Table 2 Assessment of risk of bias in included studies
Study | Randomization | Blinding | Allocation concealment | Withdrawals and dropouts | Use of intention-to-treat analysis | Overall |
|---|---|---|---|---|---|---|
Preisinger 1996 [32] | Yes | Yes | Unclear | Yes | Unclear | 3 |
McMurdo 1997 [33] | Yes | Unclear | Unclear | Unclear | Yes | 2 |
Ebrahim 1997 [34] | Yes | Yes | Yes | Yes | Yes | 5 |
Robertson 2001 [35] | Yes | Yes | Yes | Yes | Yes | 5 |
Chan 2004 [36] | Yes | Unclear | Unclear | Unclear | Yes | 2 |
Ashburn 2007 [37] | Yes | Yes | Yes | Yes | Yes | 5 |
Karinkanta 2007 [38] | Yes | Yes | Yes | Yes | Yes | 5 |
Swanenburg 2007 [39] | Yes | Yes | Yes | Yes | Yes | 5 |
Haines 2009 [40] | Yes | Yes | Yes | Yes | Yes | 5 |
Zeng 2009 [41] | Yes | Unclear | Unclear | Yes | Yes | 3 |
Bischoff-Ferrari 2010 [42] | Yes | Yes | Yes | Yes | Yes | 5 |
Kemmler 2010 [43] | Yes | Yes | Yes | Yes | Yes | 5 |
Korpelainen 2010 [44] | Yes | Yes | Yes | Yes | Yes | 5 |
Smulders 2010 [45] | Yes | Yes | Yes | Yes | Yes | 5 |
Iliffe 2014 [46] | Yes | Yes | Yes | Yes | Yes | 5 |
Gill 2016 [47] | Yes | Yes | Yes | Yes | Yes | 5 |
Uusi-Rasi 2017 [48] | Yes | Yes | Unclear | Yes | Yes | 4 |
Cockayne 2017 [49] | Yes | Yes | Unclear | Yes | Yes | 4 |
Harris 2019 [50] | Yes | Yes | Unclear | Yes | Yes | 4 |
Liu-Ambrose 2019 [51] | Yes | Yes | Yes | Yes | Yes | 5 |