Table 2. Quality assessment performed using the Newcastle-Ottawa Scale (NOS).
| Selection | Exposure | Outcome | ||||
| Study | Representativeness of cohort | Demonstration that outcome of interest was not present at start of study | Ascertainment of exposure | Assessment of outcome | Was follow-up long enough for outcomes to occur? | Adequacy of follow-up of cohorts |
| Al-Bawardy, et al 10 | Yes | Yes | Yes | Yes | Yes | No |
| Backes, et al 11 | Yes | Yes | Yes | Yes | Yes | No |
| Dinelli, et al 12 | Yes | Yes | Yes | Yes | Yes | Yes |
| Schmidt, et al 13 | Yes | Yes | Yes | Yes | Yes | Yes |
| Valli, et al 14 | Yes | Yes | Yes | Yes | Yes | Yes |
| Kappelle, et al 3 | Yes | Yes | Yes | Yes | Yes | Yes |
| Bas van der Spek 15 | Yes | Yes | Yes | Yes | Yes | No |
| Markus Bauder 16 | Yes | Yes | Yes | Yes | Yes | Yes |
| Schmidt, et al 17 | Yes | Yes | Yes | Yes | Yes | Yes |
| Sarker, et al 18 | Yes | Yes | Yes | Yes | Yes | No |
| Aepli P. 19 | Yes | Yes | Yes | Yes | Yes | No |
| G. Andrisani 20 | Yes | Yes | Yes | Yes | Yes | Yes |
| Armin Kuellmer 21 | Yes | Yes | Yes | Yes | Yes | Yes |
| Maxime E. S. Bronzwaer 22 | Yes | Yes | Yes | Yes | Yes | No |
| Francesco Vitali 23 | Yes | Yes | Yes | Yes | Yes | Yes |
| Wenhai Wang 24 | Yes | Yes | Yes | Yes | Yes | Yes |
| Paola Soriani 25 | Yes | Yes | Yes | Yes | Yes | Yes |
| Susana Mão de-Ferro 26 | Yes | Yes | Yes | Yes | Yes | Yes |