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Table 1 Patient characteristics and feature distribution in the respective timeframes

From: Impact of the Covid-19 pandemic on the performance of machine learning algorithms for predicting perioperative mortality

 

pre-pandemic

1st wave

after 1st wave

2nd wave

after 2nd wave

time period

6/2014–3/2020

4/2020–5/2020

6/2020–9/2020

10/2020–5/2021

6/2021–10/2021

number of cases

107,468

2251

6504

12,112

8042

mortality

883 (0.8)

22 (1.0)

61 (0.9)

125 (1.0)

65 (0.8)

age—years

56 [38, 70]

58 [40, 72]

57 [39, 71]

57 [39, 72]

57 [38, 72]

female sex

49,282 (45.9)

1065 (47.3)

2896 (44.5)

5815 (48.0)

3789 (47.1)

BMI missing

34,276 (31.9)

484 (21.5)

1114 (17.1)

2061 (17.0)

1329 (16.5)

BMI – kg/m2

25.2 [22.5, 28.6]

24.9 [22.2, 28.4]

25.4 [22.6, 28.7]

25.3 [22.6, 28.7]

25.3 [22.5, 28.7]

ASA missing

31,407 (29.2)

440 (19.5)

1058 (16.3)

1917 (15.8)

1212 (15.1)

ASA

 1

21,204 (27.9)

415 (22.9)

1392 (25.6)

2498 (24.5)

1637 (24.0)

 2

38,999 (51.3)

889 (49.1)

2667 (49.0)

5021 (49.2)

3417 (50.0)

 3

15,113 (19.9)

474 (26.2)

1317 (24.2)

2561 (25.1)

1700 (24.9)

 4

695 (0.9)

33 (1.8)

70 (1.3)

109 (1.1)

76 (1.1)

 5

50 (0.1)

0

0

6 (0.1)

0

 Mallampati available

42,492 (39.5)

747 (33.2)

1634 (25.1)

2804 (23.2)

1624 (20.2)

Mallampati

 I

27,210 (41.9)

677 (45.0)

2358 (48.4)

4243 (45.6)

2906 (45.3)

 II

28,633 (44.1)

603 (40.1)

1893 (38.9)

3824 (41.1)

2666 (41.5)

 III

7242 (11.1)

177 (11.8)

495 (10.2)

1043 (11.2)

720 (11.2)

 IV

1891 (2.9)

47 (3.1)

124 (2.5)

198 (2.1)

126 (2.0)

 count of preop consults

2 [1, 3]

3 [2, 4.25]

3 [2, 4]

3 [2, 5]

3 [2, 5]

department

 bone&joint

19,153 (17.8)

334 (14.8)

1145 (17.6)

2037 (16.8)

1433 (17.8)

 gyn/obstetric

10,692 (10.0)

293 (13.0)

647 (10.0)

1351 (11.2)

803 (10.0)

 head&neck

25,171 (23.4)

402 (17.9)

1378 (21.2)

2406 (19.9)

1647 (20.5)

 neurosurgery

10,259 (9.6)

315 (14.0)

720 (11.1)

1353 (11.2)

895 (11.1)

 outpatient

9582 (8.9)

201 (8.9)

707 (10.9)

1347 (11.1)

880 (10.9)

 surgery

20,397 (19.0)

421 (18.7)

1104 (17.0)

2087 (17.2)

1382 (17.2)

 urology

12,160 (11.3)

285 (12.7)

801 (12.3)

1530 (12.6)

1002 (12.5)

admission

 from external hospital

2269 (2.1)

54 (2.4)

119 (1.8)

233 (1.9)

142 (1.8)

 child birth

4236 (4.0)

103 (4.6)

258 (4.0)

496 (4.1)

327 (4.1)

 elective case

77,843 (72.6)

1491 (66.8)

4704 (72.5)

8680 (71.9)

5689 (70.9)

 emergency

19,342 (18.0)

509 (22.8)

1190 (18.3)

2306 (19.1)

1543 (19.2)

 new-born

5 (0.0)

0

0

0

0

 other

661 (0.6)

21 (0.9)

61 (0.9)

151 (1.3)

166 (2.1)

 polyclinic

2853 (2.7)

54 (2.4)

154 (2.4)

213 (1.8)

159 (2.0)

 out-of-hour

7810 (7.3)

204 (9.1)

480 (7.4)

887 (7.3)

577 (7.2)

 weekend

4658 (4.3)

115 (5.1)

242 (3.7)

516 (4.3)

323 (4.0)

 PRCs ordered

29,212 (34.3)

849 (41.7)

2163 (36.8)

4023 (36.5)

2292 (31.0)

 if yes: number

4 [2, 4]

4 [2, 4]

4 [2, 4]

4 [2, 4]

2 [2, 4]

 FFPs ordered

22,724 (26.7)

621 (30.5)

1590 (27.0)

2676 (24.2)

1301 (17.6)

 if yes: number

4 [2, 4]

4 [2, 4]

4 [2, 4]

4 [2, 4]

4 [2, 4]

 PCC ordered

441 (0.5)

12 (0.6)

40 (0.7)

91 (0.8)

47 (0.6)

 if yes: number

4 [3, 4]

4 [4, 6]

4 [4, 6]

4 [3, 6]

4 [2, 4]

 CRP missing

49,466 (46.0)

879 (39.0)

2419 (37.2)

4579 (37.8)

2937 (36.5)

 CRP—mg/L

3.0 [1.0, 10.0]

3.0 [1.0, 16.0]

3.0 [1.0, 10.0]

3.0 [1.0, 10.0]

3.0 [1.0, 10.0]

 leukocytes missing

25,031 (23.3)

267 (11.9)

734 (11.3)

1312 (10.8)

758 (9.4)

 leukocytes – 106/µL

7.3 [5.9, 9.1]

7.2 [5.8, 9.2]

7.2 [5.8, 9.0]

7.2 [5.8, 9.1]

7.2 [5.8, 9.1]

 albumin missing

98,097 (91.3)

1976 (87.8)

5804 (89.2)

10,726 (88.6)

7168 (89.1)

 albumin—g/L

44 [39, 46]

43 [38, 47]

44 [39, 47]

43 [37, 46]

43 [38, 46]

 Quick missing

25,443 (23.7)

283 (12.6)

772 (11.9)

1372 (11.3)

794 (9.9)

 Quick value—%

103 [95, 112]

116 [107, 120]

108 [99, 115]

107 [98, 114]

106 [98, 113]

  1. Data are given as numbers (%) or median [interquartile range]. The laboratory values refer to those determined preoperatively
  2. BMI Body-mass-index, ASA American Society of Anaesthesiologists Physical Score, PRCs Packed red cells, FFPs Fresh frozen plasma units, PCCs Platelet concentrates, CRP C-reactive protein