Table 4.
Newcastle Ottawa Scale (NOS) for quality assessment of nonrandomized studies
| Study | Study design | Selection | Comparability | Outcome | Total points | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| S1 | S2 | S3 | S4 | C1 | C2 | O1 | O2 | O3 | |||
| Lynch (2016) [21] | Retrospective cohort | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 9 |
| du Cheyron (2010) [19] | Prospective cohort | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 8 |
| Schortgen (2000) [22] | Retrospective cohort | 1 | 0 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 6 |
| Eastwood (2012) [18] | Prospective cohort | 1 | 1 | 1 | 1 | 0 | 1 | 0* | 1 | 1 | 7 |
*Unclear if blinded assessment
For quality assessment, > 7 points is considered ‘good quality’