Alveolar nitric oxide concentration in chronic obstructive pulmonary disease(COPD) and healthy subjects calculated by different methods
| Linear 1 | Nonlinear | Mixed 1 | Mixed 2 | |
| COPD smokers | 2.3 (1.7–3.1) | 3.0 (2.4–3.8) | 2.3 (1.7–3.1) | 2.7 (1.9–3.7) |
| COPD ex-smokers | 2.8 (1.9–4.1) | 3.7 (2.7–5.1) | 2.8 (1.9–4.1) | 2.9 (2.1–4.1) |
| Healthy smokers | 3.0 (2.2–4.1) | 3.6 (2.8–4.6) | 3.0 (2.2–4.1) | 1.8 (0.0–4.2) |
| Healthy nonsmokers | 2.4 (1.6–3.5) | 3.2 (2.6–4.0) | 2.4 (1.6–3.5) | 2.6 (1.8–3.9) |
Data are presented as mean (95% confidence intervals).