The estimated prevalence of posttraumatic stress disorder (PTSD) among soldiers and Marines returning from combat zones varies from 5%-20%; little is known about those individuals whose PTSD renders them unfit for duty. This report describes the rates and correlates of PTSD in soldiers and Marines evaluated for disability. Data for service members who underwent disability evaluation between fiscal years 2005-2010 were analyzed for trends in disability rates, ratings, retirement, and comorbid disability. PTSD rates varied by age, sex, race, rank, branch of service, and component. Most cases were deployed and were considered combat-related. Over the study period, the rate and severity of disability from PTSD increased substantially. Significant increases in disability from PTSD incidence, rating, and retirement were observed in both services. Other medical conditions, largely musculoskeletal and neurological, were present in the majority of cases indicating many cases also experienced disabling physical injuries. Further research is needed to target interventions accurately for redeploying service members to minimize comorbidity associated with disability from PTSD and facilitate continuation in military service or successful transition to civilian life.

Risk factors for medical disability in U.S. enlisted Marines: fiscal years 2001 to 2009.

OBJECTIVE: To assess factors associated with medical disability in the U.S. Marine Corps. METHODS: Case-control study enrolling 11,554 medical disability cases of U.S. enlisted Marines referred to the Physical Evaluation Board fiscal year 2001 to 2009 and 42,216 controls frequency matched to cases in a 4:1 ratio on year of accession into the service were analyzed utilizing bivariate and multivariate logistic regression analysis. RESULTS: Increased age and body mass index at accession were associated with higher odds of medical disability. Females (odds ratio adjusted [OR(adj)] = 1.3, 95% confidence interval [CI] = 1.2-1.3) have higher odds of disability than males. "Healthy Warrior Effect" was observed in that those who deployed (OR(adj) = 0.48, 95% CI = 0.46-0.50) had decreased odds of medical disability than those who did not deploy. Medical waivers at accession (OR(adj) = 1.12, 95% CI = 1.01-1.23) increased the odds of medical disability. CONCLUSIONS: Continued surveillance of the disability evaluation system is needed to help develop preventive measures and to help policy makers establish evidence-based policies on accession, deployment, and retention standards over the lifecycle of service members.

A noncognitive temperament test to predict risk of mental disorders and attrition in U.S. Army recruits.

UNLABELLED: U.S. military accession mental health screening includes cognitive testing and questions regarding the applicants' past mental health history. This process relies on applicants' knowledge of and willingness to disclose symptoms and conditions. Applicants have a strong incentive to appear qualified, which has resulted in a long history of frequent mental health conditions presenting during recruit training. OBJECTIVE: To assess the predictive value of a pre-enlistment noncognitive temperament test score for risk of mental disorders and attrition in the first year of service. METHODS: A retrospective cohort study was conducted on non-high school diploma U.S. Army active duty recruits who took the Assessment of Individual Motivation (AIM). Multivariate logistic regression models were used to determine associations between AIM score quintiles, mental disorders, and attrition. RESULTS: AIM scorers in the lowest quintile were at increased risk for a mental disorder (OR, 1.44; 95% CI, 1.35-1.53) and of discharge (OR, 1.65; 95% CI, 1.44-1.68) compared to AIM scorers in the highest quintile, with significant linear trends for decreased risk with increasing AIM score. CONCLUSIONS: AIM offers the potential to improve screening of military applicants and reduce mental disorders and attrition in new recruits beyond the current process.

Temporary disability retirement cases: variations in time to final disposition and disability rating by service and medical condition.

OBJECTIVE: Service members undergoing disability evaluation are placed on the temporary disability retirement list (TDRL) when their disabling medical condition(s) may change in severity over time. Information is sparse on the epidemiology of the TDRL population and factors influencing time spent on the TDRL or changes in compensation ratings before final disability outcome. METHODS: A cross-sectional study was conducted on U.S. Army, Navy, and Marine Corps personnel placed on the TDRL between fiscal years 2005 to 2009. RESULTS: Approximately 85% of cases were finalized at first re-evaluation and more than 75% were permanently retired. Overall, about 50% of cases retained the same disability rating throughout the process. Cases with medical conditions within two or more body systems were more likely to be permanently retired and receive a change in disability rating than those with medical condition(s) within a single body system. CONCLUSIONS: Most cases retained the same disability rating and were permanently retired by the first re-evaluation. Important areas of future research include cost-benefit analyses to determine if length of time currently allowable on the TDRL can be shortened or if repeated evaluations are necessary and exploration of specific medical conditions likely to change in severity over time.

Self-reported physical activity and preaccession fitness testing in U.S. Army applicants.

The Assessment of Recruit Motivation and Strength (ARMS) study evaluated a physical fitness screening test for Army applicants before basic training. This report examines applicants' self-reported physical activity as a predictor of objective fitness measured by ARMS. In 2006, the ARMS study administered a fitness test and physical activity survey to Army applicants during their medical evaluation, using multiple logistic regression for comparison. Among both men and women, "qualified" and "exceeds-body-fat" subjects who met American College of Sports Medicine adult physical activity guidelines were more likely to pass the fitness test. Overall, subjects who met physical activity recommendations, watched less television, and played on sports teams had a higher odds of passing the ARMS test after adjustment for age, race, and smoking status. This study demonstrates that self-reported physical activity was associated with physical fitness and may be used to identify those at risk of failing a preaccession fitness test.

Risk factors for disability retirement among healthy adults joining the U.S. Army.

OBJECTIVE: From 2001 to 2006, the Army deployed over 717,000 personnel to Iraq and Afghanistan, with over 15,000 troops wounded. Little is known about the impact of military and demographic factors, particularly deployment, occupation, and pre-existing medical status, on disability retirement. METHODS: A nested case-control study of first time, active duty personnel entering from 1997 to 2004. Cases, individuals granted a medical disability retirement from 1997 to 2006, were identified by the Army Physical Disability Agency. Five controls were matched by year of entrance to each case. RESULTS: Several factors were associated with increased risk of disability retirement, including sex, age, Hispanic ethnicity, body mass index, and military occupation; deployment was associated with a lower risk. CONCLUSIONS: The reasons for increased risk among some groups are unknown. The decreased risk associated with deployment probably reflects a "healthy warrior effect," whereas the increased risk for combat arms may reflect combat exposures among the deployed and more rigorous training among the nondeployed.

Exertional heat illness among overweight U.S. Army recruits in basic training.

INTRODUCTION: Heat illness has not declined in the U.S. military despite preventive measures. The increase in overweight recruits entering the U.S. military may lead to an increase in heat-related events. This study compares the risk of heat illness among U.S. Army recruits who exceeded body fat standards at accession to those who met standards. METHODS: Recruits with excess body fat and qualified applicants to the Army were required to take a preaccession fitness test during the study period (February 2005 through September 2006). The test included a 5-min step test and 1-min push-up challenge, scored as pass or fail. Incidence and outpatient usage for heat illness (any heat illness, heat stroke, heat exhaustion, and other heat illness) at 90 d of service were compared in 9667 male recruits of whom 826 had excess body fat and 8841 were qualified. There were too few heat events among women for analysis. RESULTS: The incidence odds ratio among male recruits with excess body fat compared to qualified male recruits was 3.63 (95% CI: 1.92, 6.85). Men with excess body fat had an increased incidence of heat illness with a rate ratio of 7.25 (95% CI: 4.17, 12.61). DISCUSSION: Although there were few heat illness events, the results indicate a significantly increased risk of heat illness and outpatient utilization among male recruits with excess body fat. It was estimated that approximately 70% of the relative risk for heat illnesses in men with excess body fat during basic training was associated with exceeding body fat standards. These findings may have implications for military accession and training.

Descriptive epidemiology of bipolar I disorder among United States military personnel.

Psychiatric disorders in military members require substantial medical, administrative, and financial resources, and are among the leading causes of hospitalization and early discharge. We reviewed available data to better understand the incidence of bipolar I disorder among military personnel. Defense Medical Epidemiology Database inpatient data were used. Descriptive and comparative statistics were performed. From 1997-2006 there were 3,317 first hospitalizations for bipolar I disorder with a mean of 1.2 hospitalizations per case. The rate of first occurrence among this adult population was 0.24 per 1,000 person-years. The incidence increased over time for depressed and mixed episode types among both genders. High risk groups include women, younger individuals, and whites. This population provides insight into adult onset bipolar I disorder incidence and demographic patterns not available elsewhere and offers potential opportunities to improve its understanding.

Selected infectious agents and risk of schizophrenia among U.S. military personnel.

OBJECTIVE: A number of studies have reported associations between Toxoplasma gondii (T. gondii) infection and the risk of schizophrenia. Most existing studies have used small populations and postdiagnosis specimens. As part of a larger research program, the authors conducted a hypothesis-generating case control study of T. gondii antibodies among individuals discharged from the U.S. military with a diagnosis of schizophrenia and serum specimens available from both before and after diagnosis. METHOD: The patients (N=180) were military members who had been hospitalized and discharged from military service with a diagnosis of schizophrenia. Healthy comparison subjects (3:1 matched on several factors) were members of the military who were not discharged. The U.S. military routinely collects and stores serum specimens of military service members. The authors used microplate-enzyme immunoassay to measure immunoglobulin G (IgG) antibody levels to T. gondii, six herpes viruses, and influenza A and B viruses and immunoglobulin M (IgM) antibody levels to T. gondii in pre- and postdiagnosis serum specimens. RESULTS: A significant positive association between the T. gondii IgG antibody and schizophrenia was found; the overall hazard ratio was 1.24. The association between IgG and schizophrenia varied by the time between the serum specimen collection and onset of illness. CONCLUSION: The authors found significant associations between increased levels of scaled T. gondii IgG antibodies and schizophrenia for antibodies measured both prior to and after diagnosis.

Monocyte activation detected prior to a diagnosis of schizophrenia in the US Military New Onset Psychosis Project (MNOPP).

Low-grade inflammation is present in some cases of schizophrenia, particularly in the early stages of this disorder. The inflammation source is not known but may be the result of dysbiotic processes occurring in the gut. We examined peripheral biomarkers of bacterial translocation, soluble CD14 (sCD14) and lipopolysaccharide binding protein (LBP), and of general inflammation, C-reactive protein (CRP), in a unique, pre-onset study of schizophrenia. This sample was composed of 80 case-control matched pairs of US military service members from whom blood samples were obtained at time of entry to service, before a psychiatric diagnosis was made. Elevated levels of sCD14 in individuals who were subsequently diagnosed with schizophrenia generated odds ratios of 1.22 for association with disease (p<0.02). Conversely, LBP levels for those who developed schizophrenia were unchanged or very marginally decreased compared to controls (p=0.06). No significant changes were found for CRP in schizophrenia compared with their matched controls. This diversity of patterns suggests that a dysregulated immune system is present prior to a diagnosis of schizophrenia. In particular, sCD14 elevation and discordant LBP decrease in cases support a more generalized monocyte activation rather than a specific translocation of gut bacteria into circulation. The corresponding absence of general inflammation as measured by CRP may indicate that this monocyte activation or related immune dysfunction precedes the early inflammatory stage frequently evident in schizophrenia.

Evaluation of data obtained from military disability medical administrative databases for service members with schizophrenia or bipolar disorder.

OBJECTIVE: We are studying associations between selected biomarkers and schizophrenia or bipolar disorder among military personnel. To assess potential diagnostic misclassification and to estimate the date of illness onset, we reviewed medical records for a subset of cases. METHODS: Two psychiatrists independently reviewed 182 service medical records retrieved from the Department of Veterans Affairs. Data were evaluated for diagnostic concordance between database diagnoses and reviewers. Interreviewer variability was measured by using proportion of agreement and the kappa statistic. Data were abstracted to estimate date of onset. RESULTS: High levels of agreement existed between database diagnoses and reviewers (proportion, 94.7%; kappa = 0.88) and between reviewers (proportion, 92.3%; kappa = 0.87). The median time between illness onset and initiation of medical discharge was 1.6 and 1.1 years for schizophrenia and bipolar disorder, respectively. CONCLUSIONS: High levels of agreement between investigators and database diagnoses indicate that diagnostic misclassification is unlikely. Discharge procedure initiation date provides a suitable surrogate for disease onset.

Non-Cognitive Personality Assessment and Risk of Injuries Among Army Trainees.

INTRODUCTION: Low levels of pre-accession physical fitness and activity are risk factors for stress fractures and other overuse musculoskeletal injuries among military trainees. One dimension in the Tailored Adaptive Personality Assessment System (TAPAS), a non-cognitive personality test given to Army applicants, specifically assesses propensity to engage in physical activity. This dimension may serve as a surrogate measure for activity or fitness. The study examines the associations between TAPAS dimension scores and risk of musculoskeletal injuries. METHODS: Fifteen TAPAS dimension scores for 15,082 U.S. Army trainees entering military service in 2010 were provided by the U.S. Army Research Institute for Social and Behavioral Sciences. During 2013-2015, the associations between TAPAS dimension scores (as a continuous variable) and injuries in the first 6 months of service were evaluated using logistic regression, with the measure of association being the OR. RESULTS: The TAPAS physical conditioning dimension was associated with musculoskeletal injuries and stress fractures among both men (musculoskeletal injury, OR=0.83, 95% CI=0.79, 0.86; stress fracture, OR=0.68, 95% CI=0.57, 0.80) and women (musculoskeletal injury, OR=0.77, 95% CI=0.70, 0.85; stress fracture, OR=0.60, 95% CI=0.43, 082). No other dimensions were both significantly and consistently associated with either injury. CONCLUSIONS: The TAPAS physical conditioning dimension is a strong predictor of musculoskeletal injury and stress fracture among male and female U.S. Army trainees, and may serve as a pre-accession screen for self-reported physical activity.

Excess Stress Fractures, Musculoskeletal Injuries, and Health Care Utilization Among Unfit and Overweight Female Army Trainees.

BACKGROUND: Musculoskeletal injuries are prevalent among military trainees and certain occupations. Fitness and body mass index (BMI) have been associated with musculoskeletal conditions, including stress fractures. HYPOTHESIS: The incidence of, and excess health care utilization for, stress fracture and non-stress fracture overuse musculoskeletal injuries during the first 6 months of service is higher among unfit female recruits. Those who exceeded body fat limits are at a greater risk of incident stress fractures, injuries, or health care utilization compared with weight-qualified recruits. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: All applicants to the United States Army were required to take a preaccession fitness test during the study period (February 2005-September 2006). The test included a 5-minute step test scored as pass or fail. BMI was recorded at application. There were 2 distinct comparisons made in this study: (1) between weight-qualified physically fit and unfit women and (2) between weight-qualified physically fit women and those who exceeded body fat limits. We compared the incidence of, and excess health care utilization for, musculoskeletal injuries, including stress fractures and physical therapy visits, during the first 183 days of military service. RESULTS: Among the weight-qualified women, unfit participants had a higher non-stress fracture injury incidence and related excess health care utilization rate compared with fit women, with rate ratios of 1.32 (95% CI, 1.14-1.53) and 1.18 (95% CI, 1.10-1.27), respectively. Among fit women, compared with the weight-qualified participants, those exceeding body fat limits had higher rate ratios for non-stress fracture injury incidence and related excess health care utilization of 1.27 (95% CI, 1.07-1.50) and 1.20 (95% CI, 1.11-1.31), respectively. Weight-qualified women who were unfit had a higher incidence of stress fractures and related excess health care utilization compared with fit women, with rate ratios of 1.62 (95% CI, 1.19-2.21) and 1.22 (95% CI, 1.10-1.36), respectively. Among fit women exceeding body fat limits, the stress fracture incidence and related excess health care utilization rate ratios were 0.79 (95% CI, 0.49-1.28) and 1.44 (95% CI, 1.20-1.72), respectively, compared with those who were weight qualified. CONCLUSION: The results indicate a significantly increased risk of musculoskeletal injuries, including stress fractures, among unfit recruits and an increased risk of non-stress fracture musculoskeletal injuries among recruits who exceeded body fat limits. Once injured, female recruits who were weight qualified but unfit and those who were fit but exceeded body fat limits had increased health care utilization. These findings may have implications for military accession and training policies as downsizing of military services will make it more important than ever to optimize the health and performance of individual service members.