Table 4 Risk of bias in non-randomized studies
Study | Confounding | Selection bias | Classification of intervention | Deviation from intervention | Missing data | Outcome measurement | Selection of reported results | Overall risk of bias |
|---|---|---|---|---|---|---|---|---|
Swedish et al. 2012 [25]a | + | – | ++ | ++ | – | ++ | ++ | – |
Swedish and Goldstone 2014 [34]a | + | – | ++ | ++ | – | ++ | ++ | – |
Kahn et al. [24]b | – – | – | – | ++ | – | ++ | ++ | – – |