Table 1 Baseline characteristics of patients with acute hypoxemic respiratory failure according to the ROX index
Categories | Overall (N = 1813) | Q1 (N = 454) | Q2 (N = 453) | Q3 (N = 451) | Q4 (N = 455) | P-value |
|---|---|---|---|---|---|---|
ROX index | 8.3 (5. 9, 11.3) | 4.5 (3.7, 5.3) | 7 (6.4, 7.7) | 9.6 (8.9, 10.3) | 13.6 (12.4, 15.6) | < 0.001 |
Age (year) | 67 (55, 77) | 64 (53, 74) | 69 (57, 78) | 67 (56, 78) | 68 (56, 80) | < 0.001 |
Gender | ||||||
Male | 1068 (58.9%) | 266 (58.6%) | 269 (59.4%) | 273 (60.5%) | 260 (57.1%) | 0.768 |
Female | 745 (41.1%) | 188 (41.4%) | 184 (40.6%) | 178 (39.5%) | 195 (42.9%) | |
Race | ||||||
White | 1047 (57.7%) | 253 (55.7%) | 266 (58.7%) | 264 (58.5%) | 264 (58%) | 0.210 |
Black | 166 (9.2%) | 32 (7%) | 47 (10.4%) | 39 (8.6%) | 48 (10.5%) | |
Asian | 56 (3.1%) | 10 (2.2%) | 11 (2.4%) | 21 (4.7%) | 14 (3.1%) | |
Other | 129 (7.1%) | 35 (7.7%) | 31 (6.8%) | 33 (7.3%) | 30 (6.6%) | |
Unknown | 415 (22.9%) | 124 (27.3%) | 98 (21.6%) | 94 (20.8%) | 99 (21.8%) | |
BMI (kg/m2) | 28 (23, 32) | 28 (24, 33) | 29 (24, 33) | 28 (23, 32) | 26 (22, 31) | < 0.001 |
SOFA | 9 (6, 12) | 11 (8, 14) | 9 (6, 12) | 8 (6, 11) | 7 (4, 9) | < 0.001 |
SIRS | 3 (2, 4) | 3 (3, 4) | 3 (2, 4) | 3 (2, 3.5) | 3 (2, 3) | < 0.001 |
SAPS II | 41 (33, 52) | 48 (38, 61) | 43 (34, 53) | 40 (31.5, 50) | 37 (29, 46) | < 0.001 |
Charlson comorbidity index | 6 (4, 8) | 6 (4, 8) | 6 (4, 8) | 7 (4, 9) | 6 (4, 8) | 0.004 |
Vital signs | ||||||
Heart rate (beats/min) | 84.6 (75.3, 98.2) | 89.5 (79.3, 104.6) | 84.3 (74.4, 97.7) | 84.1 (75.2, 98.1) | 80.8 (72.0, 92.0) | < 0.001 |
Respiratory rate (breaths/min) | 19.7 (17.3, 22.9) | 23.1 (20.3, 26.1) | 20.4 (18.0, 23.3) | 19.3 (17.5, 21.2) | 17.2 (15.6, 19.0) | < 0.001 |
MBP (mmHg) | 75.6 (70.5, 81.7) | 74.0 (68.8, 80.0) | 74.7 (70.2, 80.9) | 75.9 (70.8, 81.6) | 77.5 (71.7, 84.1) | < 0.001 |
SpO2 (%) | 97.6 (96.0, 98.8) | 96.2 (94.5, 97.8) | 97.4 (96.1, 98.5) | 97.9 (96.6, 99.0) | 98.4 (97.3, 99.3) | < 0.001 |
PaO2/FiO2 | 114 (74, 198) | 78.8 (55, 118.7) | 115 (77.5, 184) | 122.5 (82.5, 206) | 164 (102.7, 291.3) | < 0.001 |
Comorbidities | ||||||
Myocardial infarct | 454 (25%) | 115 (25.3%) | 115 (25.4%) | 129 (28.6%) | 95 (20.9%) | 0.063 |
Cerebrovascular disease | 325 (17.9%) | 67 (14.8%) | 79 (17.4%) | 80 (17.7%) | 99 (21.8%) | 0.052 |
Congestive heart failure | 689 (38%) | 157 (34.6%) | 197 (43.5%) | 176 (39%) | 159 (34.9%) | 0.018 |
Peripheral vascular disease | 195 (10.8%) | 56 (12.3%) | 54 (11.9%) | 41 (9.1%) | 44 (9.7%) | 0.298 |
Chronic pulmonary disease | 485 (26.8%) | 125 (27.5%) | 127 (28%) | 118 (26.2%) | 115 (25.3%) | 0.775 |
Diabetes | 591 (32.6%) | 131 (28.9%) | 165 (36.4%) | 151 (33.5%) | 144 (31.6%) | 0.100 |
Severe liver disease | 164 (9%) | 52 (11.5%) | 35 (7.7%) | 39 (8.6%) | 38 (8.4%) | 0.211 |
Renal disease | 479 (26.4%) | 108 (23.8%) | 123 (27.2%) | 132 (29.3%) | 116 (25.5%) | 0.281 |
Malignant cancer | 1549 (85.4%) | 67 (14.8%) | 60 (13.2%) | 79 (17.5%) | 58 (12.7%) | 0.171 |
Laboratory tests | ||||||
WBC (K/uL) | 15 (10.7, 20.8) | 17 (11.3, 23.8) | 16 (11.8, 22.2) | 14.6 (11, 20.4) | 13.2 (9.55, 17.15) | < 0.001 |
Platelet (K/uL) | 151 (103, 209) | 146 (88, 198.75) | 153 (101, 212) | 153 (109.5, 214) | 156 (109, 210) | 0.051 |
Albumin (g/dL), mean ± sd | 3.2 ± 0.7 | 3.1 (2.6, 3.6) | 3.2 (2.7, 3.6) | 3.2 (2.6, 3.7) | 3.3 (2.75, 3.7) | 0.014 |
Sodium (mEq/L) | 137 (134, 140) | 137 (133, 139) | 138 (134, 140) | 138 (134, 140) | 138 (135, 140) | 0.005 |
Chloride (mEq/L) | 105 (101, 108) | 105 (101, 108) | 104 (100, 107) | 105 (102, 108) | 105 (101, 108) | 0.208 |
Potassium (mEq/L) | 4.5 (3.9, 5.3) | 4.6 (4, 5.4) | 4.6 (4, 5.4) | 4.5 (3.8, 5.4) | 4.4 (3.8, 5.1) | 0.033 |
Calcium (mEq/L) | 1.06 (0.99, 1.12) | 1.04 (0.96, 1.1) | 1.06 (0.98, 1.12) | 1.06 (1, 1.12) | 1.07 (1.01, 1.12) | < 0.001 |
Glucose (mg/dL) | 136.0 (114.2, 170.3) | 141.4 (116.8, 178.9) | 139 (118, 172.6) | 135.6 (114.3, 170) | 130 (110.1, 158.8) | < 0.001 |
AST (IU/L) | 54 (28, 152) | 71 (35, 251.5) | 59 (31, 150) | 48 (27, 139.5) | 45 (25, 105) | < 0.001 |
ALT (IU/L) | 31 (18, 85) | 38 (20, 116.5) | 37 (19, 90) | 31 (16, 92.5) | 27 (16, 55.5) | < 0.001 |
BUN (mg/dL) | 25 (17, 41) | 28 (19, 48) | 26 (18, 42) | 24 (17, 37) | 22 (14, 33) | < 0.001 |
Creatinine (mg/dL) | 1.3 (0.9, 2.1) | 1.7 (1, 2.5) | 1.3 (0.9, 2.1) | 1.3 (0.9, 2) | 1 (0.8, 1.6) | < 0.001 |
INR | 1.4 (1.2, 1.7) | 1.5 (1.3, 1.9) | 1.4 (1.2, 1.7) | 1.3 (1.2, 1.6) | 1.2 (1.1, 1.5) | < 0.001 |
PT (s) | 14.8 (12.8, 18.6) | 16 (13.6, 21.7) | 15 (13.1, 18.4) | 14.7 (12.9, 17.7) | 13.6 (12.2, 16.2) | < 0.001 |
PTT (s) | 32.8 (28.3, 46.9) | 36.3 (29.7, 55.7) | 33.3 (28.7, 47.1) | 32.4 (28.2, 44.3) | 31 (27.4, 39.9) | < 0.001 |
Ventilation status | ||||||
HFNC | 195 (10.8%) | 78 (17.2%) | 47 (10.4%) | 35 (7.8%) | 35 (7.7%) | < 0.001 |
Invasive Vent | 1579 (87.1%) | 414 (91.2%) | 414 (91.4%) | 390 (86.5%) | 361 (79.3%) | < 0.001 |
Non-Invasive Vent | 116 (6.3%) | 30 (6.6%) | 40 (8.8%) | 24 (5.3%) | 22 (4.8%) | 0.065 |
Supplemental Oxygen | 1326 (73.1%) | 311 (68.5%) | 344 (75.9%) | 331 (73.4%) | 340 (74.7%) | 0.061 |
Tracheostomy | 115 (6.3%) | 32 (7%) | 30 (6.6%) | 24 (5.3%) | 29 (6.4%) | 0.745 |
Outcomes | ||||||
28-day mortality | 513 (28.3%) | 157 (34.6%) | 127 (28%) | 124 (27.5%) | 105 (23.1%) | 0.002 |
3-month mortality | 640 (35.3%) | 195 (43%) | 153 (33.8%) | 156 (34.6%) | 136 (29.9%) | < 0.001 |
6-month mortality | 705 (38.9%) | 205 (45.2%) | 174 (38.4%) | 175 (38.8%) | 151 (33.2%) | 0.003 |
1-year mortality | 775 (42.7%) | 217 (47.8%) | 198 (43.7%) | 185 (41%) | 175 (38.5%) | 0.031 |
In-ICU mortality | 276 (15.2%) | 113 (24.9%) | 69 (15.2%) | 58 (12.9%) | 36 (7.9%) | < 0.001 |
In-hospital mortality | 481 (26.5%) | 160 (35.2%) | 121 (26.7%) | 109 (24.2%) | 91 (20%) | < 0.001 |
Length of hospital stay (d) | 12.7 (6.7, 21.4) | 13.7 (7.7, 22.8) | 12.7 (7.1, 21.4) | 11.7 (6.7, 21.5) | 11.5 (5.8, 20.0) | 0.104 |
Length of ICU stay (d) | 4.9 (2.4, 9.9) | 6.14 (2.8, 12.2) | 5.2 (3.0, 9.9) | 4.8 (2.4, 9.2) | 3.7 (2.0, 8.2) | < 0.001 |