Table 2 Outcomes
OutcomeIntervention groupControl groupRR (95% CI)χ2 p value
No (%)No (%)
4 weeks
Self-reported quitting*26 (25.7)12 (12.8)2.02 (1.08 to 3.76)0.02
Self-reported quitting†26 (25.5)12 (12.2)2.08 (1.11 to 3.89)0.02
6 months
Primary outcome for the main trial:
Self-reported no smoking in last 7 days and salivary cotinine <7 ng/ml*8 (8.5)6 (6.7)1.28 (0.46 to 3.53)0.6
Self-reported no smoking in last 7 days and salivary cotinine <7 ng/ml†8 (7.8)6 (6.1)1.28 (0.46 to 3.56)0.6
Secondary outcomes—smoking:
Self-reported no smoking in last 7 days*15 (15.5)19 (20.4)0.76 (0.41 to 1.40)0.3
Self-reported 28 days continuous abstinence*14 (14.4)17 (18.1)0.80 (0.42 to 1.53)0.4
Secondary outcome—adverse:
Self-reported involvement in vehicle crashes*1 (1.0)4 (4.3)0.24 (0.03 to 2.11)0.2
Pain in thumb while texting*0 (0.0)1 (1.1)0.3
  • *Missing data excluded. †Missing data treated as smokers.