Table 1 Comparison of participants included versus excluded due to missing data
Characteristic | Overall | Included | Excluded | P value |
|---|---|---|---|---|
(n = 671) | (n = 562) | (n = 109) | ||
Age (yr) | 47.9 (15.2) | 48.0 (15.0) | 47.1 (16.4) | 0.55 |
Female sex | 363 (54.1) | 300 (53.4) | 63 (57.8) | 0.40 |
Ethnicity (n=652, 555, 97) | ||||
White/Caucasian | 378 (58.0) | 327 (58.9) | 51 (52.6) | 0.41 |
Unknown/Mixed/Other | 143 (21.9) | 117 (21.1) | 26 (26.8) | |
Aboriginal | 85 (13.0) | 74 (13.3) | 11 (11.3) | |
Asian | 46 (7.1) | 37 (6.7) | 9 (9.3) | |
Any co-morbidity | 607 (90.5) | 513 (91.3) | 94 (86.2) | 0.10 |
Obesity | 167 (24.9) | 150 (26.7) | 17 (15.6) | 0.01 |
Diabetes mellitus | 170 (25.3) | 146 (26.0) | 24 (22.0) | 0.38 |
Chronic obstructive pulmonary disease | 119 (17.7) | 98 (17.4) | 21 (19.3) | 0.65 |
Alcohol abuse | 83 (12.4) | 74 (13.2) | 9 (8.3) | 0.15 |
Chronic kidney disease | 56 (8.4) | 48 (8.5) | 8 (7.3) | 0.68 |
H1N1 status | ||||
Confirmed | 574 (85.5) | 479 (85.2) | 95 (87.2) | 0.60 |
Probable | 97 (14.5) | 83 (14.8) | 14 (12.8) | |
Days of symptoms pre-hospital (n = 635, 532, 103) | 4.0 (2.0-7.0) | 4.0 (2.0-7.0) | 3.0 (1.0-6.0) | 0.01 |
Days of symptoms pre-ICU (n = 653, 549, 104) | 5.0 (3.0-8.0) | 5.0 (3.0-8.0) | 4.5 (2.5-7.0) | 0.04 |
Day 1 support, physiology, and laboratory values | ||||
APACHE II score (n = 594, 508, 86) | 20.8 (9.8) | 21.1 (9.2) | 19.1 (13.1) | 0.19 |
SOFA score (n = 411, 361, 50) | 11.2 (3.7) | 11.2 (3.8) | 10.9 (3.6) | 0.61 |
Invasive mechanical ventilation (n = 652, 553, 99) | 431 (66.1) | 384 (69.4) | 47 (47.5) | <0.0001 |
Inotrope or vasopressor | 281 (41.9) | 251 (44.7) | 30 (27.5) | 0.0009 |
Mean arterial pressure (mmHg) (n = 613, 522, 91) | 74.1 (18.7) | 74.4 (18.9) | 72.5 (17.4) | 0.37 |
Heart rate (beats/min) (n = 504, 433, 71) | 104.1 (24.0) | 104.5 (24.1) | 101.5 (23.3) | 0.33 |
Temperature (°C) (n = 472, 405, 67) | 37.6 (1.3) | 37.6 (1.2) | 37.5 (1.8) | 0.48 |
PaO2/FiO2 (n = 570, 496, 74) | 160 (120) | 153 (96) | 212 (215) | 0.02 |
CK (U/L) (n = 270, 230, 40) | 272 (91-776) | 293 (91-835) | 224 (87-663) | 0.41 |
CK > 5000 IU/L (n = 270, 230, 40) | 15 (5.6) | 13 (5.7) | 2 (5.0) | 1.00 |
WBC (109/L) (n = 471, 409, 62) | 9.7 (6.5) | 9.5 (6.5) | 10.6 (7.0) | 0.24 |
Albumin (g/L) (n = 315, 275, 40) | 26.6 (7.2) | 26.2 (7.0) | 28.7 (8.0) | 0.04 |
Platelets (109/L) (n = 608, 520, 88) | 190 (96) | 188 (96) | 204 (95) | 0.16 |
Urea (mmol/L) (n = 89, 76, 13) | 10.2 (19.7) | 10.5 (21.0) | 8.4 (9.4) | 0.56 |
Creatinine (μmol/L) (n = 626, 537, 89) | 125 (120) | 124 (120) | 131 (119) | 0.59 |
Urine output (mL/24 hr) (n = 489, 431, 58) | 1440 (1082) | 1439 (1055) | 1446 (1278) | 0.97 |
Interventions (ICU day 1, 3, 7, 14, or 28) | ||||
Renal replacement therapy (n = 670, 561, 109) | 91 (13.6) | 85 (15.2) | 6 (5.5) | 0.007 |
Invasive mechanical ventilation (n = 669, 562, 107) | 568 (84.9) | 499 (88.8) | 69 (64.5) | <0.0001 |
Inotropes or vasopressors | 373 (55.6) | 339 (60.3) | 34 (31.2) | <0.0001 |
Antiviral treatment | 620 (92.4) | 530 (94.3) | 90 (82.6) | <0.0001 |
Outcome | ||||
Days of ICU stay (n = 640, 539, 101) | 11.0 (6.0-19.0) | 11.0 (7.0-20.0) | 5.0 (2.0-13.0) | <0.0001 |
Days of hospital stay (n = 626, 523, 103) | 18.0 (11.0-34.0) | 19.0 (12.0-35.0) | 12.0 (5.0-24.0) | <0.0001 |
Hospital mortality (n = 649, 545, 104) | 142 (21.9) | 113 (20.7) | 29 (27.9) | 0.11 |