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Table 1 Demographic characteristics of the study population

From: Increased incidence of invasive bacterial disease in chronic obstructive pulmonary disease compared to the general population-a population based cohort study

  COPD patients n = 15,403 (100%) Reference individals 1 n = 15,403 (100%) p-value
Age distribution (years)    NA
40-59 1,858 (12.1%) 1,858 (12.1%)  
60-79 9,346 (60.7%) 9,346 (60.7%)  
≥80 4,199 (27.3%) 4,199 (27.3%)  
Gender    NA
Male 8,265 (53.7%) 8,265 (53.7%)  
Socio-economic status    <0.01
Non-manual 2,569 (16.7) 3,684 (23.9)  
Manual 4,473 (29.0) 4,002 (26.0)  
Other 1,646 (10.7) 1,767 (11.5)  
Outside workforce 2 6,715 (43.6) 5,950 (38.6)  
Co-morbidity 3    
Diabetes mellitus 966 (6.3) 557 (3.6) <0.01
Kidney failure 107 (0.7) 42 (0.3) <0.01
Cardiac disease 3,775 (24.5) 1,993 (12.9) <0.01
Alcohol-related disease 573 (3.7) 159 (1.0) <0.01
Liver failure 96 (0.6) 59 (0.4) <0.01
Connective tissue disease 428 (2.8) 210 (1.4) <0.01
Immunodeficiency 57 (0.4) 23 (0.2) <0.01
HIV 8 (0.05) 2 (0.01) 0.06
Solid cancer 1,322 (8.6) 759 (4.9) <0.01
Hematological cancer 110 (0.7) 42 (0.3) <0.01
Total days in hospital (mean/median) 37.7 / 12 22.5 / 3 <0.01
No. of discharges, all diagnoses 4.4 / 2 2.2 / 1 <0.01
  1. 1Control subjects were matched for year of birth, gender and county of residence by the 31st of December of the year before first hospital discharge listing a COPD diagnosis; 2−Subjects with missing information on socio-economic status were mainly older pensioners, unemployed, disability pensioners, homemakers and students: 3-Comorbidity was based on discharge codes in the Inpatient Register before inclusion; see Appendix for specific ICD codes.