Baseline characteristics of the study subjects
| Without pirfenidone | With pirfenidone | p-value | |
| Subjects | 10 | 10 | |
| Age (years) | 72 (67–85) | 75.5 (67–88) | 0.1527 |
| Male/female | 8/2 | 8/2 | |
| BMI (kg·m−2) | 26.2 (25.2–27.6) | 24.0 (21.6–25.8) | 0.1926 |
| Brinkman index | 800 (75–1743) | 900 (39.8–1490) | 0.6855 |
| VC (L) | 2.31 (2.07–3.09) | 2.61 (2.19–2.91) | 0.588 |
| VC (% pred) | 76.2 (68.3–92.2) | 80.9 (70.7–92.5) | 0.4608 |
| FVC (L) | 2.26 (1.97–3.08) | 2.64 (2.16–2.84) | 0.5236 |
| FEV1 (L) | 1.93 (1.72–2.46) | 2.34 (1.82–2.52) | 0.3674 |
| FEV1 (% pred) | 84.1 (77.2–89.3) | 85.8 (79.0–91.8) | 0.7371 |
| DLCO (mL·min−1·mmHg−1) | 12.9 (10.8–14.8) | 10.2 (9.3–13.3) | 0.3838 |
| DLCO (% pred) | 59.8 (53.5–71.3) | 43.6 (36.0–55.3) | 0.0369 |
| PaO2 (mmHg) | 89.1 (81.6–93.4) | 82.7 (77.6–88.3) | 0.2635 |
| PaCO2 (mmHg) | 38.9 (36.8–41.4) | 40.5 (39.4–43.7) | 0.1267 |
| SpO2min of 6MWT (%) | 92 (87.5–94) | 90 (87.5–95.3) | 0.861 |
| 6MWD (m) | 430 (320–453) | 430 (358–485) | 0.6767 |
| SP-A (ng·mL−1) | 88.1 (46.6–111.7) | 70.7 (45.3–114.5) | 0.8306 |
| SP-D (ng·mL−1) | 323 (192.23–355.8) | 204.5 (114–314.5) | 0.2347 |
| KL-6 (U·mL−1) | 1100 (621.8–2218.8) | 1185 (803.8–1690) | 0.3867 |
| LDH (IU·L−1) | 255.5 (224.8–312) | 245 (223.3–300.3) | 0.8981 |
Data are presented as n or median (interquartile range), unless otherwise stated. BMI: body mass index: VC: vital capacity; FVC: forced vital capacity; FEV1: forced expiratory volume in 1 s; DLCO: diffusing capacity of the lung for carbon monoxide; PaO2: arterial oxygen tension; PaCO2: arterial carbon dioxide tension; SpO2: oxygen saturation measured by pulse oximetry; 6MWT: 6-min walk test; 6MWD: 6-min walk distance; SP-A: surfactant protein A; SP-D: surfactant protein D; KL-6: Krebs von den Lungen-6; LDH: lactate dehydrogenase.