Pbert 2020.

Study characteristics
Methods	Study design: cluster‐RCT Location: USA Setting: high schools Recruitment: parents of all 9‐12 grade students were sent letters allowing them to opt out of their adolescent participating in the study Study dates: 2014‐16
Participants	N = 146 (across 9 schools) Specialist population?: high school students Definition of smoker used: average of ≥ 5 cpd for the past 7 days Participant characteristics: 56% female; average age: 17 years; 90% white; 69% in reduced or free lunch programme; average cpd: 5; 23% high level of nicotine dependence; 43% elevated depressive symptoms
Interventions	All participants had weekly visits with the school nurse for 4 weeks, plus written self‐help materials or 1 of 2 smartphone apps Comparator 1: written self‐help materials (pamphlets) Mode of delivery: written materials, face‐to‐face Intensity: weekly visits with the school nurse over 4 weeks Pharmacotherapy: none Type of therapist/provider: school nurse BCTs: 1.2 Problem solving, 4.1 Instruction on how to perform behaviour Comparator 2: National Cancer Institute QuitSTART App, a free smartphone app developed as a smoking cessation resource for teens Mode of delivery: smartphone app, face‐to‐face Intensity: app intensity unclear, weekly visits with the school nurse over 4 weeks Pharmacotherapy: none Type of therapist/provider: school nurse, smartphone app BCTs: 1.1 Goal setting (behaviour), 1.2 Problem solving, 2.3 Self‐monitoring of behaviour, 15.4 Self‐talk Intervention: craving to quit (C2Q) app adapted for teens, based on core elements of mindfulness training for smoking Mode of delivery: smartphone app, face‐to‐face Intensity: 22 training modules plus 4 bonus modules (5‐15 min/module), weekly visits with the school nurse over 4 weeks Pharmacotherapy: none Type of therapist/provider: school nurse, smartphone app BCTs: 1.1 Goal setting (behaviour), 1.2 Problem solving, 2.3 Self‐monitoring of behaviour
Outcomes	Definition of abstinence: 7‐day point prevalence Longest follow‐up: 6 months Biochemical verification: salivary cotinine < 11.4 ng/mL Other relevant outcomes reported: none
Notes	Relevant comparisons: mindfulness training app (C2Q) + school nurse vs QuitSTART app + school nurse mindfulness training app (C2Q) + school nurse vs self‐help materials + school nurse Funding source: National Institute on Drug Abuse (R34 DA037886) Author conflicts of interest: "JB owns stock in Claritas MindSciences, the company that developed the Craving to Quit app. The other authors declare that they have no competing interest."
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method not reported
Allocation concealment (selection bias)	Unclear risk	Concealment not reported
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Abstinence biochemically verified
Incomplete outcome data (attrition bias) All outcomes	Low risk	At 6‐month follow‐up 8.3% (4/48) were lost to follow‐up in the intervention (C2Q) group, 2.0% (1/50) in the QuitSTART group, and 4.2% (2/48) in the materials group
Selective reporting (reporting bias)	Low risk	Prespecified outcomes reported