Author (Year) Country | USA | USA | USA | Nigeria | 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 |