title: Smoking duration, respiratory symptoms, and COPD in adults aged ≥45 years with a smoking history.
abstract: 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.
  
  
  CONCLUSIONS
  These state population data confirm that prolonged tobacco use is associated with respiratory symptoms and COPD after controlling for current smoking behavior.
authors.affiliation: Division of Population Health, Centers for Disease Control and Prevention, Atlanta, Ga, USA.
authors.forename: Yong
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Division of Pulmonary, Allergy, and Critical Care Medicine, Duke University School of Medicine, Durham, NC, USA.
authors.forename: Roy A
authors.initials: RA
authors.lastname: Pleasants
authors.affiliation: Division of Population Health, Centers for Disease Control and Prevention, Atlanta, Ga, USA.
authors.forename: Janet B
authors.initials: JB
authors.lastname: Croft
authors.affiliation: Division of Population Health, Centers for Disease Control and Prevention, Atlanta, Ga, USA.
authors.forename: Anne G
authors.initials: AG
authors.lastname: Wheaton
authors.affiliation: Chronic Disease Epidemiology Office, Department of Health and Environmental Control, South Carolina, SC, USA.
authors.forename: Khosrow
authors.initials: K
authors.lastname: Heidari
authors.affiliation: Office of Smoking and Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Ann M
authors.initials: AM
authors.lastname: Malarcher
authors.affiliation: Section on Pulmonary, Critical Care, Allergy and Immunologic Disease, Wake Forest University, Winston Salem, NC, USA.
authors.forename: Jill A
authors.initials: JA
authors.lastname: Ohar
authors.affiliation: Department of Medicine, University of Arizona, Phoenix, AZ, USA.
authors.forename: Monica
authors.initials: M
authors.lastname: Kraft
authors.affiliation: Division of Pulmonary, Critical Care, and Sleep Medicine, Pulmonary Epidemiology Research Laboratory, University of Kentucky, Lexington, KY, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Mannino
authors.affiliation: Division of Pulmonary, Critical Care, Allergy and Sleep Medicine, Medical University of South Carolina, Charleston, SC, USA.
authors.forename: Charlie
authors.initials: C
authors.lastname: Strange
mesh_terms: D000367:Age Factors; D000368:Aged; D003371:Cough / Q000453:epidemiology / Q000503:physiopathology; D003430:Cross-Sectional Studies; D004417:Dyspnea / Q000453:epidemiology / Q000503:physiopathology; D017079:Exercise Tolerance; D005260:Female; D006306:Health Surveys; D006801:Humans; D016014:Linear Models; D016015:Logistic Models; D008168:Lung / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D015995:Prevalence; D011379:Prognosis; D065840:Protective Factors; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology / Q000628:therapy; D018570:Risk Assessment; D012307:Risk Factors; D040242:Risk Reduction Behavior; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects* / Q000453:epidemiology*; D016540:Smoking Cessation; D000074606:Smoking Prevention; D013022:South Carolina / Q000453:epidemiology; D013997:Time Factors
keywords: chronic obstructive pulmonary disease; population-based study; respiratory symptoms; tobacco use