Pallonen 1994.

Methods	Setting: community cardiovascular risk factor study, Finland Recruitment: male smokers identified via survey
Participants	165 male smokers who were classified as pre‐contemplators or contemplators according to the SoC model; average age 52 years, average cpd 19
Interventions	∙ Self‐help: five 10 to 20‐page self‐help manuals matched to SoC; mailed after each 6‐month assessment ∙ Usual care and annual telephone assessment
Outcomes	Sustained abstinence at 2 years (point prevalence) Validation: none
Notes	Included in main analysis although targeted materials Demoninators are smokers for whom complete follow‐up data were available
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomised in 2:1 ratio, but prepared smokers in treatment condition then offered clinic, so groups were not balanced by SoC
Allocation concealment (selection bias)	Unclear risk	No details given
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Unclear if control participants knew the nature of the intervention; no biochemical validation; different intensities of intervention
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	37% lost to follow‐up by 2 years and not re‐included in MA, as group not given Study authors report sensitivity analysis of effect of excluding people with incomplete follow‐up and state that bias was not introduced