Angle of covered self-expandable metallic stents after placement is a risk factor for recurrent biliary obstruction

Table 4 Risk factors for recurrent biliary obstruction following covered self-expandable metallic stent placement by Cox proportional hazards analysis

		n	Case (%)	Univariate analysis		Multivariate analysis
				Unadjusted HR (95%CI)	P value	Adjusted HR (95%CI)	P value
Age (continuous, yr)		87	18 (20.7)	1.00 (0.95-1.04)	0.91
Sex	Female	32	5 (15.6)	1.00
	Male	55	13 (23.6)	1.44 (0.51-4.05)	0.49
ASA-PS	1	24	2 (8.3)	1.00
	2	44	9 (20.5)	2.59 (0.56-12.00)	0.23
	3	19	7 (36.8)	5.12 (1.06-24.81)	0.04	1.76 (0.85-3.62)	0.13
Primary disease	Others	29	8 (27.6)	1.00
	Pancreatic cancer	58	10 (17.2)	0.80 (0.31-2.05)	0.64
Clinical stage	II	3	1 (33.3)	1.00
	III	8	4 (50.0)	2.34 (0.26-21.22)	0.45
	IV	76	13 (17.1)	0.79 (0.10-6.18)	0.82
Chemotherapy	No	39	8 (20.5)	1.00
	Yes	48	10 (20.8)	1.13 (0.44-2.88)	0.80	1.02 (0.40-2.61)	0.97
Radiotherapy	No	76	17 (22.4)	1.00
	Yes	11	1 (9.1)	0.43 (0.06-3.24)	0.41
Total bilirubin level (continuous, mg/dL)		87	18 (20.7)	1.01 (0.99-1.03)	0.26
Length of stricture (continuous, mm)		87	18 (20.7)	1.03 (1.00-1.07)	0.10
Total procedure time (continuous, min)		87	18 (20.7)	1.00 (0.98-1.03)	0.75
EST	No	27	5 (18.5)	1.00
	Yes	60	13 (21.7)	1.19 (0.42-3.35)	0.75
CSEMS type (1)	Partially	38	9 (23.7)	1.00
	Fully	49	9 (18.4)	0.85 (0.34-2.15)	0.73
CSEMS type (2)	Laser-cut	6	1 (16.7)	1.00
	Braided	81	17 (21.0)	1.27 (0.17-9.73)	0.82
Length of CSEMS	≤ 6 cm	48	8 (16.7)	1.00
	7 cm	10	3 (30.0)	2.33 (0.61-8.89)	0.22
	8 cm	29	7 (24.1)	1.63 (0.64-4.14)	0.45
Diameter of CSEMS	< 10 mm	6	1 (16.7)	1.00
	≥ 10 mm	81	17 (21.0)	1.37 (0.18-10.47)	0.76
Angle of CSEMS (continuous, per 10°)		87	18 (20.7)	0.67 (0.51-0.87)	< 0.01	0.71 (0.54-0.92)	0.01

Data are presented as medians for continuous variables and as numbers for categorical variables. For categorical data, comparisons between groups were performed using the chi-squared test (or Fisher’s exact test, when necessary, because of small sample sizes), whereas continuous data were compared using Mann-Whitney U test. ASA-PS: American Society of Anesthesiologist Physical Status classification; EST: Endoscopic sphincterotomy; CSEMS: Covered self-expandable metallic stents; IQR: Interquartile range; HR: Hazard ratio; CI: Confidence interval.