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Table 1 Characteristics and variables used to calculate APPROVE score in each cohort

From: Multicenter derivation and validation of an early warning score for acute respiratory failure or death in the hospital

  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     0 (0%)   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%)
  1. Data presented as counts and percentages or mean ± standard deviation
  2. APPROVE Accurate Prediction of Prolonged Ventilation, AVAPS average volume assured pressure support, BIPAP bilevel positive airway pressure, CPAP continuous positive airway pressure, FiO2 fraction of inspired oxygen, PaCO2 partial pressure of carbon dioxide, PaO2 partial pressure of oxygen, RASS Richmond Agitation-Sedation Scale
  3. *Any use of indicated medication at selected time point