Liao 2018.

Methods	Study design: RCT Country: China Recruitment: via radio, bus billboards, online (e.g. websites, QQ, WeChat), newspapers, hospitals, and pharmacies in China Study dates: 2016‐17
Participants	Baseline characteristics (n = 1369) Mean age: 38.1 years (SD 9.79) Female: 5.4% (N = 74) High school or lower education: 25.5% (N = 349) FTND: 4.6 (SD 2.16) White: not stated Inclusion criteria: daily Chinese cigarette smokers. ≥ 18 years. Being able to read and write in Chinese. Owning a text‐capable cell phone and knowing how to text. Willing to make an attempt to quit smoking in the next month. Willing to provide informed consent to participate in the study. Exclusion criteria: non‐smokers. < 18 years. Unable to read and write in Chinese.
Interventions	High‐frequency text messaging (HFM): "Happy Quit" mobile phone‐based HFM for 12 weeks (3‐5 messages/day) Low‐frequency text messaging (LFM): "Happy Quit" mobile phone‐based LFM for 12 weeks (3‐5 messages/week) Control: 1 text message every week, thanking them for being in the study
Outcomes	Definition of abstinence: biochemically confirmed continuous abstinence at 6 months
Funding source	China Medical Board (CMB) Open Competition Program (Grant Number 15‐226)
Conflicts of interest	None declared
Notes	We compared HFM and LFM to control in the text messaging vs minimal SC support analysis, and compared HFM to LFM in the comparison of higher vs lower frequency text messaging
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Participants were randomly allocated using an independent telephone randomisation system that included a minimisation algorithm balancing for sex (male, female), age (18–34 years, > 34 years), educational level (years of education: < = 12 years, > 12 years), and FTND score (< = 5, > 5)
Allocation concealment (selection bias)	Low risk	Quote: "Participants, investigators, and research personnel were masked to treatment allocation" Participants were randomly allocated using an independent telephone randomisation system
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Abstinence was biochemically verified
Incomplete outcome data (attrition bias) All outcomes	Low risk	Quote: "By the end of the 24‐week trial period, the trial was completed by 83.2%, 74.6%, and 87.1% of participants in the HFM group, LFM group, and control group, respectively"