Table 3.
Risk of bias assessment of included studies, (a) the Newcastle-Ottawa Scale for non-randomised studies and (b) the Cochrane Risk of Bias evaluation 1.0 for randomised studies.
| a. The Newcastle-Ottawa Scale for Non-Randomised Studies | ||||||
| Study (Publication Year) | Selection (Max 4 Stars) | Comparability (Max 2 Stars) |
Outcome (Max 3 Stars)
Loss to Follow up <10% Earns a Star if Unlikely to Introduce Bias |
Total (Max 9 Stars) | ||
| Call et al (2015) [19] | *** | ** | ** | 7 | ||
| Cata et al (2016) [20] | *** | ** | ** | 7 | ||
| De Oliveira et al (2014) [21] | **** | ** | ** | 8 | ||
| Huang et al (2018) [23] | *** | ** | ** | 7 | ||
| Kim et al (2019) [24] | *** | ** | ** | 7 | ||
| Lazzara et al (2018) [25] | *** | * | 4 | |||
| Merk et al (2016) [26] | *** | ** | *** | 8 | ||
| Okazumi et al (2004) [27] | *** | * | 4 | |||
| Sandini et al (2018) [28] | *** | * | ** | 6 | ||
| Shimada et al (2004) [30] | ** | * | *** | 6 | ||
| Yu et al (2015) [33] | **** | ** | ** | 8 | ||
| Zhu et al (2017) [34] | *** | ** | ** | 7 | ||
| b. The Cochrane Risk of Bias Evaluation 1.0 for Randomised Studies | ||||||
| Study (Publication Year) | Selection Bias | Performance Bias | Detection Bias | Attrition Bias | Reporting Bias | |
| Sequence Generation | Allocation Concealment | Blinding of participants and Personnel | Blinding of Outcome Assessors | Incomplete Outcome Data | Selective Outcome Reporting | |
| Yano et al (2005) [32] | Unclear risk of bias | Unclear risk of bias | Unclear risk of bias | Unclear risk of bias | Unclear risk of bias | Low risk of bias |
| Singh et al (2015) [31] | Low risk of bias | Low risk of bias | Low risk of bias | Unclear risk of bias | Low risk of bias | Low risk of bias |
| Sato et al (2002) [29] | Low risk of bias | Low risk of bias | Low risk of bias | Unclear risk of bias | Low risk of bias | Low risk of bias |
| Gan et al (2015) [22] | Low risk of bias | Low risk of bias | Low risk of bias | Low risk of bias | Low risk of bias | Low risk of bias |
Each non-randomised study was judged according to a ‘star-system’ in which a number of stars (*) was awarded in line with predefined criteria by the Newcastle-Ottawa Scale. Three broad perspectives were judged, and zero to four stars could be given in the Selection category; zero to two stars in the Comparability category; and zero to three stars in the Outcome category. A total of zero to three stars to reflect a high risk of bias; four to six stars a medium risk of bias; and seven to nine stars a low risk of bias.