| Methods |
Setting: ALA Quitline, USA
Recruitment: Quitline callers |
| Participants |
990 callers; 38% M, av. age 43, av. cigs/day 22 |
| Interventions |
1. Reactive counselling
2. Mailed S‐H materials (Freedom from Smoking) |
| Outcomes |
Abstinence at 12 m (PP)
Validation: Saliva cotinine only for convenience sample, refusals not recorded |
| Notes |
Test of different interventions for people calling a quitline. Comparison 2 |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Low risk |
Random‐number list created by independent statistician |
| Allocation concealment (selection bias) |
Low risk |
Enrolment and assignment by researchers independent of helpline staff. Concealment until assigned |
| Blinding of outcome assessment (detection bias)
All outcomes |
Unclear risk |
Quote: "Interviewer assessing outcomes was blinded"; biochemical validation in a convenience sample (16/28 agreed); participants who did not agree to biochemical validation but self‐reported abstinence counted as abstinent |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
47% loss to follow‐up, similar across groups, included as smokers |
