Table 1 Characteristics and variables used to calculate APPROVE score in each cohort
| Â | Retrospective 2013 cohort | Prospective 2017 cohort | ||||
|---|---|---|---|---|---|---|
Variable | Fitting cohort (N = 34,387) | Validation cohort (N = 34,388) | Total (N = 68,775) | Number (%) missing | Validation cohort (N = 2258) | Number (%) missing |
Qualifying event, yes | 958 (3%) | 1072 (3%) | 2030 (3%) | 0 (0%) | 35 (1.5%) | 0 (0%) |
Demographics | ||||||
 Age | 57.8 ± 19.5 | 58.0 ± 19.5 | 57.9 ± 19.5 | 0 (0%) | 55.9 ± 20.4 | 0 (0%) |
 Body mass index | 29.6 ± 9.0 | 29.6 ± 8.9 | 29.6 ± 9.0 | 12,595 (18%) | 31.3 ± 9.2 | 146 (6.4%) |
 Height (cm) | 165.8 ± 12.8 | 165.6 ± 13.0 | 165.7 ± 12.9 | 11,900 (17%) | 163.4 ± 10.4 | 136 (6.0%) |
 Sex, female | 20,452 (59%) | 20,595 (60%) | 41,047 (60%) | 0 (0%) | 1658 (67%) | 0 (0%) |
 Weight (kg) | 81.6 ± 26.9 | 81.4 ± 26.9 | 81.5 ± 26.9 | 7907 (11%) | 83.4 ± 27.7 | 99 (4.4%) |
Medication use (yes)* | ||||||
 Dobutamine | 24 (0%) | 22 (0%) | 46 (0%) | 0 (0%) | 0 | 0 (0%) |
 Dopamine | 20 (0%) | 20 (0%) | 40 (0%) | 0 (0%) | 0 | 0 (0%) |
 Epinephrine | 6 (0%) | 3 (0%) | 9 (0%) | 0 (0%) | 0 | 0 (0%) |
 Norepinephrine | 165 (0%) | 137 (0%) | 302 (0%) | 0 (0%) | 4 | 0 (0%) |
 Vasopressin | 17 (0%) | 13 (0%) | 30 (0%) | 0 (0%) | 2 | 0 (0%) |
 Oxygen requirement, FiO2 | 0.5 ± 0.2 | 0.5 ± 0.2 | 0.5 ± 0.2 | 0 (0%) | 0.5 ± 0.3 | 0 (0%) |
 RASS | −0.8 ± 1.5 | −0.8 ± 1.5 | −0.8 ± 1.5 | 59,105 (86%) | −0.89 (1.76) | 2245 (99.3%) |
Oxygen devices | Â | Â | Â | 0 (0%) | Â | 0 (0%) |
 Room air (or no device) | 30,677 (89%) | 30,557 (89%) | 61,234 (89%) |  | 1684 (68%) |  |
 Flow/hood/tent/isolette/mask | 76 (0%) | 81 (0%) | 157 (0%) |  | 8 (0%) |  |
 Low-flow nasal cannula | 3409 (10%) | 3535 (10%) | 6944 (10%) |  | 650 (26%) |  |
 High-flow nasal cannula | 7 (0%) | 6 (0%) | 13 (0%) |  | 17 (1%) |  |
 Nonrebreather mask | 66 (0%) | 63 (0%) | 129 (0%) |  | 31 (1%) |  |
 CPAP, AVAPS, or BIPAP | 152 (0%) | 146 (0%) | 298 (0%) |  | 70 (3%) |  |
Vital signs | ||||||
 Systolic blood pressure | 125.9 ± 21.8 | 126.4 ± 21.8 | 126.2 ± 21.8 | 3575 (5%) | 129.0 ± 13.6 | 3 (0%) |
 Diastolic blood pressure | 68.9 ± 14.3 | 68.9 ± 14.3 | 68.9 ± 14.3 | 3612 (5%) | 69.9 ± 13.6 | 3 (0%) |
 Heart rate | 82.7 ± 16.8 | 82.1 ± 16.8 | 82.4 ± 16.8 | 5842 (8%) | 83.3 ± 15.8 | 3 (0%) |
 Respiratory rate | 19.0 ± 3.6 | 18.9 ± 3.4 | 18.9 ± 3.5 | 3876 (6%) | 18.79 ± 3.72 | 2 (0%) |
 Oxygen saturation | 97.8 ± 3.5 | 97.8 ± 3.5 | 97.8 ± 3.5 | 11,424 (17%) | 96.9 ± 6.3 | 85 (4%) |
 Temperature (C) | 36.8 ± 0.6 | 36.8 ± 0.5 | 36.8 ± 0.5 | 3796 (6%) | 36.9 ± 0.5 | 3 (0%) |
Laboratory findings | ||||||
 Arterial PaCO2 (mmHg) | 39.9 ± 10.6 | 39.9 ± 10.4 | 39.9 ± 10.5 | 58,426 (85%) | 45.3 ± 12.8 | 1819 (74%) |
 Arterial PaO2 (mmHg) | 134.0 ± 80.9 | 134.2 ± 81.2 | 134.1 ± 81.1 | 58,430 (85%) | 80.9 ± 60.0 | 1862 (76%) |
 Arterial pH | 7.4 ± 0.1 | 7.4 ± 0.1 | 7.4 ± 0.1 | 58,422 (85%) | 7.4 ± 0.1 | 1819 (74%) |
 Hematocrit (%) | 31.9 ± 6.4 | 32.0 ± 6.4 | 31.9 ± 6.4 | 4273 (6%) | 32.6 ± 6.4 | 81 (3%) |
 Hemoglobin (g/dl) | 10.6 ± 2.2 | 10.6 ± 2.2 | 10.6 ± 2.2 | 4301 (6%) | 10.9 ± 2.1 | 81 (3%) |
 Platelet count (1000/μl) | 227.7 ± 113.1 | 227.6 ± 113.9 | 227.7 ± 113.5 | 4306 (6%) | 237.3 ± 101.9 | 85 (4%) |
 White blood count (1000/μl) | 10.0 ± 7.8 | 10.0 ± 7.8 | 10.0 ± 7.8 | 4305 (6%) | 9.7 ± 4.8 | 85 (4%) |
 Lactate (arterial or venous) (nM/L) | 2.8 ± 3.2 | 2.1 ± 2.0 | 2.5 ± 2.8 | 67,076 (98%) | 2.1 ± 1.3 | 1888 (77%) |
 Serum albumin (g/dl) | 3.4 ± 0.7 | 3.4 ± 0.7 | 3.4 ± 0.7 | 22,145 (32%) | 3.5 ± 0.7 | 1187 (48.3%) |
 Serum bicarbonate (meq/l) | 23.8 ± 4.2 | 23.8 ± 4.2 | 23.8 ± 4.2 | 7058 (10%) | 24.8 ± 4.2 | 254 (10%) |
 Serum calcium (mg/dl) | 8.8 ± 0.8 | 8.8 ± 0.8 | 8.8 ± 0.8 | 12,099 (18%) | 8.8 ± 0.8 | 254 (10%) |
 Serum chloride (meq/l) | 102.1 ± 6.0 | 102.1 ± 6.0 | 102.1 ± 6.0 | 7055 (10%) | 102.1 ± 5.7 | 254 (10%) |
 Serum creatinine (mg/dl) | 1.7 ± 1.9 | 1.7 ± 1.9 | 1.8 ± 1.9 | 6681 (10%) | 1.6 ± 1.9 | 254 (10%) |
 Serum glucose (mg/dl) | 139.2 ± 73.8 | 139.0 ± 74.4 | 139.1 ± 74.1 | 6836 (10%) | 145.0 ± 75.6 | 251 (10%) |
 Serum potassium (meq/l) | 4.1 ± 0.6 | 4.1 ± 0.6 | 4.1 ± 0.6 | 6883 (10%) | 4.3 ± 0.6 | 251 (10%) |
 Serum sodium (meq/l) | 138.1 ± 5.0 | 138.1 ± 5.0 | 138.1 ± 5.0 | 6858 (10%) | 140.5 ± 5.0 | 247 (10%) |
 Serum total bilirubin (mg/dl) | 1.6 ± 3.7 | 1.5 ± 3.5 | 1.5 ± 3.6 | 21,489 (31%) | 1.4 ± 3.5 | 1192 (48%) |
 Anion gap | 15.9 ± 3.4 | 15.9 ± 3.4 | 15.9 ± 3.4 | 14,453 (21%) | 18.08 ± 3.50 | 257 (11.3%) |