Table 3. Quality appraisal (Newcastle-Ottawa Quality Assessment Scale (NCOS): non-randomised clinical trials/cohort study) .
| Baser et al. [8] | Bektas et al. [9] | Bertossi et al. [10] | De Rosa et al. [11] | Esen et al. [5] | Giammarioli and Liberti [2] | He et al. [12] | Josipovic et al. [13] | Jung et al. [14] | Ramos et al. [15] | Santorelli and Marlino [4] | Trivisonno et al. [16] | |
| Representativeness of the exposed cohort | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Selection of the non-exposed cohort | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Ascertainment of exposure | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Demonstration that outcome of interest was not present at the start of the study | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Comparability of cohorts based on the design or analysis | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 0 | 0 | 1 | 1 |
| Assessment of outcome | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Was follow-up long enough for outcomes to occur? | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Adequacy of follow-up of cohorts | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| Total Score | 7 | 7 | 7 | 7 | 6 | 7 | 6 | 7 | 6 | 6 | 7 | 7 |