Smoking duration, respiratory symptoms, and COPD in adults aged ≥45 years with a smoking history

BACKGROUND The purpose of this study was to assess the relationship of smoking duration with respiratory symptoms and history of chronic obstructive pulmonary disease (COPD) in the South Carolina Behavioral Risk Factor Surveillance System survey in 2012. METHODS Data from 4,135 adults aged ≥45 years with a smoking history were analyzed using multivariable logistic regression that accounted for sex, age, race/ethnicity, education, and current smoking status, as well as the complex sampling design. RESULTS The distribution of smoking duration ranged from 19.2% (1-9 years) to 36.2% (≥30 years). Among 1,454 respondents who had smoked for ≥30 years, 58.3% were current smokers, 25.0% had frequent productive cough, 11.2% had frequent shortness of breath, 16.7% strongly agreed that shortness of breath affected physical activity, and 25.6% had been diagnosed with COPD. Prevalence of COPD and each respiratory symptom was lower among former smokers who quit ≥10 years earlier compared with current smokers. Smoking duration had a linear relationship with COPD (P<0.001) and all three respiratory symptoms (P<0.001) after adjusting for smoking status and other covariates. While COPD prevalence increased with prolonged smoking duration in both men and women, women had a higher age-adjusted prevalence of COPD in the 1-9 years, 20-29 years, and ≥30 years duration periods. CONCLUSION These state population data confirm that prolonged tobacco use is associated with respiratory symptoms and COPD after controlling for current smoking behavior.