Table 4. Item-wise risk of bias scores of the included studies.
| Author, Year | Q1 | Q2 | Q3 | Q4 | Q5 | Q6 | Q7 | Q8 | Q9 |
|---|---|---|---|---|---|---|---|---|---|
| Macdonald et al. 1988 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 0 |
| Osborn et al. 1990 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
| Conrad et al. 1991 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
| Conrad et al. 1992 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
| Conrad et al. 1993 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
| Nakladalova et al. 1995 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
| Liss et al. 1995 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 |
| Scoggins and Campbell. 1995 | 0 | 0 | 1 | 1 | 0 | 0 | 1 | 0 | 0 |
| Rice et al. 1996 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Akesson et al. 1999 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Lalumandier et al. 2000 | 0 | 0 | 1 | 0 | 0 | 0 | 1 | 0 | 0 |
| Hamann et al. 2001 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
| Anton et al. 2002 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
| Werner et al. 2002 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
| Mamatha et al. 2005 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 0 |
| Werner et al. 2005 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
| Cherniack et al. 2006 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 |
| Greathouse et al. 2009 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 0 |
| Shaffer et al. 2012 | 1 | 1 | 1 | 1 | 0 | 0 | 1 | 0 | 0 |
| Haghighat et al. 2012 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Borhan et al. 2013 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 0 | 0 |
| Khan et al. 2014 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Pai et al. 2014 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Munirah et al. 2014 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
| Hodacova et al. 2015 | 0 | 0 | 1 | 1 | 0 | 0 | 0 | 0 | 0 |
| Nor Rasid et al. 2016 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
| Ehsan et al. 2016 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Prasad et al. 2017 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 0 | 0 |
| Jaoude et al. 2017 | 1 | 1 | 0 | 0 | 0 | 0 | 1 | 0 | 0 |
| De JeSUS et al. 2018 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 |
| Inbasekharan et al. 2018 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
| Alhusain et al. 2019 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| Meisha et al. 2019 | 1 | 1 | 0 | 1 | 0 | 0 | 1 | 0 | 0 |
| Al Muraikhi et al. 2020 | 1 | 1 | 1 | 1 | 0 | 0 | 0 | 0 | 0 |
| Harris et al. 2020 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 |
| Berdouses et al. 2020 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 |
| Maghsoudipour et al. 2021 | 0 | 0 | 1 | 0 | 0 | 1 | 1 | 0 | 0 |
Q1: Study’s target population a close representation of the national population in relation to relevant variables; Q2: Sampling frame a true or close representation of the target population; Q3: Random selection used to select the sample; Q4: Likelihood of non-response; Q5: Data collected from subjects; Q6: Acceptable case definition; Q7: reliability and validity of the instrument; Q8: Same mode of data collection; Q9: Appropriate numerators and denominators; 0: low risk; 1: high risk.