Table 2.
Quality assessment of included cohort studies
| Source | Selection | Comparability | Outcome | Scores | |||||
|---|---|---|---|---|---|---|---|---|---|
| Author, year | Representativeness of the exposed cohort | Selection of the non exposed cohort | Ascertainment of exposure | Demonstration that outcome was not present at start of study | select the most important factora | Assessment of outcome | Follow-up long enough | Adequacy of follow up of cohorts | |
| Aboutaleb,2012 [9] | – | – | ★ | ★ | ★★ | ★ | ★ | ★ | 7 |
| Armagan,2015 [10] | – | – | ★ | ★ | ★★ | ★ | – | ★ | 6 |
| Bozkur,2011 [11] | ★ | ★ | ★ | ★ | ★★ | ★ | ★ | ★ | 9 |
| Chung,2008 [12] | – | – | ★ | ★ | ★★ | ★ | ★ | ★ | 7 |
| Ferroud,2011 [13] | – | – | ★ | ★ | ★★ | ★ | ★ | ★ | 7 |
| Hu, 2016 [15] | ★ | ★ | ★ | ★ | ★★ | ★ | ★ | ★ | 9 |
| Kirac,2013 [16] | ★ | ★ | ★ | ★ | ★★ | ★ | ★ | ★ | 9 |
| Kruck,2013 [17] | – | – | ★ | ★ | ★★ | ★ | ★ | ★ | 7 |
| Ozgor,2016 [19] | – | – | ★ | ★ | ★★ | ★ | ★ | ★ | 7 |
| Ozgor, 2018 [20] | – | – | ★ | ★ | ★★ | ★ | ★ | ★ | 7 |
| Pan, 2013 [21] | – | – | ★ | ★ | ★★ | ★ | ★ | ★ | 7 |
| Sabnis,2012 [22] | – | – | ★ | ★ | ★★ | ★ | ★ | ★ | 7 |
| Schoenthaler,2015 [24] | ★ | ★ | ★ | ★ | ★★ | ★ | – | ★ | 8 |
| Wilhelm,2015 [25] | – | – | ★ | ★ | ★★ | ★ | – | ★ | 6 |
| Zhang,2014 [26] | – | – | ★ | ★ | ★★ | ★ | – | ★ | 6 |
aA maximum of two stars can be awarded for select the most important factor or additional factor