Newcastle Ottawa criteria (Yes, No, Uncertain) | El Ansari et al. [4] | Lee et al. [5] | Jahan et al. [7] | Nur et al. [8] | Balmus et al. [9] | Chu et al. [10] | Gomathi et al. [11] | Awadalla et al. [12] | Chu et al. [13] | Rahman et al. [14] |
Representative of the exposed cohort | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
Selection of external control | No | No | No | No | Yes | No | No | No | No | No |
Ascertainment of exposure | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
The desired outcome is not present at the start of the investigation. | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
Comparability of the main factor | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
Comparability of the additional factor | Yes | Yes | Yes | No | No | No | No | Yes | Yes | Yes |
Assessment of outcome | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
Enough time for follow-up | No | No | No | No | No | No | No | No | No | No |
Adequacy of follow up | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes | Yes |
Evaluation | 7/9 | 7/9 | 7/9 | 6/9 | 7/9 | 6/9 | 6/9 | 6/9 | 7/9 | 6/9 |