Table 2.
Newcastle–Ottawascale scores for observational studies.
| Study Design | Study | Newcastle–Ottawa Scale | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Selection | Comparability | Exposure /Outcome |
Total Score | |||||||
| 1 | 2 | 3 | 4 | 1 | 1 | 2 | 3 | |||
| 1 | Aweid et al., 2014 [24] | ★ | ★ | ★★ | ★ | ★ | ★★★★★(6) | |||
| Loudon and Reiman, 2012 [25] | ★ | ★ | ★★ | ★ | ★ | ★ | ★★★★★★★(7) | |||
| Naderi et al., 2019 [26] | ★ | ★ | ★ | ★ | ★★ | ★ | ★ | ★ | ★★★★★★★★★(9) | |
| Tweed et al., 2008 [27] | ★ | ★ | ★ | ★ | ★★ | ★ | ★ | ★★★★★★★★(8) | ||
| 2 | Loudon and Dolphino, 2010 [28] | ★ | ★ | ★ | ★★ | ★ | ★ | ★★★★★★★(7) | ||
| Mulvad et al., 2018 [29] | ★ | ★ | ★ | ★★★(3) | ||||||
| Nielsen et al., 2014 [30] | ★ | ★ | ★ | ★★ | ★ | ★ | ★★★★★★★(7) | |||
| Nielsen et al., 2014 [31] | ★ | ★ | ★ | ★ | ★ | ★ | ★★★★★★(6) | |||
| Raissi et al., 2009 [32] | ★ | ★ | ★ | ★★★ (3) | ||||||
| 3 | Gaeta et al., 2006 [33] | ★ | ★★ | ★ | ★★ | ★ | N/A | ★★★★★★★(7) | ||
Case–control studies: Selection (maximum ★★★★): (1) Is the case definition adequate?, (2) Representativeness of the cases, (3) Selection of controls, (4) Definition of controls; Comparability (maximum ★★): (1) Comparability of cases and controls on the basis of the design or analysis; Exposure (maximum ★★★): (1) Ascertainment of exposure, (2) Cases and controls: same ascertainment method, (3) Cases and controls: same non response date. Cohort studies: Selection (maximum ★★★★): (1) Representativeness of the exposed cohort, (2) Selection of the non exposed cohort, (3) Ascertainment of exposure, (4) Demonstration that outcome of interest was not present at the start of the study; Comparability (maximum ★★): (1) Comparability of cohorts on the basis of the design or analysis; Outcome (maximum ★★★): (1) Assessment of outcome, (2) Was follow-up long enough for outcomes to occur, (3) Adequacy of the follow-up of cohorts. Cross-sectional studies: A modified Newcastle–Ottawa scale for cross-sectional studies was used. Selection (maximum ★★★★★): (1) Representativeness of the sample, (2) Sample size, (3) Non respondents, (4) Ascertainment of the exposure (risk factor); Comparability (maximum ★★): (1) The subjects in different outcome groups are comparable, based on the study design or analysis. Confounding factors are controlled; Outcome (maximum ★★★): (1) Assessment of outcome; (2) Statistical test. N/A: not applicable.