Table 2. Quality assessment of eligible studies Newcastle–Ottawa scale (NOS).
| Author | Country | Selection | Comparability | Outcome | Total | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Adequate of case definition | Representativeness of the cases | Selection of Controls | Definition of Controls | Comparability of cases and controls | Ascertainment of exposure | Same method of ascertainment | Non-response rate | |||
| Ma, X. (2019) | China | NA | * | * | * | ** | * | * | * | 8 |
| Dong, Y. (2018) | China | * | * | * | * | ** | * | * | * | 9 |
| Cui, X. (2018) | China | * | * | * | * | ** | * | * | * | 9 |
| Jin, B. (2017) | China | * | * | * | * | ** | * | * | * | 9 |
| Zhang, J. (2017) | China | * | * | * | * | * | * | * | * | 8 |
| Liu, Y. (2018) | China | * | * | * | * | ** | * | * | NA | 8 |
| Wu, D. (2018) | China | * | * | * | * | ** | * | * | * | 9 |
| Huang, L. (2018) | China | * | * | * | * | ** | * | * | * | 9 |
| Qu, C. (2019) | China | * | * | * | * | ** | * | * | * | 9 |
| Kong, Q. (2018) | China | * | * | * | * | ** | * | * | * | 9 |
| Ma, Y. (2017) | China | * | * | * | * | ** | * | * | * | 9 |
| Du, Y. (2018) | China | * | * | * | * | ** | * | * | NA | 8 |
| Chen, S. (2015) | China | * | * | * | * | * | * | * | * | 8 |
| Guo, X. (2018) | China | * | * | * | * | ** | * | * | * | 9 |
| Ma, Z. (2017) | China | * | * | * | * | * | * | * | NA | 7 |
Note: NA: not available
Reasons:
1: Adequate of case definition (Ma, X. (2019)): Small number of patients in this study (n=24) would make Result bias to a certain extent.
2: Comparability of cases and controls (Zhang, J. (2017); Chen, S. (2015); Ma, Z. (2017)): these three studies without reporting the “cut-off value”, and reduced the comparability between the experimental group and the control group to a certain extent.
3: Non-response rate (Liu, Y. (2018); Du, Y. (2018); Ma, Z. (2017)): these three studies lack of follow-up time of patient, and we don't known whether the patient cooperates with treatment from beginning to end.