Table 3. Assessment of risk bias in cohort studies.
| Study | Type | Selection | Comparability | Outcome | NOS score | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Representativeness of the exposed cohort | Selection of the non-exposed cohort | Ascertainment of exposure | Demonstration that outcome of interest was not present at start of study | Comparability of cohorts on the basis of the design or analysis | Assessment of outcome | Was follow-up long enough for outcomes to occur | Adequacy of follow up of cohorts | |||||
| Meng 2003 (29) | Cohort | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 6 | ||
| Peng 2004 (30) | Cohort | 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | 6 | ||
| Wang 2004 (31) | Cohort | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 1 | 5 | ||
| Wang 2005 (32) | Cohort | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 6 | ||
| Chen 2006 (33) | Cohort | 0 | 0 | 1 | 0 | 0 | 1 | 1 | 1 | 4 | ||
| Yam 2007 (34) | Cohort | 0 | 0 | 1 | 0 | 0 | 1 | 1 | 1 | 4 | ||
| Ma 2008 (35) | Cohort | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 7 | ||
| Lau 2009 (36) | Cohort | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 6 | ||
| Arabi 2018 (37) | Cohort | 1 | 1 | 1 | 0 | 2 | 1 | 1 | 1 | 8 | ||
| Zhou 2020 (38) | Cohort | 0 | 0 | 1 | 0 | 1 | 1 | 0 | 1 | 4 | ||
| Wu 2020 (39) | Cohort | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 5 | ||
| Wang 2020 (40) | Cohort | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 5 | ||
| Shang 2020 (41) | Cohort | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 5 | ||
| Ding 2005 (42) | Cohort | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | ||
| Ni 2020 (43) | Cohort | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 0 | 5 | ||
| He 2003 (44) | Cohort | 0 | 0 | 1 | 0 | 0 | 1 | 1 | 1 | 4 | ||
| Shen 2006 (45) | Cohort | 0 | 1 | 0 | 1 | 1 | 1 | 0 | 0 | 4 | ||
| Hu 2004 (46) | Cohort | 1 | 1 | 0 | 0 | 1 | 0 | 0 | 1 | 4 | ||
| Jin 2004 (47) | Cohort | 0 | 0 | 1 | 0 | 0 | 1 | 1 | 1 | 4 | ||
| Li 2004 (49) | Cohort | 1 | 1 | 1 | 0 | 2 | 1 | 0 | 1 | 7 | ||
| Zhou 2004 (50) | Cohort | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 0 | 6 | ||
| Auyeung 2005 (51) | Cohort | 0 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 5 | ||