Table 2: Risk of Bias assessed by QUADAS-2.
| Author | Year | Country | Risk of Bias | Applicability Concerns |
| Patient Selection | Index Test | Reference Standard | Flow and Timing | Patient Selection | Index Test | Reference Standard |
| Yang et.al | 2009 | China | Low | Low | Low | Low | Low | Low | Low |
| Esmaili et.al | 2006 | Iran | Low | Low | Low | Low | Low | Low | Low |
| Boskovic et.al | 2014 | Serbia | Low | Low | Low | Low | Low | Low | Low |
| Rastogi et.al | 2009 | India | High | Low | Low | Low | Low | Low | Low |
| Russo et.al | 2016 | United States | Low | Low | Low | Low | Low | Low | Low |
| Tolia et.al | 1986 | United States | Low | Low | Low | Low | Low | Low | Low |
| Dehghani et.al | 2006 | Iran | Low | Low | Low | High | Low | Low | Low |
| Mowat et.al | 1976 | UK | Low | Low | Low | Low | Low | Low | Low |
| Guelrud et.al | 1991 | Venezuela | Low | Low | Low | High | Low | Low | Low |
| Faweya et.al | 1991 | Iran | Unclear | Low | Low | Low | Low | Low | Low |
| Jensen et.al | 2012 | United States | Low | Low | Low | Low | Low | Low | Low |
| Yachha et.al | 1996 | India | Low | Low | Low | Low | Low | Low | Low |
| Park et.al | 1997 | S.Korea | Low | Low | Low | Low | Unclear | Low | Low |
| Poddar et.al | 2009 | India | Low | Low | Low | Low | Low | Low | Low |
| Cox et.al | 1987 | United States | Low | Low | Low | Low | Low | Low | Low |
| Ferry et.al | 1985 | United States | Low | High | Low | High | High | Low | Low |
| Hays et.al | 1967 | United States | Low | Low | Low | Low | Low | Low | Low |
| Lai et.al | 1994 | Taiwan | Low | Low | Low | Low | Low | Low | Low |
| Manolaki et.al | 1983 | UK | Low | Low | Low | Low | Low | Low | Low |
| Wongsawasdi et.al | 2008 | Thailand | Low | Low | Low | Low | Low | Low | Low |