ISRCTN54228638.

Study name	Lung age or exhaled carbon monoxide feedback combined with very brief advice and support for smoking cessation in Medical Faculty Skopje Macedonia
Methods	Multicenter non‐blinded 3‐armed randomized controlled trial
Participants	Target: 885 people who currently smoke, smoking at least 10 cigarettes per day and aged ≥ 35 years
Interventions	Intervention 1: participants will receive lung age with very brief advice and support to quit smoking Intervention 2: participants will receive feedback on exhaled carbon monoxide levels with very brief advice and support to quit smoking Intervention 3: participants will receive very brief advice alone and support to quit smoking
Outcomes	7‐day point prevalence abstinence, prolonged abstinence with smoking induction period of 3 weeks post‐randomization, confirmed with salivary cotinine at 4, 12 and 26 weeks
Starting date	June 2017
Contact information	Radmila Ristovska
Notes