Table 2 Quality assessment of studies
Study (Year) | Selection bias | Allocation bias | Confounders | Blinding | Data collection methods | Withdrawals and dropouts | Category of quality |
|---|---|---|---|---|---|---|---|
Randomised controlled trials | |||||||
Barclay (2008) [21] | Strong | Strong | Strong | Strong | Strong | Strong | Strong |
Bo (2007) [23] | Strong | Strong | Strong | Strong | Strong | Strong | Strong |
Greaves (2008) [25] | Strong | Strong | Strong | Strong | Strong | Moderate | Strong |
Kulzer (2009) [26] | Weak | Strong | Strong | Weak | Strong | Strong | Weak |
McConnon (2007) [28] | Weak | Strong | Strong | Weak | Strong | Weak | Weak |
Tsai (2010) [30] | Weak | Strong | Weak | Weak | Strong | Strong | Weak |
Whittemore (2009) [31] | Moderate | Strong | Strong | Strong | Strong | Strong | Strong |
Non-Equivalent Groups Design trials/ Single group pre-post trials | |||||||
Absetz (2007) [19] | Moderate | Weak | Strong | Weak | Strong | Strong | Weak |
Arrebola (2011) [20] | Weak | Weak | Strong | Weak | Strong | Weak | Weak |
Bjorkelund (1991) [22] | Moderate | Weak | Weak | Weak | Strong | Strong | Weak |
Gilis-Januszewska (2011) [24] | Weak | Weak | Weak | Weak | Strong | Moderate | Weak |
Laatikainen (2007) [27] | Moderate | Weak | Strong | Weak | Strong | Moderate | Weak |
Rohrer (2008) [29] | Moderate | Weak | Strong | Weak | Strong | Strong | Weak |