Associations of Self-Reported Cigarette Smoking with Chronic Obstructive Pulmonary Disease and Co-Morbid Chronic Conditions in the United States

Background<bold>: </bold>The question of how smoking, COPD, and other chronic diseases are related remains unresolved. Therefore, we examined relationships between smoking, COPD, and 10 other chronic diseases and assessed the prevalence of co-morbid chronic conditions among people with COPD. Methods<bold>: </bold>We analyzed cross-sectional data from 405,856 US adults aged 18 years or older in the 2011 Behavioral Risk Factor Surveillance System. We used log-linear regression to estimate prevalence ratios (PRs) and their corresponding 95% confidence intervals (CIs) for these relationships adjusting for age, gender, race/ethnicity, marital status, educational attainment, annual household income, and health insurance coverage. Results<bold>: </bold>Overall, 17.5% reported being current cigarette smokers, 6.9% reported having COPD, and 71.2% reported another chronic condition. After age-adjustment, prevalence of COPD was 14.1% (adjusted PR = 3.9; 95% CI: 3.7, 4.1) among current smokers and 7.1% (adjusted PR = 2.5; 95% CI: 2.4, 2.7) among former smokers compared to 2.9% among never smokers. The most common chronic conditions among current smokers after age-adjustment were high cholesterol (36.7%), high blood pressure (34.6%), arthritis (29.4%), depression (27.4%), and asthma (16.9%). In separate multivariable models, smoking and COPD were associated with each of the 10 other chronic conditions (p < 0.05), which also included cancer, coronary heart disease, diabetes, kidney disease, and stroke; COPD modified associations between smoking and co-morbidities, while smoking did not modify associations between COPD and co-morbidities. Conclusions<bold>: </bold>Our findings confirm previous evidence and highlight the continuing importance of comprehensive care coordination for people with COPD and co-morbid chronic conditions and also tobacco prevention and control strategies.