Abstract
BACKGROUND: The effectiveness of providing feedback on spirometry results for smoking cessation remains inconclusive according to the current evidence. OBJECTIVES: To assess the effectiveness of a motivational intervention based on spirometry results in achieving prolonged smoking abstinence (12 months post-intervention). DESIGN AND SETTING: A randomised, controlled, observer-blinded, multicentre clinical trial was conducted (from January 2012 to December 2015) in 20 primary healthcare centres in the Tarragona province, Spain. METHODS: 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. RESULTS: The prolonged abstinence rate was 7.8% in the IG, compared to 2.6% in the CG (p = 0.004). At 12 months, in the multivariate analysis, the intervention was identified as an independent factor for smoking cessation (OR 2.8; 95%CI 1.2 to 7.7), a trend maintained throughout the follow-up (HR 2.74; 95%CI 1.13 to 6.62). Moreover, according to the Prochaska and DiClemente model, the preparation or action phase to quit was also associated with smoking cessation (HR 2.55, 95%CI 1.07 to 6.09). CONCLUSION: A primary care-delivered intervention involving brief counselling and detailed spirometry information proves effective in increasing abstinence rates among active smokers without known respiratory disease. Additionally, smoking cessation is also influenced by the individual's stage of change. TRIAL REGISTRATION: ClinicatTrials.gov NCT02153047.