Logistic regression assessing potential risk factors for sudden onset exacerbations
| OR (95% CI) | p Value | |
| Chronic sputum production (y/n) | 0.86 (0.64 to 1.15) | 0.303 |
| Current smoker (y/n) | 1.37 (0.99 to 1.91) | 0.060 |
| FEV1 % predicted (per 1%) | 0.99 (0.98 to 1.00) | 0.112 |
| Male sex | 1.11 (0.82 to 1.50) | 0.504 |
| Low BMI (<20 kg/m2) | 1.11 (0.65 to 1.87) | 0.708 |
| Overweight BMI (25–30 kg/m2) | 1.05 (0.75 to 1.49) | 0.763 |
| Obese BMI (≥30 kg/m2) | 1.05 (0.68 to 1.60) | 0.838 |
| History of cardiovascular disease (y/n) | 0.76 (0.55 to 1.05) | 0.092 |
| Age (per year) | 1.00 (0.98 to 1.02) | 0.936 |
| Winter season (Nov–Feb) | 1.02 (0.78 to 1.34) | 0.869 |
| Spring season (Mar–Apr) | 0.72 (0.52 to 0.98) | 0.038 |
| Summer season (May–Aug) | 0.89 (0.67 to 1.18) | 0.419 |
| Viral cold symptoms (0, 1 or 2) | 1.21 (1.03 to 1.43) | 0.024 |
| Sputum purulence (0, 1) | 12.10 (8.27 to 17.80) | <0.001 |
BMI, body mass index; FEV1, forced expiratory volume in 1 s.