Respiratory Health Effects of Airborne Hazards Exposures in the Southwest Asia Theater of Military Operations (2020) / Chapter Skim
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3 Evaluation of the Evidence Base and Background of Major Studies and Cohorts
3 Evaluation of the Evidence Base and Background of Major Studies and Cohorts
Pages 43-80
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From page 43... ...
The chapter begins with a description of the approach and process used by the committee to identify and evaluate the scientific and medical literature on the association between exposure to airborne hazards and respiratory health outcomes among military personnel and veterans who served in Afghanistan and the Southwest Asia Theater of Military Operations1 from 1990 to the present. The majority of the evidence considered by the committee when making its conclusions on the strength of the evidence of an association between exposure to airborne hazards in theater and a specific respiratory health outcome consisted of published epidemiologic studies.
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From page 44... ...
That set included full and abbreviated names, common and scientific names, BOX 3-1 MeSH Search Terms Respiratory Health Outcomes* mortality, bronchitis, asthma, bronchiolitis, chronic bronchitis, chronic obstructive pulmonary disease, bronchiolitis obliterans, cough, dyspnea, emphysema, pulmonary eosinophilia, gastroesophageal reflux, extrinsic allergic alveolitis, idiopathic pulmonary fibrosis, obstructive sleep apnea, pneumonia, pulmonary hypertension, respiratory tract diseases, respiratory tract infections, respiratory signs and symptoms, rhinitis, sarcoidosis, sinusitis, spirometry, vocal cord dysfunction, respiratory sounds, esophageal neo plasms, laryngeal neoplasms, lung neoplasms, nose neoplasms, nasopharyngeal neoplasms, mouth neoplasms, oropharyngeal neoplasms, oropharynx neoplasms Airborne Hazards Exposures Industrial exposure: industrial environment OR occupational air pollutants OR occupational asthma OR occupational diseases OR occupational illnesses OR occupational exposure Environmental exposure: air pollutants OR environmental air pollutants OR air pollution OR environmental illness OR environmental illnesses OR environmental hypersensitivities OR environmental hypersensitivity OR environmental pollutants OR environmental carcinogens Burn pits: incineration OR solid waste incineration OR burn pits OR open burning OR open pits OR open air burning OR solid waste incineration OR uncontrolled burning OR uncontrolled combustion Fossil fuels: petroleum OR fuel oils OR gasoline OR diesel OR kerosene OR kerosine OR coal Geographic Region Middle East OR Afghanistan OR Bahrain OR Iraq OR Kuwait OR Oman OR Qatar OR Saudi Arabia OR United Arab Emirates OR Djibouti OR Indian Ocean OR Persian Gulf OR Red Sea OR Arabian Sea OR Gulf of Aden OR Gulf of Oman OR Saudi–Iraqi neutral zone Military Personnel Air Force OR Armed Forces OR Army OR Navy OR Coast Guard OR Marines OR military OR military deployment OR sailors OR soldiers OR submariners OR veterans *
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From page 45... ...
The search terms for respiratory health outcomes included mortality, cancer, bronchial asthma, chronic bronchitis, sinusitis, constrictive bronchiolitis, and other relevant respiratory health outcomes. The airborne hazards exposure terms included industrial exposures, environmental exposures, and fossil fuels as well as hazards associated with burn pit exposures.
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From page 46... ...
Several types of epidemiologic studies were captured and evaluated, including cohort, case–control, and cross-sectional designs. Because Southwest Asia theater veterans are the topic of the charge to the committee, the committee chose not to consider studies of respiratory health outcomes in other non-military populations with ostensibly similar exposures.
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From page 47... ...
Joan Reibman from the New York University (NYU) Grossman School of Medicine, NYU Langone Health, NYU/Bellevue Asthma Clinic, and the World Trade Center Environmental Health Center, presented on the respiratory health outcomes in community members exposed to environmental toxins from the World Trade Center disaster and its pertinence to Gulf War veterans (Reibman, 2019)
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From page 48... ...
As part of its evaluation, the committee first outlined the components of an ideal epidemiologic study so that when individual studies were assessed, these aspects were given the most weight. The categories of association used for making conclusions about the strength of the relationship between exposure to airborne hazards and respiratory health outcomes among Southwest Asia theater veterans are presented as the final topic of this section.
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From page 49... ...
Using the assessments of the individual studies and supplemental evidence where available, the committee discussed the evidence until it came to a consensus regarding the conclusion and assigned a category of association based on the strength of the evidence of a link between exposure to airborne hazards in the Southwest Asia theater and the respiratory health outcome under scrutiny. The committee did not use a formulaic approach to determining the number of studies that would be necessary to assign a specific category of association.
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From page 50... ...
. Categories of Association To rate the strength of the scientific evidence for respiratory health outcomes following exposure to airborne hazards in Southwest Asia, the committee used a system of four categories of association.
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The four categories of association and the criteria for each are described below. Sufficient Evidence of an Association For effects to be classified as having "sufficient evidence of an association," a positive association between one or more in-theater airborne exposures and a respiratory health outcome in humans must have been observed in studies in which chance, bias, and confounding can be ruled out with reasonable confidence.
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From page 52... ...
Limited or Suggestive Evidence of No Association The category of "limited or suggestive evidence of no association" is used for health outcomes for which several adequate studies covering the full range of human exposure were consistent in showing no association or a reduced risk with an exposure to airborne hazards encountered in the Southwest Asia theater at any concentration, with the studies having relatively narrow confidence intervals. A conclusion of "no association" is inevitably limited to the conditions, exposures, and observation periods covered by the available studies, and the possibility of a small increase in risk related to the magnitude of exposure studied can never be excluded.
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From page 53... ...
The Statement of Task directs the committee to pay particular attention to … emerging evidence on respiratory health outcomes in service members from research such as the Millennium Cohort Study, Study of Active Duty Military for Pulmonary Disease Related to Environ mental Deployment Exposures (STAMPEDE) , National Health Study for a New Generation of U.S.
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From page 54... ...
as well as bias between panels and in the overall study. To date, more than 100 papers using data from the Millennium Cohort Study have been published, but few of these examine respiratory health outcomes or airborne hazards exposures among Southwest Asia theater military personnel.
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Multivariable logistic regression adjusted for sex, birth year, marital status, race/ethnicity, education, smoking status, service component, military pay grade, and occupational code was used to compare the adjusted odds of the newly reported respiratory outcomes for deployed versus nondeployed participants. Additional models were used to assess associations between the respiratory health outcomes and cumulative deployment length, adjusted for the same covariates.
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From page 56... ...
. In its analysis of the association between deployment to areas near burn pits and respiratory health outcomes, the Armed Forces Health Surveillance Center (AFHSC, 2010)
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A total of 1,693 participants completed a pre-deployment questionnaire that collected data on demographics, smoking status, and respiratory health and underwent baseline chest radiography, spirometry, and impulse oscillometry. The post-deployment evaluation was conducted within 2 weeks of return from deployment for those individuals who returned to the Fort Hood processing center and included the same questions as on the pre-deployment questionnaire but also included additional questions on current medications; medical history including respiratory illnesses; respiratory symptoms before, during, and after deployment; run time performance on the physical fitness test; and airborne exposures experienced during deployment (dust and/ or sand, vehicle exhaust, burning trash, and industrial fumes)
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. Two NewGen studies that report on respiratory health outcomes -- Barth et al.
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From page 59... ...
As of early 2020, the study was in the analysis stage, and no publications related to respiratory health outcomes were available for the committee's review (Schneiderman, 2019; Schneiderman et al., 2020)
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Its investigators study the impact of exposure to airborne hazards on a variety of health outcomes, including respiratory health. Studies conducted by AHCE involve many of the same tests used in specialty care, such as assessment of cardiopulmonary function and exercise ability.
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From page 61... ...
Only the overall results were presented because, as the authors state, service-stratified and time-stratified analyses were similar to the overall cohort. Additional analyses of respiratory health outcomes were conducted using data merged with those collected as part of the Millennium Cohort Study (described earlier in this chapter)
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From page 62... ...
Other Studies of Post-9/11 Operations Veterans Eight other epidemiologic studies of military personnel involved in post-9/11 operations in the Southwest Asia theater have addressed multiple respiratory health outcomes. Their study parameters are summarized below, while the results of these studies are presented where applicable in the outcomes sections of Chapter 4.
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From page 63... ...
The study population consisted of a case series of military personnel who had a medical encounter for a qualifying cardiovascular or respiratory event recorded in either Joint Medical Workstation or Transportation Command Regulating and Command and Control Evacuation System during the time period of environmental sampling and for whom deployment data at the time of the health event were known. The case status was defined as having any one of the qualifying outcomes in the medical record (ICD-9 390–459 "diseases of the circulatory system" or ICD-9 460–519 "diseases of the respiratory system")
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From page 64... ...
The primary aim of this retrospective cohort study was to characterize the post-deployment respiratory health status of the U.S. Army personnel potentially exposed to emissions from that event and to compare the risk of plausible adverse health outcomes among this group with the risks in unexposed personnel.
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From page 65... ...
(2020) sought to describe deployment-related respiratory disease and the diagnostic utility of resting and exercise pulmonary function testing with a retrospective study of 127 military personnel, veterans, and civilian contractors who supported military operations in Southwest Asia who presented with new-onset respiratory symptoms between 2009 and 2017.
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From page 66... ...
(2016) conducted a small cohort study to look for associations between various health outcomes, which were based on ICD-9 codes assigned from post-deployment medical encounters, and known exposures to burn pits, which were based on deployment location.
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From page 67... ...
Four of these -- the first paper to describe this effort and three other papers that address respiratory health outcomes -- are summarized below. Chapter 4 also cites some additional NHS-related studies.
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From page 68... ...
Other Studies of U.S. Gulf War Veterans Several other studies of Gulf War veterans have examined respiratory outcomes.
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(2006) conducted a large study of post-deployment hospitalization events of active-duty service members to examine respiratory conditions, including asthma, for service members deployed to Southwest Asia for peacekeeping missions post-Gulf War (n = 254,080)
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of whom deployed to the Southwest Asia theater. Veterans who were female, nonwhite, served in the Army, or were active duty were all slightly over represented relative to the stratified recruitment panel.
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(2002) conducted a case–control study of 873 Gulf War veterans with a physician diagnosis of asthma versus 2,464 controls without asthma or other respiratory system diagnoses who were participants of the DoD Comprehensive Clinical Evaluation Program.
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In the initial study of the Australian Gulf War veterans, all 1,871 Australian veterans deployed to the Gulf War region from August 2, 1990, to September 4, 1991, were included; naval personnel made up 86.5% of this cohort (Sim et al., 2003)
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From page 73... ...
Respiratory health was assessed at both baseline and follow-up, but the scope of respiratory health data collected and the mode of data collection changed for some factors, which limited the ability to assess change over time for some of the outcomes. The follow-up study collected information on respiratory symptoms and medical conditions, including asthma, using a brief list of outcomes that were assessed via self-report questionnaire.
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From page 74... ...
2012. Does Deployment to Iraq and Afghanistan Affect Respiratory Health of US Military Personnel?
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From page 75... ...
Presentation before the Committee on the Respiratory Health Effects of Airborne Hazards Exposures in the Southwest Asia Theater of Military Operations. October 3, 2019.
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From page 76... ...
University of Iowa Carver College of Medicine. Presentation before the Committee on the Respiratory Health Effects of Airborne Hazards Exposures in the Southwest Asia Theater of Military Operations.
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Miami VA Medical Center. Presentation before the Committee on the Respi ratory Health Effects of Airborne Hazards Exposures in the Southwest Asia Theater of Military Operations.
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Brooke Army Medical Center. Presentation before the Committee on the Respiratory Health Effects of Airborne Hazards Exposures in the Southwest Asia Theater of Military Operations.
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Naval Health Research Center. Presentation before the Committee on the Respiratory Health Effects of Airborne Hazards Exposures in the Southwest Asia Theater of Military Operations.
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Pacific Northwest National Laboratory. Presentation before the Committee on the Respiratory Health Effects of Airborne Hazards Exposures in the Southwest Asia Theater of Military Operations.
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