Patient characteristics
| All | ILD group | non-ILD group | p-value | |
| Subjects | 74 | 32 | 42 | |
| Age years | 73.5 (66.0–80.0) | 74.0 (68.5–80.8) | 68.0 (66.5–73.0) | 0.125 |
| Male sex | 40 (83.3%) | 22 (68.8%) | 27 (64.3%) | 0.805 |
| Ever-smokers | 46 (62.2%) | 20 (62.5%) | 26 (61.9%) | 1.000 |
| BMI kg·m−2 | 21.8 (19.5–24.0) | 22.4 (19.1–24.0) | 21.0 (19.8–24.0) | 0.291 |
| Previous use of corticosteroids | 69 (93.2%) | 31 (96.9%) | 38 (90.5%) | 0.381 |
| Previous use of immunosuppressants | 27 (36.5%) | 10 (31.3%) | 17 (40.5%) | 0.471 |
| PCP prophylaxis | 1 (1.4%) | 0 (0.0%) | 1 (2.4%) | 1.000 |
| Underlying diseases | ||||
| IIPs | 9 (12.2%) | 9 (28.1%) | 0 (0.0%) | <0.001 |
| CTD | 24 (32.4%) | 11 (34.4%) | 13 (31.0%) | 0.806 |
| Solid tumour | 20 (27.0%) | 5 (15.6%) | 15 (35.7%) | 0.067 |
| Haematologic malignancy | 8 (10.8%) | 2 (6.3%) | 6 (14.3%) | 0.453 |
| Others | 13 (17.6%) | 5 (15.6%) | 8 (19.0%) | 0.331 |
| Diagnostic procedures of PCP | ||||
| BALF GMS stain | 19 (25.7%) | 11 (34.4%) | 8 (19.0%) | 0.181 |
| BALF PCR | 38 (51.4%) | 15 (46.9%) | 23 (54.8%) | 0.639 |
| Sputum PCR | 23 (31.1%) | 9 (28.1%) | 14 (33.3%) | 0.800 |
| Laboratory findings | ||||
| Lymphocyte count cells per µL | 695.0 (346.0–1067.5) | 648.0 (326.0–980.0) | 695.0 (367.0–1100.0) | 0.688 |
| Albumin mg·dL−1 | 2.7 (2.3–3.1) | 2.6 (2.4–2.9) | 2.8 (2.2–3.4) | 0.271 |
| LDH U·L−1 | 434.0 (295.0–540.5) | 434.0 (298.0–544.0) | 453.0 (293.0–544.0) | 0.819 |
| KL-6# U·mL−1 | 754.0 (476.0–1705.0) | 1170.0 (703.0–2271.8) | 585.5 (411.5–965.8) | 0.001 |
| CRP mg·dL−1 | 6.7 (3.3–11.5) | 4.8 (2.1–10.9) | 6.9 (5.0–14.0) | 0.230 |
| eGFR mL·min−1·1.73 m−2 | 60.2 (42.3–81.5) | 58.0 (43.0–69.9) | 64.7 (41.8–85.1) | 0.285 |
| β-d-glucan pg·mL−1 | 87.0 (66.0–80.0) | 78.4 (28.5–281.8) | 86.7 (46.8–240.0) | 0.382 |
| PaO2/FIO2 ratio | 248.0 (155.8–298.0) | 175.0 (107.0–289.5) | 251.5 (180.0–301.0) | 0.025 |
| BALF findings¶ | ||||
| Neutrophils | 12.2% (4.9–40.5%) | 22.6% (10.6–47.9%) | 6.6% (3.2–38.1%) | 0.012 |
| Lymphocytes | 34.3% (11.3–55.3%) | 30.0% (9.5–48.0%) | 46.0% (8.75–64.9%) | 0.101 |
| Eosinophils | 1.0% (0.0–2.3%) | 0.2% (0.0–2.0%) | 1.0% (0.0–3.0%) | 0.69 |
| Macrophages | 34.0% (18.0–49.0%) | 37.5% (22.3–54.8%) | 33.0% (18.0–49.0%) | 0.312 |
Data are presented as median (interquartile range) unless otherwise stated. ILD: interstitial lung disease; BMI: body mass index; PCP: Pneumocystis pneumonia; IIP: idiopathic interstitial pneumonia; CTD: connective tissue disease; BALF: bronchoalveolar lavage fluid; GMS: Gomori methenamine silver; LDH: lactate dehydrogenase; KL-6: Krebs von den Lungen-6; CRP: C-reactive protein; eGFR: estimated glomerular filtration rate; PaO2: arterial oxygen tension; FIO2: inspiratory oxygen fraction. #: n=69; ¶: n=53. The p-values refer to comparisons between the ILD and non-ILD groups.