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Table 1 Baseline characteristics of normoxemic patients with AHF between the two groups before matching

From: Is oxygen therapy beneficial for normoxemic patients with acute heart failure? A propensity score matched study

Characteristicsa Total
(n = 2922)
Ambient Air
(n = 1692)
Oxygen Therapy
(n = 1230)
P value SMD
Demographics
 Age (years) 72 (61–82) 72 (61–82) 72 (60–82) 0.316 0.047
 Gender [male, n (%)] 1586 (54.3) 915 (54.1) 671 (54.6) 0.799 0.010
 BMI (kg/m2) 28.7 (24.2–34.5) 28.6 (24.3–34.4) 28.8 (24.2–34.7) 0.716 0.004
de novo AHF [n (%)] 1155 (39.5) 659 (38.9) 496 (40.3) 0.452 0.028
Comorbidities on admission [n (%)]
 Sepsis 306 (10.5) 183 (10.8) 123 (10.0) 0.477 0.027
 AKI 65 (2.2%) 45 (2.7%) 20 (1.6%) 0.061 0.071
History of disease [n (%)]
 AF 668 (22.9) 381 (22.5) 287 (23.3) 0.604 0.019
 CAD
  MI 561 (19.2) 331 (19.6) 230 (18.7) 0.559 0.022
  PCI 335 (11.5) 200 (11.8) 135 (11.0) 0.479 0.027
  CABG 344 (11.8) 194 (11.5) 150 (12.2) 0.546 0.023
 Hypertension 1869 (64.0) 1041 (61.5) 828 (67.3) 0.001 0.121
 Stroke 301 (10.3) 178 (10.5) 123 (10.0) 0.648 0.017
 DM 1145 (39.2) 656 (38.8) 489 (39.8) 0.590 0.020
 CKD 775 (26.5) 451 (26.7) 324 (26.3) 0.850 0.007
 Hyperthyroidism 346 (11.8) 190 (11.2) 156 (12.7) 0.230 0.045
Vital signs at presentation
 SBP (mmHg) 121.0 (120.0–127.0) 121.0 (120.0–127.0) 121.0 (120.0–127.0) 0.467 0.021
 HR (beats/min) 86.0 (73.0–101.0) 86.0 (73.0–101.0) 87.0 (74.0–101.0) 0.179 0.043
 SpO2 (%) 97.0 (95.0–99.0) 97.0 (95.0–99.0) 97.0 (95.0–99.0) 0.946 0.013
Laboratory findings and blood gas analysis
 Albumin (mg/dL) 3.1 (2.7–3.5) 3.1 (2.7–3.5) 3.1 (2.7–3.5) 0.941 0.007
 Creatinine (μmol/L) 1.3 (0.9–2.2) 1.310 (0.9–2.2) 1.3 (0.9–2.1) 0.195 0.062
 Glucose (mg/dL) 109.0 (91.0–138.0) 109.0 (91.0–137.3) 110.0 (91.0–139.0) 0.420 0.010
 BUN (mg/dL) 27.0 (18.0–44.0) 27.0 (18.0–44.0) 27.0 (18.0–43.0) 0.957 0.038
 Hematocrit (%) 32.1 (6.9) 31.9 (6.9) 32.3 (6.9) 0.110 0.060
 Hemoglobin (g/dL) 10.5 (8.8–12.1) 10.5 (8.8–12.0) 10.5 (8.9–12.2) 0.137 0.062
 Platelet (109/L) 183.5 (136.0–241.0) 180.0 (134.0–238.0) 186.8 (138.0–244.0) 0.072 0.101
 WBC (109/L) 8.5 (6.3–11.6) 8.4 (6.3–11.4) 8.6 (6.4–11.8) 0.224 0.011
 Potassium (mmol/L) 3.9 (3.5–4.3) 3.9 (3.5–4.3) 3.9 (3.5–4.3) 0.784 0.018
 Sodium (mmol/L) 136.0 (133.0–139.0) 137.0 (134.0–140.0) 135.0 (132.0–138.0) 0.002 0.125
Scoring system
 OASIS 19.0 (14.0–25.0) 20.0 (15.0–26.0) 19.0 (12.0–25.0) <  0.001 0.214
 SOFA 4.0 (2.0–6.0) 4.0 (2.0–6.0) 4.0 (2.0–6.0) 0.248 0.053
 GCS 15.0 (15.0–15.0) 15.0 (15.0–15.0) 15.0 (15.0–15.0) 0.665 0.008
Management of AHF [n (%)]
 Intra-aortic balloon pump 41 (1.4) 23 (1.4) 18 (1.5) 0.813 0.009
 RRT 149 (5.1) 102 (6.0) 47 (3.8) 0.007 0.102
 In-hospital medication
  Inotrope 465 (15.9) 242 (14.3) 223 (18.1) 0.001 0.158
  Diuretic 2221 (76.0) 1259 (74.4) 962 (78.2) <  0.001 0.150
  ACEI/ARB 1730 (59.2) 958 (56.6) 772 (62.8) <  0.001 0.214
  CCB 171 (5.9) 82 (4.8) 89 (7.2) 0.007 0.100
  Beta-blocker 1495 (51.2) 690 (40.8) 805 (65.4) <  0.001 0.371
Oxygen therapy
 Duration of oxygen therapy (days) / / 2.5 (1.6–4.1) / /
 Median SpO2 during treatment period (%) 97.9 (96.5–98.8) 97.1 (95.5–97.8) 98.7 (97.4–99.8) <  0.001 /
  1. aValues are n (%) or median (interquartile range). SMD standardized mean difference, BMI body mass index, AHF acute heart failure, AKI acute kidney injury, AF atrial fibrillation, CAD coronary artery disease, MI myocardial infarction, PCI percutaneous coronary intervention, CABG coronary artery bypass grafting, DM diabetes mellitus, CKD chronic kidney disease, SBP systolic blood pressure, HR heart rate, SpO2 pulse oximetry-derived oxygen saturation, BUN blood urea nitrogen, WBC white blood cell, OASIS oxford acute severity of illness score, SOFA sequential organ failure assessment score, GCS glasgow coma scale, RRT renal replacement treatment, ACEI/ARB angiotensin-converting-enzyme inhibitors/angiotensin receptor blockers, CCB calcium channel blocker