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