Participant-level meta-analysis of mobile phone-based interventions for smoking cessation across different countries.

With meta-analysis, participant-level data from five text messaging-based smoking cessation intervention studies were pooled to investigate cessation patterns across studies and participants. Individual participant data (N=8315) collected in New Zealand (2001-2003; n=1705), U.K. (2008-2009; n=5792), U.S. (2012; n=503; n=164) and Turkey (2012; n=151) were collectively analyzed in 2014. The primary outcome was self-reported 7-day continuous abstinence at 4weeks post-quit day. Secondary outcomes were: (1) self-reported 7-day continuous abstinence at 3months and (2) self-reported continuous abstinence at 6months post-quit day. Generalized linear mixed models were fit to estimate the overall treatment effect, while accounting for clustering within individual studies. Estimates were adjusted for age, sex, socioeconomic status, previous quit attempts, and baseline Fagerstrom score. Analyses were intention to treat. Participants lost to follow-up were treated as smokers. Twenty-nine percent of intervention participants and 12% of control participants quit smoking at 4weeks (adjusted odds ratio [aOR]=2.89, 95% CI [2.57, 3.26], p<.0001). An attenuated but significant effect for cessation for those in the intervention versus control groups was observed at 3months (aOR=1.88, 95% CI [1.53, 2.31]) and 6months (aOR=2.24, 95% CI [1.90, 2.64]). Subgroup analyses were conducted but few significant findings were noted. Text messaging-based smoking cessation programs increase self-reported quitting rates across a diversity of countries and cultures. Efforts to expand these low-cost and scalable programs, along with ongoing evaluation, appear warranted.