Background: There is current controversy about the efficacy of smoking cessation interventions that are based on information obtained by spirometry. The objective of this study is to evaluate the effectiveness in the primary care setting of structured motivational intervention to achieve smoking cessation, compared with usual clinical practice.
Design: Multicentre randomized clinical trial with an intervention and a control group.
Setting: 12 primary care centres in the province of Tarragona (Spain).
Subjects of study: 600 current smokers aged between 35 and 70 years with a cumulative habit of more than 10 packs of cigarettes per year, attended in primary care for any reason and who did not meet any of the exclusion criteria for the study, randomly assigned to structured intervention or standard clinical attention.
Intervention: Usual advice to quit smoking by a general practitioner as well as a 20-minute personalized visit to provide detailed information about spirometry results, during which FEV1, FVC, FEF 25-75% and PEF measurements were discussed and interpreted in terms of theoretical values. Additional information included the lung age index (defined as the average age of a non-smoker with the same FEV1 as the study participant), comparing this with the chronological age to illustrate the pulmonary deterioration that results from smoking.
Measurements: Spirometry during the initial visit. Structured interview questionnaire administered at the primary care centre at the initial visit and at 12-month follow-up. Telephone follow-up interview at 6 months. At 12-month follow-up, expired CO was measured in patients who claimed to have quit smoking.
Main variables: Smoking cessation at 12 months.
Analysis: Data will be analyzed on the basis of "intention to treat" and the unit of analysis will be the individual smoker.
Expected results: Among active smokers treated in primary care we anticipate significantly higher smoking cessation in the intervention group than in the control group.
Discussion: Application of a motivational intervention based on structured information about spirometry results, improved abstinence rates among smokers seen in actual clinical practice conditions in primary care.
Trial registration: ClinicalTrial.gov, number NCT01194596.