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OCR for page 39
Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense)
9
Mortality Results
VITAL STATUS DATA AND ALL-CAUSE MORTALITY
Table 9-1 shows vital status percentages and the availability of cause-of-death information by analysis group. There are no large differences in the percentage assumed alive between Project SHAD (Shipboard Hazard and Defense) participants and controls within exposure group, and with the exception of group B, the proportion assumed alive is roughly three-quarters for both participants and controls. Subjects with only date of death or fact of death include those whose death occurred before 1979 (for whom we were unable to obtain causes) and represent 4–5 percent of participants or controls across all groups.
Table 9-2 shows the availability of follow-up information by exposure group and Project SHAD participation status. Mortality follow-up was done by matching both the Beneficiary Identification and Records Locator Subsystem (BIRLS) file, using military service number as well as Social Security number (SSN), and the National Death Index (NDI) file, using only SSNs. Because we consider mortality follow-up that relied on NDI to be virtually complete, only study subjects with SSN can be considered well followed, evidenced by the fact that the crude death rate among subjects with SSNs (22.7 percent) was roughly eight-fold higher than among subjects without SSNs (2.8 percent). Table 9-2 shows that in all but group B controls, the percentage of not-well-followed subjects (i.e., the sum of the first two columns) is less than 6 percent. Subsequent mortality analyses will therefore be done using all subjects and then only subjects with SSNs; although the latter omits some known deaths identified by BIRLS without SSNs, it does mean that all such subjects will have been searched for in the National Death Index. The results of these two analyses of all-cause mortality are shown in Tables 9-3 and 9-4, respectively.
Table 9-3 shows the results of proportional hazards analyses of total mortality by exposure group with all subjects included, regardless of completeness of mortality follow-up. All analyses were adjusted for age, race, and pay grade, but only in group B were there sufficient Marines to adjust also for service branch. There were no statistically significant differences in all-cause mortality between Project SHAD participants and controls, although in group B the hazard ratio (HR) was 1.25 (95 percent confidence interval [CI] 0.99–1.60). The effect of age was statistically significant in all groups, while race was significant only in group B, in which nonwhites had significantly higher mortality than whites; in all other groups, all-cause mortality was lower among nonwhites. Officers had significantly lower mortality than enlisted personnel in all groups, except for group C, and Marines in group B had significantly higher mortality than Navy personnel in group B.
OCR for page 40
Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense)
TABLE 9-1 Vital Status and Availability of Death Data by Project SHAD Participant Status and Exposure Group
Vital Status and Death Data Availability
Group A Participant
Group A Control
Group B Participant
Group B Control
Group C Participant
Group C Control
Group D Participant
Group D Control
Assumed alive
2,537
(76.5%)
2,762
(76.7%)
712
(83.4%)
749
(86.3%)
560
(77.7%)
844
(77.6%)
666
(78.6%)
960
(80.0%)
Date or fact of death only
149
(4.5%)
163
(4.5%)
32
(3.7%)
34
(3.9%)
35
(4.9%)
53
(4.9%)
35
(4.1%)
50
(4.2%)
Cause of death
632
(19.1%)
677
(18.8%)
110
(12.9%)
85
(9.8%)
126
(17.5%)
190
(17.5%)
146
(17.2%)
190
(15.8%)
Total subjects
3,318
(100%)
3,602
(100%)
854
(100%)
868
(100%)
721
(100%)
1,087
(100%)
847
(100%)
1,200
(100%)
NOTE: Group A = participants potentially exposed only to Bacillus globigii (BG) simulant agent or methylacetoacetate (MAA); group B = participants potentially exposed only to trioctyl phosphate (TOF); group C = participants potentially exposed to any active chemical or biological agent; group D = participants potentially exposed only to simulants and not in groups A or B.
TABLE 9-2 Percentage of Study Subjects with SSN and BIRLS Record, by Exposure Group and Project SHAD Participation Status
Exposure Group and Participation Status*
No SSN and No BIRLS Record Found
Only BIRLS Record Found
SSN Only
Both SSN and BIRLS Record Found
Group A participants
(N = 3,318)
2.0%
0.8%
14.2%
83.0%
Group A controls
(N = 3,602)
3.1%
2.1%
15.5%
79.4%
Group B participants
(N = 854)
4.8%
0.8%
10.2%
84.2%
Group B controls
(N = 868)
10.9%
3.0%
20.9%
65.2%
Group C participants
(N = 721)
3.1%
2.1%
13.6%
81.3%
Group C controls
(N = 1,087)
2.6%
2.9%
15.6%
79.0%
Group D participants
(N = 847)
2.0%
0.8%
13.8%
83.4%
Group D controls
(N = 1,200)
2.4%
1.2%
12.0%
84.4%
*Group A = participants potentially exposed only to BG or MAA; group B = participants potentially exposed only to TOF; group C = participants potentially exposed to any active chemical or biological agent; group D = participants potentially exposed only to simulants and not in groups A or B.
Table 9-4 shows the results of the same proportional hazards analysis of all-cause mortality, including only those with SSN in whom mortality follow-up was assumed to be most complete. With the exception of group B, the results of this analysis are much the same as shown in Table 9-3. In group B, the hazard ratios associated with race and pay grade are no longer statistically significant.
Table 9-5 shows the results of proportional hazards ratio analyses of selected cause-specific mortality end points for only subjects with SSNs. Group A participants had a statistically significantly higher hazard ratio than
OCR for page 41
Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense)
TABLE 9-3 Proportional Hazards Analysis of Total Mortality, by Exposure Group, Including All Subjects, Regardless of Completeness of Mortality Follow-Up
Exposure Groupa and Risk Factorb
Hazard Ratio (95% CI)
Group A
Participant versus control
1.01 (0.92–1.11)
Age (per year)
1.10 (1.09–1.11)
Race (nonwhite versus white)
0.91 (0.78–1.07)
Pay grade (officer versus enlisted)
0.50 (0.41–0.62)
Group B
Participant versus control
1.26 (0.99–1.60)
Age (per year)
1.08 (1.05–1.10)
Race (nonwhite versus white)
1.44 (1.05–1.97)
Pay grade (officer versus enlisted)
0.59 (0.38–0.90)
Branch (Marine versus Navy)
1.49 (1.13–1.95)
Group C
Participant versus control
0.90 (0.74–1.09)
Age (per year)
1.10 (1.09–1.12)
Race (nonwhite versus white)
0.69 (0.47–1.00)
Pay grade (officer versus enlisted)
0.73 (0.52–1.02)
Group D
Participant versus control
1.06 (0.88–1.28)
Age (per year)
1.09 (1.08–1.11)
Race (nonwhite versus white)
0.92 (0.62–1.37)
Pay grade (officer versus enlisted)
0.50 (0.33–0.76)
Total
Participant versus control
1.02 (0.95–1.10)
Age (per year)
1.09 (1.09–1.10)
Race (nonwhite versus white)
0.96 (0.85–1.09)
Pay grade (officer versus enlisted)
0.56 (0.48–0.65)
NOTE: Statistically significant hazard ratios are in bold.
aGroup A = participants potentially exposed only to BG or MAA; group B = participants potentially exposed only to TOF; group C = participants potentially exposed to any active chemical or biological agent; group D = participants potentially exposed only to simulants and not in groups A or B.
bEach factor is adjusted for all others in the list.
controls for death because of cardiovascular disease. Group B participants had statistically significantly higher hazard ratios for cancer and cardiovascular deaths. Although group B participants had higher death rates than controls for many of the selected mortality outcomes in Table 9-5, most differences were not statistically significant, due to the relatively small number of deaths. Finally, comparing all Project SHAD participants versus all controls, heart disease deaths showed a statistically significant increase.
Standardized Mortality Ratios
As explained in Chapter 8, standardized mortality ratios (SMRs) are used to compare the number of observed deaths in a cohort with the number of expected deaths in the U.S. general population of the same age, race, and sex. An SMR value of 100 indicates that the number of observed deaths equals the number expected. Table 9-6 shows SMRs for subjects with SSNs by analysis group for various causes of death. Because we did not have
OCR for page 42
Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense)
TABLE 9-4 Proportional Hazards Analysis of Total Mortality, by Exposure Group, Including Only Subjects with SSNs, Presumably with Virtually Complete Mortality Follow-Up
Exposure Groupa and Risk Factorb
Hazard Ratio (95% CI)
Group A
Participant versus control
1.00 (0.91–1.10)
Age (per year)
1.09 (1.09–1.10)
Race (nonwhite versus white)
0.91 (0.77–1.07)
Pay grade (officer versus enlisted)
0.55 (0.44–0.68)
Group B
Participant versus control
1.15 (0.90–1.46)
Age (per year)
1.08 (1.05–1.10)
Race (nonwhite versus white)
1.29 (0.94–1.76)
Pay grade (officer versus enlisted)
0.66 (0.43–1.02)
Branch (Marine versus Navy)
1.57 (1.19–2.07)
Group C
Participant versus control
0.87 (0.71–1.06)
Age (per year)
1.10 (1.09–1.12)
Race (nonwhite versus white)
0.69 (0.47–1.00)
Pay grade (officer versus enlisted)
0.81 (0.57–1.14)
Group D
Participant versus control
1.06 (0.88–1.28)
Age (per year)
1.09 (1.08–1.10)
Race (nonwhite versus white)
0.90 (0.60–1.34)
Pay grade (officer versus enlisted)
0.51 (0.34–0.78)
Total
Participant versus control
1.01 (0.93–1.08)
Age (per year)
1.09 (1.09–1.10)
Race (nonwhite versus white)
0.95 (0.84–1.08)
Pay grade (officer versus enlisted)
0.61 (0.52–0.71)
NOTE: Statistically significant hazard ratios are in bold.
aGroup A = participants potentially exposed only to BG or MAA; group B = participants potentially exposed only to TOF; group C = participants potentially exposed to any active chemical or biological agent; group D = participants potentially exposed only to simulants and not in groups A or B.
bEach factor is adjusted for all others in the list.
causes for deaths prior to 1979, the follow-up period for calculation of SMRs begins in 1979. The causes of death in Table 9-6 mirror those in Table 9-5, except that diabetes has replaced endocrine disease.
All-cause SMRs are all close to 100, save for group A controls and group B participants, indicating that overall mortality in these analysis groups is close to that of the U.S. population. However, all-cause SMRs for all participants and all controls combined are slightly, but statistically significantly, greater than 100. Although the cancer mortality SMR is slightly above 100 in almost all groups, it is statistically significant only for all controls and group A controls. Most of the excess cancer deaths were due to lung cancer, which might be attributable to smoking, and several participant and control group SMRs for nonmalignant respiratory disease are above 100, but not statistically significantly different from 100. SMRs for heart disease deaths are all close to 100, with the exception of group B participants. Deaths due to external causes tended to have low SMRs, and were statistically significantly lower among all participants.
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Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense)
TABLE 9-5 Survival Analysis Using Proportional Hazards Regression: Cause-Specific Mortality Comparing Participants to Controls (Adjusted for Age, Race, Pay Grade, and Branch in Group B Only), Including Only Subjects with SSNs, Presumably with Virtually Complete Mortality Follow-Up
Participants
Controls
Adjusted HR*
95% CI
Group A
(# with death information: 3,318)
(# with death information: 3,602)
# died
# died
Cancer
221
251
0.97
0.81–1.16
Heart disease
220
192
1.24
1.02–1.51
Respiratory disease
23
18
1.39
0.75–2.58
Endocrine/metabolic disease
58
62
0.99
0.69–1.42
Infectious disease
43
53
0.84
0.56–1.27
Injury/external causes
41
60
0.76
0.51–1.13
Group B
(# with death information: 854)
(# with death information: 868)
# died
# died
Cancer
36
21
1.92
1.12–3.31
Heart disease
48
28
1.71
1.06–2.75
Respiratory disease
2
2
1.31
0.18–9.43
Endocrine/metabolic disease
10
4
2.31
0.71–7.51
Infectious disease
11
11
1.04
0.45–2.41
Injury/external causes
6
10
0.65
0.23–1.81
Group C
(# with death information: 721)
(# with death information: 1,087)
# died
# died
Cancer
49
62
1.10
0.75–1.61
Heart disease
36
57
0.89
0.59–1.36
Respiratory disease
7
10
0.89
0.34–2.38
Endocrine/metabolic disease
12
23
0.74
0.37–1.49
Infectious disease
10
10
1.61
0.53–3.07
Injury/external causes
9
12
1.27
0.66–3.64
Group D
(# with death information: 848)
(# with death information: 1,200)
# died
# died
Cancer
47
64
1.04
0.71–1.52
Heart disease
47
70
0.96
0.67–1.40
Respiratory disease
6
4
2.08
0.58–7.43
Endocrine/metabolic disease
11
12
1.26
0.55–2.85
Infectious disease
10
15
1.00
0.45–2.23
Injury/external causes
11
15
1.16
0.52–2.55
Total
(# with death information: 5,741)
(# with death information: 6,757)
# died
# died
Cancer
353
398
1.06
0.95–1.10
Heart disease
351
347
1.20
1.03–1.39
Respiratory disease
38
34
1.32
0.83–2.10
Endocrine/metabolic disease
91
101
1.03
0.78–1.38
Infectious disease
74
89
0.97
0.71–1.32
Injury/external causes
67
97
0.86
0.63–1.17
*Adjusted for age, race, pay grade, and branch.
OCR for page 44
Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense)
TABLE 9-6 Mortality Analysis Using Standardized Mortality Ratios (SMRs): Observed Number of Deaths and SMRs for Participants and Controls with SSNs for Selected Causes of Death, 1979–2004, by Analysis Group
Participants: Number of deaths
SMR* (95% CI)
Controls: Number of deaths
SMR* (95% CI)
Group A
All causes
677
105 (97–113)
721
108 (100–116)
Cancer
201
106 (92–122)
233
119 (104–135)
Heart disease
198
100 (86–114)
190
92 (80–106)
Respiratory disease
47
118 (87–157)
41
99 (71–134)
Diabetes
16
93 (53–151)
20
115 (70–177)
Injury/external causes
52
82 (62–108)
77
117 (92–146)
Group B
All causes
126
126 (105–150)
98
106 (86–129)
Cancer
29
121 (81–174)
25
112 (72–165)
Heart disease
40
156 (112–213)
25
105 (68–155)
Respiratory disease
8
179 (77–353)
2
48 (6–174)
Diabetes
3
118 (24–346)
0
—
Injury/external causes
9
50 (23–96)
11
66 (33–117)
Group C
All causes
137
101 (85–120)
205
109 (95–125)
Cancer
48
122 (90–161)
56
103 (78–133)
Heart disease
36
87 (61–120)
45
79 (58–106)
Respiratory disease
9
106 (49–202)
17
152 (89–244)
Diabetes
3
84 (17–245)
9
182 (83–345)
Injury/external causes
9
66 (30–126)
14
70 (38–117)
Group D
All causes
158
107 (91–125)
210
102 (89–117)
Cancer
46
108 (79–144)
61
102 (78–131)
Heart disease
48
107 (79–142)
65
105 (81–133)
Respiratory disease
10
113 (54–207)
15
122 (69–202)
Diabetes
4
104 (28–265)
2
38 (5–136)
Injury/external causes
12
74 (38–130)
19
83 (50–130)
Total
All causes
1,098
107 (100–113)
1,234
107 (101–113)
Cancer
324
110 (98–122)
375
113 (102–125)
Heart disease
322
104 (93–116)
325
93 (83–104)
Respiratory disease
74
120 (94–150)
75
109 (85–136)
Diabetes
26
96 (62–140)
31
104 (70–147)
Injury/external causes
82
74 (59–92)
121
97 (80–115)
NOTE: Statistically significant differences are in bold.
*SMRs are comparisons to national death rates, adjusted for age, race, sex, and calendar year of death (see text for details).
Representative terms from entire chapter:
participants potentially
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