Background: Case-finding of chronic obstructive pulmonary disease (COPD) using spirometry may deter people with normal lung function from stopping smoking. The objective of this study was to observe the percentage of smokers screened with normal lung function that quit smoking.
Methods: As part of a study on early detection of COPD, 518 smokers were screened with normal lung function (post-bronchodilator FEV(1)/FVC ≥ 70%). They were invited for a follow-up measurement after an average of 2.4 years. Non-smoking was validated by carbon monoxide (<10 ppm), and respiratory health related quality of life was measured with the Clinical COPD Questionnaire (CCQ).
Results: A total of 255 participants were followed up (49%). The point prevalence rate of non-smoking at follow-up was 18% (N = 47), and 9% assuming that all non-respondents were smokers. This rate was not lower than the expected rate of quitting in the Dutch population (8-9%) and primary "care as usual" in smokers screened with abnormal lung function (10%; p > 0.05 for all comparisons). The average decline in post-bronchodilator FEV(1) was 26 mL/year, which was unrelated to smoking status at follow-up. Non-smokers showed a clinically meaningful and statistically significant (p < 0.001) improvement in CCQ respiratory symptoms (-0.96) and total score (-0.51).
Conclusions: Our results do not suggest that early detection of airflow limitation to motivate smoking cessation reduces the rate of quitting in smokers shown to have normal lung function. Such smokers should be advised to quit smoking on the grounds that they are likely to improve their respiratory health in the short term and reduce their risk for smoking related diseases in the long term.
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