Narrow band imaging and white light endoscopy in the characterization of a polypectomy scar: A single-blind observational study

Table 1 Baseline patient’s characteristics n (%)

Total number of lesions	112
Mean age, years (SD)	67.7 (10.1)
Sex ratio, % male	57.1
Weight (Kg, SD)	74.7 (15.4)
BMI (Kg/m2, SD)	27.6 (5.1)
Family History of CRC	27 (24.1)
Personal History of CRC	7 (6.3)
Current smoking	20 (17.9)
Diabetes	19 (17.0)
Lesion size, mm (median, interquartile range)	20 (14-30)
Categorical size
10-19 mm	47 (42.0)
20-39 mm	52 (46.4)
≥ 40 mm	13 (11.6)
Location of the lesion
Cecum	15 (13.4)
Ascending	53 (47.3)
Transverse	20 (17.9)
Descending	4 (3.6)
Sigmoid	10 (8.9)
Rectum	10 (8.9)
ASA classification
ASA I	18 (16.1)
ASA II	56 (50.0)
ASA III	38 (33.9)
Paris classification
0-Is	48 (42.9)
0-IIa	50 (44.6)
Other combinations (IIa + Is/IIc)	14 (12.5)
NICE classification
NICE I	17 (15.2)
NICE II	94 (83.9)
NICE III	1 (0.9)
Number of resected pieces
2-5 pieces	46 (41.1)
> 5 pieces	66 (58.9)
Baseline histology
Hyperplastic	4 (3.6)
Adenoma with LGD	53 (47.3)
Adenoma with HGD	39 (34.8)
Sessile serrated adenoma (SSA)	11 (9.8)
Traditional serrated adenoma (TSA)	2 (1.8)
Adenocarcinoma (pT1 stage)	3 (2.7)
Use of clips	59 (52.7)
Clips per lesion (median, interquartile range)	3 (1-3)
Use of clips
Prophylactic	56 (94.9)
Intraprocedural bleeding	2 (3.4)
Suspicion of deep mural injury	1 (1.7)
Tattooed lesion after EPMR	38 (33.9)
Endoscopist who performed piecemeal EMR
Expert endoscopists	98 (87.5)
General gastroenterologists	14 (12.5)
Median time to review (months, interquartile range)	3.9 (3.0-5.3)

BMI: Body mass index; ASA: American society of anesthesia; CRC: Colorectal cancer; EMR: Endoscopic mucosal resection; LGD: Low-grade dysplasia; HGD: High-grade dysplasia; EPMR: Endoscopic piecemeal mucosal resection.

Table 2 Characteristics between groups at protocol study

	WLE-NBI (n = 57)	NBI-WLE (n = 55)	P value
Sex (male, %)	54.4	60.0	0.36
Age (yr)	67.3	68.2	0.65
BMI (mean)	28.2	27.0	0.23
Baseline polyp size			0.002
10-19 mm	16 (28.1)	31 (56.4)
20-39 mm	30 (52.6)	22 (40.0)
≥ 40 mm	11 (19.3)	2 (3.6)
Location, right sided (%)	79.0	78.2	0.92
Paris Classification			0.34
0-Is	26 (45.6)	22 (40.0)
0-IIa	22 (38.6)	28 (50.9)
Other Combinations	9 (15.8)	5 (9.1)
NICE Classification			0.90
NICE I	8 (14.0)	9 (16.4)
NICE II	48 (84.2)	46 (83.6)
NICE III	1 (1.8)	0 (0)
Baseline histology			0.78
Hyperplastic	2 (3.5)	2 (3.6)
Adenoma with LGD	26 (45.6)	27 (49.1)
Adenoma with HGD	22 (38.6)	17 (30.9)
Sessile Serrated Adenoma (SSA)	5 (8.8)	6 (10.9)
Traditional serrated adenoma	0 (0)	2 (3.6)
Adenocarcinoma (pT1 stage)	2 (3.5)	1 (1.8)
Morphology of scar on site 1			0.12
Flat	29 (50.9)	20 (36.4)
Nodular elevated	28 (49.1)	35 (63.6)
Presence of clips on scar	3 (5.3)	8 (14.6)	0.12
Residual neoplasia on histology assessment			0.74
Negative	38 (66.7)	35 (63.6)
Positive	19 (33.3)	20 (36.4)
Polyps resected (mean, SD)	2.4 (2.7)	2.4 (2.7)	0.92
Mean time baseline EPMR colonoscopy (min)	55.9	51.9	0.38

WLE: White light endoscopy; NBI: Narrow band imaging; BMI: Body mass index; LGD: Low-grade dysplasia; HGD: High-grade dysplasia; EPMR: Endoscopic piecemeal mucosal resection.

Table 3 Diagnostic performance of white light endoscopy and narrow band imaging for each group

	WLE-NBI group			NBI-WLE group
	WLE (95%CI)	NBI (95%CI)		NBI (95%CI)	WLE (95%CI)
Sensitivity	78.9% (56.7-91.5)	89.5% (68.6-97.1)		85.0% (64.0-94.8)	80.0% (58.4-91.9)
Specificity	84.2% (69.6-92.6)	84.2% (69.6-92.6)		77.1% (61.0-87.9)	82.9% (67.3-91.9)
False positive	15.8% (7.4-30.4)	15.80% (7.4-30.4)		22.9% (12.1-39.0)	17.1% (8.1-32.7)
False negative	21.1% (8.5-43.3)	10.50% (2.9-31.4)		15.00% (5.2-36.0)	20.0% (8.1-41.6)
PPV	71.4% (50.0-86.2)	73.9% (53.5-87.5)		68.0% (48.4-82.8)	72.7% (51.8-86.8)
NPV	88.9% (74.7-95.6)	94.1% (80.9-98.4)		90.0% (74.4-96.5)	87.9% (72.7-95.2)
LR +	5 (2.3-10.8)	5.7 (2.7-12.0)		3.7 (2.0-7.0)	4.7 (2.2-10.0)
LR -	0.3 (0.1-0.6)	0.1 (0.03-0.5)		0.2 (0.1-0.6)	0.2 (0.1-0.6)
Global accuracy	82.5% (70.6-90.2)	86.0% (74.7-92.7)		80.0% (67.6-88.4)	81.8% (69.7-89.8)
AUC	81.6% (70.5-92.7)	86.8% (77.6-96.0)	P = 0.15	81.1% (70.4-91.8)	81.4% (70.4-92.4)	P = 0.9

CI: Confidence interval; WLE: White light endoscopy; NBI: Narrow band imaging; PPV: Positive predictive value; NPV: Negative predictive value; LR: Likelihood ratio; AUC: Area under the curve.