Table 4.
The equilibrium test of training set and testing set
| Variable | Description (n = 636) | Training set (n = 445) | Testing set (n = 191) | Statistical magnitude | P |
|---|---|---|---|---|---|
| Gender, n (%) | χ2 = 0.383 | 0.536 | |||
| Male | 425 (66.82) | 294 (66.07) | 131 (68.59) | ||
| Female | 211 (33.18) | 151 (33.93) | 60 (31.41) | ||
| Age, Mean ± SD | 70.82 ± 9.88 | 70.62 ± 9.91 | 71.27 ± 9.80 | t = − 0.757 | 0.449 |
| BMI, Mean ± SD | 23.48 ± 2.95 | 23.42 ± 3.01 | 23.61 ± 2.79 | t = − 0.750 | 0.453 |
| Acute exacerbation in previous 1 year, n (%) | χ2 = 1.740 | 0.187 | |||
| No | 430 (67.61) | 308 (69.21) | 122 (63.87) | ||
| Yes | 206 (32.39) | 137 (30.79) | 69 (36.13) | ||
| Smoking status, n(%) | Z = 0.336 | 0.737 | |||
| Never smoked | 321 (50.47) | 229 (51.46) | 92 (48.17) | ||
| Smoked before | 93 (14.62) | 59 (13.26) | 34 (17.80) | ||
| Smoker at present | 222 (34.91) | 157 (35.28) | 65 (34.03) | ||
| Daily amount of smoking, M (Q1, Q3) | 0.00 (0.00, 15.00) | 0.00 (0.00, 12.00) | 0.00 (0.00, 15.00) | Z = − 0.135 | 0.893 |
| Duration of smoking, M (Q1, Q3) | 0.00 (0.00, 30.00) | 0.00 (0.00, 30.00) | 0.00 (0.00, 30.00) | Z = − 0.243 | 0.808 |
| Number of years of smoking packets, M (Q1, Q3) | 0.00 (0.00, 21.00) | 0.00 (0.00, 25.00) | 0.00 (0.00, 20.00) | Z = − 0.133 | 0.894 |
| LAMA, n(%) | χ2 = 1.067 | 0.302 | |||
| No | 479 (75.31) | 330 (74.16) | 149 (78.01) | ||
| Yes | 157 (24.69) | 115 (25.84) | 42 (21.99) | ||
| SAMA, n(%) | χ2 = 0.861 | 0.353 | |||
| No | 634 (99.69) | 443 (99.55) | 191 (100.00) | ||
| Yes | 2 (0.31) | 2 (0.45) | 0 (0.00) | ||
| LABA, n(%) | χ2 = 0.035 | 0.852 | |||
| No | 413 (64.94) | 290 (65.17) | 123 (64.40) | ||
| Yes | 223 (35.06) | 155 (34.83) | 68 (35.60) | ||
| SABA, n(%) | χ2 = 0.189 | 0.664 | |||
| No | 555 (87.26) | 390 (87.64) | 165 (86.39) | ||
| Yes | 81 (12.74) | 55 (12.36) | 26 (13.61) | ||
| PDE4I, n(%) | χ2 = 0.129 | 0.720 | |||
| No | 617 (97.01) | 431 (96.85) | 186 (97.38) | ||
| Yes | 19 (2.99) | 14 (3.15) | 5 (2.62) | ||
| ICS, n(%) | χ2 = 0.101 | 0.751 | |||
| No | 422 (66.35) | 297 (66.74) | 125 (65.45) | ||
| Yes | 214 (33.65) | 148 (33.26) | 66 (34.55) | ||
| Congestive heart-failure, n (%) | χ2 = 0.004 | 0.950 | |||
| No | 572 (89.94) | 400 (89.89) | 172 (90.05) | ||
| Yes | 64 (10.06) | 45 (10.11) | 19 (9.95) | ||
| Diabetes, n (%) | χ2 = 2.515 | 0.113 | |||
| No | 498 (78.30) | 356 (80.00) | 142 (74.35) | ||
| Yes | 138 (21.70) | 89 (20.00) | 49 (25.65) | ||
| Hypertension, n (%) | χ2 = 0.507 | 0.476 | |||
| No | 280 (44.03) | 200 (44.94) | 80 (41.88) | ||
| Yes | 356 (55.97) | 245 (55.06) | 111 (58.12) | ||
| Atrial fibrillation, n (%) | χ2 = 0.124 | 0.725 | |||
| No | 596 (93.71) | 418 (93.93) | 178 (93.19) | ||
| Yes | 40 (6.29) | 27 (6.07) | 13 (6.81) | ||
| Combined with other diseases, n (%) | χ2 = 1.130 | 0.288 | |||
| No | 432 (67.92) | 308 (69.21) | 124 (64.92) | ||
| Yes | 204 (32.08) | 137 (30.79) | 67 (35.08) | ||
| Systolic blood pressure, Mean ± SD | 133.46 ± 17.34 | 132.66 ± 16.44 | 135.31 ± 19.16 | t = − 1.665 | 0.097 |
| Diastolic blood pressure, Mean ± SD | 78.73 ± 10.82 | 78.21 ± 10.42 | 79.95 ± 11.62 | t = − 1.859 | 0.063 |
| Respiratory rate, Mean ± SD | 19.28 ± 2.53 | 19.17 ± 2.41 | 19.52 ± 2.77 | t = − 1.604 | 0.109 |
| Temperature, Mean ± SD | 36.86 ± 0.56 | 36.85 ± 0.54 | 36.90 ± 0.60 | t = − 1.055 | 0.292 |
| Heart rate, Mean ± SD | 81.65 ± 11.35 | 81.40 ± 11.24 | 82.24 ± 11.60 | t = − 0.860 | 0.390 |
| Hb, Mean ± SD | 132.51 ± 17.26 | 132.36 ± 17.41 | 132.85 ± 16.88 | t = − 0.328 | 0.743 |
| RBC, Mean ± SD | 4.33 ± 0.55 | 4.32 ± 0.55 | 4.35 ± 0.54 | t = − 0.654 | 0.514 |
| WBC, M (Q1, Q3) | 6.90 (5.53, 8.93) | 6.85 (5.53, 8.68) | 7.18 (5.50, 9.64) | Z = 1.141 | 0.254 |
| PLT, M (Q1, Q3) | 188.50 (151.75, 235.00) | 189.00 (155.00, 234.00) | 187.00 (144.50, 239.00) | Z = − 0.845 | 0.398 |
| NEUT, M (Q1, Q3) | 4.68 (3.53, 6.65) | 4.54 (3.52, 6.41) | 5.13 (3.54, 7.11) | Z = 1.663 | 0.096 |
| Percentage of neutrophils, Mean ± SD | 70.54 ± 11.65 | 69.96 ± 11.43 | 71.90 ± 12.03 | t = − 1.926 | 0.055 |
| LYM, M (Q1, Q3) | 1.29 (0.91, 1.80) | 1.28 (0.93, 1.80) | 1.31 (0.85, 1.79) | Z = − 0.681 | 0.496 |
| Percentage of lymphocytes, M (Q1, Q3) | 19.42 (12.47, 27.13) | 19.60 (12.80, 27.50) | 18.90 (11.25, 26.30) | Z = − 1.593 | 0.111 |
| MONO, M (Q1, Q3) | 0.44 (0.33, 0.60) | 0.44 (0.34, 0.60) | 0.44 (0.33, 0.61) | Z = − 0.826 | 0.409 |
| Percentage of monocytes, M (Q1, Q3) | 6.30 (4.90, 8.00) | 6.40 (5.00, 8.20) | 6.10 (4.80, 7.80) | Z = − 1.907 | 0.057 |
| EOS, M (Q1, Q3) | 0.10 (0.03, 0.19) | 0.10 (0.03, 0.19) | 0.08 (0.03, 0.16) | Z = − 0.577 | 0.564 |
| Percentage of eosinophils, M(Q1, Q3) | 1.46 (0.40, 2.90) | 1.50 (0.40, 3.00) | 1.40 (0.40, 2.55) | Z = − 0.830 | 0.406 |
| RDW, Mean ± SD | 13.20 ± 1.05 | 13.20 ± 1.04 | 13.20 ± 1.06 | t = 0.053 | 0.957 |
| ALT, M (Q1, Q3) | 15.50 (11.00, 23.00) | 15.40 (11.00, 23.00) | 15.60 (10.00, 23.35) | Z = − 0.244 | 0.807 |
| AST, M (Q1, Q3) | 18.00 (14.00, 23.10) | 18.00 (14.30, 23.70) | 17.30 (13.25, 22.20) | Z = − 1.658 | 0.097 |
| TBIL, M (Q1, Q3) | 9.35 (6.70, 13.30) | 9.60 (6.80, 13.40) | 9.00 (6.60, 12.45) | Z = − 0.492 | 0.623 |
| ALB, Mean ± SD | 39.89 ± 4.67 | 39.95 ± 4.78 | 39.74 ± 4.38 | t = 0.521 | 0.602 |
| BUN, M (Q1, Q3) | 5.44 (4.45, 6.68) | 5.47 (4.43, 6.77) | 5.36 (4.51, 6.64) | Z = − 0.221 | 0.825 |
| Cr, M (Q1, Q3) | 76.20 (64.40, 93.75) | 75.80 (64.00, 92.50) | 78.70 (65.20, 93.95) | Z = 1.035 | 0.301 |
| Uric acid, M (Q1, Q3) | 288.50 (226.00, 352.00) | 289.00 (232.00, 355.00) | 287.00 (215.50, 347.00) | Z = − 0.829 | 0.407 |
| Hypersensitive C-reactive protein, M (Q1, Q3) | 8.40 (2.00, 36.67) | 8.00 (2.20, 34.40) | 9.30 (1.75, 43.15) | Z = 0.697 | 0.486 |
| mMRC grade, n (%) | Z = 1.634 | 0.102 | |||
| 0 | 1 (0.16) | 0 (0.00) | 1 (0.52) | ||
| 1 | 138 (21.70) | 103 (23.15) | 35 (18.32) | ||
| 2 | 279 (43.87) | 196 (44.04) | 83 (43.46) | ||
| 3 | 189 (29.72) | 131 (29.44) | 58 (30.37) | ||
| 4 | 29 (4.56) | 15 (3.37) | 14 (7.33) | ||
| CAT score, Mean ± SD | 20.28 ± 5.34 | 20.16 ± 5.19 | 20.58 ± 5.67 | t = − 0.917 | 0.360 |
| FEV1, M (Q1, Q3) | 1.60 (1.10, 2.21) | 1.60 (1.09, 2.21) | 1.64 (1.12, 2.20) | Z = 0.081 | 0.936 |
| FVC, M (Q1, Q3) | 2.26 (1.66, 3.64) | 2.23 (1.65, 3.60) | 2.30 (1.67, 3.67) | Z = 0.381 | 0.704 |
| FEV1/FVC, Mean ± SD | 67.25 ± 13.27 | 67.23 ± 13.17 | 67.30 ± 13.50 | t = − 0.060 | 0.952 |
| FEV1 in predicted value FEV1, Mean ± SD | 55.33 ± 17.82 | 55.81 ± 17.73 | 54.19 ± 17.97 | t = 1.048 | 0.295 |
| Use of systemic glucocorticoid, n (%) | χ2 = 2.348 | 0.126 | |||
| No | 472 (74.21) | 338 (75.96) | 134 (70.16) | ||
| Yes | 164 (25.79) | 107 (24.04) | 57 (29.84) | ||
| Antibacterial agents, n (%) | χ2 = 1.642 | 0.200 | |||
| No | 13 (2.04) | 7 (1.57) | 6 (3.14) | ||
| Yes | 623 (97.96) | 438 (98.43) | 185 (96.86) | ||
| Oxygen therapy, n (%) | χ2 = 0.220 | 0.639 | |||
| No | 126 (19.81) | 86 (19.33) | 40 (20.94) | ||
| Yes | 510 (80.19) | 359 (80.67) | 151 (79.06) | ||
| Mechanical ventilation, n (%) | χ2 = 0.098 | 0.755 | |||
| No | 628 (98.74) | 439 (98.65) | 189 (98.95) | ||
| Noninvasive ventilation | 8 (1.26) | 6 (1.35) | 2 (1.05) | ||
| Group, n (%) | χ2 = 1.687 | 0.194 | |||
| Non-readmission group | 449 (70.60) | 321 (72.13) | 128 (67.02) | ||
| Readmission group | 187 (29.40) | 124 (27.87) | 63 (32.98) |
LAMA long-acting muscarinic antagonist, LABA long-acting β agonist, SAMA short-acting muscarinic antagonist, SABA short-acting β agonist, PDE4I phosphodiesterase 4 inhibitor, ICS inhaled corticosteroids, Hb hemoglobin, RBC red blood cells, WBC white blood cells, PLT platelets, NEUT neutrophil count, LYM lymphocyte count, MONO monocytes count, EOS eosinophil count, RDW red blood cell distribution width, ALT glutamic-pyruvic transaminase, AST glutamic oxalacetic transaminase, TBIL total bilirubin, ALB albumin, BUN blood urea nitrogen, Cr creatinine, mMRC modified Medical Research Council, CAT COPD assessment test, FEV1 forced expiratory volume in 1 s, FVC forced vital capacity