Table 2.
Quality assessment using the Newcastle–Ottawa Scale for the included studies.
| Author | Representativeness of Cases | Selection of Controls | Ascertainment of Exposure | Outcome of Interest Was Not Present at Start of Study | Comparability | Assessment of Outcome | Follow-Up Long Enough | Adequacy of Follow-Up | Total |
|---|---|---|---|---|---|---|---|---|---|
| Copper AW et al.—2021 [6] | ★ | - | ★ | - | ★ | - | - | - | 3★ |
| Janson D et al.—2021 [7] | ★ | ★ | - | - | - | - | - | 2★ | |
| Marr SJ et al.—1993 [11] | ★ | - | ★ | - | - | - | - | - | 2★ |
| Dobson JA et al.—2018 [14] | ★ | - | ★ | - | - | - | - | - | 2★ |
| Dobson JA et al.—2017 [15] | ★ | - | ★ | - | ★ | - | - | - | 3★ |
| Dobson JA et al.—2020 [16] | - | ★ | ★ | - | ★ | - | - | - | 3★ |
| Brans R. et al.—2023 [9] | ★ | - | ★ | - | - | - | - | - | 2★ |
Note: The total quality score ranged from 0 to 9, with studies scoring ≥ 5 points being considered as having a low risk of bias while those scoring < 5 points were classified as having a high risk of bias. A study can be given a maximum of one star for each numbered item within the Selection and Outcome categories. A maximum of two stars can be given for Comparability.