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Table 3 Risk of bias assessment according to the Cochrane Back Review Group (CBRG)

From: Cost-effectiveness of pain management services for chronic low back pain: a systematic review of published studies

Risk of bias itemSkouen 2002 [19]Rivero-Arias 2005 [22]Smeets 2009 [21]Lambeek 2010 [20]Johnsen 2014 [18]
Was the method of randomisation adequate?LowLowLowLowLow
Was the treatment allocation concealed?LowUnclear riskLowLowLow
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?LowHighLowLowLow
Did the analysis include intention-to-treat analysis?LowLowLowLowLow
Are the study reports free of suggestion of selective outcome reporting?Unclear riskUnclear riskUnclear riskHighUnclear risk
Were the groups similar at baseline?Unclear riskLowLowLowHigh
Were co-interventions avoided?Unclear riskHighHighUnclear riskUnclear risk
Was the compliance acceptable in all groups?Unclear riskHighHighHighUnclear risk
Was the timing of outcome assessment similar in two groups?LowLowLowLowLow
Summary risk of biasHIGHHIGHLOWLOWHIGH
  1. Unclear = item not reported clearly
  2. The study will be considered to have a low risk of bias if 6 or more items are satisfied, otherwise it will be considered to have a high risk of bias