Predictors of long-term abstinence in a randomized controlled trial of smoking cessation by mobile phone text messaging (‘Happy Quit’) in China

INTRODUCTION: The mobile phone-based text messaging intervention (‘Happy Quit’) is a minimal and effective intervention with very wide reach; thus, it has the possibility of a population impact on quitting rates. Obtaining information on predictors of long-term quit rates is crucial for developing and implementing more effective mobile-based interventions. The study aimed to explore the predictors of long-term abstinence following the ‘Happy Quit’ intervention. METHODS: This study is a secondary analysis of a randomized controlled trial (RCT) that compared 12-week text messaging intervention (‘Happy Quit’) versus control intervention with follow-up at 24 weeks, in China. Only participants who had biochemically verified continuous smoking abstinence at 24 weeks were followed up at 52 weeks after the quit date. This predictor regression analysis is for those who were biochemically verified continuous 52-week quitters (n=67) compared with the other participants (n=1302) in the RCT. RESULTS: Of the 69 smokers who were continuously abstinent at 24 weeks, 97.1% (n=67) remained continuously abstinent at 52 weeks. The biochemically verified long-term (52 weeks or 1year) quit rate was 6.3% in the intervention group (60/958), 1.7% in the control group (7/411) (OR=3.677; 95% CI: 1.67–8.11, p<0.001). Multivariable regression analysis revealed that only smoked ≤10 cigarettes per day (compared with >10 cigarettes per day) was the only predictor for long-term abstinence. CONCLUSIONS: This study suggests that individuals who are light smokers might get the most benefit from the text messaging intervention (‘Happy Quit’) in China.