Demographic characteristics of study patients
| Underweight (BMI <18.5 kg/m2) | Normal (BMI 18.5–24.9 kg/m2) | Overweight (BMI 25–29.9 kg/m2) | Obese (BMI 30–39.9 kg/m2) | Severely obese (BMI >40 kg/m2) | p-Value | |
| N (% (95% CI)) | 184 (3.7% (3.2 to 4.3)) | 1995 (40.1% (38.8 to 41.5)) | 1781 (35.8% (34.5 to 37.2)) | 792 (15.9%; (14.9 to 16.9)) | 216 (4.3%; (3.8 to 4.9)) | |
| Age, years, mean (SD) | 55 (19) | 57 (19) | 61 (17) | 61 (14) | 55 (14) | <0.001 |
| Body mass index, kg/m2, mean (SD) | 17 (1) | 23 (2) | 27 (1) | 33 (3) | 50 (11) | <0.001 |
| Female, N (% (95% CI)) | 84 (45.6% (38.3 to 51.3)) | 823 (41.2% (39.0 to 43.4)) | 586 (32.9% (30.7 to 35.1)) | 357 (45.0% (41.6 to 48.6)) | 117 (54.1% (47.2 to 60.9)) | <0.001 |
| SAPS II, points, mean (SD) | 43 (19) | 43 (18) | 43 (17) | 44 (17) | 42 (17) | 0.587 |
| Reason for mechanical ventilation, N (% (95% CI)) | ||||||
| Chronic obstructive pulmonary disease | 14 (7.6% (4.2 to 12.4)) | 101 (5.1% (4.1 to 6.1)) | 80 (4.5% (3.6 to 5.5)) | 56 (7.0% (5.4 to 9.1)) | 16 (7.4% (4.3 to 11.7)) | 0.025 |
| Asthma | 2 (1.0% (0.1 to 3.8)) | 23 (1.1% (0.7 to 1.7)) | 20 (1.1% (0.7 to 1.7)) | 13 (1.6% (0.9 to 2.8)) | 5 (2.3% (0.7 to 5.3)) | 0.504 |
| Chronic pulmonary disease | 8 (4.3% (1.9 to 8.4)) | 26 (1.3% (0.8 to 1.9)) | 20 (1.1% (0.7 to 1.7)) | 13 (1.6% (0.9 to 2.8)) | 18 (8.3% (5.0 to 12.8)) | <0.001 |
| Acute respiratory failure | ||||||
| Acute respiratory distress syndrome | 12 (6.5% (3.4 to 11.1)) | 63 (3.1% (2.4 to 4.0)) | 44 (2.5% (1.8 to 3.3)) | 28 (3.5% (2.4 to 5.1)) | 1 (0.5% (0 to 2.5)) | 0.004 |
| Postoperative | 31 (16.8% (11.7 to 23.0)) | 408 (20.4% (18.7 to 22.3)) | 384 (21.6% (19.7 to 23.5)) | 183 (23.1% (20.2 to 26.2)) | 47 (21.7% (16.4 to 27.8)) | 0.324 |
| Congestive heart failure | 5 (2.7% (0.9 to 6.2)) | 112 (5.6% (4.6 to 6.7) | 95 (5.3% (4.4 to 6.5)) | 59 (7.4% (5.7 to 9.5)) | 14 (6.5% (3.6 to 10.6)) | 0.084 |
| Aspiration | 9 (4.9% (2.3 to 9.1)) | 64 (3.2% (2.5 to 4.1)) | 47 (2.6% (1.9 to 3.5)) | 17 (2.1% (1.2 to 3.4)) | 2 (0.9% (0.1 to 3.3)) | 0.079 |
| Community Pneumonia | 23 (12.5% (8.1 to 18.2)) | 168 (8.4% (7.2 to 9.7)) | 125 (7.0% (5.9 to 8.3)) | 47 (5.9% (4.4 to 7.8)) | 13 (6.0% (3.2 to 10.0)) | 0.011 |
| Hospital Pneumonia | 14 (7.6% (4.2 to 12.4)) | 63 (3.1% (2.4 to 4.0)) | 56 (3.1% (2.4 to 4.1)) | 16 (2.0% (1.1 to 3.3)) | 3 (1.4% (0.3 to 4.0)) | 0.001 |
| Sepsis | 11 (5.9% (3.0 to 10.4)) | 177 (8.8% (7.7 to 10.2)) | 161 (9.0 (7.7 to 10.5)) | 70 (8.8% (6.9 to 11.3)) | 30 (13.9% (9.6 to 19.2)) | 0.079 |
| Trauma | 9 (4.9% (2.3 to 9.1)) | 111 (5.5% (4.6 to 6.7)) | 103 (5.8% (4.7 to 6.9)) | 47 (5.9% (4.4 to 7.8)) | 14 (6.5% (3.6 to 10.6)) | 0.959 |
| Cardiac arrest | 11 (5.9% (3.0 to 10.4)) | 91 (4.6% (3.7 to 5.8)) | 89 (4.9% (4.0 to 6.1)) | 39 (4.9% (3.5 to 6.7)) | 9 (4.2% (1.9 to 7.8)) | 0.883 |
| Other | 17 (9.2% (5.5 to 14.4)) | 173 (8.7% (7.5 to 9.9)) | 152 (8.5% (7.3 to 9.9)) | 73 (9.2% (7.3 to 11.4)) | 17 (7.8% (4.6 to 12.3)) | 0.965 |
| Coma | 14 (7.6% (4.2 to 12.4)) | 386 (19.3% (17.6 to 21.1)) | 389 (21.8% (19.9 to 23.8)) | 126 (15.9% (13.4 to 18.6)) | 23 (10.6% (6.9 to 15.5)) | <0.001 |
| Neuromuscular disease | 4 (2.2% (0.6 to 5.5)) | 29 (1.4% (0.9 to 2.1)) | 16 (0.9% (0.5 to 1.4)) | 5 (0.6% (0.2 to 1.5)) | 4 (1.8% (0.5 to 4.7)) | 0.136 |