Methodological quality score of 12 studies included in the systematic review based on Newcastle-Ottawa quality assessment score
| Author (year) | Selection | Comparability | Outcome | Total score | |||||
| Representativeness of the exposed cohort | Selection of the non-exposed cohort | Ascertainment of exposure | Demonstration that outcome of interest was not present at start of study | Comparability of cohorts on the basis of the design or analysis | Assessment of outcome | Was follow-up long enough for outcomes to occur | Adequacy of follow-up of cohorts | (Out of 9) | |
| Skaaby et al. 30 (2021) | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 6 |
| Lytras et al. 29 | 1 | 1 | 0 | 1 | 2 | 1 | 1 | 1 | 8 |
| Faruque et al. 24 (2020) | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 7 |
| Alif et al.1 (2019) | 1 | 1 | 0 | 1 | 2 | 1 | 1 | 1 | 8 |
| Bui et al. 23 (2019) | 1 | 1 | 0 | 1 | 0 | 1 | 1 | 1 | 6 |
| Tagiyeva et al.32 (2017) | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 7 |
| Liao et al.28 (2015) | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 6 |
| de Jong et al.2 (2014) | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 6 |
| Harber et al.25 | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 7 |
| Sunyer et al.31 (2005) | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 7 |
| Humerfelt et al.26 (1993) | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 7 |
| Krzyzanowiski et al.27 (1985) | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 7 |