TABLE 2.
Risk of bias assessment cohort studies (Newcastle-Ottawa Quality Assessment Scale criteria).
| Studies | Selection | Comparability | Outcome | Risk of bias | ||||||||
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| Representativeness of the exposed cohort | Non-exposed cohort |
Ascertainment of exposure |
Outcome of interest not present at start | Comparability of cohorts |
Assessment of outcome |
Follow-up duration sufficient |
Adequacy of follow-up |
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| Adank et al. (12) | 1a | 1 | 1 | 1 | 1 | 1 | 1 | 1 | Lowb | |||
| Chen et al. (13) | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | Low | |||
| Pecks et al. (17) | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | Low | |||
| Kim et al. (14) | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | Low | |||
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| Risk of bias assessment case-control studies (Newcastle-Ottawa Quality Assessment Scale criteria) | ||||||||||||
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| Studies | Selection | Comparability | Exposure | Risk of bias | ||||||||
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| Adequacy case definition | Representativeness of cases | Selection of controls | Definition of controls | Comparability of cases and controls | Ascertainment of exposure | Same method of ascertainment |
Non-response rate |
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| Serizawa et al. (18) | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | Low | |||
| Kramer et al. (15) | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | Low | |||
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| Risk of bias assessment cross-sectional studies (11-item checklist) | ||||||||||||
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| Studies | Define the source of information | Inclusion and exclusion criteria | Time period used for identifying patients | Whether or not subjects were consecutive |
Other aspects of the status of the participants |
Assessments undertaken for quality assurance purposes | Explain any patient exclusions from analysis | Describe how confounding was assessed and/or controlled | Explain how missing data were handled in the analysis | Patient response rates and completeness of data collection | Incomplete data or follow-up | Risk of bias |
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| Parlakgumus et al. (16) | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | Lowd |
| Abdel-Hamid et al. (11) | 1c | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | Low |
aIf the study met the criteria, it got one score; If not, it got no score.
bLow, 7–9; medium, 4–6; high, 0–3.
cIf it was answered “Yes,” it got one score; if answered “No” or “Unclear,” it got no score.
dLow, 8–11; medium, 4–7; high, 0–3.