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Table 2 Characteristics of the final study population and participants excluded due to pre-existing respiratory symptoms or conditions: the ARIC study

From: Occupation and three-year incidence of respiratory symptoms and lung function decline: the ARIC Study

  Excluded participants1 (N = 3,763) Final study population (N = 8,967)  
  No. (%) No. (%)  
Age, in years    
   45-49 921 (24.5) 2,475 (27.6)  
   50-54 937 (24.9) 2,424 (27.0)  
   55-59 954 (25.4) 2,167 (24.2)  
   60-65 951 (25.3) 1,901 (21.2)  
χ23df test    p < 0.01
Race    
   Black 742 (19.7) 2,089 (23.3)  
   White 3,021 (80.3) 6,878 (76.7)  
χ21df test    p < 0.01
Sex    
   Female 1,930 (51.3) 5,018 (56.0)  
   Male 1,833 (48.7) 3,949 (44.0)  
χ21df test    p < 0.01
Smoking status    
   Current smoker 1,479 (39.3) 1,460 (16.3)  
No. cigarettes per day, on average Mean ± SD 21.0 ± 12.5 15.3 ± 10.3  
Median 20.0 15.0  
Minimum-Maximum < 1 - 80 < 1 - 80  
Wilcoxon-Mann-Whitney test    p < 0.01
Former smoker, ≤ 3 years since last cigarette 259 (6.9) 354 (3.9)  
Former smoker, > 3 years since last cigarette 1,071 (28.5) 3,253 (36.3)  
Lifetime non-smoker 954 (25.4) 3,900 (43.5)  
   χ23df test    p < 0.01
  1. 1 Excluded due to self-reported respiratory health symptoms or conditions (n = 3,289) or airway obstruction (n = 474) at visit 1