Quinn, who made important contributions of expertise and time. A Committee and Consultant Biographies. B Agendas for Information-Gathering Meetings.
Between and , the U. Navy ships to chemical and biological warfare agents. These tests involved use of active chemical and biological agents, stimulants, tracers, and decontaminants. In the s some veterans who participated in the SHAD tests expressed concerns to the Department of Veterans Affairs VA that they were experiencing health problems that might be the result of exposures in the testing. These concerns led to a request from VA to the Institute of Medicine IOM to carry out an epidemiological study of the health of SHAD veterans and a comparison population of veterans who had served on similar ships or in similar units during the same time period.
In response to continuing concerns, Congress in requested an additional IOM study. This second study expands on the previous IOM work by making use of additional years of follow up and some analysis of diagnostic data from Medicare and the VA health care system.
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Page ii Share Cite. Copyright by the National Academy of Sciences. All rights reserved. Page iii Share Cite. Page iv Share Cite. This page intentionally left blank. Page v Share Cite. Page vi Share Cite. Where the size of the exposed group and the variation in the number of potential exposures were considered sufficient, the committee established subgroups to reflect the range of exposure experience e. Appendix D includes a description of the process used to evaluate the distribution of exposure opportunities and determine the exposure subgroups.
The committee evaluated the causes of deaths in the study population since the s and the diagnoses assigned at hospital and outpatient visits in data from Medicare from through and from the VA health system from late through Mortality follow-up for SHAD participants began at the date of their first test exposure, and ended on the date of death or December 31, , whichever came first.
Data on cause of death were obtained from the National Death Index or from death certificates obtained from state vital statistics offices for 91 percent of the members of the study population who were identified as deceased. The underlying cause of death was assigned a code corresponding to the International Classification of Diseases ICD, 9th or 10th revisions.
After leaving military service, some veterans receive medical care from VA facilities, many receive care from clinicians and facilities in the community, and some may receive care from both sources.
On reaching age 65, almost all veterans become eligible for Medicare, but some may continue to receive some or all of their care through VA or private insurance. The SHAD II study assessed morbidity through records collected into automated databases as a byproduct of medical care received through VA or under the auspices of Medicare billing. As of December 31, , 83 percent of the study participants assumed alive were 65 years of age or older. These files captured overlapping information on inpatient and outpatient encounters.
Data on diagnoses were derived from the Medicare Provider Analysis and Review MedPAR file hospital stays and the Outpatient and Carrier files services provided in non-inpatient facilities and care by physicians. The Medicare data do not include information about care provided to Medicare Managed Care enrollees or care provided outside of the Medicare program. Diagnostic data are available only for conditions for which diagnoses have been recorded as part of a health care claim, and some conditions that could have been diagnosed are not recorded.
The population for this study was made up of 5, Project SHAD participants and 6, other veterans who served as the comparison group. Approximately 60 percent of both groups were born in , and about 18 to 19 percent born earlier and 15 to 16 percent born later. Date of birth was unknown for 5. The proportion of personnel who were white was 87 to 88 percent of those whose race was known in participant and comparison groups. In both groups, the majority served in the Navy 86 percent of SHAD veterans and 91 percent of the comparison group and were enlisted personnel 92 and 93 percent, respectively.
Similar proportions of the two groups had evidence from a VA disability application of service in Vietnam or presumed or documented exposure to Agent Orange. The similarity of the two groups on these factors offered some assurance that the two populations were reasonably comparable.
As of December 31, , approximately 30 percent of both the SHAD veterans and the comparison population had died. Kaplan-Meier survival analysis showed no evidence of statistically significant difference between the participant and comparison groups in the overall number or timing of deaths.
When cause of death, grouped by broad ICD categories, was examined using a Cox proportional hazards model that adjusted for age, Project SHAD veterans showed no statistically significant increases in hazard over the comparison population.
This held true as well when the enlisted and officer groups were examined separately. No significant differences emerged when the enlisted group was examined separately or when the analysis took into account whether the SHAD veterans had a greater or lesser number of exposures to these substances. All-cause mortality among the members of the groups of special interest was not significantly different from that among their comparison groups, and stratifying the groups on the basis of rank officer and enlisted resulted in no statistically significant differences.
Hall or to the crew of the comparison vessel for the Granville S. Hall external control , but this difference was accounted for by the older age of this subgroup of SHAD veterans. For three groups—those exposed to any biological substance, to any chemical substance except TOF, or to any decontaminant—it was possible to assess whether higher or lower.
Using two or three levels of exposure, depending upon the numbers of people exposed and the distribution of the exposure counts across the group, no significant differences emerged at any level of exposure. This type of dose—response analysis was not feasible for the other exposure groups because of the limited variation within the group in the number of exposure opportunities.
When mortality attributed to specific causes was examined, an increase in risk among SHAD participants was seen only in the crew of the USS George Eastman , for heart disease mortality. However, when the committee applied a statistical adjustment to take into account the multiple comparisons in the analysis, the result no longer attained statistical significance.
Diagnoses noted in records generated as a result of medical care received under the auspices of the Medicare program or through VA were the basis for the assessment of morbidity in the study population. Approximately 55 percent of the SHAD veterans and 52 percent of the comparison population had ever been enrolled in the fee-for-service form of Medicare.
By , usage of VA health services among SHAD veterans remained higher than that of the comparison population, but the rate of increase in use from year to year became similar in the two groups. Overall morbidity was evaluated using median hospital days per person-year of enrollment among Medicare enrollees hospitalized during the study period.
Roughly 42 percent of both Project SHAD participant and comparison groups who had been enrolled in Medicare during the study period had a hospitalization during that time. Median hospital days per person-year of enrollment among those hospitalized was slightly lower among Project SHAD participants than the comparison group, but the difference was not statistically significant.
Looking at broad categories of disease showed that circulatory disease was the most common diagnosis in the Medicare data in both groups, with approximately 51 percent in each group having such a diagnosis.
The proportions receiving diagnoses of other types were also comparable in the two groups. Again in data from VA, the percentages of diagnoses in various categories were not higher in the SHAD veteran group than in the comparison group. The committee focused its morbidity analysis on the members of the study population with exposure to the substances for which hypotheses regarding health outcomes were developed.
Of those enrolled in Medicare, 41 to 53 percent were hospitalized during the study. Among those hospitalized, median hospital days per person-year of enrollment were not statistically higher in the SHAD veterans in the exposure groups than in their comparison groups. Testimony and other information from SHAD veterans was essential in helping the committee gain a better understanding of the context of the SHAD tests and the experience of those who had been present.
The study also benefited from the efforts during the previous IOM study to establish and validate the cohort of Project SHAD test participants from ship logs and diaries.
The previous IOM study also provided the unique benefit of a comparison population of military personnel with service more comparable in time and character to that of the SHAD veterans than would typically be found. With nearly 50 years of follow-up since the first SHAD test, the study had an opportunity to assess the mortality experience of the study population across a broad range of causes of death, including those that appear later in life.
Similarly, the long follow-up period made it feasible to turn to Medicare data to examine morbidity. But the study also faced important challenges. The time that has elapsed since the tests took place in the s makes it difficult to account for all the factors beyond the SHAD tests that will have influenced the health of the veterans who participated in the tests. What kind of disability benefits can I get? Health care Compensation payments. How do I get these benefits? Find out how to file a claim for disability compensation If you were part of Projects or SHAD from to and want to know more about a certain test site, ship, or unit, see the declassified Department of Defense fact sheets.
Get declassified Department of Defense fact sheets If you have a question about the tests, including whether you may have been part of them—or if you have any information that can help show you were part of them—contact the Department of Defense at Last updated: September 22, Back to top.
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