Baseline characteristics between cases of acute respiratory distress syndrome(ARDS), controls, survivors and nonsurvivors
| Controls | Cases | p-value | Survivors | Nonsurvivors | p-value | |
| Subjects | 441 | 212 | 114 | 98 | ||
| Females | 179 (41) | 101 (48) | 0.09 | 50 (44) | 51 (52) | 0.3 |
| Age yrs | 69 (18–94) | 65 (18–97) | 0.05 | 51 (18–89) | 73 (22–97) | <0.001 |
| APACHE III# | 64 (14–130) | 68 (8–136) | 0.07 | 69 (8–115) | 88 (40–150) | <0.001 |
| Diabetes¶ | 116 (26) | 34 (16) | 0.004 | 20 (18) | 14 (14) | 0.6 |
| History of alcohol abuse | 42 (10) | 27 (13) | 0.2 | 10 (9) | 17 (17) | 0.07 |
| Tobacco abuse+ | 217 (49) | 105 (50) | 0.4 | 57 (50) | 48 (49) | 0.7 |
| Chronic liver disease¶ | 18 (4) | 12 (6) | 0.2 | 4 (4) | 8 (8) | 0.2 |
| End stage renal disease | 23 (5) | 6 (3) | 0.7 | 2 (2) | 4 (4) | 0.4 |
| History of steroid use | 37 (8) | 20 (9) | 0.7 | 6 (5) | 14 (14) | 0.03 |
| Transfusion of PRBC | 218 (49) | 133 (63) | 0.001 | 64 (56) | 69 (70) | 0.03 |
| Number of PRBC transfused | 0 (0–74) | 2 (0–63) | 0.005 | 1 (0–31) | 2 (0–63) | 0.01 |
| Systolic BP <90 mmHg | 304 (69) | 163 (77) | 0.04 | 85 (75) | 78 (80) | 0.4 |
| Creatinine >2.0 mg·L−1 | 149 (34) | 65 (31) | 0.5 | 28 (25) | 37 (38) | 0.05 |
| Bilirubin >2.0 mg·dL−1 | 52 (12) | 39 (18) | 0.03 | 14 (12) | 24 (24) | 0.03 |
| Haematological failure platelets ≤80000·mm−3 | 60 (14) | 47 (22) | 0.007 | 20 (18) | 27 (28) | 0.1 |
Data are presented as n, n (%) or median (range), unless otherwise stated. APACHE: Acute Physiology, Age and Chronic Health Evaluation; PRBC: packed red blood cells; BP: blood pressure. #:for development of ARDS, APACHE III physiology score for cases and controls were calculated without the arterial oxygen tension/inspiratory oxygen fraction component. For survivors and nonsurvivors in ARDS, the APACHE III physiology score was calculated with all components; ¶: chronic health information was missing on one case and two controls; +: tobacco history was missing in 56 (26%) cases and 97 (22%) controls.