Table 1

Demographic, exposure and clinical characteristics of the study population by smoking status (never-smokers vs ever-smokers)

Never-smokers
n=2295
Per centEver-smokers
n=2598
Per centAdjusted p value*
Sex (men)89138.82120546.380.0023
Ethnicity (Caucasian)201988.0245694.50.0022
Age, year, mean±SD55.69±11.1758.18±11.030.0021
Age, years0.0020
 40–4970230.5967225.87
 50–5975032.6881131.22
 60–6950121.8367425.94
 70+34214.9044116.97
BMI, kg/m2, mean±SD27.51±5.6628.27±5.960.0019
Education, year, mean±SD16.06±3.5114.81±3.490.0018
Pack years >20123147.38
Exposures
 Organic dust2028.802439.351.0000
 Inorganic dust462.001124.310.0017
 Gases/vapours893.881555.970.0112
 Biomass fuel†
  ≥10 years cooking19612.0322513.161.0000
  ≥10 years heating24615.1031218.250.1639
 Passive smoking at home1064.6236113.900.0016
 Childhood hospitalisation for respiratory illness1114.841736.660.0871
Comorbidities, ever
 HD/HT/DM‡72831.7299938.450.0015
 Asthma36916.0842416.321.0000
 TB311.35351.350.9914
Use of respiratory medications74632.685532.91.0000
 Prescribed medication41618.253420.60.149
 Bronchodilator27211.937314.40.1224
 Inhaled steroid33214.542816.50.4432
 Oral steroid100.4100.41.0000
 Anti-inflammatory (other)160.7210.81.0000
 OTC§ medication30613.429011.20.1341
  • Data are mean±SD or count and %. p Values of tests between never-smokers and ever-smokers; Kruskal-Wallis test (without assumption of normal distribution of data) and χ2 test are used for continuous variables and categorical variables, respectively.

  • *p Values adjusted after Holm-Bonferroni correction.

  • †Calculated based on six sites with available biomass data.

  • ‡Heart disease, systemic hypertension or diabetes.

  • §Includes antihistamines, decongestants and antitussives.

  • BMI, body mass index; HD/HT/DM, heart disease/ systemic hypertension/diabetes mellitus.