Russell 1983.

Study characteristics
Methods	Design: 3‐group randomized controlled trial Setting: 6 group practices in London and Kent, UK Recruitment: Completed in practice
Participants	2106 adults who smoked aged 16 years or more; 57% F; mean age 40.5 years; 17.5 cigarettes per day on average
Interventions	Intervention 1: participants were advised to quit smoking and given a booklet Intervention 2: participants were advised to quit smoking, given a booklet and a prescription for free NRT gum Control: no intervention, no advice. No further details reported
Outcomes	Abstinence (undefined) at 12m Validation: Expired CO < 8 ppm Quit attempts
Funding Source	Financial support was provided by the Medical Research Council and the AB Leo Research Foundation, Sweden
Author's declarations of interest	Not reported
Notes	Strategy: Cost‐free medications Level: Patient Comparison type: Single component vs. standard care
Risk of bias
Bias	Authors' judgement	Support for judgement
Sequence Generation	High risk	Participants were assigned to groups according to their week of attendance
Allocation concealment	High risk	Not concealed
Blinding of outcome assessors All outcomes	High risk	Smoking status was self‐reported. Authors state that the control group had no advice, which implies that face‐to‐face contact was greater in the intervention groups
Incomplete outcome data All outcomes	Low risk	The overall loss to follow‐up was 8.0% (n = 168/2106); 8.8% (n = 65/740) in the 'advice+booklet' group, 6.9% (n = 50/729) in the 'advice+booklet+prescription' group and 8.3% (n = 53/637) in the control group were lost to follow‐up at 12 months