Results
A total of 722 participants (mean [SD] age, 41.5 [12.7] years; 716 men [99.2%]; all of Chinese ethnicity) were randomly assigned to the intervention group (360 participants) or the control group (362 participants). Biochemically verified continuous abstinence at 6 months was 6.9% in the intervention group and 3.0% in the control group (odds ratio [OR], 2.66; 95% CI, 1.21-5.83). Among smokers with low nicotine dependence, the intervention group had significantly better abstinence rates for most of the indicators after adjusting for covariates (eg, biochemically verified 24-hour point prevalence of abstinence at 1 month: adjusted OR, 2.15; 95% CI, 1.05-4.38). Among smokers with moderate and high nicotine dependence, only the biochemically verified 24-hour point prevalence of abstinence at 6 months was statistically significant (adjusted OR, 4.17; 95% CI, 1.34-3.00). The pattern was similar for quitting intention, and the personalized text message–based intervention was more effective for smokers who had strong quitting intention than for those who had weak quitting intention.