Risk factors contributed to severe acute exacerbation or community-acquired pneumonia requiring hospitalisation in patients with COPD
| OR | 95% CI | P value | |
| Age | 0.93 | 0.77 to 1.12 | 0.47 |
| C5, the number of doubling concentration | 2.19 | 1.08 to 4.44 | 0.029 |
| mMRC scores, grade | 4.29 | 0.91 to 20.1 | 0.065 |
| FEV1, %predicted | 0.88 | 0.77 to 1.01 | 0.078 |
| Eosinophils ≥300/ µL, + | 45.9 | 1.09 to 1934 | 0.045 |
The number of doubling concentration was shown as follows; for example, 0.61 µM, 1.22 µM, 2.44 µM, 4.88 µM, 9.76 µM, 19.52 µM, 39.04 µM, 78.1 µM, 156.2 µM and 312.5 µM correspond to 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 doubling concentrations, respectively.
C5, concentration of inhaled capsaicin required to induce at least five coughs; FEV1, forced expiratory volume in 1 s; mMRC, modified Medical Research Council.