Table 2

Risk of bias in selected studies

Jang et al.28 Johansson et al.26 Kauer et al.29
Reid et al.30
Reid et al. 31
Whittaker et al.27
Random sequence generation
(selection bias)
N/A−*
Allocation concealment
(selection bias)
N/A
Selective reporting
(reporting bias)
(?)*(?)(?)(?)
Other bias(?)
Blinding of participants and personnel
(performance bias)
(+++)*(?)(?)
Blinding of outcome assessment
(detection bias)
(+++)
Incomplete outcome data
(attrition bias)
(?)
  • * (+++): high risk of bias; (?): unclear risk of bias; −: low risk of bias.

  • Source: Adapted from Moher  et al  (2009)45.