Table 2.
Bronchial epithelial features of smokers and ex-smokers with COPD
| COPD Smokers | COPD Ex-smokers | p-value § | |||
| combined group | quit < 3.5 years | quit ≥3.5 years | |||
| SCM (% of epithelium) | 0 (0–27.5) | 0 (0-0)* | 0 (0–10.4) | 0 (0-0) | 0.076 |
| SCM (% of patients) | 45.7 | 22.5* | 26.3 | 19.0* | 0.049 |
| PAS/AB+ area (%) | 14.4 (5.2–20.7) | 8.1 (3.7–17.2)† | 13.5 (6.6–19.6) | 7.9 (2.2–16.2)*‡ | 0.011 |
| Ki-67+ cells (/mm BSM) | 18.6 (5.3–38.8) | 6.2 (1.5–15.6)* | 6.9 (4.4–27.6) | 2.8 (0.23–13.1)* | <0.001 |
| EGFR+ area (%) | 11.4 (3.2–17.6) | 8.2 (3.2–20.4) | 6.7 (2.4–20.4) | 8.6 (3.9–21.5) | 0.95 |
| Intensity EGFR+ area (grey value) | 697 (175–1182) | 513 (203–1479) | 372 (125–1479) | 517 (215–1424) | 0.95 |
Data represent median (IQR: 25th – 75th percentile). PAS/AB = Periodic acid-Schiff/Alcian blue, SCM = squamous cell metaplasia, EGFR = Epidermal growth factor receptor.
* p < 0.05: compared to COPD smokers, † p < 0.05: compared to COPD smokers adjusted for differences in squamous cell metaplasia (linear regression), ‡ p < 0.05: compared to COPD ex-smokers who quit <3.5 yrs, §p-value from Kruskal-Wallis test between current smokers, < and ≥3.5 yrs ex-smokers with COPD.