RESUMO
BACKGROUND: Smoking is the main preventable cause of morbidity and mortality in our region, it being the main causative agent of chronic obstructive pulmonary disease. There still is no consensus on the use of spirometry as a strategy for smoking cessation, given that there is insufficient scientific evidence from high quality studies to recommend the use of this technique. METHODS/DESIGN: This is to be a randomized, multicentre, open-label clinical trial. A total of 444 smokers over 40 years of age will be recruited by 39 general practitioners from 22 health centers. Primary objective of this study is to assess the effectiveness of spirometry together with information regarding the test for smoking cessation after 1 year in smokers over 40 years of age with a more than 10 pack-year history and no previous diagnosis of chronic obstructive pulmonary disease. Groups of 45 patients who smoke will be randomly selected from the lists of the participating doctors. The names will be sent to the corresponding doctors who will contact candidate patients and assess whether they meet the selection criteria. Patients who meet these criteria will be randomly allocated to an intervention or control group. For patients in both groups, a nurse will conduct an interview and perform a spirometry test to measure forced vital capacity. Then, all patients will be referred for an appointment with their doctor for brief anti-smoking intervention, patients from the intervention group additionally being informed about the result of the spirometry test. After 1 year, smoking status will be assessed and, in those who report that they have quit smoking, abstinence will be confirmed by co-oximetry. Data will be analyzed on an intention-to-treat basis using the chi-squared test for outcomes and binary logistic regression if it is considered to be necessary to adjust for confounding variables. DISCUSSION: Performing a spirometry test and providing information on pulmonary function may increase awareness of the effect of smoking among smokers who are asymptomatic or have few symptoms and make them decide to quit. Specifically, in patients with chronic obstructive pulmonary disease it might increase levels of motivation to quit smoking in early stages of the disease. If this strategy were to be effective, it could be included in the health promotion activities offered in primary care. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01821885.