Jamrozik 1984.

Methods	Setting: 6 general practices, the UK Recruitment: clinic, first visit Selected: outpatients
Participants	2110 smokers (defined as a person admitting to smoking cigarettes) out of 6052 screened. 1040 in relevant arms 61% female, no detailed patient characteristics given. Significant difference of social classes between groups Therapist: physician
Interventions	Intervention: demonstration of participant exhaled CO plus verbal advice plus booklet Control: verbal advice plus booklet 2 study arms were not relevant to this review
Outcomes	Definition of abstinence: point prevalence Duration of follow‐up: 12 months Biochemical validation of non‐smokers: urinary cotinine in a sample (41%) of self‐reported non‐smokers
Identification
Notes	Outcome based on unvalidated data. Between 24% and 40% may have misrepresented smoking status, but no evidence of differential misreporting between groups. Sources of funding: Nuffield Dominions Trust and the Health Education Council. National Institute on Drug Abuse, DA 2507, D A0007 for cotinine assays. Helen Van Vunakis is the recipient of a US Public Health Service Career Award 5K6/A 12372.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	Randomised according to day of attendance, balanced over 4 weeks
Allocation concealment (selection bias)	High risk	Allocation known at enrolment, possibility of selection bias
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Outcome based on unvalidated data. Between 24% and 40% may have misrepresented smoking status, but no evidence of differential misreporting between groups.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	28% lost to follow‐up across all 4 arms, treated as smokers. No information on differential loss