Health impact of US military service in a large population-based military cohort: findings of the Millennium Cohort Study, 2001-2008.

BACKGROUND: Combat-intense, lengthy, and multiple deployments in Iraq and Afghanistan have characterized the new millennium. The US military's all-volunteer force has never been better trained and technologically equipped to engage enemy combatants in multiple theaters of operations. Nonetheless, concerns over potential lasting effects of deployment on long-term health continue to mount and are yet to be elucidated. This report outlines how findings from the first 7 years of the Millennium Cohort Study have helped to address health concerns related to military service including deployments. METHODS: The Millennium Cohort Study was designed in the late 1990s to address veteran and public concerns for the first time using prospectively collected health and behavioral data. RESULTS: Over 150,000 active-duty, reserve, and National Guard personnel from all service branches have enrolled, and more than 70% of the first 2 enrollment panels submitted at least 1 follow-up survey. Approximately half of the Cohort has deployed in support of operations in Iraq and Afghanistan. CONCLUSION: The Millennium Cohort Study is providing prospective data that will guide public health policymakers for years to come by exploring associations between military exposures and important health outcomes. Strategic studies aim to identify, reduce, and prevent adverse health outcomes that may be associated with military service, including those related to deployment.

The physical and mental health of a large military cohort: baseline functional health status of the Millennium Cohort.

BACKGROUND: The US military is currently involved in large, lengthy, and complex combat operations around the world. Effective military operations require optimal health of deployed service members, and both mental and physical health can be affected by military operations. METHODS: Baseline data were collected from 77,047 US service members during 2001-2003 as part of a large, longitudinal, population-based military health study (the Millennium Cohort Study). The authors calculated unadjusted, adjusted, and weighted means for the Medical Outcomes Study Short Form 36-item Survey for Veterans physical (PCS) and mental component summary (MCS) scores over a variety of demographic and military characteristics at baseline. RESULTS: The unadjusted mean PCS and MCS scores for this study were 53.4 (95% confidence interval: 53.3-53.4) and 52.8 (95% confidence interval: 52.7-52.9). Average PCS and MCS scores were slightly more favorable in this military sample compared to those of the US general population of the same age and sex. Factors independently associated with more favorable health status included male gender, being married, higher educational attainment, higher military rank, and Air Force service. Combat specialists had similar health status compared to other military occupations. Having been deployed to Southwest Asia, Bosnia, or Kosovo between 1998 and 2000 was not associated with diminished health status. CONCLUSION: The baseline health status of this large population-based military cohort is better than that of the US general population of the same age and sex distribution over the same time period, especially in older age groups. Deployment experiences during the period of 1998-2001 were not associated with decreased health status. These data will serve as a useful reference for other military health studies and for future longitudinal analyses.

Complementary and alternative medicine use among US Navy and Marine Corps personnel.

BACKGROUND: Recently, numerous studies have revealed an increase in complementary and alternative medicine (CAM) use in US civilian populations. In contrast, few studies have examined CAM use within military populations, which have ready access to conventional medicine. Currently, the prevalence and impact of CAM use in US military populations remains unknown. METHODS: To investigate CAM use in US Navy and Marine Corps personnel, the authors surveyed a stratified random sample of 5,000 active duty and Reserve/National Guard members between December 2000 and July 2002. Chi-square tests and multivariable logistic regression were used to assess univariate associations and adjusted odds of CAM use in this population. RESULTS AND DISCUSSION: Of 3,683 service members contacted, 1,446 (39.3%) returned a questionnaire and 1,305 gave complete demographic and survey data suitable for study. Among respondents, more than 37% reported using at least one CAM therapy during the past year. Herbal therapies were among the most commonly reported (15.9%). Most respondents (69.8%) reported their health as being very good or excellent. Modeling revealed that CAM use was most common among personnel who were women, white, and officers. Higher levels of recent physical pain and lower levels of satisfaction with conventional medical care were significantly associated with increased odds of reporting CAM use. CONCLUSION: These data suggest that CAM use is prevalent in the US military and consistent with patterns in other US civilian populations. Because there is much to be learned about CAM use along with allopathic therapy, US military medical professionals should record CAM therapies when collecting medical history data.

Millennium Cohort: enrollment begins a 21-year contribution to understanding the impact of military service.

OBJECTIVE: In response to health concerns of military members about deployment and other service-related exposures, the Department of Defense (DoD) initiated the largest prospective study ever undertaken in the U.S. military. STUDY DESIGN AND SETTING: The Millennium Cohort uses a phased enrollment strategy to eventually include more than 100,000 U.S. service members who will be followed up through the year 2022, even after leaving military service. Subjects will be linked to DoD and Veterans Affairs databases and surveyed every 3 years to obtain objective and self-reported data on exposures and health outcomes. RESULTS: The first enrollment phase was completed in July 2003 and resulted in 77,047 consenting participants, well representative of both active-duty and Reserve/Guard forces. This report documents the baseline characteristics of these Cohort members, describes traditional, postal, and Web-based enrollment methods; and describes the unique challenges of enrolling, retaining, and following such a large Cohort. CONCLUSION: The Millennium Cohort was successfully launched and is becoming especially relevant, given current deployment and exposure concerns. The Cohort is representative of the U.S. military and promises to provide new insight into the long-term effects of military occupations on health for years to come.

Millennium Cohort: the 2001-2003 baseline prevalence of mental disorders in the U.S. military.

OBJECTIVES: The 12-month prevalence of common mental illnesses in the United States is estimated to be 26%, accounting for an increasing fraction of all disability in the general population. The U.S. military is a unique group involved in response and defense during times of conflicts and disasters. The mental health of service members affects organizational productivity and effectiveness and is of great importance to the health of U.S. military members and public health in general. STUDY DESIGN AND SETTING: In the present report, the authors describe the baseline prevalence of mental disorders in a large U.S. military cohort, the Millennium Cohort, established for a 22-year longitudinal study of the health effects of military service. Using crude and weighted prevalence and multivariable logistic regression, the mental health morbidity of the Millennium Cohort is reported for various demographics. RESULTS: These analyses suggest that although the cohort compares favorably to other populations, there are military subpopulations, including women, younger, less educated, single, white, short-term service, enlisted, and Army members, who are at greater odds for some mental disorders. CONCLUSION: With ongoing U.S. involvement in combat operations around the world, these baseline data are essential to assessing long-term mental health morbidity in U.S. military service members.

Myopericarditis following smallpox vaccination.

Myopericarditis has been a rare or unrecognized event after smallpox vaccinations with the New York City Board of Health strain of vaccinia virus (Dryvax; Wyeth Laboratories, Marietta, Pennsylvania). In this article, the authors report an attributable incidence of at least 140 clinical cases of myopericarditis per million primary smallpox vaccinations with this strain of vaccinia virus. Fifty-eight males and one female aged 21-43 years with confirmed or probable acute myopericarditis were detected following vaccination of 492,730 US Armed Forces personnel from December 15, 2002, through September 30, 2003. The cases were identified through sentinel reporting to military headquarters, active surveillance using the Defense Medical Surveillance System, or reports to the Vaccine Adverse Event Reporting System. The observed incidence (16.11/100,000) of myopericarditis over a 30-day observation window among 347,516 primary vaccinees was nearly 7.5-fold higher than the expected rate of 2.16/100,000 (95% confidence interval: 1.90, 2.34) among nonvaccinated, active-duty military personnel, while the incidence of 2.07/100,000 among 145,155 revaccinees was not statistically different from the expected background rate. The cases were predominantly male (58/59; 98.3%) and White (51/59; 86.4%), both statistically significant associations (p = 0.0147 and p = 0.05, respectively).

Self-reported mental health among US military personnel prior and subsequent to the terrorist attacks of September 11, 2001.

There is much concern over the potential for short- and long-term adverse mental health effects caused by the terrorist attacks on September 11, 2001. This analysis used data from the Millennium Cohort Study to identify subgroups of US military members who enrolled in the cohort and reported their mental health status before the traumatic events of September 11 and soon after September 11. While adjusting for confounding, multivariable logistic regression, analysis of variance, and multivariate ordinal, or polychotomous logistic regression were used to compare 18 self-reported mental health measures in US military members who enrolled in the cohort before September 11, 2001 with those military personnel who enrolled after September 11, 2001. In contrast to studies of other populations, military respondents reported fewer mental health problems in the months immediately after September 11, 2001.

Incidence and follow-up of inflammatory cardiac complications after smallpox vaccination.

OBJECTIVES: The purpose of this study was to assess the follow-up of patients with vaccinia-associated myocarditis. BACKGROUND: With the threat of biological warfare, the U.S. Department of Defense resumed a program for widespread smallpox vaccinations on December 13, 2002. One-year afterwards, there has been a significant increase in the occurrence of myocarditis and pericarditis among those vaccinated. METHODS: Cases were identified through sentinel reporting to military headquarters, systematic surveillance, and spontaneous reports. RESULTS: A total of 540,824 military personnel were vaccinated with a New York City Board of Health strain of vaccinia from December 2002 through December 2003. Of these, 67 developed myopericarditis at 10.4 +/- 3.6 days after vaccination. The ST-segment elevation was noted in 57%, mean troponin on admission was 11.3+/- 22.7 ng/dl, and peak cardiac enzymes were noted within 8 h of presentation. On follow-up of 64 patients (96%) at a mean of 32 +/- 16 weeks, all patients had objective normalization of echocardiography, electrocardiography, laboratory testing, graded exercise testing, and functional status; 8 (13%) reported atypical, non-limiting persistent chest discomfort. CONCLUSIONS: Post-vaccinial myopericarditis should be considered in patients with chest pain within 30 days after smallpox vaccination. Normalization of echocardiography, electrocardiography, and treadmill testing is expected, and nearly all patients have resolution of chest pain on follow-up.

Can we prevent a second 'Gulf War syndrome'? Population-based healthcare for chronic idiopathic pain and fatigue after war.

In the 1991 Gulf War less than 150 of nearly 700,000 deployed US troops were killed in action. Today, however, over 1 in 7 US veterans of the war has sought federal healthcare for related-health concerns, and fully 17% of UK Gulf War veterans describe themselves as suffering from the 'Gulf War syndrome', a set of poorly defined and heterogeneous ailments consisting mainly of chronic pain, fatigue, depression and other symptoms. Even though over 250 million dollars of federally funded medical research has failed to identify a unique syndrome, the debate regarding potential causes continues and has included oil well smoke, contagious infections, exposure to chemical and biological warfare agents, and posttraumatic stress disorder. Historical analyses completed since the Gulf War have found that postwar syndromes consisting of chronic pain, fatigue, depression and other symptoms have occurred after every war in the 20th century. These syndromes have gone by a variety of names such as Da Costa's syndrome, irritable heart, shell shock, neurocirculatory asthenia, and battle fatigue. Though the direct causes of these syndromes are typically elusive, it is clear that war sets in motion an undeniable cycle of physical, emotional, and fiscal consequences for war veterans and for society. These findings lead to important healthcare questions. Is there a way to prevent or mitigate subsequent postwar symptoms and associated depression and disability? We argue that while idiopathic symptoms are certain to occur following any war, a population-based approach to postwar healthcare can mitigate the impact of postwar syndromes and foster societal, military, and veteran trust. This article delineates the model, describes its epidemiological foundations, and details examples of how it is being adopted and improved as part of the system of care for US military personnel, war veterans and families. A scientific test of the model's overall effectiveness is difficult, yet healthcare systems for combatants and their families are already being put to pragmatic tests as troops return from war in Iraq and Afghanistan and from other military challenges.

Chemical warfare and the Gulf War: a review of the impact on Gulf veterans' health.

It is unlikely that Gulf War veterans are suffering chronic effects from illnesses caused by chemical warfare nerve agent exposure. Extensive investigation and review by several expert panels have determined that no evidence exists that chemical warfare nerve agents were used during the Gulf War. At no time before, during, or after the war was there confirmation of symptoms among anyone, military or civilian, caused by chemical warfare nerve agent exposure. However, studies of Gulf War veterans have found belief that chemical weapons were used, significantly associated with both severe and mild-moderate illnesses. The psychological impact of a chemical warfare attack, either actual or perceived, can result in immediate and long-term health consequences. The deployment or war-related health impact from life-threatening experiences of the Gulf War, including the perceived exposure to chemical warfare agents, should be considered as an important cause of morbidity among Gulf War veterans.

Myopericarditis following smallpox vaccination among vaccinia-naive US military personnel.

CONTEXT: In the United States, the annual incidence of myocarditis is estimated at 1 to 10 per 100,000 population. As many as 1% to 5% of patients with acute viral infections involve the myocardium. Although many viruses have been reported to cause myopericarditis, it has been a rare or unrecognized event after vaccination with the currently used strain of vaccinia virus (New York City Board of Health). OBJECTIVE: To describe a series of probable cases of myopericarditis following smallpox vaccination among US military service members reported since the reintroduction of vaccinia vaccine. DESIGN, SETTING, PARTICIPANTS: Surveillance case definitions are presented. The cases were identified either through sentinel reporting to US military headquarters surveillance using the Defense Medical Surveillance System or reports to the Vaccine Adverse Event Reporting System using International Classification of Diseases, Ninth Revision. The cases occurred among individuals vaccinated from mid-December 2002 to March 14, 2003. MAIN OUTCOME MEASURE: Elevated serum levels of creatine kinase (MB isoenzyme), troponin I, and troponin T, usually in the presence of ST-segment elevation on electrocardiogram and wall motion abnormalities on echocardiogram. RESULTS: Among 230,734 primary vaccinees, 18 cases of probable myopericarditis after smallpox vaccination were reported (an incidence of 7.8 per 100,000 over 30 days). No cases of myopericarditis following smallpox vaccination were reported among 95,622 vaccinees who were previously vaccinated. All cases were white men aged 21 years to 33 years (mean age, 26.5 years), who presented with acute myopericarditis 7 to 19 days following vaccination. A causal relationship is supported by the close temporal clustering (7-19 days; mean, 10.5 days following vaccination), wide geographic and temporal distribution, occurrence in only primary vaccinees, and lack of evidence for alternative etiologies or other diseases associated with myopericarditis. Additional supporting evidence is the observation that the observed rate of myopericarditis among primary vaccinees is 3.6-fold (95% confidence interval, 3.33-4.11) higher than the expected rate among personnel who were not vaccinated. The background incidence of myopericarditis did not show statistical significance when stratified by age (20-34 years: 2.18 expected cases per 100,000; 95% confidence interval [CI], 1.90-2.34), race (whites: 1.82 per 100,000; 95% CI, 1.50-2.01), and sex (males: 2.28 per 100,000; 95% CI, 2.04-2.54). CONCLUSION: Among US military personnel vaccinated against smallpox, myopericarditis occurred at a rate of 1 per 12 819 primary vaccinees. Myopericarditis should be considered an expected adverse event associated with smallpox vaccination. Clinicians should consider myopericarditis in the differential diagnosis of patients presenting with chest pain 4 to 30 days following smallpox vaccination and be aware of the implications as well as the need to report this potential adverse advent.

The millennium Cohort Study: a 21-year prospective cohort study of 140,000 military personnel.

Does military service, in particular operational deployment, result in a higher risk of chronic illness among military personnel and veterans? The Millennium Cohort Study, the largest Department of Defense prospective cohort study ever conducted, will attempt to answer this question. The probability-based sample of 140,000 military personnel will be surveyed every 3 years during a 21-year period. The first questionnaire, scheduled for release in summer 2001, will be sent to 30,000 veterans who have been deployed to southwest Asia, Bosnia, or Kosovo since August 1997 and 70,000 veterans who have not been deployed to these conflict areas. Twenty thousand new participants will be added to the group in each of the years 2004 and 2007 to complete the study population of 140,000. The participants will have the option of completing the study questionnaire either on the paper copy received in the mail or through the World Wide Web-based version, which is available at www.MillenniumCohort.org. This will be one of the first prospective studies ever to offer such an option. The initial survey instrument will collect data regarding demographic characteristics, self-reported medical conditions and symptoms, and health-related behaviors. Validated instruments will be incorporated to capture self-assessed physical and mental functional status (Short Form for Veterans), psychosocial assessment (Patient Health Questionnaire), and post-traumatic stress disorder (Patient Checklist-17). Information obtained from the survey responses will be linked with other military databases, including data on deployment, occupation, vaccinations, health care utilization, and disability. In addition to revealing changes in veterans' health status over time, the Millennium Cohort Study will serve as a data repository, providing a solid foundation upon which additional epidemiological studies may be constructed.