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Table 3 Likelihood of respiratory symptoms a by lung function category

From: Pulmonary function, chronic respiratory symptoms, and health-related quality of life among adults in the United States – National Health and Nutrition Examination Survey 2007–2010

  %b(95% CI) Adjusted PRc(95% CI)
Frequent cough    
  Normal lung function 8.6 (7.1-10.3) 1.00   --
  Restrictive impairment 13.0 (8.9-18.7) 1.12 (0.75-1.66)
  Mild obstruction 9.3 (6.4-13.2) 0.83 (0.53-1.29)
  Moderate–severe obstruction 24.2 (18.7-30.7) 1.63 (1.20-2.20)
Frequent phlegm    
  Normal lung function 5.9 (5.2-6.8) 1.00   --
  Restrictive impairment 10.0 (6.4-15.3) 1.14 (0.72-1.81)
  Mild obstruction 9.1 (6.0-13.6) 1.21 (0.76-1.93)
  Moderate–severe obstruction 19.8 (14.5-26.4) 1.99 (1.31-3.03)
Wheeze    
  Normal lung function 10.2 (9.0-11.5) 1.00   --
  Restrictive impairment 18.5 (13.7-24.6) 1.36 (0.99-1.87)
  Mild obstruction 11.8 (8.7-15.7) 1.23 (0.89-1.71)
  Moderate–severe obstruction 31.9 (25.8-38.8) 2.65 (2.04-3.43)
Any respiratory symptoms    
  Normal lung function 17.1 (15.1-19.3) 1.00   --
  Restrictive impairment 29.0 (23.8-34.8) 1.32 (1.06-1.63)
  Mild obstruction 19.9 (15.8-24.8) 1.06 (0.81-1.38)
  Moderate–severe obstruction 47.4 (39.9-55.0) 2.10 (1.69-2.60)
  1. a Respiratory symptoms included the following: cough most days (at least 3 months), bring up phlegm most days (at least 3 months), or had wheeze or whistle in chest (in past 12 months).
  2. b Unadjusted.
  3. c Adjusted prevalence ratio (PR) and 95% confidence interval (CI) obtained from multivariable logistic regression that included sex, age, race/ethnicity, education, number of non-respiratory chronic illnesses, smoking status, and BMI as covariates.