Table 2.
Quality assessment of included studies a
| |
|
Quality assessment criteria |
|||
|---|---|---|---|---|---|
| Author | Study design | Selection | Comparability | Outcome/exposure | Overall quality |
| Kreiger N
[17] |
Case–control |
*** |
** |
*** |
8 |
| Johnell O
[18] |
Case–control |
*** |
* |
** |
6 |
| Tavani A
[19] |
Case–control |
*** |
* |
** |
7 |
| Chen Z
[20] |
Cohort |
*** |
* |
** |
6 |
| Hallström H
[21] |
Cohort |
**** |
** |
*** |
9 |
| Jha RM
[22] |
Case–control |
** |
** |
* |
5 |
| Kanis J
[23] |
Case–control |
*** |
** |
*** |
8 |
| Zeng FF
[24] |
Case–control |
*** |
** |
** |
7 |
| Tomata Y [25] | Cohort | *** | *** | ** | 8 |
aThe study quality is evaluated by Downs and Black score and Newcastle-Ottowa Scale (NOS). The NOS were obtained to assess the selection, comparability and exposure of the case–control study, while the selection, comparability and outcome for the cohort study.
*: one point; **: two points; ***: three points.