Table 2.
Quality of the studies on the Newcastle-Ottawa scale
| Study | Selection | Comparability | Exposure/Outcome | Total Stars |
|---|---|---|---|---|
| Coelho 2016 | ***** | * | ** | 8 |
| Aghahosseini 2013 | **** | ** | ** | 8 |
| Mintziori 2014 | **** | ** | * | 7 |
| Unuane 2017 | *** | ** | ** | 7 |
| Michalakis 2011 | **** | ** | * | 7 |
| Muller 1999 | *** | ** | ** | 7 |
| Chai 2014 | **** | * | ** | 7 |
| Weghofer 2015 | **** | ** | * | 7 |
| Baker 2006 | *** | ** | ** | 7 |
| Karmon 2014 | **** | ** | ** | 8 |
| Cai 2017 | **** | ** | ** | 8 |
| Seungdamrong 2017 | **** | ** | ** | 8 |
| Zhang 2012 | ***** | ** | * | 8 |
| Ba 2013 | *** | ** | ** | 7 |
| Reh 2010 | *** | ** | ** | 7 |
| Zeng 2014 | ***** | * | ** | 8 |
| Gingold 2016 | **** | ** | * | 7 |
| Wu 2017 | **** | ** | * | 7 |
* means 1 score