Guarino 2006.

Methods	Cluster RCT Risk of Bias: High Trial aim: To compare an informed consent document developed with input from a consumer group of Gulf War veterans to a consent document developed by trial investigators in terms of self‐reported participant understanding, satisfaction with trial participation, trial refusal and adherence to the parent trial protocol.
Participants	20 medical centers that previously had recruited participants with Gulf War veterans’ illnesses into the parent trial of the current trial were randomised to receive either the consumer‐developed consent form or the investigator‐developed consent form. Setting: 18 Veterans Affairs and two Department of Defence medical centers Country: USA
Interventions	Type of process: Consumer involvement in research. The intervention group (10 medical centers/505 veterans) received a consumer‐developed consent form. The control group (10 centers/514 veterans) received a investigator‐developed consent form.
Outcomes	Self‐reported participant understanding, satisfaction with study participation, adherence to the protocol and refusal to participate.
Notes	Overall mean participant education was 14.1 years. Years of education were significantly higher in the intervention group than in the control group.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Unclear risk	B ‐ Unclear