Author

(Year)

Country

Patton et al. (2017)

USA

Merrill et al. (2005)

USA

Meadows et al. (2015)

USA

Chimah et al. (2015)

Nigeria

Adejimi et al. (2021)

Nigeria

1. Were the groups comparable other than the presence or absence of service/deployment in controls?

0

N/A

0.5

0

0

2. Were cases and controls matched appropriately?

0

N/A

0.5

0

N/A

3. Were the same criteria used for identification of cases and controls?

1

N/A

1

1

N/A

4. Was exposure measured in a standard, valid and reliable way?

0

N/A

0.5

0.5

1

5. Was exposure measured in the same way for cases and controls?

1

0

0.5

1

N/A

6. Were confounding variables identified?

N/A

1

1

0

0.5

7. Were strategies to deal with confounding variables stated?

N/A

0

1

0

0.5

8. Were outcomes assessed in a standard, valid and reliable way for cases and controls?

1

1

1

0

0.5

9. Was the exposure period of interest long enough to be meaningful?

N/A

1

N/A

N/A

N/A

10. Was appropriate statistical analysis used?

1

0

0

0

0.5

Overall score

3

3

6

2.5

3

Risk of bias

High

High

Moderate

High

High