Table 3 Adjusted odds ratios for severe exacerbations of COPD relative to the number of comorbid diseases or comorbid groups in both cohorts

Entire cohort*

 No. of comorbid diseases (range, 0–12)

  0

Ref

< 0.001

Ref

  1 or 2

1.35

(1.11 to − 1.65)

1.24

(1.01 to − 1.53)

  3 or 4

1.54

(1.25 to − 1.89)

1.35

(1.09 to − 1.68)

  ≥ 5

1.87

(1.50 to − 2.32)

1.40

(1.12 to − 1.77)

 No. of comorbidity groups (range, 0–5)***

  0

Ref

< 0.001

Ref

  1 or 2

1.34

(1.10 to − 1.62)

1.22

(1.00 to − 1.49)

  3 or 4

1.70

(1.39 to − 2.08)

1.44

(1.16 to − 1.77)

  5

3.26

(1.77 to − 5.99)

2.20

(1.16 to − 4.18)

Health-screening cohort**

 No. of comorbid diseases (range, 0–12)

  0

Ref

0.004

Ref

  1 or 2

1.59

(1.09 to − 2.31)

1.63

(1.22 to − 2.17)

  3 or 4

1.82

(1.24 to − 2.67)

1.77

(1.31 to − 2.38)

  ≥ 5

2.04

(1.36 to − 3.07)

1.78

(1.28 to − 2.46)

 No. of comorbidity groups (range, 0–5)***

  0

Ref

< 0.001

Ref

  1 or 2

1.63

(1.13 to − 2.36)

1.68

(1.26 to − 2.23)

  3 or 4

1.96

(1.34 to − 2.87)

1.81

(1.35 to − 2.44)

  5

5.59

(2.08 to − 14.98)

2.23

(1.01 to − 4.93)