title: Asthma, chronic obstructive pulmonary disease, and mortality in the U.S. population.
abstract: BACKGROUND
  COPD and asthma are common diseases in the U.S. population and can coexist. Our goal was to determine the prevalence of self-reported, physician-diagnosed asthma and COPD in a sample of the U.S. population and their association with lung function impairment and mortality.
  
  
  METHODS
  We used baseline data from NHANES III and the follow-up mortality data. We used logistic regression and Cox Proportional Hazards models, adjusting for age, sex, race/ethnicity, education level, smoking status, and disease stage.
  
  
  RESULTS
  The sample consisted of 15,203 subjects, of whom 4,542 died during the follow-up period. Coexisting COPD and asthma was reported by 357 (2.7%), COPD by 815 (5.3%), and asthma by 709 (5.3%). Subjects with both conditions had a higher proportion of obstruction (30.9%) than those with COPD (24.3%), asthma (13.3%), or no lung disease (5.4%). In survival models adjusting for all factors except baseline lung function, coexisting COPD and asthma had the highest risk for mortality (Hazard Ratio [HR] 1.83, 95% confidence interval [CI] 1.34, 2.49), followed by COPD only (HR 1.44, 95% CI 1.28, 1.62), and asthma only (HR 1.16, 95% CI 0.94, 1.42). These affects were attenuated after controlling for baseline lung function: coexisting asthma and COPD (HR 1.45, 95% CI 1.06, 1.98), COPD only (1.28, 95% CI 1.13, 1.45), and asthma only (HR 1.04, 95% CI 0.85, 1.27).
  
  
  CONCLUSIONS
  In this analysis, subjects who report coexisting asthma and COPD have a higher risk of obstruction on spirometry and a higher risk of death during follow-up.
authors.affiliation: Division of Pulmonary, Sleep & Critical Care Medicine, University of Kentucky College of Medicine, 740 S. Limestone Street, Lexington, KY 40536, USA. enriquedgz@uky.edu
authors.forename: Enrique
authors.initials: E
authors.lastname: Diaz-Guzman
authors.forename: Mehdi
authors.initials: M
authors.lastname: Khosravi
authors.forename: David M
authors.initials: DM
authors.lastname: Mannino
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001249:Asthma / Q000150:complications / Q000401:mortality*; D015992:Body Mass Index; D005260:Female; D006306:Health Surveys; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications / Q000401:mortality*; D012737:Sex Factors; D012907:Smoking / Q000453:epidemiology; D013147:Spirometry; D014481:United States / Q000453:epidemiology; D044465:White People