Table 1 Differences in procedure volumes and mortality between study periods (1-year pre/post COVID-19 outbreak in March 2020) and COVID-19 prevalence combined across primary and secondary surgical procedures

Digestive surgical procedure groups (2 + 4); N = 176,783 patients

 Surgery on the esophagus (5–42)

3,326

3,071

-255 (-7.7)

.001

168 (5.1)

186 (6.1)

1.21 [0.98, 1.50]

.089

1,938 (58.3)

1,642 (52.9)

-314 (-16.2)

 < .001

 Surgery on the stomach (5–43, 5–44)

9,596

8,916

-680 (-7.1)

 < .001

662 (6.9)

621 (7.0)

1.01 [0.90, 1.13]

.882

5,517 (53.3)

4,516 (50.7)

-601 (-11.7)

 < .001

 Surgery on small intestine and colon (5–45, 5–46)

45,696

38,516

-7,180 (-15.7)

 < .001

1,944 (4.3)

1,782 (4.6)

1.09 [1.02, 1.17]

.009

27,127 (59.4)

21,259 (55.2)

-5,868 (-21.6)

 < .001

 Surgery on appendix (5–47)

8,067

7,471

-596 (-7.4)

 < .001

58 (0.7)

79 (1.1)

1.48 [1.05, 2.07]

.030

2,527 (31.3)

2,230 (29.8)

-297 (-11.8)

 < .001

 Surgery on rectum (5–48)

4,330

3,697

-633 (-14.6)

 < .001

122 (2.8)

116 (3.1)

1.12 [0.86, 1.45]

.437

3.039 (70.2)

2,420 (65.5)

-619 (-20.4)

 < .001

 Surgery on the anus (5–49)

6,393

4,847

-1,546 (-24.2)

 < .001

20 (0.3)

19 (0.4)

1.25 [0.67, 2.35]

.586

3,890 (60.8)

2,820 (58.2)

-1,070 (-27.5)

 < .001

 Surgery on the liver (5–50)

1,389

1,284

-105 (-7.6)

.042

97 (7.0)

86 (6.7)

0.96 [0.71, 1.29]

.829

955 (68.8)

862 (67.1)

-93 (-9.7)

.029

 Surgery on the gallbladder and bile ducts (5–51)

21,112

18,458

-2,654 (-12.6)

 < .001

538 (2.5)

504 (2.7)

1.07 [0.95, 1.21]

.272

11,928 (56.5)

9,586 (51.9)

-2,342 (-19.6)

 < .001

 Surgery on the pancreas (5–52)

1,559

1,560

1 (0.1)

.986

117 (7.5)

87 (5.6)

0.73 [0.55, 0.97]

.035

925 (59.3)

928 (59.5)

3 (0.3)

.944

 Closure of abdominal hernias (5–53)

18,702

14,227

-4475 (-23.9)

 < .001

144 (0.8)

148 (1.0)

1.35 [1.08, 1.71]

.011

15,052 (80.5)

11,024 (77.5)

-4,028 (-26.8)

 < .001

 Other surgery in the abdominal region (5–54)

9,568

8,535

-1,033 (-10.8)

 < .001

927 (9.7)

838 (9.8)

1.01 [0.92, 1.12]

.788

5,375 (56.2)

4,548 (53.3)

-827 (-15.4)

 < .001

Selected surgical procedures (3 + 5); N = 48,684 patients

 Thyroidectomy

3,315

2,313

-1,002 (-30.2)

 < .001

6 (0.2)

8 (0.3)

1.91 [0.66, 5.52]

.342

3,057 (92.2)

2,116 (91.5)

-941 (-30.8)

 < .001

 Appendectomy

6,976

6,424

-552 (-7.9)

 < .001

15 (0.2)

17 (0.3)

1.23 [0.61, 2.47]

.006

1,881 (27.0)

1,632 (25.4)

-249 (-13.2)

 < .001

 Cholecystectomy

12,712

10,754

-1,958 (-15.4)

 < .001

143 (1.1)

160 (1.5)

1.33 [1.06, 1.67]

.017

7,444 (58.6)

5,624 (52.3)

-1,820 (-24.4)

 < .001

 Colon resection for cancer

2,161

1,966

-195 (-9.0)

.002

117 (5.4)

87 (4.4)

0.81 [0.61, 1.08]

.164

1,397 (64.6)

1,290 (65.6)

-107 (-7.7)

.309

 Rectum resection for cancer

1,123

1,080

-43 (-3.8)

.360

30 (2.7)

34 (3.1)

1.18 [0.72, 1.95]

.509

872 (77.6)

848 (78.5)

-24 (-2.8)

.563

Digestive surgical procedure groups (2 + 4); N = 176,783 patients

 Surgery on the esophagus (5–42)

48 (2.5)

44 (2.7)

1.10 [0.72, 1.66]

.742

1,388 (41.7)

1,447 (47.1)

59 (4.3)

.268

120 (8.6)

142 (9.8)

1.15 [0.89, 1.48]

.313

30 (1.0)

6 (20.0)

 Surgery on the stomach (5–43, 5–44)

209 (4.1)

178 (3.9)

0.96 [0.79, 1.18]

.761

4,479 (46.7)

4,400 (49.3)

-79 (-1.8)

.402

453 (10.1)

443 (10.1)

0.99 [0.87, 1.14]

.971

138 (1.5)

36 (26.1)

 Surgery on small intestine and colon (5–45, 5–46)

668 (2.5)

541 (2.5)

1.03 [0.92, 1.16]

.585

18,569 (40.6)

17,248 (44.8)

-1,321 (-7.1)

 < .001

1,276 (6.9)

1,241 (7.2)

1.05 [0.97, 1.14]

.240

264 (0.7)

77 (29.2)

 Surgery on appendix (5–47)

25 (1.0)

27 (1.2)

1.23 [0.71, 2.12]

.553

5,540 (68.7)

5,241 (70.2)

-299 (-5.4)

.004

33 (0.6)

52 (1.0)

1.67 [1.08, 2.59]

.027

37 (0.5)

1 (2.7)

 Surgery on rectum (5–48)

47 (1.5)

41 (1.7)

1.10 [0.72, 1.67]

.747

1,291 (29.8)

1,277 (34.5)

-14 (-1.1)

.782

75 (5.8)

75 (5.9)

1.01 [0.73, 1.41]

 > .999

24 (0.6)

4 (16.7)

 Surgery on the anus (5–49)

5 (0.1)

6 (0.2)

1.66 [0.51, 5.43]

.592

2,503 (39.2)

2,027 (41.8)

-476 (-19.0)

 < .001

15 (0.6)

13 (0.6)

1.07 [0.51, 2.26]

 > .999

14 (0.3)

1 (7.1)

 Surgery on the liver (5–50)

56 (5.9)

48 (5.6)

0.95 [0.64, 1.41]

.865

434 (31.2)

422 (32.9)

-12 (-2.8)

.682

41 (9.4)

38 (9.0)

0.95 [0.60, 2.51]

.916

11 (0.9)

1 (9.1)

 Surgery on the gallbladder and bile ducts (5–51)

219 (1.8)

183 (1.9)

1.04 [0.85, 1.27]

.732

9,184 (43.5)

8,872 (48.1)

-312 (-3.4)

.020

319 (3.5)

321 (3.6)

1.04 [0.89, 1.22]

.627

108 (0.6)

19 (17.6)

 Surgery on the pancreas (5–52)

69 (7.5)

45 (4.8)

0.63 [0.43, 0.93]

.025

634 (40.7)

632 (40.5)

-2 (-0.3)

.955

48 (7.6)

42 (6.6)

0.87 [0.57, 1.34]

.595

13 (0.8)

2 (15.4)

 Closure of abdominal hernias (5–53)

45 (0.3)

42 (0.4)

1.28 [0.84, 1.94]

.305

3,650 (19.5)

3,203 (22.5)

-447 (-12.2)

 < .001

99 (2.7)

106 (3.3)

1.23 [0.93, 1.62

.169

35 (0.5)

11 (31.4)

 Other surgery in the abdominal region (5–54)

332 (6.2)

268 (5.9)

0.95 [0.81, 1.12]

.583

4,193 (43.8)

3,987 (46.7)

-206 (-4.9)

.023

595 (14.2)

570 (14.3)

1.01 [0.89, 1.14]

.916

91 (1.1)

30 (33.0)

Selected surgical procedures (3 + 5); N = 48,684 patients

 Thyroidectomy

3 (0.1)

3 (0.1)

1.45 [0.29, 7.17]

.967

258 (7.8)

197 (8.5)

-61 (-23.6)

.004

3 (1.2)

5 (2.5)

2.21 [0.52, 9.38]

.456

5 (0.2)

0 (0.0)

 Appendectomy

5 (0.3)

3 (0.2)

0.69 [0.16, 2.90]

.878

5,095 (73.0)

4,792 (74.6)

-303 (-5.9)

.002

10 (0.2)

14 (0.3)

1.49 [0.66, 3.36]

.445

28 (0.4)

0 (0.0)

 Cholecystectomy

48 (0.6)

42 (0.7)

1.16 [0.77, 1.76]

.554

5,26841.4)

2,961 (27.5)

-2,307 (-43.8)

 < .001

95 (1.8)

118 (4.0)

2.26 [1.72, 2.97]

 < .001

45 (0.4)

11 (24.4)

 Colon resection for cancer

56 (4.0)

49 (3.8)

0.95 [0.64, 1.40]

.856

764 (35.4)

676 (34.4)

-88 (-11.5)

.020

61 (8.0)

38 (5.6)

0.69 [0.45, 1.04]

.096

19 (1.0)

7 (36.8)

 Rectum resection for cancer

17 (1.9)

20 (2.4)

1.21 [0.63, 2.34]

.676

251 (22.4)

232 (21.5)

-19 (-7.6)

.387

13 (5.2)

14 (6.0)

1.18 [0.54, 2.56]

.833

7 (0.6)

1 (14.3)