Fig. 2

Risk of Bias of Included Studies. *Assessment of Incomplete Outcome Data. †Knowledge Prevention of Allocated Interventions. This figure summarises the risk of bias assessment of the articles included in this review. Risk assessment was based on criteria for EPOC reviews [16]. Allocation was adequately concealed (low risk) if the unit of allocation was by institution, team or professional, and allocation was performed on all units at the start of the study or if the unit of allocation was by patient or episode of care and a centralised randomisation scheme was used. The allocation sequence is adequately generated (low risk) if a random component in the sequence generation process is described. If there is no evidence of selective outcome reporting, this criterion is assessed as low risk. Baseline outcome measurements should show no important differences across study groups prior to the intervention (low risk). Baseline characteristics are assessed as low risk if reported and similar. Missing outcome measures should be unlikely to bias the results (low risk). Knowledge of the allocated intervention by assessors of primary outcome variables should be adequately prevented or the outcomes should be objective (low risk). The study was adequately protected against contamination if allocation was by community, institution or practice, and it is unlikely that the control group received the intervention. The ninth criterion is ‘other risks of bias’