Predictive factors for the failure of endoscopic stent-in-stent self-expandable metallic stent placement to treat malignant hilar biliary obstruction

Table 1 Comparison of the characteristics and the target biliary duct status of patients in the success and failure groups

	Success (n = 49)	Failure (n = 13)	P value
Age, median (range), yr	74 (42-88)	71 (16-76)	0.45
Sex (male), n (%)	33 (67.3)	8 (61.5)	0.75
Diagnoses
Primary lesion (Biliary tract or pancreatic cancer)	40	10	0.70
Metastases	9	3
Pancreatic cancer	1
Lung cancer	1
Tracheal cancer	1
Colon cancer	3	2
Uterine cancer	1
Gastric cancer	1	1
Prostatic cancer	1
Bismuth classification			0.98
II	12	3
III	18	5
IV	19	5
Target biliary duct status,
Diameter of the target biliary duct, median (range), mm	6.4 (2.0-15.9)	6.6 (4.4-17.3)1	0.45
Diameter of the target biliary stricture, median (range), mm	0 (0-1.6)	0 (0-0.9)	0.94
Diameter of the first implanted SEMS, median (range), mm	5.8 (3.1-11.7)	6.7 (3.4-12.6)	0.25
Length of the target biliary stricture, median (range), mm	11.0 (3.0-69.6)	7.9 (1.7-34.2)1	0.44
Angle between the target biliary duct stricture and the first implanted SEMS, median (range), degree	44.4 (7-119)	75.3 (28-109.3)1	< 0.01

¹Data of one of the patient were not available. SEMS: Self-expandable metallic stent.

Table 2 Comparison of the endoscopic retrograde cholangiopancreatography procedures and outcomes employed in the success and failure groups n (%)

	Success (n = 49)	Failure (n = 13)	P value
Procedure time, median (range), min	70 (20-160)	90 (40-150)1	0.30
Clinically effective rate	49 (100)	11 (84.6)	0.04
Adverse effects	1 (2)	1 (7.7)	0.38
Post-ERCP pancreatitis	1	0
Perforation of biliary duct	0	1
Wire passage of the first SEMS cell	49 (100)	9 (69.2)	0.006
Diameter of wire (0.025/0.035)	32/142	6/61	0.31
Catheter usage to dilate the a first SEMS cell	24	8	0.54
Catheter passage of the first SEMS cell	22 (92)	4 (50)	0.02
Dilator usage to dilate first SEMS cell	18	5	1.00
Dilator passage of the first SEMS cell	17 (94)	2 (40)	0.02
Balloon catheter usage to dilate the first SEMS lumen	5	1	1.00
Balloon catheter usage to dilate the first SEMS cell	18	3	0.51
Balloon catheter passage of the first SEMS cell	18 (100)	0 (0)	< 0.001
The number of used dilation devices, median (range)	1 (0-3)	1 (0-3)	0.79
Type of first SEMS used (braided/laser), n	41/8	9/4	0.26
Stenting order			0.22
Left→Left	2	1
Left→Right	28	6
Right→Left	12	6
Right→Right	7	0
Procedure sessions			0.328
1	42	13
2	7	0
Area of first SEMS cell, median (range), mm2	18.3 (3.5-39.3)	18.3 (3.5-18.3)3	0.59

¹Data for one patient were not available;

²Data for three patients were not available;

³Data for two patients were not available. ERCP: Endoscopic retrograde cholangiopancreatography; SEMS: Self-expandable metallic stent.

Table 3 Comparison of the endoscopic retrograde cholangiopancreatography procedures procedures employed in the success and failure groups (Angle between the target biliary duct stricture and the first implanted self-expandable metallic stent > 49.7 degrees) n (%)

	Success (n = 19)	Failure (n = 12)	P value
Diameter of the first implanted SEMS, median (range), mm	6.2 (3.1-15.9)	6.5 (4.4-17.3)	0.16
Wire passage of the first SEMS cell	19 (100)	8 (69.2)	0.02
Diameter of wire (0.025/0.035)	12/61	5/61	0.44
Catheter usage to dilate the a first SEMS cell	8	7	0.47
Catheter passage of the first SEMS cell	87.5 (7/8)	42.9 (3/7)	0.12
Dilator usage to dilate first SEMS cell	6	4	1.00
Dilator passage of the first SEMS cell	6 (100)	1 (25)	0.03
Balloon catheter usage to dilate the first SEMS lumen	1	1	1.00
Balloon catheter usage to dilate the first SEMS cell	7	2	0.42
Balloon catheter passage of the first SEMS cell	7 (100)	0 (0)	0.03
The number of used dilation devices, median (range)	1 (0-2)	1 (0-3)	0.76
Type of first SEMS used (braided/laser)	13/6	8/4	1.00
Stenting order			0.53
Left→Left	1	1
Left→Right	12	5
Right→Left	6	6
Procedure sessions			0.27
1	16	12
2	3	0
Area of first SEMS cell, median (range), mm2	18.3 (3.5-18.3)	18.3 (3.5-18.3)2	0.96

¹Data for one patient were not available;

²Data for two patients were not available. SEMS: Self-expandable metallic stent.