Construction and analysis of an ulcer risk prediction model after endoscopic submucosal dissection for early gastric cancer

Table 3 Comparison of endoscopic features of ulcer group and non-ulcer group, n (%)

Endoscopic features	Ulcer group (n = 40)	Non-ulcer group (n = 156)	χ2 value	P value
Lesion site			2.132	0.344
Upper 1/3 of stomach	12 (30.00)	61 (39.10)
1/3 of stomach	20 (50.00)	76 (48.72)
Lower 1/3 of stomach	8 (20.00)	19 (12.18)
Mucosal discoloration	28 (70.00)	63 (40.38)	11.227	< 0.001
Convergence folds	28 (60.00)	49 (31.41)	19.877	< 0.001
Lesion surface			1.105	0.576
Bulge	11 (27.50)	52 (33.33)
Flat	15 (37.50)	62 (39.74)
Sag	14 (35.00)	42 (26.93)