Univariate logistic regression for factors associated with virus-positive exacerbation
| Independent variable | Frequency (%) in virus-positive exacerbation (n=37) | Frequency (%) in virus-negative exacerbation (n=40) | OR | 95% CI | p Value |
|---|---|---|---|---|---|
| A) Clinical parameters | |||||
| Wet cough | 35 (94.5%) | 38 (95%) | 0.9 | 0.1 to 6.9 | 0.93 |
| Cough severity score ≥ 2 | 36 (97.3%) | 35 (87.5%) | 5.1 | 0.5 to 46.3 | 0.14 |
| Sputum production | 16 (43.2%) | 25 (62.5%) | 0.4 | 0.2 to 1.1 | 0.09 |
| Sputum colour≥3 on BronkoTest | 17 (46%) | 21 (52.5%) | 0.8 | 0.3 to 1.9 | 0.56 |
| Chest pain | 5 (13.5%) | 11 (27.5%) | 0.4 | 0.1 to 1.3 | 0.14 |
| Breathlessness | 12 (32.4%) | 12 (30%) | 1.1 | 0.4 to 2.9 | 0.81 |
| Haemoptysis | 0 | 0 | – | ||
| Fever | 11 (30%) | 4 (10%) | 3.8 | 1.1 to 13.3 | 0.03 |
| Crackles and/or wheeze | 23 (62%) | 13 (32.5%) | 3.4 | 1.3 to 8.7 | 0.01 |
| Hypoxia | 8 (21.6%) | 1 (2.5%) | 10.8 | 1.3 to 90.9 | 0.03 |
| B) Haematological parameters* | |||||
| Raised WCC | 6 (16.2%) | 2 (5%) | 3.7 | 0.7 to 19.5 | 0.13 |
| Raised neutrophil % | 11 (30%) | 4 (10%) | 3.8 | 1.1 to 13.3 | 0.04 |
| Raised lymphocyte % | 1 (2.7%) | 0 (0%) | – | ||
| Raised monocyte % | 2 (5.4%) | 2 (5%) | 1.1 | 0.1 to 8.1 | 0.93 |
| Raised eosinophil % | 8 (21.6%) | 8 (20%) | 1.1 | 0.4 to 3.3 | 0.86 |
| C) Potential systemic markers | |||||
| CRP>3 mg/L | 26 (70.3%) | 13 (32.5%) | 4.9 | 1.9 to 12.9 | 0.001 |
| Fibrinogen>4.5 g/L | 4 (10.8%) | 3 (7.5%) | 1.5 | 0.3 to 7.2 | 0.61 |
| SAA>5 mg/L | 16 (43.2%) | 14 (35%) | 1.4 | 0.6 to 3.5 | 0.46 |
| IL-6>2 ng/L | 16 (43.2%) | 10 (25%) | 2.3 | 0.9 to 6.0 | 0.09 |
| PCT>0.09 µg/L | 5 (13.5%) | 3 (7.5%) | 1.9 | 0.4 to 8.7 | 0.39 |
| D) Lung function | |||||
| FEV1<80% predicted | 12 (54.5%) (n=22) | 11 (42.3%) (n=26) | 1.8 | 0.6 to 5.6 | 0.32 |
| R5>130% predicted | 9 (n=26) (34.6%) | 7 (n=30) (23.3%) | 5.1 | 1.4 to 17.9 | 0.35 |
*Cut-offs based on age-dependent criteria.
Bold typeface means statistically significant at p<0.2.
CRP, C reactive protein; FEV1, forced expiratory volume in first second; IL-6, interleukin 6; PCT, procalcitonin; R5, resistance at 5 Hz; SAA, serum amyloid A; WCC, white cell count.