Reassessment of the Department of Veterans Affairs Airborne Hazards and Open Burn Pit Registry (2022) / Chapter Skim
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5 Use for Etiologic Research
5 Use for Etiologic Research
Pages 133-164
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From page 133... ...
. Additionally, the reassessment committee's Statement of Task requires that it offer "recommendations on how to address gaps identified in the initial report and on burn pit and airborne hazards research, diagnosis, and treatment in general." The committee considered that the best method by which to address the Congressional mandate to assess whether exposures to airborne hazards and burn pits cause health outcomes is etiologic research, which it defined as the use of hypothesis testing to answer questions about whether a particular condition or factor, such as exposure to an environmental agent, causes adverse health outcomes.
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From page 134... ...
Evidence of an association may be based on cross-sectional study designs or on other designs that do not account specifically for temporality between the exposure and outcome; however, to assess causality with certainty, temporality must be established. CURRENT USE OF AH&OBP REGISTRY DATA The initial assessment committee identified several challenges to using the AH&OBP Registry data to examine associations between airborne hazards and health outcomes, including participation biases, recall biases, and data quality.
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From page 135... ...
; 3 Personal communication, Michael Falvo, co-director, VA Airborne Hazards and Burn Pits Center of Excellence, War Related Illness and Injury Study Center. January 18, 2021.
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Because the registry comprises a concerned, engaged population who report high rates of exposures (such as emissions from burn pits and dust) , it could be useful for examining seemingly unrelated issues, such as COVID19, although there would still be underlying data limitations.
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From page 137... ...
These assessments help AHBPCE make recommendations regarding the management of symptoms and follow-up care to improve the quality of life among veterans exposed to airborne hazards, including burn pits (VA, 2022b)
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. CHARACTERISTICS OF AN EXPOSURE REGISTRY TO BE USED IN ETIOLOGIC RESEARCH Chapter 2 describes the more general use of exposure registries and common types of biases and their effects; this section describes characteristics that bear on the usefulness of registries as a resource for etiologic research in general but also on airborne hazards exposures and health outcomes specifically.
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From page 139... ...
, the participants are not representative of the total eligible population, based on era of service and their demographic and military characteristics. Notably, compared with the entire eligible 1990–1991 Gulf War population, registry participants were more likely to be women, to be over 50 years of age, to have served in the Army and as National Guard or reserve, and to have had a different distribution of eligible deployment segments.
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From page 140... ...
The decision to participate in a voluntary registry is often the result of personal experience and priorities, which can introduce a high likelihood of selection bias. Selection bias in this case means that individuals who are concerned about their health or who have a diagnosis they believe is due to deployment-related exposures -- or burn pits specifically -- are more likely to participate than individuals who do not perceive themselves as having been exposed to a deployment-related hazard or who are not experiencing adverse health issues.
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From page 141... ...
civilian population, the Millennium Cohort Study participants, nondeployed service members and veterans, and VA health care users. However, the committee finds that none of these groups would provide satisfactory comparisons because none of these populations have been asked the same exposure or health outcome questions nor has information been collected on them that is equal to that in the AH&OBP Registry.
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From page 142... ...
This has often been the case with research on exposure to open burn pits, which has numerous limitations including the use of single-time environmental sampling rather than sampling over the entire time of exposure; the burned materials having unknown compositions, which can vary dramatically; environmental air monitors that do not cover the full range of chemicals; and other methodologic concerns, such as an inability to fully account for the contributions of other sources of airborne hazards (IOM, 2011; NRC, 2010)
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From page 143... ...
Similarly, responses to other registry questions related to airborne hazards exposures -- e.g., dust storms, symptoms attributed to poor air quality, and smoke or fumes from a burn pit entering housing or work locations -- also had little variability and were reported by at least 80% of participants (see Questions with Limited Variability in Responses in Chapter 3)
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From page 144... ...
For example, the questionnaire does not ask about exposure to other sources of combustion products, such as burning trash and other materials, in the absence of large burn pits. Nor are there questions about high-exposure jobs other than duties that included the burn pit.
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From page 145... ...
, summarized earlier in this chapter, that attempted to crudely validate the self-reported exposure information provided by the AH&OBP Registry participants. Although some environmental monitoring was conducted by DoD at a few locations with operating burn pits and for limited times, several flaws have been noted regarding the sampling methods and the chemical components measured (IOM, 2011)
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From page 146... ...
There are wording problems with many questions that make it problematic to use the questionnaire responses in etiologic research. There continues to be substantial scientific uncertainty about the health conditions that may result from service members' exposure to airborne hazards in the Southwest Asia theater, and some studies have shown that organs and organ systems other than the respiratory system can be affected (IOM, 2011)
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From page 147... ...
Thus, measurement error in self-reported health outcome information is systematic -- registry participants are more likely to report having a health condition which does not appear in their VA medical record resulting in an overestimate of all health conditions (except for allergies and hypertension) when based on self-reports relative to an estimate based on medical records.
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From page 148... ...
, hobbies, and prior residences. However, as the initial assessment committee observed, the questionnaire contains a substantial number of questions on nonmilitary, nondeployment factors, which are of little relevance to the registry's stated purpose -- exploring possible associations between deployment exposures to airborne hazards and health outcomes in service members and veterans -- and should be removed (VA, 2021a)
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From page 149... ...
Smoking would be a confounder if, for example, smokers are more likely to have burn pit duties or if they spend more time outside because of their tobacco use as they would also be more likely to be exposed to airborne hazards on the whole. Conclusion The AH&OBP Registry does not have several characteristics that are necessary for an exposure registry to be used for etiologic research, notably a representative sample of the eligible population, an appropriate comparison group, an adequate quality of exposure assessment, and an adequate quality of health outcome assessment.
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From page 150... ...
Before ILER can be used for research, validation studies comparing ILER exposure extrapolations with other exposure indicators of known accuracy will be most informative to ensure that ILER accurately compiles and presents exposure information adequately at the individual and group levels. Potential research applications of ILER would include a range of exposures of concern that occur during deployment, but the committee's focus is on its application to address the health consequences of exposure to open burn pits and other airborne hazards.
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From page 151... ...
locations and general exposures as well as more granular exposure data, the ability to passively identify exposed and unexposed service members and veterans in ILER means that appropriate comparison groups could be identified in order to conduct more precise analyses of health effects and specific exposures. The size and composition of these comparison groups will depend on the exposures that are being assessed and the health outcomes that are available in the VA and DoD health records and group characteristics that may be of interest, such as sex, age, and service branch or component.
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From page 152... ...
Health Outcome Assessment of Adequate Quality Although several sources of health information are or will be available in ILER, the earliest available data on health outcomes from DoD sources are from October 2012; VA electronic health record information earlier than 2001 is considered to be unreliable, and the earliest dates for VA health information in ILER are unclear. Pre- and post-deployment health assessments are also only available beginning in 2012 (after most open burn pits had ceased operation)
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From page 153... ...
Low response rates and potential biases related to participation and loss to follow-up are additional considerations that can affect representativeness. The Millennium Cohort Study captures post-9/11 service members and veterans with a range of deployment experiences, including subsets who have had burn pit or airborne hazards exposures as well as those who have been deployed elsewhere or not deployed at all.
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From page 154... ...
. The committee finds that the Gulf War Registry satisfies a few but not all of the characteristics necessary for an exposure registry to be used in etiologic research, and therefore it is not appropriate for use in etiologic research on airborne hazards exposures and health outcomes.
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From page 155... ...
The committee recommends that VA support the conduct of epidemiologic studies to examine the asso ciations between exposures to airborne hazards and open burn pits and health outcomes. The studies should be designed specifically to fulfill the characteristics needed for etiologic research -- a sufficient sample size for precise estimates, a sample that is representative of the eligible population, identification of an appropriate comparison group, an exposure assessment of adequate quality, a health outcome assessment of adequate quality, and identification of other relevant and contributing factors.
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From page 156... ...
Among early participants eligible to answer this question, nonresponse was 1.5%, whereas among late participants the nonresponse rate was 21.8%. Long-term retrospective recall bias also affects the responses to these questionnaire sections; for example, questions on previous residence up to 13 years of age and such responses would not be useful in etiologic research models of airborne hazards exposures and respiratory outcomes.
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From page 157... ...
Respiratory Health Effects of Airborne Hazards Exposures in the Southwest Asia Theater of Military Operations was published on 11 September 2020. It is expected that this document will help direct VA's future research agenda on airborne hazards, burn pits, and health outcomes.
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From page 158... ...
" The committee considered ILER, the Millennium Cohort Study, the Gulf War Registry, and other previous and new epidemiologic studies of the population eligible for the AH&OBP Registry. Although the Gulf War Registry satisfies some of the needed characteristics for use in etiologic research, it does not fulfill them all and therefore is not appropriate for use in etiologic research on airborne hazards exposures and health outcomes.
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From page 159... ...
The committee recommends that VA support the conduct of epidemiologic studies to examine the asso ciations between exposures to airborne hazards and open burn pits and health outcomes. The studies should be designed specifically to fulfill the characteristics needed for etiologic research -- a sufficient sample size for precise estimates, a sample that is representative of the eligible population, identification of an appropriate comparison group, an exposure assessment of adequate quality, a health outcome assessment of adequate quality, and identification of other relevant and contributing factors.
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From page 160... ...
. Ongoing service member and veteran health research programs, most notably the Millennium Cohort Study, have a number of relevant strengths and could be adapted to address the exposures of concern by targeting the population of interest and incorporating more detailed exposure information regarding burn pits and airborne hazards.
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From page 161... ...
2016. Burn pit emissions exposure and respiratory and cardiovascular conditions among Airborne Hazards & Open Burn Pit Registry participants.
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From page 162... ...
key=HMD-BPH-20-06. VA AHBPCE (Department of Veterans Affairs Airborne Hazards and Burn Pits Center of Excellence)
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From page 163... ...
Presentation by Dr. Edward Boyko to the Committee to Reassess the Department of Veterans Affairs Airborne Hazards and Open Burn Pit Registry.
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