Table 3 Risk of bias assessment according to the Cochrane Back Review Group (CBRG)
Risk of bias item | Skouen 2002 [19] | Rivero-Arias 2005 [22] | Smeets 2009 [21] | Lambeek 2010 [20] | Johnsen 2014 [18] |
|---|---|---|---|---|---|
Was the method of randomisation adequate? | Low | Low | Low | Low | Low |
Was the treatment allocation concealed? | Low | Unclear risk | Low | Low | Low |
Was the patient blinded to the intervention? | Not possible | ||||
Was the care provider blinded to the intervention? | |||||
Was the outcome assessor blinded to the intervention? | |||||
Was the dropout rate described and acceptable? | Low | High | Low | Low | Low |
Did the analysis include intention-to-treat analysis? | Low | Low | Low | Low | Low |
Are the study reports free of suggestion of selective outcome reporting? | Unclear risk | Unclear risk | Unclear risk | High | Unclear risk |
Were the groups similar at baseline? | Unclear risk | Low | Low | Low | High |
Were co-interventions avoided? | Unclear risk | High | High | Unclear risk | Unclear risk |
Was the compliance acceptable in all groups? | Unclear risk | High | High | High | Unclear risk |
Was the timing of outcome assessment similar in two groups? | Low | Low | Low | Low | Low |
Summary risk of bias | HIGH | HIGH | LOW | LOW | HIGH |