Associations Between Physical Activity, Smoking Status, and Airflow Obstruction and Self-Reported COPD: A Population-Based Study

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a preventable and treatable disease with an increased mortality rate in recent years, mainly caused by exposure to tobacco smoke. Regular physical activity is thought to diminish the risk of COPD exacerbation, while very few studies investigate the interaction between smoking and physical activity on COPD development. This study aims to investigate the association between smoking status, physical activity and prevalent COPD. METHODS: This study analyzed data of adults 20 to 79 years old from the National Health and Nutrition Examination Survey (NHANES) 2007–2012. RESULTS: A total of 6404 participants aged 20–79 were included and divided into four groups by their physical activity levels and smoking status. Amongst, 2819 (43.7%) were physically active non-smokers, 957 (14.8%) were physically inactive non-smokers, 1952 (30.3%) were physically active smokers, and 717 (11.1%) were physically inactive smokers. Prevalence of airflow obstruction were 5.7%, 7.1%, 17.7% and 18.6%, respectively. After adjustment, physically active smokers (aOR=2.71, 95% CI=1.94–3.80) and physically inactive smokers (aOR=2.70, 95% CI=1.78–4.09) but not physically active non-smokers were more likely to have airflow obstruction than physically active non-smokers. These associations were similar among most subgroups by age, sex, or BMI. Among smokers, being physically inactive was not significantly associated with a greater chance for prevalent airflow obstruction than being physically active. CONCLUSION: Smokers, regardless of their physical activity level, are more likely to have airflow obstruction as compared with physically active non-smokers. Within smokers, being physically inactive poses no excess chance to be airflow obstructed. The findings indicate that physical activity level seem not altering the relationship between smoking and airflow obstruction.