| Methods |
Setting: 2 chest clinics in Scotland, UK
Recruitment: smokers attending outpatient clinic (unselected) |
| Participants |
1206 smokers referred for chest radiography, 44% aged > 50 |
| Interventions |
∙ Self‐help; 13‐page booklet
∙ No treatment control |
| Outcomes |
Abstinence at 1 year (self‐report of no smoking for 6 months)
Validation: expired CO < 10 ppm; non‐attenders classified as smokers |
| Notes |
Face‐to‐face contact but no advice |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
High risk |
Quasi‐random (interventions alternated fortnightly) |
| Allocation concealment (selection bias) |
High risk |
All smoking patients attending were eligible, so potential for selection bias probably low, but imbalance in age distribution between groups |
| Blinding (performance bias and detection bias)
All outcomes |
Low risk |
Control group unlikely to know what intervention group was receiving; same amount of personal contact; biochemical validation used |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
Follow‐up 74.5% intervention, 74.1% control; losses included in ITT analysis |
