Table 1 Baseline characteristics and comparison between non-difficult ESD and difficult ESD.

No. patients

405

345

60

Age, year

50.37 ± 11.13

49.11 ± 12.35

59.41 ± 8.25

 < 0.001

  < 60

298 (73.58%)

274 (79.44%)

24 (40.00%)

 < 0.001

   ≥ 60

107 (26.42%)

71 (20.56%)

36 (60.00%)

 < 0.001

Gender

  Male

191 (47.16%)

163 (47.25%)

29 (48.33%)

0.951

  Female

214 (52.84%)

182 (52.75%)

31 (51.67%)

Histology

  Epithelial lesions

251 (61.97%)

210 (60.87%)

41 (68.33%)

0.306

  Negative for neoplasia

98 (24.20%)

90 (26.08%)

8 (13.33%)

0.101

  Indefinite for dysplasia

6 (1.48%)

6 (1.74%)

0 (0.00%)

0.401

  Low-grade dysplasia

66 (16.30%)

56 (16.23%)

10 (16.67%)

0.929

  High-grade dysplasia

80 (19.75%)

58 (16.81%)

22 (36.67%)

0.005

  Invasive neoplasia

1 (0.25%)

0 (0.00%)

1 (1.67%)

0.198

  Non-epithelial lesions

154 (38.02%)

135 (39.13%)

19 (31.67%)

0.306

Location

  Upper third

60 (14.81%)

53 (15.36%)

7 (11.67%)

0.268

  Middle third

56 (13.83%)

41 (11.89%)

15 (25.00%)

0.096

  Lower third

289 (71.36%)

251 (72.75%)

38 (63.33%)

0.163

Gross type

  Elevated

360 (89.89%)

311 (90.14%)

49 (81.67%)

0.095

  Flat

35 (8.64%)

26 (7.54%)

9 (15.00%)

0.010

  Depressed

10 (2.47%)

8 (2.32%)

2 (3.33%)

0.396

Surface configuration

  Erythema

70 (17.28%)

46 (13.22%)

24 (40.00%)

 < 0.001

  Ulcer

53 (13.09%)

43 (12.46%)

10 (16.67%)

0.448

  Nodularity

43 (10.62%)

31 (8.99%)

12 (20.00%)

0.043

Submucosal fibrosis

0.038

  No

384 (94.81%)

331 (95.94%)

53 (88.33%)

  Yes

21 (5.19%)

14 (4.06%)

7 (11.67%)

Invasion depth

 < 0.001

  Mucosa

248 (61.23%)

227 (65.80%)

21 (35.00%)

  Non-mucosa

157 (38.77%)

118 (34.20%)

39 (65.00%)

  Procedure time, min

61.09 ± 32.28

50.84 ± 22.67

133.00 ± 40.38

 < 0.001

  Lesion size, mm

19.61 ± 10.44

17.97 ± 9.15

29.05 ± 12.36

 < 0.001