Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
| Study | Selection | Comparability | Exposure | Total Score | |||||
|---|---|---|---|---|---|---|---|---|---|
| Definition adequate | Representativeness | Selection of controls | Definition of controls | Ascertainment | Same method | Non-response rate | |||
| Xu et al. (2019) | ★ | ★ | ★ | ★★ | ★ | ★ | ★ | 8 | |
| Yang et al. (2016) | ★ | ★ | ★ | ★★ | ★ | ★ | ★ | 8 | |
| Song et al. | ★ | ★ | ★★ | ★ | ★ | ★ | 7 | ||
| Li et al. (2011) | ★ | ★ | ★ | ★ | ★ | ★ | ★ | ★ | 8 |
| Li et al. (2010) | ★ | ★ | ★ | ★ | ★ | ★ | ★ | ★ | 8 |
| Wang et al. (2010) | ★ | ★ | ★ | ★★ | ★ | ★ | ★ | 8 | |
