Table 5.

Risk of bias for randomised studies using Cochrane risk-of-bias tool

Study	Random sequence generation	Allocation concealment	Blinding of participants and personnel	Blinding of outcome assessment	Incomplete outcome data	Selective reporting	Other bias	Summary
Gulliver et al. [69]	aAutomated computer system used	aConditions allocated by researchers not involved in day-to-day management	aDescribed method used to reduce likelihood of participant knowledge of intervention	bUnclear whether assessors had knowledge of treatment groups when assessing effects	aAnalyses adjusted for data being missing at random	aAll outcome measure effects were reported, along with effect sizes for each group	aStudy limitations were addressed and caution is urged when interpreting significant effects	Low risk of bias for this study. One domain (blinding of outcome assessors) was unclear but it is unlikely if that influenced the results given the online format of the intervention and data collection
Van Raalte et al. [74]	bMethod not disclosed	bUnclear who performed randomisation	bUnclear if participants were or were not blinded to their intervention	b Unclear whether assessors had knowledge of treatment groups when assessing effects	a Analyses adjusted for data being missing at random	aAll outcome measure effects were reported, along with effect sizes for each group	aAuthors were transparent about each stage of the intervention design	Unclear risk of bias for this study. Information on selection, performance and detection bias was not disclosed, though attrition and reporting bias was low
Summary of bias across studies	Random sequence generation was performed in both studies, but one did not disclose the method	Methods of allocation were mixed, with one not providing information and the other having a low risk of bias	Across the two studies, one was unclear for blinding participants and the other controlled for contamination	Both studies demonstrated an unclear risk of bias for blinding the assessors’ knowledge	The risk of bias was low for both studies on controlling for missing data	There was a low risk of bias across the studies for reporting outcomes	Transparency was ensured by both studies, resulting in a low risk of bias	Findings were mixed for sequence generation, allocation concealment and blinding of participants, collectively unclear for blinding outcomes, and both positive in terms of controlling for missing data, selective reporting and other biases

^aLow risk of bias

^bUnclear risk of bias

^cHigh risk of bias