Table 2.
Assessment of study quality using the GRADE quality assessment criteria
| Study | Risk of bias | Inconsistency | Indirectness | Imprecision | Publication bias | Quality rating |
|---|---|---|---|---|---|---|
| 1 | Not serious | Not serious | Serious | Not serious | Undetected | Moderate |
| 2 | Not serious | Not serious | Serious | Not serious | Undetected | Moderate |
| 3 | Not serious | Not serious | Not serious | Not serious | Undetected | High |
| 4 | Not serious | Serious | Not serious | Not serious | Undetected | Moderate |
| 5 | Not serious | Not serious | Serious | Not serious | Undetected | Moderate |
| 6 | Not serious | Not serious | Not serious | Not serious | Undetected | High |
| 7 | Not serious | Not serious | Serious | Not serious | Undetected | Moderate |
| 8 | Not serious | Not serious | Serious | Not serious | Undetected | Moderate |
| 9 | Not serious | Serious | Not serious | Not serious | Undetected | Moderate |
| 10 | Not serious | Not serious | Not serious | Not serious | Undetected | High |
| 11 | Not serious | Not serious | Serious | Not serious | Undetected | Moderate |
| 12 | Not serious | Not serious | Serious | Not serious | Undetected | Moderate |
| 13 | Not serious | Serious | Serious | Not serious | Undetected | Low |
| 14 | Not serious | Serious | Serious | Serious | Undetected | Low |
| 15 | Serious | Not serious | Serious | Serious | Undetected | Low |
| 16 | Not serious | Serious | Serious | Not serious | Undetected | Low |
| 17 | Not serious | Serious | Serious | Not serious | Undetected | Low |
| 18 | Not serious | Serious | Not serious | Not serious | Undetected | Moderate |
| 19 | Not serious | Serious | Not serious | Not serious | Undetected | Moderate |
| 20 | Not serious | Not serious | Not serious | Not serious | Undetected | High |
| 21 | Not serious | Not serious | Not serious | Not serious | Undetected | High |