Potential Biomarkers Selection for Bipolar Disorder Identification

<p><em>A biomarker is a measurable indicator of the severity or presence of some disease. A biomarker is anything that can be used as an indicator of a particular disease state or some other physiological state of an organism. The space Decomposition-Gradient-Regression (DGR) method has been developed (Li et al., 2012; Li et al., 2015) to select biomarkers for schizophrenia. This study performs the DGR approach on data for bipolar disorder patients, which contains 56 biomarkers and 8 infectious agent’s antibodies. Serum specimens were collected from 132 United States military service members </em><em>(118 males and 14 females) </em><em>with a diagnosis of bipolar disorder from 1992 to 2005 and their matched healthy controls.. Trefoil Factor3 (TFF3), Gliadin, prolactin (PRL), Apolipoprotein A-II (Apo A-II) and Immunoglobulin A (IGA) </em><em>were found to be significant predictors of Bipolar Disorder (BD) in males. Macrophage-Derived Chemokine (MDC), Alpha-1-Antitrypsin (AAT), Gliadin, Beta-2-Microglobulin (B2M) and Monocyte Chemotactic Protein 2 (MCP-2) might be used to identify </em><em>bipolar disorder</em><em> in females. A predictive biomarker panel for BD offers the potential to aid in the diagnosis, initiate treatment earlier and ideally alter the course of disease with reduced morbidity and functional impairment.</em></p>

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.

The Relationship Between Deployment Frequency and Cumulative Duration, and Discharge for Disability Retirement Among Enlisted Active Duty Soldiers and Marines

BACKGROUND

The frequency and duration of deployments associated with increased morbidity is a significant concern for force health protection within the military population. Understanding the association between deployment and disability may provide a clearer understanding of factors adversely affecting U.S. military force readiness.

METHODS

A case-control analysis was conducted using records on enlisted active duty personnel in the Army and Marine Corps who were evaluated for a musculoskeletal disability and received a final disability disposition between FY 2003 and 2012. The study compared deployment, deployment frequency, and total time deployed in personnel who received musculoskeletal disability retirement to those with a musculoskeletal disability discharge other than retirement.

RESULTS

For females and males in either service, any deployment was associated with an increased risk of disability retirement (adjusted odds ratios [aOR] [95% confidence intervals (CI)]: males 1.76 [1.65-1.87]; females 1.41 [1.21-1.64]). Furthermore, increasing number of deployments (3+ deployments males aOR [95% CI]: 2.21 [1.92-2.53]) and time spent deployed (24+ months Army Males aOR [95% CI]: 2.07 [1.79-2.40]) significantly increased the odds for disability retirement.

CONCLUSION

Increasing frequency and duration of military deployments has an increased risk of disability retirement in service members with a musculoskeletal disability. Further research on this relationship is needed in a more representative sample of the U.S. military population.

Fitness, obesity and risk of asthma among Army trainees

BACKGROUND

Epidemiological data suggest an association between overweight/obesity and asthma. However, less is known about the relationship between physical fitness and asthma.

AIMS

To enumerate new-onset asthma diagnoses in Army recruits during the first 2 years of service and determine associations with fitness and excess body fat (EBF) at military entrance.

METHODS

New asthma diagnoses over 2 years in Army recruits at six entrance stations were obtained from military health and personnel records. Poisson regression models were used to determine associations of asthma diagnosis with pre-accession fitness testing, EBF and other potential factors.

RESULTS

In 9979 weight-qualified and 1117 EBF entrants with no prior history of asthma, 256 new cases of asthma were diagnosed within 2 years of military entry. Low level of fitness, defined by a step test and EBF, was significantly associated with new asthma diagnosis [adjusted incidence rate ratio (IRR), 1.47; 95% confidence interval (CI) 1.11-1.96 and adjusted IRR, 1.53; 95% CI 1.06-2.20, respectively].

CONCLUSIONS

Individuals with low fitness levels, EBF or both are at higher risk of asthma diagnosis in the first 2 years of military service.

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.

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 psychiatric disability without posttraumatic stress disorder among U.S. Army and Marine Corps personnel evaluated for disability discharge

Psychiatric disorders are a common reason for disability discharge from the U.S. military. Research on psychiatric disorders in military personnel evaluated for disability discharge has historically focused on posttraumatic stress disorder (PTSD), yet 40% of service members evaluated for a psychiatric-related disability do not have PTSD. This study's objective was to describe characteristics and correlates of disability in Army and Marine Corps personnel diagnosed with psychiatric disorders other than PTSD. In this cross-sectional study, the chi-square and Wilcoxon-Mann-Whitney tests compared the distribution of demographic, disability and deployment characteristics between those evaluated for non-PTSD psychiatric disability (N = 9125) versus those evaluated for any other non-psychiatric condition (N = 78,072). Multivariate logistic regression examined associations between disability retirement and demographic and disability characteristics. Results show a significantly higher prevalence of disability retirement, deployment, and comorbidity among Army and Marine Corps personnel evaluated for disability discharge related to a non-PTSD psychiatric disorder. Mood disorders, anxiety disorders and dementia were the most commonly evaluated psychiatric disorders. Characteristics associated with increased odds of non-PTSD psychiatric-related disability retirement includes being in the Marine Corps (OR = 1.24), being black (OR = 1.29) or other race (OR = 1.33), having a combat-related condition (OR = 2.50), and older age. Service members evaluated for a non-PTSD psychiatric disability have similar rates of disability retirement as those evaluated for PTSD, suggesting non-PTSD psychiatric disorders cause a severe and highly compensated disability. Additional research is needed describing the epidemiology of specific non-PTSD psychiatric disorders, such as depression, in service members evaluated for disability discharge.

Risk factors for disability discharge in enlisted active duty Army soldiers

BACKGROUND

The rate of permanent disability retirement in U.S. Army soldiers and the prevalence of combat-related disabilities have significantly increased over time. Prior research on risk factors associated with disability retirement included soldiers retired prior to conflicts in Iraq and Afghanistan.

OBJECTIVE

To identify risk factors for disability discharge among soldiers enlisted in the U.S. Army during military operations in Iraq and Afghanistan.

METHODS

In this case-control study, cases included active duty soldiers evaluated for disability discharge. Controls, randomly selected from soldiers with no history of disability evaluation, were matched to cases based on enlistment year and sex. Conditional logistic regression models calculated odds of disability discharge. Attributable fractions estimated burden of disability for specific pre-existing condition categories. Poisson regression models compared risk of disability discharge related to common disability types by deployment and combat status.

RESULTS

Characteristics at military enlistment with increased odds of disability discharge included a pre-existing condition, increased age or body mass index, white race, and being divorced. Musculoskeletal conditions and overweight contributed the largest proportion of disabilities. Deployment was protective against disability discharge or receiving a musculoskeletal-related disability, but significantly increased the risk of disability related to a psychiatric or neurological condition.

CONCLUSIONS

Soldiers with a pre-existing condition at enlistment, particularly a musculoskeletal condition, had increased odds of disability discharge. Risk of disability was dependent on condition category when stratified by deployment and combat status. Additional research examining conditions during pre-disability hospitalizations could provide insight on specific conditions that commonly lead to disability discharge.

Biomarker identification and effect estimation on schizophrenia - a high dimensional data analysis

Biomarkers have been examined in schizophrenia research for decades. Medical morbidity and mortality rates, as well as personal and societal costs, are associated with schizophrenia patients. The identification of biomarkers and alleles, which often have a small effect individually, may help to develop new diagnostic tests for early identification and treatment. Currently, there is not a commonly accepted statistical approach to identify predictive biomarkers from high dimensional data. We used space decomposition-gradient-regression (DGR) method to select biomarkers, which are associated with the risk of schizophrenia. Then, we used the gradient scores, generated from the selected biomarkers, as the prediction factor in regression to estimate their effects. We also used an alternative approach, classification and regression tree, to compare the biomarker selected by DGR and found about 70% of the selected biomarkers were the same. However, the advantage of DGR is that it can evaluate individual effects for each biomarker from their combined effect. In DGR analysis of serum specimens of US military service members with a diagnosis of schizophrenia from 1992 to 2005 and their controls, Alpha-1-Antitrypsin (AAT), Interleukin-6 receptor (IL-6r) and connective tissue growth factor were selected to identify schizophrenia for males; and AAT, Apolipoprotein B and Sortilin were selected for females. If these findings from military subjects are replicated by other studies, they suggest the possibility of a novel biomarker panel as an adjunct to earlier diagnosis and initiation of treatment.

Risk factors for disability retirement among active duty Air Force personnel

OBJECTIVE

To determine risk factors for disability retirement in Air Force personnel, as well as the conditions contributing to disability retirement.

METHODS

A matched case-control study was conducted. Air Force personnel with accession records who were disability retired between 2002 and 2011 were included as cases. Controls were matched by accession year from the population of accessions not evaluated for disability at a ratio of 2:1. Conditional logistic regression was used to determine the odds of disability retirement.

RESULTS

Women and those aged 25 or older were significantly more likely to be disability retired. Deployment was also associated with disability retirement but was significantly protective. Among women, the odds of disability retirement did not vary when stratified by deployment history. Preexisting medical conditions were not associated with disability retirement. Psychiatric conditions were the most common condition type among those who were disability retired in the Air Force.

CONCLUSIONS

Additional studies are needed to assess risk factors for psychiatric disability, the most common disability retired condition, as well as to describe the role of occupation and combat exposure in disability retirement from the Air Force.

Association between antibodies to multiple infectious and food antigens and new onset schizophrenia among US military personnel

INTRODUCTION

Multiple studies have documented immune activation in many individuals with schizophrenia suggesting that antigens capable of generating a prolonged immune response may be important environmental factors in many cases of this disorder. While existing studies have found single-agent associations of antibodies to food and neurotropic infectious agents with schizophrenia, a simultaneous examination of multiple agents may shed light on agent interactions or possible etiopathogenic pathways.

METHODS

We used traditional regression and novel statistical techniques to examine associations of single and combined infectious and food antigens with schizophrenia. We tested 6106 serum samples from 855 cases and 1165 matched controls.

RESULTS

Higher antibody levels to casein were borderline significant in the prediction of schizophrenia (HR=1.08, p=0.06). Study participants with higher cytomegalovirus (CMV) IgG antibody levels had a reduced risk of developing schizophrenia (HR=0.90; p=0.02). While IgG antibodies to gliadin, Toxoplasma gondii, vaccinia, measles, and human herpesvirus-6 (HHV-6) showed no significant independent associations with schizophrenia, the increase in antibody levels to several combinations of agents, to include casein, measles, CMV, T. gondii and vaccinia, was predictive of an 18-34% increase in the risk of developing schizophrenia.

CONCLUSION

Certain patterns of antibodies, involving some agents, were predictive of developing schizophrenia, with the magnitude of association rising when the level of antibodies increased to two or more agents. A heightened antibody response to a combination of several infectious/food antigens might be an indicator of an altered immune response to antigenic stimuli.

A prospective study of physical fitness, obesity, and the subsequent risk of mental disorders among healthy young adults in army training

OBJECTIVE

Mental health disorders contribute substantially to medical and occupational morbidity. The role of fitness and physical activity in the prevention of mental health disorders is not well established, but epidemiologic data suggest that physical activity can protect against anxiety and depression.

METHOD

The analyses presented in this report, from a prospective cohort study, evaluate the association between fitness (as measured by a 5-minute step test), and being overweight (defined as exceeding weight and body fat allowances) at military entrance, with subsequent onset of mental disorder diagnosis in the first year of service. The association between risk factors and mental disorder diagnosis was analyzed using multivariate Poisson regression with the adjusted incidence rate ratio (aIRR) as the measure of association.

RESULTS

Among weight-qualified participants, factors associated with increased incidence of mental disorder included failing the physical fitness test (aIRR: 1.36, p<0.0001), female sex (aIRR: 2.17, p<0.0001), and smoking (aIRR: 1.49, p<0.0001). Among fit participants, being overweight was not significantly associated with mental disorder (aIRR: 1.11, p=0.1540).

CONCLUSIONS

This test has potential military utility as an adjunct part of the medical examination process. Additional research is needed among civilians to determine if similar associations exist. If so, intervention studies should be conducted to determine if improving physical fitness reduces subsequent psychiatric disorder risk, particularly among young adults entering into stressful situations.

Accession medical waivers and deployment duration in the U.S. Army

To examine the performance of active duty U.S. Army personnel with accession medical waivers during combat deployments, the deployment duration and likelihood of early return from theater for medically waived (n = 18,093) and medically qualified (n = 250,209) personnel deploying between September 2001 and March 2011 were determined. The mean and median deployment duration for waived men (309.4 ± 107.5 and 346) and for waived women (291.8 ± 115.3 and 341) was not shorter than for medically qualified men (304.6 ± 112.1 and 346) and women (289.5 ± 116.3 and 337). When adjusted for other accession factors in a multivariate linear regression model, neither waived men (p = 1.00) nor women (p = 0.7713) had significantly shorter deployments. In a case-control analysis, 24,369 men and 3,094 women were defined as having a short deployment. Multivariate logistic regression found that medically waived men (odds ratio [OR] = 0.87, 95% confidence interval [CI] = 0.82-0.92) and women (OR = 1.02, 95% CI = 0.87-1.19) were not more likely to have shorter deployments compared to medically qualified individuals. These findings show that those with an accession medical waiver were not more likely to have shorter deployments or more likely to return early from deployment than those without waivers.

Descriptive epidemiology and underlying psychiatric disorders among hospitalizations with self-directed violence

Background

Suicide claims over one million lives worldwide each year. In the United States, 1 per 10,000 persons dies from suicide every year, and these rates have remained relatively constant over the last 20 years. There are nearly 25 suicide attempts for each suicide, and previous self-directed violence is a strong predictor of death from suicide. While many studies have focused on suicides, the epidemiology of non-fatal self-directed violence is not well-defined.

Objective

We used a nationally representative survey to examine demographics and underlying psychiatric disorders in United States (US) hospitalizations with non-fatal self-directed violence (SDV).

Method

International Classification of Disease, 9^th Revision (ICD-9) discharge diagnosis data from the National Hospital Discharge Survey (NHDS) were examined from 1997 to 2006 using frequency measures and adjusted logistic regression.

Results

The rate of discharges with SDV remained relatively stable over the study time period with 4.5 to 5.7 hospitalizations per 10,000 persons per year. Excess SDV was documented for females, adolescents, whites, and those from the Midwest or West. While females had a higher likelihood of self-poisoning, both genders had comparable proportions of hospitalizations with SDV resulting in injury. Over 86% of the records listing SDV also included psychiatric disorders, with the most frequent being affective (57.8%) and substance abuse (37.1%) disorders. The association between psychiatric disorders and self-injury was strongest for personality disorders for both males (OR = 2.1; 95% CI = 1.3–3.4) and females (OR = 3.8; 95% CI = 2.7–5.3).

Conclusion

The NHDS provides new insights into the demographics and psychiatric morbidity of those hospitalized with SDV. Classification of SDV as self-injury or self-poisoning provides an additional parameter useful to epidemiologic studies.

Identification of a blood-based biological signature in subjects with psychiatric disorders prior to clinical manifestation

OBJECTIVES

To determine whether a molecular signature is present in blood of patients with psychiatric disorders before manifestation of symptoms.

METHODS

Multiplex immunoassay analyses were carried out using serum obtained from two case-control studies of schizophrenia (n = 75) and bipolar disorder (n = 110) patients and their matched controls. The samples were drawn within 1 month before estimated onset of illness.

RESULTS

This led to identification of 20 molecules which were altered in pre-schizophrenia and 14 molecules in pre-bipolar disorder subjects compared to controls. Only two of these molecular changes were identical in both data sets and predictive testing confirmed that the biomarker signatures for pre-schizophrenia and pre-bipolar disorder were dissimilar.

CONCLUSION

The present results suggest that there are distinct serum alterations that occur before clinical manifestation of schizophrenia and bipolar disorder. These findings could lead to development of diagnostic tests to help clinical psychiatrists identify and classify vulnerable patients early in the disease process, allowing for earlier and more effective therapeutic intervention.

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.

Step test performance and risk of stress fractures among female army trainees

BACKGROUND

Stress fractures and other musculoskeletal injuries are major sources of morbidity among female military trainees. Several risk factors have been postulated, particularly pre-existing fitness, usually assessed with post-entry run time for ≥ 1.0 mile.

PURPOSE

Physical fitness is not formally evaluated prior to Army entry. If a valid and simple test that identified women at increased risk of stress fracture were available and could be applied prior to entry, it would facilitate cost-benefit studies of deferral or interventions. These analyses were undertaken to determine if a 5-minute step test conducted before entry identified women at increased risk.

METHODS

A prospective study was conducted of weight-qualified women entering the Army in 2005-2006, with analyses completed in 2011. At the pre-entry examination, information was collected on age, BMI, smoking, race, and activity level. Everyone took the step test. All outpatient medical encounters were captured, and stress fractures and other musculoskeletal injuries identified. Women with stress fractures and those with other musculoskeletal injuries were evaluated separately.

RESULTS

1568 women were included in the study; 109 developed stress fractures and 803 other musculoskeletal injury. Women who failed the step test had a 76% higher stress fracture incidence and a 35% higher incidence of other musculoskeletal injuries. There was effect modification between age and test failure for stress fracture.

CONCLUSIONS

A step test that can be administered before military entry identifies women with increased incidence of stress fracture and other musculoskeletal injury. This test could be used pre-entry to defer or target high-risk recruits for tailored fitness training before or after military entrance.

Psychiatric and general medical conditions comorbid with bipolar disorder in the National Hospital Discharge Survey

OBJECTIVE

From 40% to 65% of patients with bipolar disorder are estimated to have diagnoses of one or more comorbid conditions. The purpose of this study was to identify comorbid disorders and compare their prevalence in hospitalizations of persons with or without bipolar disorder.

METHODS

Data from the 1979-2006 National Hospital Discharge Survey (NHDS) were analyzed to examine temporal trends in the proportional morbidity of bipolar disorder, demographic characteristics, and the most frequent comorbid conditions in hospitalizations of patients with or without bipolar disorder. Among discharges of patients ages 13-64, the conditions of those with a primary diagnosis of bipolar disorder (N=27,054) were compared with those with other primary diagnoses (N=2,325,247). Proportional morbidity ratios (PMRs) were calculated.

RESULTS

There was an average 10% (p<.001) increase per year in the proportion of discharges with bipolar disorder. Proportions of discharge records that noted bipolar disorder were higher among females and whites and were highest among persons ages 13-19 and those from the Northeast. Discharge records noting a primary diagnosis of bipolar disorder showed higher proportions of most psychiatric and some general medical conditions, including acquired hypothyroidism (proportional morbidity ratio=2.6), viral hepatitis (1.6), obesity (1.4), and various diseases of the skin and subcutaneous tissue (range 2.6-4.2) and of the nervous (1.4-3.8), respiratory (1.4-2.3), and musculoskeletal (1.2-1.9) systems.

CONCLUSIONS

Patients with bipolar disorder have an increased illness burden from many psychiatric and general medical conditions. Knowledge of the most prevalent comorbid conditions and methods for their prevention, early diagnosis, and treatment are critical in improving the prognosis of patients with bipolar disorder.

Association between bovine casein antibody and new onset schizophrenia among US military personnel

Schizophrenia is a pervasive neuropsychiatric disorder of uncertain etiology. Multiple studies have documented immune activation in individuals with schizophrenia. One antigen capable of inducing a prolonged immune response is bovine casein derived from ingested milk products. Increased levels of casein antibodies have been found in individuals with schizophrenia after diagnosis. This study was directed at determining the potential association between schizophrenia and pre-illness onset levels of immunoglobulin G (IgG) antibodies to bovine casein. Parallel analyses for casein antibody levels with bipolar disorder were included as comparison. Cases were service members who received medical discharges from the military with a schizophrenia diagnosis from 1992 to 2005. Serum specimens were selected for 855 cases and 1165 matched healthy controls. IgG antibodies to bovine whole-casein were measured by solid phase enzyme-linked immunosorbent assays (ELISAs). Hazard ratios (HR) were calculated to examine the associations of casein IgG level with risk of schizophrenia by time to diagnosis and by subjects' initial level. Increasing casein IgG antibody levels among those with a high initial level, drawn before diagnosis, was associated with an 18% increase in the hazard risk of schizophrenia per unit increase (value of low-positive standard) in IgG antibody levels (HR=1.18; 95% CI 1.04, 1.34). This is the first report to identify an association between the risk of schizophrenia and elevated antibodies to bovine casein prior to disease onset. Additional research is required to elucidate the complex genetic environmental interactions involved in the pathogenesis of schizophrenia and to identify potentially modifiable risk factors.

Incidence of adult onset schizophrenic disorders in the US military: patterns by sex, race and age

BACKGROUND

There are limited data describing the epidemiology of adult-onset schizophrenic disorders in the United States. Although the military is not proportionately comparable in all demographic characteristics to the civilian population, it is drawn from all racial/ethnic subgroups, and members range in age from 17 to >60 years. We describe the incidence of hospitalization for new onset schizophrenic disorders among military members by sex, race, and age.

METHODS

Using military inpatient data, we evaluated patterns of initial hospitalizations for schizophrenic disorders among military personnel for 2000-2009, focusing on sex, race, and age. No individual-level data were available.

RESULTS

From 2000-2009, 1976 military personnel had a first schizophrenic disorder hospitalization, with an overall incidence rate of 0.14/1000 person-years. There were no consistent changes in rates over time. While overall incidence rates were similar for men and women (incidence rate ratio (IRR)=1.10), rates were higher among men than women below age 25; after 25-30 rates were higher among women. Incidence was higher among blacks and other racial groups, with IRR=2.0 and 1.3, respectively.

CONCLUSION

Medical screening of military applicants prevents persons with overt or a reported history of psychosis, and most with serious behavior problems, from enlisting; therefore, first hospitalization is likely to reflect new illness. No pre-military socioeconomic data were available, however, essentially all study subjects were high school graduates; unmeasured differences in socioeconomic status were unlikely to explain the observed results. This report may provide lower bound estimates of the schizophrenic disorder incidence in the United States.

Body mass index, medical qualification status, and discharge during the first year of US Army service

BACKGROUND

The high prevalence of overweight and obesity in military recruits and in the US population as a whole necessitates understanding the health effects of body composition and associated morbidity.

OBJECTIVE

In this study, we examined the effect of body mass index (BMI; in kg/m(2)) and medical status on premature discharge from the US Army in a large cohort of first-time-enlisted, active-duty soldiers.

DESIGN

We determined the odds ratios (ORs) associated with BMI and medical status at enlistment by using a retrospective cohort of first-time, active-duty army recruits.

RESULTS

ORs for BMI, calculated by using 24-24.9 as a reference, exhibited a U-shaped pattern. Soldiers with a BMI >34 had the highest ORs for all-cause (OR: 1.47; 95% CI: 1.32, 1.64) and medical (OR: 1.68; 95% CI: 1.46, 1.93) discharges. A BMI <17 was 1.35 times as likely (95% CI: 1.02, 1.80) to result in an all-cause discharge and 1.45 times as likely (95% CI: 1.01, 2.08) to result in a medical discharge. ORs for soldiers who required a medical reexamination did not vary when all-cause discharge (OR: 1.10; 95% CI: 1.06, 1.14) and medical discharge (OR: 1.10; 95% CI: 1.05, 1.15) were compared. The medical discharge OR for soldiers who required a medical waiver to enter the army (OR: 1.56; 95% CI: 1.48, 1.64) was higher than the OR for all-cause discharge (OR: 1.27; 95% CI: 1.22, 1.32).

CONCLUSION

Enlistment BMI and medical qualification status play an important role in early discharge and may provide a valuable tool in the development of fitness, nutrition, and injury-prevention interventions in higher-risk groups.

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.

Psychiatric and general medical conditions comorbid with schizophrenia in the National Hospital Discharge Survey

OBJECTIVE

Morbidity and mortality from general medical conditions are elevated among patients with schizophrenia compared with the general U.S. population. More than 50% of patients with schizophrenia have one or more comorbid psychiatric or general medical conditions. This study determined types of comorbid disorders and their prevalence among hospitalized patients with and without schizophrenia.

METHODS

Data from the National Hospital Discharge Survey, a nationally representative sample, were analyzed for 1979-2003 (N=5,733,781 discharges). For discharges of patients aged 15 to 64 with at least one comorbid condition, the conditions of those with a primary diagnosis of schizophrenia (N=26,279) were compared with those with other primary diagnoses (N=1,936,876). Proportional morbidity ratios (PMRs) were calculated.

RESULTS

The proportion of discharges listing schizophrenia, particularly schizoaffective disorder, increased significantly over time among both males and females. The proportion was higher among males, blacks, and discharges in the Northeast. Discharge records with a primary diagnosis of schizophrenia showed higher proportions of all comorbid psychiatric conditions examined and of some general medical conditions, including acquired hypothyroidism (PMR=2.9), contact dermatitis and other eczema (PMR=2.9), obesity (PMR=2.0), epilepsy (PMR=2.0), viral hepatitis (PMR=1.4), diabetes type II (PMR=1.2), essential hypertension (PMR=1.2), and various chronic obstructive pulmonary diseases (PMR range 1.2-1.5).

CONCLUSIONS

Knowledge of the risks of comorbid psychiatric and general medical conditions is critical both for clinicians and for patients with schizophrenia. Closer attention to prevention, early diagnosis, and treatment of comorbid conditions may decrease associated morbidity and mortality and improve prognosis among patients with 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.

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.

Understanding the effect of deployment on the risk of fatal motor vehicle crashes: a nested case-control study of fatalities in Gulf War era veterans, 1991-1995

Motor vehicle crashes (MVCs) are an important cause of morbidity and premature loss of life among military personnel during peacetime and particularly following combat. A nested case-control study of fatal MVC occurring between 1991 and 1995 was conducted in a cohort of Gulf War era veterans. Cases were validated MVC deaths in the Fatality Analysis Reporting System. Controls were selected using risk set sampling by gender and year of case ascertainment in a 10:1 ratio. Preliminary results, consistent with previous reports of increased fatal MVC risk among returning combat veterans, showed a crude odds ratio of 1.45 (95% confidence interval 1.27-1.65). Multivariable logistic regression modeling was used to identify important independent predictors, as well as to quantify the influence of deployment on a risk profile for fatal MVC. Because of significant interaction between deployment and inpatient diagnosis of substance abuse, the final model was stratified by deployment status. Results suggest that demographic, military, and behavioral characteristics of deployed healthy warriors are similar to the risk profile for fatal MVC. In addition to young, single, high school-educated, enlisted male personnel, those who served during times of ground combat, particularly in infantry, gun crews, or seamanship occupations, should be targeted for preventive interventions.

Motor vehicle fatalities among Gulf War era veterans: characteristics, mechanisms, and circumstances

OBJECTIVES

Our objective was to describe fatal motor vehicle crashes (MVC) among veterans of the 1991 Gulf War era and to compare the distribution of crash and individual characteristics between those deployed to the Gulf War (GWV) and those not deployed (NDV).

METHODS

We compared individual characteristics, crash mechanisms, and crash circumstances between 765 GWV and 553 NDV who died from MVC within the first five years of the war, between May 1991 and December 1995.

RESULTS

Overall, GWV and NDV who died from a MVC were more likely to be enlisted males (97%), 21-30 years old (72%), have a high school education or less (91%), drive a passenger car (52%), and not use restraints (60%). The overall annual rate of motor vehicle fatalities for GWV (23.6 per 100,000; 95% confidence interval: 21.9-25.3) was significantly greater than the rate for NDV (15.9, 95% CI: 14.6-17.3). GWV with the highest motor vehicle fatality rates include males (24.8, 95% CI: 23.0-26.6), 17-20 year olds (105.0, 95% CI: 78.2-138.1), and those not married (27.3, 95% CI: 25.1-30.1). Adjusting for differences in age distribution across GWV and NDV did not account for the difference in rates. Characteristics of MVC fatalities that were over-represented among GWV include serving as regular active duty (p = 0.001), having a high school education or less (p = 0.01), being involved in a single-vehicle crash (p = 0.008), and dying within the first hour following the crash (p = 0.004). Also, we identified a greater proportion of alcohol-related crashes among GWV during the late night and early morning hours.

CONCLUSIONS

The highest rates of motor vehicle fatality among young, single males in the military mirror the experience of the general population. Further research is necessary to determine modifiable risk factors that can be targeted for specific interventions and whether the elevated late night alcohol-related crash rate among GWV is an effect of deployment or an inherent population bias among those selected for operational deployments.

Leveraging existing databases to study vehicle crashes in a combat occupational cohort: epidemiologic methods

BACKGROUND

The US military is a large, well-defined occupational cohort offering tremendous opportunities to study risk factors for important health outcomes. This article describes our nested case-control methods to evaluate risk factors for fatal motor vehicle crashes (MVC) within all Service branches in a 1991 Gulf War era cohort.

METHODS

We identified 1,343 cases of fatal MVC between 1991 and 1995 that were also included in the Department of Transportation's Fatality Analysis Reporting System database and, using risk set sampling, selected 13,430 controls. Our final analytic dataset consisted of 980 male driver cases and 12,807 controls linked to multiple databases.

RESULTS

Cases were disproportionately younger, less educated, not married, enlisted, and deployed to the Gulf War, compared to controls.

CONCLUSIONS

The ability to leverage multiple databases to study risk factors for fatal MVC is clearly advantageous and could eventually lead to the reduction of fatalities in similar occupational cohorts.

Projecting mental disorder prevalence from national surveys to populations-of-interest--an illustration using ECA data and the U. S. Army

BACKGROUND

Psychiatric epidemiology can further public health practice and inform mental health policy through the development of methodologies that provide rapid and cost efficient estimation of the prevalence of mental disorders at the local, regional, and population levels.

OBJECTIVE

The aim of this study was to illustrate an efficient method for the estimation of mental disorder prevalence in population groups where no direct prevalence data are available. This study demonstrated a new method to extrapolate prevalences from a national calibration survey to a target population where no observations are available and sociodemographic differences are prominent.

METHOD

We restricted the ECA sample to full-time employed participants (approximately 10,500) and used the total active duty U. S. Army population (approximately 460,000) for illustration. Sociodemographic data for the Army came from the official military database (mid-year 2000). Our logistic regression projections represented an extension of sociodemographic-driven synthetic methods used among demographers. Outcomes were lifetime prevalences for 13 DIS/DSM disorders.

RESULTS

Compared to the ECA employed population, extrapolations to the Army revealed lower/similar estimates for nine of 13 DIS/DSM disorders. Projections were twice as high for alcohol abuse/dependence and antisocial personality, and one-third higher for social phobia and schizophrenia in the Army. Estimates compared favorably to one other military prevalence study, and to results derived using traditional standardization/adjustment methods based on the ECA sample weighted to the working general population.

CONCLUSIONS

The synthetic estimation technique using ECA data to project lifetime prevalences for the U. S. Army generated sound estimates while illustrating an attractive method to extrapolate national data to demographically diverse communities seeking policy-relevant data.

A case-control study of asthma among U.S. Army Gulf War veterans and modeled exposure to oil well fire smoke

OBJECTIVE

Thousands of American troops were exposed to oil well fire smoke during the Persian Gulf War, but the actual impact of this on their health is unknown. To assess the potential association between physician-diagnosed asthma and objective estimates of oil fire smoke, we conducted a case-control study of Army Gulf War veterans.

METHODS

Subjects were participants in the Comprehensive Clinical Evaluation Program. Cases had physician-diagnosed asthma; controls were selected from the population of noncases. The two estimates of exposure were cumulative exposure and number of days at high levels.

RESULTS

A total of 873 cases and 2,464 controls were included. Significant associations were observed between asthma and both estimates of exposure, with an adjusted odds ratio of 1.4 (95% confidence interval = 1.11.8) for both the highest levels of cumulative exposure and days exposed to high levels. A dose response was observed for both exposure measures.

CONCLUSIONS

We found significant associations between asthma and oil fire smoke exposure. Because much of the medical history was not available, an etiological association cannot be determined from this study, and additional research is needed.

Caring for medically unexplained physical symptoms after toxic environmental exposures: effects of contested causation

Medically unexplained physical symptoms (MUPS) are persistent idiopathic symptoms that drive patients to seek medical care. MUPS syndromes include chronic fatigue syndrome, fibromyalgia syndrome, and multiple chemical sensitivities. When MUPS occur after an environmental exposure or injury, an adversarial social context that we call "contested causation" may ensue. Contested causation may occur publicly and involve media controversy, scientific disagreement, political debate, and legal struggles. This adversarial social context may diminish the effectiveness of the provider-patient relationship. Contested causation also may occur privately, when disagreement over the causes of MUPS takes place in the patient-provider context. These patient-provider disagreements over causation often occur because of the enigmatic nature of MUPS. We suggest that a context of contested causation may have serious negative effects on healthcare for individuals with MUPS. Context plays a larger role in MUPS care than it does for most medical care because of the uncertain nature of MUPS, the reliance of standard MUPS therapies on a potentially tenuous patient-provider partnership, and the clinical need to rely routinely on subjective MUPS assessments that often yield discordant patient and provider conclusions. Contested causation may erode patient-provider trust, test the provider's self-assurance and capacity to share power with the patient, and raise problematic issues of compensation, reparation, and blame. These issues may distract patients and providers from therapeutic goals. In occupational and military settings, the adverse impact of contested causation on the patient-provider partnership may diminish therapeutic effectiveness to a greater degree than it does in other medical settings. Contested causation therefore raises questions regarding generalizability of standard therapies for MUPS and related syndromes to these settings. Future research is needed to learn whether intuitively sensible and evidence-based MUPS therapies benefit occupational and military medical patients who are afforded care in the context of contested causation.

Children of human immunodeficiency virus-infected members of the Army Reserve components

OBJECTIVES

Little is known about the numbers of children who will be left without one or both parents because of human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome. This report evaluates childbearing patterns among U.S. Army reserve component members, a group largely made up of men with limited contact with the military.

METHODS

HIV status was determined from routinely collected data, with demographic information obtained from personnel records. Number of children was estimated from number of dependents reported. No information was available on the infection status of children or spouses of members.

RESULTS

There were 1,884 HIV-positive members, with an estimated total of 843 children. Childbearing patterns varied across several demographic characteristics. Among 14 metropolitan statistical areas, the proportion reporting any children and the number of children of infected members per 100,000 varied substantially.

CONCLUSIONS

This report documents the numbers of children of HIV-positive adults in this population and provides evidence that certain metropolitan areas will be disproportionately affected.