Fig 1.
PRISMA flow diagram.
Table 1.
Studies included in the scoping review.
Table 2.
Characteristics of included studies.
Fig 2.
Risk of bias for the randomised controlled trials.
An overall interpretation of the quality of the twelve RCTs is shown in Fig 2. None of the studies was completely free of the possibility of bias.
Table 3.
Characteristics of psychological theories underpinning reported studies.