Methods
RESPIRATORY DISEASE
Participants, active smokers aged 35–70 without known respiratory disease, were recruited from primary healthcare centres by family doctors and nurses. They were randomly assigned to either the intervention group (IG = 308) or the control group (CG = 306). Both groups received brief smoking cessation counselling. Additionally, the IG underwent spirometry and received detailed information about the results, including lung age. The primary outcome was prolonged abstinence, defined as lasting at least 12 months and validated through cotinine measurement in urine.