Buchkremer 1991 1

Methods	Setting: cessation clinic, Germany Recruitment: community volunteers
Participants	256 smokers, no demographic details
Interventions	5 conditions, partly factorial. All received nicotine patch, dose individualised for conditions 1 to 4, plus 9 weekly sessions, including reduction, self‐monitoring, contract management, risk avoidance. TQD after 6 weeks 1. Additional training in relapse‐coping strategies (during cessation phase) 2. Additional 3 booster sessions, 6 months after end of main therapy 3. Relapse‐coping and boosters 4. Control 5. Control (fixed‐dose nicotine patch)
Outcomes	Abstinence 12 months post‐EOT (point prevalence). Rates estimated from graphs Validation: random urine nicotine, 'almost 100% conformity', no correction
Notes	3 versus 4 in contact matched comparison, 1 plus 2 versus 4 in extended contact comparison Inclusion of control group 5 (fixed dose) would marginally increase intervention benefit
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	"Randomly assigned to experimental groups after previously being matched for age, sex and cigarette consumption"
Allocation concealment (selection bias)	Unclear risk	No details given
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	No information provided
Blinding of outcome assessment (detection bias) All outcomes	Low risk	No blinding reported but biochemical confirmation taken at random, with 'almost 100% conformity'
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	15/256 (5.9%) dropouts excluded, assignment not given, so not included in analysis