Table 2.
Factors associated with sputum production at baseline: comparative and multivariable analyses
| Baseline factors | Sputum + n = 3139 | Sputum − n = 6665 | p value | OR (95% CI) for sputum production | p value |
|---|---|---|---|---|---|
| Age, yeara | 54.0 ± 13.9 | 53.4 ± 13.2 | 0.04 | 1.10 (1.06–1.14) | < 0.0001 |
| Male sex, % | 47.0 | 26.1 | < 0.0001 | 2.34 (2.07–2.65) | < 0.0001 |
| BMI, kg/m2 | 22.5 ± 3.4 | 22.2 ± 3.2 | < 0.0001 | 1.00 (0.98–1.01) | 0.87 |
| Smoking history (ex or current), % | 47.6 | 29.0 | < 0.0001 | 1.49 (1.33–1.68) | < 0.0001 |
| COPD, % | 2.2 | 0.6 | < 0.0001 | 2.21 (1.44–3.38) | 0.0003 |
| Asthma, % | 6.3 | 3.1 | < 0.0001 | 1.53 (1.22–1.90) | 0.0002 |
| Prolonged cough, % | 16.6 | 7.6 | < 0.0001 | 2.31 (2.00–2.66) | < 0.0001 |
| Allergic rhinitis, % | 37.7 | 34.0 | 0.0003 | 1.02 (0.92–1.12) | 0.76 |
| Sinusitis, % | 14.1 | 8.3 | < 0.0001 | 1.39 (1.20–1.60) | < 0.0001 |
| Post-nasal drip, % | 32.3 | 15.9 | < 0.0001 | 2.40 (2.15–2.68) | < 0.0001 |
| Diabetes mellitus, % | 7.0 | 4.4 | < 0.0001 | 1.25 (1.02–1.52) | 0.03 |
| FSSG score ≥ 8, % | 32.7 | 18.0 | < 0.0001 | 1.92 (1.73–2.13) | < 0.0001 |
| Stress, % | 74.3 | 71.1 | 0.0007 | 1.30 (1.17–1.45) | < 0.0001 |
OR odds ratio, CI confidence interval, BMI body mass index, COPD chronic obstructive pulmonary disease, FSSG Frequency Scale for Symptoms of Gastroesophageal Reflux Disease
aAge per 10-year increase
For multivariable analysis