Table 3.
Assessment of risk of bias in individual studies
| Study | Selection bias | Performance bias | Detection bias | Attrition bias | Reporting bias | Other bias | |
|---|---|---|---|---|---|---|---|
| Sampling bias | Measurement bias | ||||||
| Coelho 2016 | – | + | – | – | – | ? | – |
| Aghahosseini 2013 | – | – | ? | – | + | – | – |
| Mintziori 2014 | + | – | + | – | – | – | + |
| Unuane 2017 | + | – | – | – | – | + | + |
| Michalakis 2011 | + | ? | + | – | – | ? | + |
| Muller 1999 | – | + | – | + | – | ? | – |
| Chai 2014 | + | + | – | – | – | – | + |
| Weghofer 2015 | – | ? | + | + | – | ? | + |
| Baker 2006 | ? | – | + | – | + | – | – |
| Karmon 2014 | – | ? | – | – | + | – | – |
| Cai 2017 | – | – | ? | – | – | ? | + |
| Seungdamrong 2017 | – | – | – | + | – | – | + |
| Zhang 2012 | – | + | – | + | – | – | + |
| Ba 2013 | + | – | ? | – | – | – | – |
| Reh 2010 | – | + | + | – | + | ? | + |
| Zeng 2014 | ? | – | + | – | – | ? | – |
| Gingold 2016 | ? | – | + | – | – | – | + |
| Wu 2017 | – | ? | + | – | + | – | – |
+ high risk of bias; − low risk of bias;? unclear risk of bias