| Intervention (%) | Comparison (%) | p Value | |
| Responder estimates | |||
| Attempted to quit (ni = 918; nc = 345) | 83.8 | 74.8 | ⩽0.001 |
| Quit at 3 months (ni = 863; nc = 329) | 46.0 | 29.5 | ⩽0.001 |
| Quit at 6 months (ni = 832; nc = 305) | 37.1 | 26.2 | ⩽0.001 |
| Quit at 12 months (ni = 672; nc = 257) | 33.2 | 28.0 | NS |
| Period prevalence (sustained quitting from 3-month to 6-month follow-ups) (ni = 861; nc = 329) | 20.7 | 13.1 | ⩽0.01 |
| Period prevalence (sustained quitting from 3-month to 12-month follow-ups) (ni = 748; nc = 303) | 2.7 | 2.0 | NS |
| Conservative estimates | |||
| Attempted to quit (conservative estimate: ni = 1000; nc = 377) | 76.9 | 68.4 | ⩽0.001 |
| Quit at 3 months (ni = 1000; nc = 377) | 39.7 | 25.7 | ⩽0.001 |
| Quit at 6 months (ni = 1000; nc = 377) | 30.9 | 21.2 | ⩽0.001 |
| Quit at 12 months (ni = 1000; nc = 377) | 22.3 | 19.1 | NS |
| Period prevalence 3–6 months (ni = 1000; nc = 377) | 2.0 | 1.6 | NS |
| Period prevalence 3–12 months (ni = 1000; nc = 377) | 2.0 | 1.6 | NS |
ni, number in sample (that is, denominator) for intervention group; nc, number in sample for comparison group.