Table 1.
The quality assessment for included studies.
| Author, Year, and Country | Study design | Confounder | Total score out of 9 | Overall investigation quality | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Is the case definition adequate? | Representatives of the cases | Selection of controls | Definition of control | Comparability of case and controls on the basis of design and analysis | Ascertainment of exposure | The same method of ascertainment for cases and controls | Non-response rate | ||||
|
Aslan et al.22 (2020, Turkey) |
Case–Control | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 6 | High |
|
Ayyildiz et al.23 (2019, Turkey) |
Case–Control | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 0 | 5 | Moderate |
|
Bae et al.24 (2019, South Korea) |
Case–Control | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 0 | 5 | Moderate |
|
Bodur et al.25 (2018, Turkey) |
Case–Control | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 5 | Moderate |
|
Daluwatte et al.26 (2013, USA) |
Case–Control | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 7 | High |
|
Fan et al.27 (2009, USA) |
Case–Control | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 6 | High |
|
Garcia-Medina et al.28 (2017, Spain) |
Case–Control | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 7 | High |
|
Garcia-Medina et al.29 (2020, Spain) |
Case–Control | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 6 | High |
|
Grönlund et al.30 (2007, Sweden) |
Case–Control | 1 | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 6 | High |
|
Hergüner et al.15 (2018, Turkey) |
Case–Control | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 0 | 5 | Moderate |
| Işık et al.31 (2020, Turkey) | Case–Control | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 0 | 5 | Moderate |
| Lynch et al.32 (2018, USA) | Case–Control | 1 | 1 | 0 | 1 | 1 | 1 | 1 | 0 | 6 | High |
|
Sánchez-Guillén et al.29 (2020, Spain) |
Case–Control | 1 | 1 | 0 | 1 | 2 | 1 | 1 | 0 | 7 | High |
|
Tarakcioglu et al.33 (2020, Turkey) |
Case–Control | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 0 | 5 | Moderate |
|
Ulucan Atas et al.34 (2020, Turkey) |
Case–Control | 1 | 1 | 0 | 1 | 2 | 1 | 1 | 1 | 8 | High |