| Methods |
Country: USA
Setting: community volunteers (telephone recruitment) |
| Participants |
1044 smokers aged 18 to 65, able to quit for 24 h, and without serious illness. Motivated to maintain abstinence
42% female, average age 40, average cpd 20 |
| Interventions |
1. Nicotine gum (2 mg, 1/h, at least 10/day and not more than 30/day)
2. Self‐help materials
3. Nicotine gum plus materials
4. Incentive alone
All groups offered incentive of USD 100 for quitting at 6 months
Level of support: low |
| Outcomes |
PP abstinence at 12 months
Validation: CO < 9 ppm/salivary cotinine < 20 ng/ml |
| Notes |
Until 2008 only groups 1 and 4 compared. Since the trial was factorial and shows no evidence of interaction, both gum groups now used; 1 and 3 vs 2 and 4. The RR is unaltered but CIs narrow
Study was funded by the National Heart, Lung, and Blood Institute |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Unclear risk |
Quote: "Randomization was stratified by gender and cigarette consumption". No further detail |
| Allocation concealment (selection bias) |
Unclear risk |
Method not stated |
| Blinding (performance bias and detection bias)
All outcomes |
Unclear risk |
Not stated |
| Incomplete outcome data (attrition bias)
All outcomes |
Unclear risk |
3.9% dropped out at 6 months, and 6.2% at 12 months. Unclear whether dropouts were included, although disconfirmations were reclassified as smokers |
