Supplementary Table 1.
NOS score of the included articles
| Author | Is the case definition adequate | Representativeness of the cases | Selection of controls | Definition of controls | |
|---|---|---|---|---|---|
| N.E,.Gulcelik | Yes, with independent validation★ | Consecutive or obviously representative series of cases★ | No description | No history of disease (endpoint)★ | |
| Goh Eun Chung | Yes, with independent validation★ | Potential for selection biases or not stated | Hospital controls | No history of disease (endpoint)★ | |
| Masayoshi Ohnishi | Yes, with independent validation★ | Potential for selection biases or not stated | Hospital controls | No history of disease (endpoint)★ | |
| Fei Zhou | Yes, with independent validation★ | Consecutive or obviously representative series of cases★ | No description | No history of disease (endpoint)★ | |
| Mehmet Demir | Yes, with independent validation★ | Potential for selection biases or not stated | Hospital controls | No history of disease (endpoint)★ | |
| Yusuf Kayar | Yes, with independent validation★ | Consecutive or obviously representative series of cases★ | No description | No history of disease (endpoint)★ | |
| Sherifa Ahmed Hamed | Yes, with independent validation★ | Potential for selection biases or not stated | No description | No history of disease (endpoint)★ | |
| Author | Comparability of cases and controls on the basis of the design or analysis | Ascertainment of exposure | Same method of ascertainment for cases and controls | Nonresponse rate | NOS quality assessment |
| N.E,.Gulcelik | Select the most important factor★ | Secure record (e.g., surgical records)★ | Yes★ | Nonrespondents described | ★★★★★★ |
| Goh Eun Chung | Select the most important factor★ | Secure record (e.g., surgical records)★ | Yes★ | Nonrespondents described | ★★★★★ |
| Masayoshi Ohnishi | Select the most important factor★ | Secure record (e.g., surgical records)★ | Yes★ | Nonrespondents described | ★★★★★ |
| Fei Zhou | Select the most important factor★ | Secure record (e.g., surgical records)★ | Yes★ | Nonrespondents described | ★★★★★★ |
| Mehmet Demir | Select the most important factor★ | Secure record (e.g., surgical records)★ | Yes★ | Nonrespondents described | ★★★★★ |
| Yusuf Kayar | Select the most important factor★ | Secure record (e.g., surgical records)★ | Yes★ | Nonrespondents described | ★★★★★★ |
| Sherifa Ahmed Hamed | Select the most important factor★ | Secure record (e.g., surgical records)★ | Yes★ | Nonrespondents described | ★★★★★ |
NOS: Newcastle–Ottawa Scale.