Table 2.
Quality evaluation for included studies
| Study | Selection |
Comparability |
Outcome |
Total points |
| (1) Representativeness of exposed cohort(2) Selection of non-exposed cohort(3) Ascertainment of exposure(4) Demonstration that the outcome ofinterest was not present at the startof the study | (1) Comparabilityof cohorts onthe basis of the design or analysis | (1) Assessment of outcome (2) Was follow-up long enough for outcomes to occur (3) Adequacy of follow-up of cohorts | ||
| Gao et al., 2007 | *1), *2), *3), *4) | none | *2) | 5 |
| Kobayashi et al., 2007 | *1), *2), *3), *4) | none | *2), *3) | 6 |
| Sasaki et al., 2008 | *1), *2), *3), *4) | none | *2), *3) | 6 |
| Shen et al., 2011 | *1), *2), *3), *4) | none | *3) | 5 |
| Chen et al., 2011 | *3), *4) | none | *2) | 3 |
| Huang et al., 2012 | *1), *2), *3), *4) | none | *1), *2), *3) | 7 |
| Mathai et al., 2012 | *1), *2), *3), *4) | none | *2), *3) | 6 |
| Wang et al., 2012 | *1), *2), *3), *4) | none | *2), *3) | 6 |
| Zhou et al., 2010 | *2), *3), *4) | none | *3) | 4 |
| Fu et al., 2007 | *1), *2), *3), *4) | none | none | 4 |
| Ju et al., 2009a | *1), *2), *3), *4) | none | *2) | 5 |
| Cai et al., 2009 | *1), *2), *3), *4) | none | *2), *3) | 6 |
| Ju et al., 2009b | *3), *4) | none | *2) | 3 |
| Zhou et al., 2006 | *1), *2), *3), *4) | none | none | 4 |
| Gao et al., 2009 | *1), *2), *3), *4) | none | none | 4 |
| Lin et al., 2013 | *1), *2), *3), *4) | none | none | 4 |