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Table 4 The equilibrium test of training set and testing set

From: Prediction of readmission in patients with acute exacerbation of chronic obstructive pulmonary disease within one year after treatment and discharge

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)   
  1. 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