Methodological quality and risk of bias
The assessment of bias is presented in Figure 2. There was a low risk of
bias for amount or handling of incomplete outcome data and other bias in
five RCTs (100%). Separately, the risk of bias was associated with
inadequate generation of randomised sequences and inadequate concealment
of allocations prior to assignments. There was also inadequate outcome
reporting selection of participants in four studies (80%) and unclear
outcome reporting in one study. The risk of bias associated with
assessor blinding was unclear in three studies (60%) and low in two
studies (20%). In addition, the risk of bias associated with
participants and personnel blinding was low in one study (20%) and
unclear in others. Although the risk of bias in blinding is generally
unclear, this is considered to be due to the nature of the intervention.
Overall, most of the included studies were classified as low risk for
bias.