Clinical risk for ARDS and baseline characteristics by BMI categories*
| Baseline characteristics | Underweight (n = 83) | Normal (n = 627) | Overweight (n = 605) | Obese (n = 364) | Severely obese (n = 116) | p Value |
| Clinical risk for ARDS, n (%) | ||||||
| Sepsis syndrome | 29 (35%) | 212 (34%) | 200 (33%) | 112 (31%) | 41 (35%) | 0.8 |
| Pneumonia source | 23 (28%) | 134 (21%) | 110 (18%) | 71 (20%) | 22 (19%) | 0.07 |
| Extrapulmonary source | 6 (7%) | 78 (13%) | 90 (15%) | 41 (11%) | 19 (16%) | |
| Septic shock | 47 (57%) | 310 (49%) | 282 (47%) | 186 (51%) | 61 (53%) | 0.3 |
| Pneumonia source | 32 (39%) | 188 (30%) | 168 (27%) | 85 (23%) | 30 (26%) | 0.003 |
| Extrapulmonary source | 15 (18%) | 122 (19%) | 114 (19%) | 101 (28%) | 31 (27%) | |
| Trauma | 3 (4%) | 41 (7%) | 63 (10%) | 27 (7%) | 8 (7%) | 0.06 |
| Massive transfusion | 4 (5%) | 68 (11%) | 69 (11%) | 46 (13%) | 9 (8%) | 0.2 |
| Aspiration | 7 (8%) | 65 (10%) | 56 (9%) | 33 (9%) | 4 (3%) | 0.2 |
| Direct pulmonary injury | 58 (70%) | 367 (59%) | 342 (57%) | 181 (50%) | 55 (47%) | <0.0001 |
| >1 risk for ARDS | 8 (10%) | 77 (12%) | 75 (12%) | 46 (13%) | 9 (8%) | 0.6 |
| Age (mean (SD)), years | 61 (20) | 63 (18) | 62 (17) | 60 (17) | 54 (14) | <0.0001 |
| Female gender, n (%) | 48 (58%) | 234 (37%) | 184 (30%) | 155 (43%) | 58 (50%) | <0.0001 |
| Caucasians, n (%) | 78 (94%) | 576 (92%) | 557 (92%) | 330 (91%) | 110 (95%) | 0.6 |
| Co-morbid conditions, n (%) | ||||||
| Diabetes | 14 (17%) | 113 (18%) | 144 (24%) | 140 (38%) | 52 (45%) | <0.0001 |
| Chronic liver disease | 3 (4%) | 40 (6%) | 31 (5%) | 17 (5%) | 8 (7%) | 0.6 |
| End-stage renal disease | 4 (5%) | 38 (6%) | 35 (6%) | 27 (7%) | 11 (9%) | 0.5 |
| History of alcohol abuse | 8 (10%) | 81 (13%) | 77 (13%) | 33 (9%) | 9 (8%) | 0.2 |
| Metastatic cancer | 1 (1%) | 26 (4%) | 14 (2%) | 9 (2%) | 3 (3%) | 0.3 |
| Corticosteroid use prior to ICU admission | 5 (6%) | 67 (11%) | 40 (7%) | 35 (10%) | 14 (12%) | 0.07 |
| Severity of illness on ICU admission | ||||||
| APACHE physiology score (mean (SD)) | 59 (18) | 57 (21) | 57 (22) | 57 (20) | 58 (22) | 0.9 |
| APACHE III total score (mean (SD)) | 70 (22) | 70 (23) | 69 (24) | 68 (22) | 67 (25) | 0.07 |
| Highest glucose within 24 h after ICU admission (median 25–75%) | 173 (131–228) | 172 (138–228) | 183 (148–240) | 190 (149–250) | 195 (155–257) | <0.0001 |
| Haematological failure (platelets <80×109/l), n (%) | 13 (16%) | 96 (15%) | 113 (19%) | 49 (13%) | 11 (9%) | 0.06 |
| Systolic BP <90 mm Hg, n (%) | 63 (76%) | 452 (72%) | 420 (69%) | 248 (68%) | 76 (66%) | 0.3 |
| Acute respiratory failure requiring intubation, n (%) | 51 (61%) | 421 (67%) | 442 (73%) | 266 (73%) | 80 (69%) | <0.05 |
| Transfusion of PRBCs, n(%) | 38 (46%) | 337 (54%) | 313 (52%) | 190 (52%) | 57 (49%) | 0.6 |
| ICU mortality, n (%) | 12 (15%) | 93 (15%) | 80 (13%) | 49 (14%) | 21 (18%) | 0.7 |
| Days from ICU admission to fulfilment of ARDS criteria among those who develop ARDS* (mean (SD)) | 0.55 (1.06) | 1.9 (3.0) | 2.5 (4.1) | 2.5 (4.4) | 2.8 (4.1) | 0.01 |
*Only calculated for patients with ARDS in each weight category.
APACHE, Acute Physiology and Chronic Health Evaluation; ARDS, acute respiratory distress syndrome; BP, blood pressure; ICU, intensive care unit; PRBCs, packed red blood cells.