Emmen 2005.

Methods	RCT.
Participants	123 Dutch patients who visited an outpatient clinic for problem drinking.
Interventions	Dutch version of Drinker's Checkup (n= 61) vs care as usual (n= 62).
Outcomes	Physiological primary: Serum carbohydrate‐deficient transferrin. Non‐physiological primary: Units per day in previous six months. Secondary: Motivation to change.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	"...balanced block randomisation. The main researcher (M.J.E) used sealed envelopes to generate the allocation sequence."
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit judgment.
Blinding (performance bias and detection bias) Patients and providers	Low risk	No blinding, but most outcomes were physiological and also used to validate self‐reports, and not likely to be influenced by lack of blinding.
Blinding (performance bias and detection bias) Assessors	Low risk	Not blinded, but most outcomes were physiological and also used to validate self‐reports, and not likely to be influenced by lack of blinding.
Incomplete outcome data (attrition bias) All outcomes	Low risk	9% lost‐to‐follow‐up at 6 months. Balanced drop‐out. Reasons stated. ITT performed.
Selective reporting (reporting bias)	Low risk	The published report included all expected outcomes based on the study hypotheses.
Other bias	Low risk	Serum carbohydrate‐deficient transferrin (CDT) was measured (biological data). There were no differences between groups at baseline. No additional sources of bias appear to be present.