Assessing Health Outcomes Among Veterans of Project SHAD (Shipboard Hazard and Defense) (2016) / Chapter Skim
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4 The Mortality Experience of SHAD Veterans
4 The Mortality Experience of SHAD Veterans
Pages 73-90
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From page 73... ...
Because the SHAD tests occurred during the period of the Vietnam War, the committee was concerned that service in Vietnam or presumed exposure to Agent Orange among members of the study population might complicate the analysis of health effects experienced by SHAD veterans, especially if there were marked differences between the SHAD participants and the comparison group. Ideally, it would be possible to fully document the service histories of all members of the study population, but the necessary records are not available in electronic form.
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From page 74... ...
Race was unknown for 16.9 percent of SHAD participants and 35.8 percent of the comparison population. b Vietnam service is defined as duty or visitation within the country of South Vietnam, including Navy veterans who entered inland waterways on ships, went ashore from offshore ships, or served only aboard offshore ships and never went ashore or entered inland waterways (Personal communication, J
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From page 75... ...
showed that the small differences between the two curves were not statistically significant. TABLE 4-2 Vital Status and Availability of Data on Death for Project SHAD Participants and the Comparison Population as of December 31, 2011 Vital Status and Death Data Project SHAD Comparison Available Participants Population Total Assumed alive 3,975 (67.7%)
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From page 76... ...
version 9.4 was used for the Kaplan-Meier analysis. Another approach to comparing the overall mortality experience of the SHAD veterans with the comparison population makes use of the Cox proportional hazards model.
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From page 77... ...
For example, the adjusted hazard ratio for Project SHAD participants is adjusted for age, rank, and service branch. Ship ID was used in the model as a random effect to control for shipclustering: estimated standard error for the random effects is 0.0059.
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From page 78... ...
Examination of the enlisted and officer groups separately indicated statistically significantly fewer deaths from injury and external causes among the enlisted personnel in the SHAD participant population compared to the enlisted personnel in the comparison group. The committee did not pursue this result further because its interest was in the potential for increased rather than decreased risk among Project SHAD exposure groups.1 No statistically significant differences were seen among the much smaller group of officers in this or any of the other analyses discussed in this chapter (data not shown)
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From page 79... ...
as of December 31, 2011. TABLE 4-5 Vital Status of SHAD Participants by Potential Exposure to Agents, Simulants, and Decontaminants for Which Health Outcomes Were Hypothesized Exposure and Project SHAD Comparison Vital Status Participants Group Coxiella burnetii Total group 141 212 Assumed alive 84 (59.6%)
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From page 80... ...
. TABLE 4-6 Proportional Hazards Regression for All-Cause Mortality for SHAD Participants with Exposure to Selected Substances and the Comparison Groups Unadjusted Hazard Adjusted Hazard Exposure and Risk Factor Ratio (95% CI)
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From page 81... ...
Similarly, a proportional hazards analysis that included adjustment for age and rank found no statistically significant excess risk among SHAD participants (see Table 4-8) for the two categories for which there were sufficient number of cases to pursue the analysis (i.e., exposure to betapropriolactone or zinc cadmium sulfide)
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From page 82... ...
burnetii and sarin were too similar across the exposed groups to justify establishing higher and lower levels of exposure. Exploratory Analyses of Mortality In addition to testing the hypotheses regarding specific health outcomes that were identified as potentially associated with exposure to certain substances used in Project SHAD, the committee examined mortality for broader exposure groupings and other subgroups of special interest.
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From page 83... ...
Members of the tug and Project SHAD technical staff groups had higher crude mortality when compared to the other members of the crew of the USS Granville S Hall (internal control)
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From page 84... ...
29 (3.3%) Internal External Tugs and Project SHAD Technical Staff Comparison Comparison Total group 103 127 210 Assumed alive 59 (57.2%)
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From page 85... ...
Hall who were not part of the Project SHAD technical staff. d Comparison is an "external control" made up of the crew of the USS Interceptor, which was the comparison ship for the USS Granville S
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From page 86... ...
Details of the basis for this grouping are provided in Appendix D Table 4-12 shows the hazard ratios and confidence intervals for risk of mortality from any cause associated with varying numbers of potential exposures to the substances listed for each the special subgroups considered, compared with people on similar ships without any SHAD exposures.
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From page 87... ...
TABLE 4-13 Survival Analysis Using Proportional Hazards Regression: Cause-Specific Mortality for SHAD Participant Subgroups of Special Interest Versus Comparison Groups Deaths SHAD Compari- Enlisted Only a Exposure Group and Partici- son Unadjusted HR Adjusted HR Adjusted HRb Cause of Death pants Group (95% CI)
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From page 88... ...
0.34 (0.10-1.12) Tugs and Project SHAD Technical Staff (n = 103)
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From page 89... ...
Hall who were not part of the Project SHAD technical staff. d Comparison is an "external control" made up of the crew of the USS Interceptor, which was the comparison ship for the USS Granville S
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