COPD in non-smokers: Report from the Tunisian burden of obstructive lung disease study

The present study aimed to investigate the prevalence, risk factors and profiles of COPD among non-smokers based on the Tunisian Burden of Obstructive Lung Disease study. We surveyed a representative random sample of 807 adults aged 40 years+ selected from the general population and have collected information on respiratory history and symptoms, risk factors for COPD and quality of life. The diagnosis of COPD was based on the post-bronchodilator FEV₁/FVC ratio, according to current GOLD (Global Initiative for Obstructive Lung Disease) guidelines. In addition, the lower limit of normal (LLN) was evaluated as an alternative threshold for the FEV₁/FVC ratio. 661 subjects were included in the final analysis. Among 485 non-smokers, 3.5% met the criteria for stage I+ COPD. These proportions were similar even when the LLN was used as a threshold. None of the non-smokers with COPD had ever received a previous doctor diagnosis of COPD compared to 7.1% of smokers. Among all the subjects fulfilling the GOLD spirometric criteria of COPD, non-smokers, accounted for 45%; they were predominately male and reported asthma more frequently than obstructive smokers. When comparing non-smokers with versus without COPD, significantly more symptoms and higher co-morbidity were found in the first group. Predictors of COPD in non-smokers include age, gender, occupational exposure, lower body mass index and a previous diagnosis of asthma. This study confirms previous evidence that non-smokers comprise a substantial proportion of individuals with COPD. Non-smoking COPD may have different profiles from smoking COPD and non-smokers should, thus, receive far greater attention to prevent and treat chronic airway obstruction.