Table 2 Risk of bias and quality assessment for cohort studies with the Newcastle–Ottawa Scale (NOS) for cohort studies
Source | Selection (scale, 1–4) | Comparability (scale, 1–2) | Outcome (scale, 1–3) | Total (1–9) | Study quality |
|---|---|---|---|---|---|
Wang et al., 2006 [13] | 3 | 1 | 3 | 7 | Good |
Yadav et al., 2007 [14] | 3 | 1 | 3 | 7 | Good |
Hamada et al., 2008 [15] | 3 | 1 | 1 | 5 | Poor |
Staykov et al., 2009 [16] | 3 | 2 | 3 | 8 | Good |
Xia et al., 2014 [18] | 3 | 1 | 3 | 7 | Good |
Obaid et al., 2015 [19] | 3 | 2 | 3 | 8 | Good |
Ogiwara et al., 2021 [20] | 3 | 1 | 2 | 6 | Fair |