Table 2. Newcastle-Ottawa Quality Assessments Scale.
| Author | Year | Selection | Comparability | Exposure | Scores | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | |||||
| Frank (11) | 2016 | ★ | ★ | ★ | ★ | ★★ | ★ | ★ | – | 8 | ||
| Magana-Valladares (12) | 2018 | ★ | – | – | ★ | ★★ | ★ | ★ | ★ | 7 | ||
| Schneider (13) | 2016 | ★ | ★ | – | ★ | ★★ | ★ | ★ | ★ | 8 | ||
| Bowen (14) | 2012 | ★ | – | – | ★ | ★★ | – | ★ | ★ | 6 | ||
1, representativeness of the exposed cohort; 2, selection of the non-exposed cohort; 3, ascertainment of exposure; 4, outcome of interest not present at start of study; 5, control for important factor or additional factor; 6, assessment of outcome; 7, follow-up long enough for outcomes to occur; 8, adequacy of follow up of cohorts.