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Suggested Citation:"9 Mortality Results." Institute of Medicine. 2007. Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense). Washington, DC: The National Academies Press. doi: 10.17226/11900.
×

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.

Suggested Citation:"9 Mortality Results." Institute of Medicine. 2007. Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense). Washington, DC: The National Academies Press. doi: 10.17226/11900.
×

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

Suggested Citation:"9 Mortality Results." Institute of Medicine. 2007. Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense). Washington, DC: The National Academies Press. doi: 10.17226/11900.
×

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

Suggested Citation:"9 Mortality Results." Institute of Medicine. 2007. Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense). Washington, DC: The National Academies Press. doi: 10.17226/11900.
×

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.

Suggested Citation:"9 Mortality Results." Institute of Medicine. 2007. Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense). Washington, DC: The National Academies Press. doi: 10.17226/11900.
×

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.

Suggested Citation:"9 Mortality Results." Institute of Medicine. 2007. Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense). Washington, DC: The National Academies Press. doi: 10.17226/11900.
×

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).

Suggested Citation:"9 Mortality Results." Institute of Medicine. 2007. Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense). Washington, DC: The National Academies Press. doi: 10.17226/11900.
×
Page 39
Suggested Citation:"9 Mortality Results." Institute of Medicine. 2007. Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense). Washington, DC: The National Academies Press. doi: 10.17226/11900.
×
Page 40
Suggested Citation:"9 Mortality Results." Institute of Medicine. 2007. Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense). Washington, DC: The National Academies Press. doi: 10.17226/11900.
×
Page 41
Suggested Citation:"9 Mortality Results." Institute of Medicine. 2007. Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense). Washington, DC: The National Academies Press. doi: 10.17226/11900.
×
Page 42
Suggested Citation:"9 Mortality Results." Institute of Medicine. 2007. Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense). Washington, DC: The National Academies Press. doi: 10.17226/11900.
×
Page 43
Suggested Citation:"9 Mortality Results." Institute of Medicine. 2007. Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense). Washington, DC: The National Academies Press. doi: 10.17226/11900.
×
Page 44
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Long-Term Health Effects of Participation in Project SHAD (Shipboard Hazard and Defense) Get This Book
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More than 5,800 military personnel, mostly Navy personnel and Marines, participated in a series of tests of U.S. warship vulnerability to biological and chemical warfare agents, Project SHAD (Shipboard Hazard and Defense), in the period 1962-1973. Only some of the involved military personnel were aware of these tests at the time. Many of these tests used simulants, substances with the physical properties of a chemical or biological warfare agent, thought at the time to have been harmless. The existence of these tests did not come to light until many decades later.

In September 2002, the Institute of Medicine (IOM) agreed to undertake a scientific study, funded by the Veterans' Affairs, of potential long-term health effects of participation in Project SHAD. In general, there was no difference in all-cause mortality between Project SHAD participants and nonparticipant controls, although participants statistically had a significantly higher risk of death due to heart disease, had higher levels of neurodegenerative medical conditions and higher rates of symptoms with no medical basis.

Long-Term Health Effects of Participation in Project SHAD focuses on the potential health effects of participation in Project SHAD. It is a useful resource for government defense agencies, scientists and health professionals.

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