DISCUSSION
smoking reduction
PMT
To our knowledge, this is the first randomised controlled trial using personalised text messages for a mobile cessation intervention with a positive control group design conducted in a a country with limited tobacco control policy, and the first to report the effects from the perspective of smokers who failed to reach abstinence. Considering the high response rate from participants, our findings provide a deep insight into the positive change resulting from a text message-based smoking cessation intervention in the context of China.We found personalised text messages encouraged more smokers to reduce their smoking amount and frequency. Because most mobile cessation interventions have a relatively lower abstinence rate (<10%) [However, abrupt quitting interventions are generally recommended in clinical treatment guidelines and suggested by medical professionals. However, a Cochrane review found no difference in outcomes between reducing smoking over time and quitting abruptly; thus, individuals could be given a choice of how to quit [We also managed to identify the psychological determinants of reducing smoking frequency from daily to weekly and reducing smoking amount. The comparison between groups showed that the personalised intervention decreased the intrinsic rewards of smoking and increased perceived severity of smoking, making it a notable determinant of positive change in smoking behaviour. It also provides some indications as to why a personalised intervention is more likely than a non-personalised intervention to encourage smokers who fail to reach abstinence to reduce their smoking amount and frequency.This study has several limitations. First, most of our participants were male and Chinese, limiting generalisability to other populations. Second, our follow-up period only lasted until six months after the intervention was implemented, and a long-term evaluation may produce different results. Third, only daily regular smokers reported their smoking amount at baseline and each follow-up point. Therefore, we only included participants who were daily smokers at baseline when measuring the effect on smoking reduction and frequency-changing results. Fourth, the results can be biased because we only conducted point-to-point comparisons for PMT construct scores; more robust analyses should account for the correlated nature of the repeated measures in the data. Fifth, the results can also be influenced by other important issues, such as recall or selection bias and social acceptability problems, since the data were collected from individuals who decided to participate in our study.However, our study has important implications. Although research has found that text message-based interventions could provide smoking cessation support, their low quitting rate remains a challenge for expanding their usage to promote smoking cessation and gaining government support. Our study suggest that text message-based interventions can both help smokers quit and bring change those who fail to reach abstinence, making it suitable for countries with limited smoking cessation resources by allowing minimal expenses for maximum effects. We also found some psychological determinants of smoking reduction; among them, self-efficacy of quitting was associated with reductions in both smoking frequency and amount. This finding was also confirmed by other smoking cessation studies showing that self-efficacy was the most significant variable associated with forwards progress towards quitting [