Lewis 2010.

Methods	Cluster‐randomized to decision aid vs usual care
Participants	211 + 232 patients considering colorectal cancer screening in the USA
Interventions	DA: web‐based, DVD and VHS videotape formats + stage targeted brochures (and booster kit if patients had not been screened) on options' outcomes, clinical problem, outcome probabilities, others' opinion, guidance (encouraged patients to communicate with their practitioners by asking questions and sharing preferences; summary) Comparator: usual care using Aetna annual reminders to obtain CRC screening
Outcomes	Knowledge of the age at which screening should begin (post‐DA), completion of colorectal cancer screening (pre, post‐DA), intrusive thoughts (pre, post‐DA), interest in CRC screening (pre, post‐DA), intent to ask provider about screening (pre, post‐DA), readiness to be screened (pre, post‐DA), perceived risk of colon cancer (pre, post‐DA), general beliefs about colon cancer (pre, post‐DA), fears about colorectal cancer screening (pre, post‐DA), perceptions about whether participants had enough information (post‐DA), whether participants had enough information about specific screening tests (post‐DA), willingness to pay for screening tests (post), desire to participate in medical decision (post) Practice level measures: assess CRC screening practices (pre, post‐DA), referrals (pre, post‐DA), quality improvement initiatives
Notes	Primary outcome was not specified
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"Randomisation was done using matched pairs and a blocking procedure." (p 2, Practice recruitment and randomization section)
Allocation concealment (selection bias)	Unclear risk	"Thus, purposive assignment to treatment group was used, resulting in a hybrid randomisation" (p 3, Practice recruitment and randomization section). There is no mention of the effect of this purposive assignment on the study
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	As mentioned above, staff used purposive assignment and were therefore not blinded, but there is no mention of the effect on the study.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	The study did not address this outcome, but outcomes were objectively measured.
Incomplete outcome data (attrition bias) All outcomes	Low risk	There appear to be no missing outcome data
Selective reporting (reporting bias)	Unclear risk	No mention of study protocol
Other bias	High risk	Unadjusted cluster analysis