Table 1 Participant demographics (baseline assessment)
Characteristics | All subjects n = 9804 | Transient sputum productiona n = 1022 | Persistent sputum productiona n = 1609 | Sputum production at follow-up onlya,b n = 1256 | No sputum production at both assessmentsa n = 4406 | p value among the four groups |
|---|---|---|---|---|---|---|
Age, years | 53.6 ± 13.4 | 53.6 ± 13.8 | 54.9 ± 13.3 | 53.7 ± 12.4 | 53.8 ± 12.9 | 0.01 |
Sex (male/female), % | 32.8/67.2 | 40.6/59.4 | 50.4/49.6 | 30.8/69.2 | 23.7/76.3 | < 0.0001 |
Sputum production (baseline/follow-up), % | 32.0/34.5 | 100/0 | 100/100 | 0/100 | 0/0 | – |
Sputum production on awakening (baseline/follow-up), % | 16.7/19.6 | 32.9/8.5 | 49.0/58.8 | 8.9/38.4 | 3.9/2.5 | < 0.0001/< 0.0001 |
Smoking history (ex or current), % | 35.0 | 40.9 | 49.8 | 33.4 | 26.1 | < 0.0001 |
COPD, % | 1.1 | 1.5 | 2.1 | 1.1 | 0.5 | < 0.0001 |
Asthma, % | 4.1 | 5.5 | 6.6 | 4.0 | 2.9 | < 0.0001 |
Prolonged cough, % | 10.4 | 14.7 | 18.3 | 10.4 | 7.0 | < 0.0001 |
Sinusitis, % | 10.2 | 12.5 | 15.7 | 10.5 | 7.9 | < 0.0001 |
Post-nasal drip (baseline/follow-up), % | 21.1/24.9 | 28.8/24.7 | 35.5/39.7 | 22.1/36.6 | 14.4/16.2 | < 0.0001/< 0.0001 |
FSSG score ≥ 8 (baseline/follow-up), % | 22.7/22.0 | 26.7/23.4 | 36.5/36.3 | 25.2/28.1 | 15.8/14.8 | < 0.0001/< 0.0001 |