COPD in never-smokers : BOLD Australia study

Purpose: Tobacco smoking is the major risk factor for COPD, and it is common for other risk factors in never-smokers to be overlooked. We examined the prevalence of COPD among never-smokers in Australia and identified associated risk factors. Methods: We used data from the Australia Burden of Obstructive Lung Disease (BOLD) study, a cross-section of people aged ≥40 years from six sites. Participants completed interviews and post-bronchodilator spirometry. COPD was primarily defined as an FEV₁/FVC ratio <0.70 and secondarily as the ratio less than the lower limit of normal (LLN). Results: The prevalence of COPD in the 1656 never-smokers who completed the study was 10.5% (95% CI: 9.1–12.1%) [ratio<LLN 4.6%]. The likelihood of having COPD increased with advancing age [odds ratio (OR) 4.11 in those 60–69 years and OR 8.73 in those 70 years and older], having attained up to 12 years of education (OR 1.75) compared to those with more than 12 years, having a history of asthma (OR 2.30), childhood hospitalization due to breathing problems before age 10 years (OR 2.50), or having a family history of respiratory diseases (OR 2.70). Being overweight or obese was associated with reduced prevalence of COPD compared with being normal weight. In males and females, advanced age, a history of asthma, and childhood breathing problems before age 10 were factors that elevated the likelihood of COPD. However, in males, additional factors such as a higher body mass index and a family history of respiratory diseases also contributed to increased odds of COPD. Conclusion: COPD was prevalent in this population of never-smokers aged 40 years and over. This finding highlights the significance of risk factors other than smoking in the development of COPD.