Nomogram to predict the risk of endoscopic removal failure with forceps/baskets for treating submandibular stones

Table 3 Results of Pearson’s chi-square test

Variables		Endoscopic removal	ERF	χ2	P value
Sex	Male	42	57	0.005	0.946
	Female	47	65
Age of the patient	< 44	54	69	0.359	0.549
	≥ 44	35	53
Intraductal stone treatment history	Yes	12	22	0.788	0.244
	No	77	100
Involved side	Left	43	57	0.052	0.819
	Right	46	65
Amounts of stones	Single	74	106	0.005	0.945
	Multiple	15	16
Palpation	Positive	38	96	28.764	< 0.001a
	Negative	51	26
Location	< 3.76 cm	75	38	58.382	< 0.001a
	≥ 3.76 cm	14	84
TD	< 4.97 mm	76	28	80.274	< 0.001a
	≥ 4.97 mm	13	94
LD	< 5.14 mm	82	32	34.586	< 0.001a
	≥ 5.14 mm	7	90

^aP < 0.05. ERF: Endoscopic removal failure; TD: Transverse diameter; LD: Longitudinal diameter; CI: Confidence interval.