Table 2:
Risk of bias summary: Systematic review. Author’s judgments of risk of bias item for each included study (NA: Not applicable)
| Reference | Random sequence generation (Selection bias) | Allocation concealment (Selection bias) | Blinding of participants and personnel (performance bias) | Blinding of outcome assessment (detection bias) | Incomplete outcome data (attrition bias) | Selective reporting (reporting bias) | Other sources of bias |
|---|---|---|---|---|---|---|---|
| Safari et al 2018 | + | ? | − | ? | + | + | + |
| Khadivzadeh et al. 2016 | + | + | − | ? | + | + | + |
| Al-Morbaty et al 2017 | + | ? | − | ? | + | + | + |
| Essa and Ismail 2015 | − | − | − | ? | + | + | + |
| Mejbel et al 2012 | − | ? | − | ? | + | + | − |
| Gabriel et al. 2009 | − | − | − | − | + | + | ? |