Table 2 Quality assessment and risk of bias using the modified Newcastle–Ottawa scale
Selection | Comparability | Exposure | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Study ID | Design | Definition of cases (Maximum: *) | Representativeness of the cases (Maximum: *) | Selection of controls (Maximum: *) | Definition of controls (Maximum: *) | Comparability of cases and controls on the basis of the design or analysis (Maximum: **) | Assessment of exposure (Maximum: *) | Same method of ascertainment for cases and controls (Maximum: *) | Non-response rate (Maximum: *) | Total score (out of 9) | Risk of bias (low/moderate/high) |
Heffner et al. | Case–control study | – | * | * | – | ** | – | * | – | 5 | Moderate |
Matthew S. Briggs et al. | Case–control study | * | * | – | – | ** | * | * | – | 6 | Moderate |
Queiroz et al. | Case–control study | * | * | * | – | ** | * | * | – | 7 | Low |
Yong Li et al. | Case–control study | * | * | * | – | ** | * | * | – | 7 | Low |
Klyne et al. | Case–control study | * | * | * | – | ** | * | * | – | 7 | Low |
Luchting B. et al. | Case–control study | - | * | * | – | ** | – | – | – | 4 | Moderate |
Queiroz et al. | Case–control study | * | * | * | – | ** | – | * | – | 6 | Moderate |
Klyne et al. | Case–control study | * | * | * | – | ** | * | * | – | 7 | Low |
Teodorczyk-Injeyan et al. | Case–control study | – | * | * | * | * | * | * | – | 6 | Moderate |
Kevin Kwan Ngai Ho et al. | Case–control study | * | * | – | – | ** | * | * | – | 6 | Moderate |
Payman Dadkhah et al. | Case–control study | * | * | * | – | ** | * | * | – | 7 | Low |
Hao-Wei Xu et al. | Case–control study | * | * | * | – | ** | * | * | – | 7 | Low |
Selection | Comparability | Exposure | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Study ID | Design | Representativeness of the exposed cohort (Maximum: *) | Selection of the non-exposed cohort (Maximum: *) | Ascertainment of exposure (Maximum: *) | Demonstration that outcome of interest was not present at start of study (Maximum: *) | Comparability of cohorts on the basis of the design or analysis (Maximum: **) | Assessment of outcome (Maximum: *) | Was follow-up long enough for outcomes to occur (Maximum: *) | Adequacy of follow-up of cohorts (Maximum: *) | Total score (out of 9) | Risk of bias (low/moderate/high) |
Katja Gebhardt et al. | Longitudinal cohort study | * | * | – | – | ** | * | * | – | 6 | Moderate |
Amber M Beynon et al. | Longitudinal cohort study | * | * | – | * | ** | * | * | – | 7 | Low |
Klyne et al. | Longitudinal cohort study | * | * | * | – | ** | * | * | – | 7 | Low |