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Table 1 Demographics among the derivation, internal-validation, and external-validation cohorts

From: Early prediction of noninvasive ventilation failure in COPD patients: derivation, internal validation, and external validation of a simple risk score

 Derivation cohort
N = 500
Internal-validation cohort
N = 323
External-validation cohort
N = 395
p
Age, years71.9 ± 10.172.2 ± 10.173.1 ± 9.70.16
Male371 (74.2%)255 (78.9%)266 (67.3%)< 0.01*
APACHE II score17.1 ± 4.917.2 ± 5.013.5 ± 5.2< 0.01*
Underlying disease
 Diabetes mellitus92 (18.4%)53 (16.4%)26 (6.6%)< 0.01*
 Hypertension190 (38.0%)126 (39.0%)119 (30.1%)0.02*
 Chronic heart disease139 (27.8%)84 (26.0%)131 (33.2%)0.08
 Chronic kidney disease47 (9.4%)22 (6.8%)13 (3.4%)< 0.01*
 Chronic liver disease35 (7.0%)31 (9.6%)1 (0.3%)< 0.01*
Data collected before NIV
 Respiratory rate, breaths/min28 ± 629 ± 624 ± 4< 0.01*
 Heart rate, beats/min109 ± 21110 ± 21103 ± 22< 0.01*
 Systolic blood pressure, mmHg139 ± 27141 ± 25134 ± 24< 0.01*
 Diastolic blood pressure, mmHg81 ± 1683 ± 1777 ± 15< 0.01*
 pH7.26 ± 0.077.27 ± 0.067.25 ± 0.080.02*
 PaCO2, mmHg82 ± 1881 ± 1779 ± 190.14
 PaO2/FiO2, mmHg197 ± 94208 ± 108217 ± 1120.02*
 GCS14.4 ± 1.514.4 ± 1.514.0 ± 2.4< 0.01*
Data collected at 1–2 h of NIV
 Respiratory rate, breaths/min23 ± 524 ± 522 ± 4< 0.01*
 Heart rate, beats/min100 ± 21100 ± 2096 ± 210.01*
 Systolic blood pressure, mmHg126 ± 23128 ± 20125 ± 200.26
 Diastolic blood pressure, mmHg73 ± 1474 ± 1372 ± 120.47
 Minute ventilation, L/min7.9 ± 3.28.0 ± 3.48.4 ± 2.90.03*
 IPAP, cmH2O17 ± 417 ± 417 ± 40.44
 EPAP, cmH2O6 ± 26 ± 25 ± 1< 0.01*
 pH7.33 ± 0.087.33 ± 0.087.31 ± 0.080.01*
 PaCO2, mmHg72 ± 1872 ± 1872 ± 190.81
 PaO2/FiO2, mmHg220 ± 89222 ± 84201 ± 81< 0.01*
 GCS14.5 ± 1.514.5 ± 1.414.2 ± 2.10.04*
Outcomes
 NIV failure94 (18.8%)61 (18.9%)35 (8.9%)< 0.01*
 Early NIV failure64 (12.8%)33 (10.2%)18 (4.6%)< 0.01*
 Late NIV failure30 (6.0%)28 (8.7%)17 (4.3%)0.05
 ICU mortality57 (11.4%)39 (12.1%)15 (3.8%)< 0.01*
 Hospital mortality66 (13.2%)47 (14.6%)23 (5.8%)< 0.01*
  1. GCS Glasgow coma scale, NIV noninvasive ventilation, IPAP inspiratory positive airway pressure, EPAP expiratory positive airway pressure, ICU intensive care unit
  2. *p < 0.05 between three groups