Baseline demographic and physiological variables
| Male | 137 (82) |
| Current or ex-smoker | 116 (69.5) |
| Definite UIP on CT | 131 (78.4) |
| Pulmonary hypertension | 31 (18.6) |
| Exertional desaturation | 98 (68.1) |
| LTOT initiation | 31 (18.6) |
| Pirfenidone use at any time | 45 (26.9) |
| Overall mortality | 67 (40.1) |
| 6-month mortality | 15 (9.0) |
| 12-month mortality | 23 (13.8) |
| 24-month mortality# | 49 (48.5) |
| Age years | 73.5 (71.9–75.0) |
| BMI kg·m−2 | 26.7 (25.9–27.6) |
| FVC % pred | 83.0 (79.6–86.5) |
| FEV1 % pred | 84.5 (80.7–88.3) |
| DLCO % pred | 52.8 (49.2–56.4) |
| FEV1/FVC ratio % | 81.5 (80.2–82.9) |
| 6-min walking distance m | 283.8 (264.9–302.8) |
| 6-min walking distance % pred | 60.6 (56.7–64.5) |
| Borg on exertion | 2.7 (2.4–2.9) |
| Lowest SaO2 on exertion | 87.5 (86.3–88.6) |
Data are presented as n (%) or mean (95% CI). UIP: usual interstitial pneumonia; CT: computed tomography; LTOT: long-term oxygen therapy; BMI: body mass index; FVC: forced vital capacity; FEV1: forced expiratory volume in 1 s; DLCO: diffusing capacity of the lung for carbon monoxide; SaO2: arterial oxygen saturation. #: n=101.