Pérez‐Milena 2012.

Methods	Country: Spain Setting: 5 high schools Study design: RCT
Participants	Participants: 91 (I = 43, C = 48), 49% female Age: mean 15.4 Criteria for inclusion: ≤ 20 years, attending participating high schools, smoking ≥ 1 cpw over last 6 months. Excluded for mental/psychiatric illness/disability, pregnancy, using any smoking cessation pharmacology, student or parents or tutors not wishing student to participate Follow‐up method: in person Inducements to enter study: none Baseline characteristic equivalence: Pre‐test smoking status assessment: self‐report, I = 84%, C = 81% were daily smokers, cpd 8.3 during the week but 15.9 at weekends, FTND 3.1, 62% were low dependence (0‐3) Post‐test smoking status assessment: biochemically validated self‐report
Interventions	Intervention: 4 x 15‐min weekly sessions with GPs, focus on initial reduction, signing a declaration to quit at 3rd visit and 4th visit for reinforcement Theoretical basis for intervention: MI Control: a single 15‐min session with brief advice and a leaflet. All participants sent a text message on quit date, the day before and a week after, and monthly emails for a year
Outcomes	Measurement: 12‐month continuous abstinence Relevant follow‐up periods: 12 months Verification: expired CO ≤ 6 ppm (Smoke Check) Loss to follow‐up: 3 of 91
Notes	New for 2017 update
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Simple randomization stratified by school, using Epidat 3.1
Allocation concealment (selection bias)	Low risk	"Blinded allocation"
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants and personnel would have been aware of group assignment, as it was a behavioural intervention
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Biochemically validated
Incomplete outcome data (attrition bias) All outcomes	Low risk	3 losses, counted as smokers for meta‐analysis