Biliary metal stents should be placed near the hilar duct in distal malignant biliary stricture patients

Table 1 Patient characteristics

	Hilar group (n = 83)	Lower group (n = 44)	P value
Age, yr	68.4 ± 11.8	71.2 ± 11.2	0.22
Sex
Female	33 (39.8)	16 (36.4)	0.85
Male	50 (60.2)	28 (63.6)
ALT, U/L	126.0 ± 116.3	174.8 ± 177.1	0.11
TB, mg/dL	5.9 ± 7.5	6.8 ± 6.8	0.47
Cause of stricture			0.77
Pancreaticobiliary tumor	73 (88.0)	40 (90.9)
Pancreas	67	31
Biliary tract	6	9
Metastasis	10 (12.0)	4 (9.1)
Lung	3	1
Stomach	3
Rhabdomyosarcoma	1
Uterine	1
Ovarian	1
Esophagus		1
Breast		1
Colon		1
Lymph node metastasis from gallbladder cancer	1
Chemotherapy	35 (42.2)	23 (52.3)	0.35
Duodenal stricture	15 (18.1)	7 (15.9)	0.81
CBD diameter above stricture, mm	11.5 ± 4.3	12.2 ± 4.0	0.40
CBD stricture diameter, mm	0.61 ± 0.89	0.72 ± 0.8	0.50
CBD stricture length, cm	2.64 ± 1.35	2.34 ± 1.11	0.21

Values are presented as the mean ± SD or n (%).

ALT: Alanine transaminase; TB: Total bilirubin; CBD: Common bile duct.

Table 2 Outcome of biliary self-expandable metallic stent placement

Variable	Hilar group (n = 83)	Lower group (n = 44)	P value
Year of procedure			0.18
2011-2015	48 (57.8)	31 (70.5)
2016-2021	35 (42.2)	13 (29.5)
Diameter of SEMS			1.0
8 mm	1 (1.2)	0 (0)
10 mm	82 (98.8)	44 (100)
USEMS:CSEMS	35:48	20:24	0.85
USEMS used
BileRush	2 (2.4)	1 (2.3)	1
Bonastent	1 (1.2)	0 (0)	1
HANARO	1 (1.2)	0 (0)	1
Niti-S Large cell	9 (10.8)	5 (11.4)	1
WallFlex	24 (28.9)	7 (15.9)	0.13
X Suit NIR	0 (0)	2 (4.5)	0.12
Zilver	0 (0)	1 (2.3)	0.35
Zilver 635	4 (4.8)	6 (13.6)	0.09
CSEMS used
Bonastent	0 (0)	1 (2.3)	0.35
HANARO	3 (3.6)	1 (2.3)	1
Niti-S Comvi	11 (13.3)	7 (15.9)	0.79
WallFlex	28 (33.7)	7 (15.9)	0.038
X Suit NIR	0 (0)	6 (13.6)	< 0.01
Technical success	83 (100)	44 (100)
Functional success	81 (97.6)	41 (93.2)	0.34
Adverse events	2 (2.4)	0 (0)	0.54
Pancreatitis	2	0
Mild	2	0
Post-EST bleeding	1	0
Severe	1	0
SEMS shortening1	1 (1.3)	2 (4.7)	0.28
SEMS dysfunction	2 (2.4)	18 (41)	< 0.01
Cause of SEMS dysfunction
Ingrowth	1	3
Overgrowth	1	2
Ingrowth and overgrowth		8
Top edge closed by CBD wall		4
Dislocation		1
Observational period, months	4.16 ± 5.76	9.12 ± 12.07	0.012

Values are presented as n, n (%), or mean ± SD.

¹The presence or absence of SEMS shortening was confirmed in 79 patients in the Hilar group and 43 patients in the Lower group.

SEMS: Self-expandable metallic stent; USEMS: Uncovered SEMS; CSEMS: Covered SEMS; EST: Endoscopic sphincterotomy; CBD: Common bile duct.

Table 3 Risk factors for self-expandable metallic stent dysfunction

	Univariate analysis			Multivariate analysis
	Hazard ratio	95%CI	P value	Hazard ratio	95%CI	P value
Lower group	11.42	2.61–49.83	< 0.01	9.94	2.25–44.0	< 0.01
Age	1.04	0.997–1.09	0.07
Sex, male	0.88	0.35–2.2	0.8
ALT	1.003	1.001–1.01	< 0.01	1.002	1.0–1.004	0.07
TB	1.05	0.99–1.12	0.1
Cause of stricture, pancreaticobiliary	0.41	0.09–1.9	0.26
Chemotherapy	0.89	0.34–2.31	0.81
Duodenal stricture	1.27	0.42–3.83	0.67
CBD above diameter stricture	1.06	0.94–1.19	0.35
CBD stricture diameter	1.004	0.56–1.79	0.99
CBD stricture length	0.99	0.69–1.41	0.95
Year (2011–2015)	1.35	0.55-3.32	0.52
Use of CSEMS	0.67	0.28–1.62	0.37
Use of covered WallFlex stent	0.4	0.12–1.36	0.14
Use of covered X Suit NIR usage stent	3.20	0.92–11.14	0.07
SEMS shortening	1.28	0.17–9.73	0.81
Observational period	0.98	0.92–1.04	0.43

SEMS: Self-expandable metallic stent; ALT: Alanine transaminase; TB: Total bilirubin; CBD: Common bile duct; CSEMS: Covered SEMS; CI: Confidence interval.