Risk of bias assessment using the Newcastle-Ottawa Scale
| Author/year | Selection | Comparability | Exposure/outcome | Total stars | Quality of study |
|---|---|---|---|---|---|
| Alizadehkhaiyat et al34 (2007) | **** | * | ** | 7 | High |
| Coombes et al30 (2015) | **** | * | *** | 8 | High |
| Coombes et al29 (2012) | **** | * | *** | 8 | High |
| Engebretsen et al36 (2010) | **** | * | ** | 7 | High |
| Garnevall et al35 (2013) | **** | * | ** | 7 | High |
| Haahr and Andersen31 (2003) | **** | * | *** | 8 | High |
| Kromer et al32 (2014) | **** | ** | ** | 8 | High |
| Lee et al33 (2014) | **** | * | *** | 8 | High |
| Silbernagel et al37 (2011) | *** | * | ** | 6 | Moderate |
| van Wilgen et al38 (2013) | *** | * | ** | 6 | Moderate |