Patients’ characteristics and comorbidities in relation to body mass index (BMI) category
| BMI kg·m−2 | |||||||
| Underweight <18.5 | Low-normal weight 18.5–22.9 | High-normal weight 23.0–24.9 | Overweight 25.0–29.9 | Obese ≥30 | Missing | p-value# | |
| Subjects n | 1781 | 5931 | 2669 | 2399 | 374 | 1629 | |
| Age years | |||||||
| 15–60 | 89 (5.0) | 315 (5.3) | 159 (6.0) | 185 (7.7) | 83 (22.2) | 82 (5.0) | <0.001 |
| 61–70 | 353 (19.8) | 1191 (20.1) | 661 (24.8) | 617 (25.7) | 93 (24.9) | 273 (16.8) | |
| 71–80 | 693 (38.9) | 2475 (41.7) | 1163 (43.6) | 1039 (43.3) | 134 (35.8) | 657 (40.3) | |
| ≥81 | 639 (35.9) | 1913 (32.3) | 676 (25.3) | 550 (22.9) | 46 (12.3) | 608 (37.3) | |
| Missing | 7 (0.4) | 37 (0.6) | 10 (0.4) | 8 (0.3) | 18 (4.8) | 9 (0.6) | |
| Sex | <0.001 | ||||||
| Male | 1028 (57.7) | 4344 (73.2) | 2113 (79.2) | 1791 (74.7) | 223 (59.6) | 1095 (67.2) | |
| Female | 753 (42.3) | 1587 (26.8) | 556 (20.8) | 608 (25.3) | 151 (40.4) | 534 (32.8) | |
| Hugh–Jones dyspnoea class | <0.001 | ||||||
| 1 | 72 (4.0) | 309 (5.2) | 144 (5.4) | 136 (5.7) | 26 (7.0) | 57 (3.5) | |
| 2 | 93 (5.2) | 411 (6.9) | 208 (7.8) | 192 (8.0) | 29 (7.8) | 78 (4.8) | |
| 3 | 120 (6.7) | 466 (7.9) | 231 (8.7) | 208 (8.7) | 30 (8.0) | 82 (5.0) | |
| 4 | 296 (16.6) | 1057 (17.8) | 513 (19.2) | 444 (18.5) | 61 (16.3) | 240 (14.7) | |
| 5 | 701 (39.4) | 2358 (39.8) | 1029 (38.6) | 928 (38.7) | 156 (41.7) | 749 (46.0) | |
| Missing | 499 (28.0) | 1330 (22.4) | 544 (20.4) | 491 (20.5) | 72 (19.3) | 423 (26.0) | |
| Japan Coma Scale score | <0.001 | ||||||
| 0-digit (alert) | 1484 (83.3) | 5208 (87.8) | 2432 (91.1) | 2176 (90.7) | 344 (92.0) | 1329 (81.6) | |
| 1-digit (dull) | 219 (12.3) | 565 (9.5) | 186 (7.0) | 177 (7.4) | 24 (6.4) | 232 (14.2) | |
| 2- or 3-digit (somnolence or coma) | 78 (4.4) | 158 (2.7) | 51 (1.9) | 46 (1.9) | 6 (1.6) | 68 (4.2) | |
| Charlson comorbidity index | <0.001 | ||||||
| 0 | 870 (48.9) | 2962 (49.9) | 1380 (51.7) | 1254 (52.3) | 225 (60.2) | 952 (58.4) | |
| 1 | 235 (13.2) | 788 (13.3) | 358 (13.4) | 342 (14.3) | 52 (13.9) | 204 (12.5) | |
| 2 | 401 (22.5) | 1316 (22.2) | 588 (22.0) | 495 (20.6) | 59 (15.8) | 311 (19.1) | |
| 3–5 | 153 (8.6) | 508 (8.6) | 198 (7.4) | 209 (8.7) | 23 (6.2) | 104 (6.4) | |
| ≥6 | 122 (6.9) | 357 (6.0) | 145 (5.4) | 99 (4.1) | 15 (4.0) | 58 (3.6) | |
| Smoking index pack-years | <0.001 | ||||||
| 0 | 977 (54.9) | 2587 (43.6) | 1062 (39.8) | 934 (38.9) | 163 (43.6) | 705 (43.3) | |
| 1–19 | 105 (5.9) | 425 (7.2) | 196 (7.3) | 156 (6.5) | 23 (6.2) | 101 (6.2) | |
| 20–39 | 201 (11.3) | 764 (12.9) | 346 (13.0) | 351 (14.6) | 49 (13.1) | 150 (9.2) | |
| 40–59 | 182 (10.2) | 830 (14.0) | 422 (15.8) | 354 (14.8) | 42 (11.2) | 163 (10.0) | |
| ≥60 | 134 (7.5) | 648 (10.9) | 351 (13.2) | 343 (14.3) | 44 (11.8) | 145 (8.9) | |
| Missing | 182 (10.2) | 677 (11.4) | 292 (10.9) | 261 (10.9) | 53 (14.2) | 365 (22.4) | |
| Intensive care unit admission | 223 (12.5) | 812 (13.7) | 371 (13.9) | 358 (14.9) | 73 (19.5) | 204 (12.5) | 0.004 |
| Emergency unit admission | 185 (10.4) | 650 (11.0) | 285 (10.7) | 259 (10.8) | 37 (9.9) | 167 (10.3) | 0.943 |
| Academic hospital | 1351 (75.9) | 4728 (79.7) | 2142 (80.3) | 1947 (81.2) | 306 (81.8) | 1395 (85.6) | <0.001 |
| Hospital length of stay days | 25 (14–44) | 25 (14–42) | 24 (14–41) | 24 (14–41) | 25.5 (15–42) | 21 (12–39) | 0.259¶ |
| Lung cancer | 208 (11.7) | 793 (13.4) | 383 (14.3) | 288 (12.0) | 28 (7.5) | 137 (8.4) | <0.001 |
| COPD | 88 (4.9) | 312 (5.3) | 129 (4.8) | 117 (4.9) | 20 (5.3) | 74 (4.5) | 0.863 |
| Chronic heart disease | 196 (11.0) | 617 (10.4) | 245 (9.2) | 280 (11.7) | 40 (10.7) | 186 (11.4) | 0.067 |
| Chronic renal failure | 74 (4.2) | 216 (3.6) | 72 (2.7) | 63 (2.6) | 6 (1.6) | 34 (2.1) | <0.001 |
| Diabetes mellitus | 332 (18.6) | 1421 (24.0) | 725 (27.2) | 697 (29.1) | 147 (39.3) | 370 (22.7) | <0.001 |
| Pneumonia | 128 (7.2) | 378 (6.4) | 191 (7.2) | 144 (6.0) | 31 (8.3) | 123 (7.6) | 0.169 |
| Pulmonary embolism | 9 (0.5) | 30 (0.5) | 16 (0.6) | 12 (0.5) | 1 (0.3) | 6 (0.4) | 0.912 |
| Noradrenaline | 50 (2.8) | 165 (2.8) | 70 (2.6) | 68 (2.8) | 15 (4.0) | 45 (2.8) | 0.799 |
| Azithromycin | 242 (13.6) | 921 (15.5) | 402 (15.1) | 380 (15.8) | 56 (15.0) | 210 (12.9) | 0.049 |
| Sulfamethoxazole trimethoprim | 966 (54.2) | 3620 (61.0) | 1680 (62.9) | 1567 (65.3) | 228 (61.0) | 876 (53.8) | <0.001 |
| Cyclophosphamide (intravenous) | 113 (6.3) | 614 (10.4) | 351 (13.2) | 375 (15.6) | 56 (15.0) | 182 (11.2) | <0.001 |
| Cyclophosphamide (oral) | 25 (1.4) | 93 (1.6) | 43 (1.6) | 42 (1.8) | 6 (1.6) | 16 (1.0) | 0.492 |
| Cyclosporin | 138 (7.7) | 631 (10.6) | 338 (12.7) | 345 (14.4) | 50 (13.4) | 152 (9.3) | <0.001 |
| Tacrolimus | 26 (1.5) | 115 (1.9) | 49 (1.8) | 64 (2.7) | 12 (3.2) | 15 (0.9) | 0.001 |
| Azathioprine | 18 (1.0) | 101 (1.7) | 57 (2.1) | 46 (1.9) | 5 (1.3) | 25 (1.5) | 0.097 |
| Pirfenidone | 68 (3.8) | 265 (4.5) | 111 (4.2) | 152 (6.3) | 23 (6.1) | 59 (3.6) | <0.001 |
| Nintedanib | 21 (1.2) | 97 (1.6) | 53 (2.0) | 47 (2.0) | 10 (2.7) | 11 (0.7) | 0.003 |
| Sivelestat sodium hydrate | 182 (10.2) | 801 (13.5) | 394 (14.8) | 379 (15.8) | 60 (16.0) | 264 (16.2) | <0.001 |
| Thrombomodulin α | 106 (6.0) | 357 (6.0) | 170 (6.4) | 157 (6.5) | 26 (7.0) | 95 (5.8) | 0.868 |
| Mechanical ventilation | 425 (23.9) | 1619 (27.3) | 787 (29.5) | 751 (31.3) | 134 (35.8) | 500 (30.7) | <0.001 |
| Haemodialysis | 31 (1.7) | 82 (1.4) | 28 (1.0) | 28 (1.2) | 3 (0.8) | 19 (1.2) | 0.344 |
| Tracheotomy | 57 (3.2) | 183 (3.1) | 86 (3.2) | 67 (2.8) | 19 (5.1) | 47 (2.9) | 0.299 |
Data are presented as n (%) or median (interquartile range), unless otherwise stated. #: all p-values obtained by Chi-squared test; ¶: Kruskal–Wallis test.