Summary of baseline demographic characteristics
| Pirfenidone | Pirfenidone+inhaled NAC | p-value | |
| Subjects | 40 | 41 | |
| Age years | 73.3±7.0 | 71.0±7.3 | 0.16 |
| Male | 33 (82.5) | 34 (82.9) | 1.00 |
| Weight kg | 59.9±10.6 | 62.5±11.4 | 0.75 |
| Smoking status never/former/current | 8/30/2 | 10/31/0 | 0.64 |
| Time since IPF diagnosis months | 36.0 | 42.2 | 0.41 |
| Classification of HRCT findings | 0.31 | ||
| Definite UIP | 28 (70.0) | 33 (80.5) | |
| Possible UIP | 12 (30.0) | 8 (19.5) | |
| Duration of pirfenidone use before randomisation days | 282±371 | 255±515 | 0.80 |
| Glucocorticoid use at randomisation | 3 (8.3) | 0 (0) | 0.24 |
| Physiological findings | |||
| FVC | 2.21±0.56 | 2.36±0.60 | 0.25 |
| FVC % | 72.2±13.1 | 73.1±13.8 | 0.77 |
| DLCO mL·min−1·Torr−1 | 8.99±2.38 | 9.71±2.70 | 0.25 |
| DLCO % | 58.1±15.1 | 58.4±18.4 | 0.94 |
| 6MWD m | 387.6±143.3 | 449.3±117.9 | 0.06 |
| KL-6 U·mL−1 | 958.0±494.3 | 1029.9±572.3 | 0.58 |
| SP-D ng·mL−1 | 247.3±200.7 | 279.2±144.5 | 0.46 |
| Total CAT score | 15.2±7.9 | 13.8±8.5 | 0.49 |
Data are presented as n, mean±sd or n (%), unless otherwise stated. NAC: N-acetylcysteine; IPF: idiopathic pulmonary fibrosis; HRCT: high-resolution computed tomography; UIP: usual interstitial pneumonia; FVC: forced vital capacity; DLCO: diffusing capacity of the lung for carbon monoxide; 6MWD: 6-min walk distance; KL-6: Krebs von der Lungen-6; SP-D: surfactant protein D; CAT: COPD Assessment Test.