Table S1. Assessment of study quality with Newcastle-Ottawa scale.
| Study ID | Year | Selection |
Comparability |
Exposure |
No. of star | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| S1 | S2 | S3 | S4 | C1 | C2 | E1 | E2 | E3 | |||||
| Chariyalertsak S | 1994 | ★ | ★ | ★ | ★ | ★ | ★ | 6 | |||||
| Kim JS | 1997 | ★ | ★ | ★ | ★ | ★ | ★ | 6 | |||||
| Kim JH | 2009 | ★ | ★ | ★ | ★ | ★ | ★ | ★ | ★ | 8 | |||
| Marx AH | 2009 | ★ | ★ | ★ | ★ | ★ | 5 | ||||||
| Kim JY | 2010 | ★ | ★ | ★ | ★ | ★ | 5 | ||||||
| Kim MA | 2011 | ★ | ★ | ★ | ★ | ★ | 5 | ||||||
| Geng YT | 2011 | ★ | ★ | ★ | ★ | ★ | ★ | ★ | 7 | ||||
| Bozzetti C | 2011 | ★ | ★ | ★ | ★ | ★ | ★ | 6 | |||||
| Zhang YL | 2012 | ★ | ★ | ★ | ★ | ★ | 5 | ||||||
| Tsapralis D | 2012 | ★ | ★ | ★ | ★ | ★ | ★ | 6 | |||||
| Fassan M | 2012 | ★ | ★ | ★ | ★ | ★ | ★ | ★ | 7 | ||||
| Asioli S | 2012 | ★ | ★ | ★ | ★ | ★ | 5 | ||||||
| Shinozaki E | 2013 | ★ | ★ | ★ | ★ | 4 | |||||||
| Pagni F | 2013 | ★ | ★ | ★ | ★ | ★ | ★ | 6 | |||||
| Kochi M | 2013 | ★ | ★ | ★ | ★ | ★ | ★ | ★ | 7 | ||||
| Fusco N | 2013 | ★ | ★ | ★ | ★ | ★ | ★ | ★ | ★ | 8 | |||
| Cho EY | 2013 | ★ | ★ | ★ | ★ | ★ | ★ | ★ | 7 | ||||
| Geng Y | 2014 | ★ | ★ | ★ | ★ | ★ | ★ | 6 | |||||
Selection contains four criteria: S1, is the case definition adequate? S2, representativeness of the cases; S3, selection of controls; S4, definition of controls. Comparability means: C1, comparability of cases; C2, controls on the basis of the design or analysis. Exposure contains three criteria: E1, ascertainment of exposure; E2, same method of ascertainment for cases and controls; E3, non-response rate.