Table 2. Crude and adjusted ORs according to previous exacerbations for the risk of suffering frequent exacerbations in the following year.
| IE | FE | ORc | 95% CI | ORa | 95% CI | |
|---|---|---|---|---|---|---|
| N=568 | N=332 | |||||
|
History of exacerbations | ||||||
| Number of exacerbations in the previous year (continuous) | — | — | 1.85 | 1.66–2.06 | 1.76 | 1.56–2.00 |
| Number of exacerbations in the previous four years (continuous) | — | — | 1.24 | 1.19–1.30 | 1.20 | 1.15–1.26 |
|
Frequent exacerbations in the previous year | ||||||
| Infrequent exacerbations (⩽1) | 438 | 125 | 1 | — | 1 | — |
| Frequent exacerbations (⩾2) | 130 | 207 | 5.58 | 4.15–7.50 | 4.97 | 3.54–6.97 |
|
Number of exacerbations in the previous year | ||||||
| None (0 exacerbations) | 275 | 50 | 1 | — | 1 | — |
| 1 exacerbation | 163 | 75 | 2.53 | 1.69–3.80 | 1.86 | 1.18–2.95 |
| ⩾2 exacerbations | 130 | 207 | 8.76 | 6.03–12.71 | 6.77 | 4.45–10.28 |
| Linear P trend | <0.001 | <0.001 | ||||
|
History of severe exacerbations (hospitalised for exacerbation) in the previous year | ||||||
| Number of COPD admissions (continuous) | — | — | 1.91 | 1.53–2.38 | 1.13 | 0.93–1.37 |
|
Frequent severe exacerbations in the previous year | ||||||
| None (0 COPD admissions) | 497 | 233 | 1 | — | 1 | — |
| ⩾1 COPD admissions | 71 | 99 | 2.97 | 2.11–4.19 | 2.13 | 1.45–3.14 |
|
Number of severe exacerbations in the previous year | ||||||
| None (0 COPD admissions) | 497 | 233 | 1 | — | 1 | — |
| 1 COPD admission | 54 | 61 | 2.41 | 1.62–3.59 | 1.75 | 1.12–2.72 |
| ⩾2 COPD admissions | 17 | 38 | 4.77 | 2.64–8.63 | 3.35 | 1.75–6.41 |
| Linear P trend | <0.001 | <0.001 | ||||
Abbreviation: CI, confidence interval; COPD, chronic obstructive pulmonary disease; FE, frequent exacerbations in the following year; IE, infrequent exacerbations in the following year; OR, odds ratio; ORc, crude OR; ORa, adjusted OR by age, gender, smoking status and COPD severity (GOLD grades 1–4).