Dijkstra 1999.

Methods	Setting: community, Netherlands Recruitment: newspaper adverts for smokers not planning to quit in the next 6 months (unmotivated volunteers)
Participants	843 smokers not planning to quit, 63% female, average age 42, average cpd 22
Interventions	No face‐to‐face contact ∙ Three tailored letters (MT) ∙ Single tailored letter (ST) ∙ Self‐help manual, 48 pages colour (SHG) ∙ No intervention (CO)
Outcomes	Abstinence at 6 months (7‐day point prevalence), self‐report by postal questionnaire Validation: none Primary outcomes for trial: SoC; intention to quit
Notes	3 vs 4 in self‐help vs control 1 and 2 vs 3 in effects of tailoring
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomised; method not described
Allocation concealment (selection bias)	Unclear risk	No details given
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Unclear if control group knew intervention arms receiving additional information; no biochemical validation
Incomplete outcome data (attrition bias) All outcomes	Low risk	89% responded at 6 months Attrition predicted by years smoking and group Denominator used in meta‐analysis includes all randomised