Impact of looping on premalignant polyp detection during colonoscopy

Table 1 Characteristics of the study subjects

Characteristics
n	12259
Age, mean (SD), yr	53.6 (12.2)
Male sex, %	50.7
Looping, none/mild/severe, n	5532/4399/2253
Insertion time, mean (SD), min	4.57 (2.66)
Withdrawal time, mean (SD), min	13.87 (4.19)
Experienced endoscopist, %	70.4
Polyp detection
Adenoma DR, %	44.7
Advanced adenoma DR, %	2.0
High-risk adenoma DR, %	9.9
CSSP DR, %	8.9
SSL DR, %	3.5
Number of adenomas, mean (SD), n	0.82 (1.25)
Number of SSLs, mean (SD), n	0.04 (0.24)

SD: Standard deviation; DR: Detection rate; CSSP: Clinically significant serrated polyp; SSL: Sessile serrated lesion.

Table 2 Subject characteristics based on looping severity

	No looping	Mild looping	Severe looping	P value
n	5532	4399	2253
Age, mean (SD), yr	51.5 (11.5)	54.2 (12.2)	56.7 (13.0)	< 0.001
Male sex, %	62.8	44.6	33.4	< 0.001
Insertion time, mean (SD), min	3.53 (1.89)	4.95 (2.41)	6.38 (3.44)	< 0.001
Withdrawal time, mean (SD), min	13.70 (4.30)	14.17 (4.29)	13.74 (3.66)	< 0.0011
Experienced endoscopist, %	61.1	73.7	87.6	< 0.001
Polyp detection
Adenoma DR, %	42.2	45.0	50.2	< 0.001
Advanced adenoma DR, %	1.8	2.1	2.3	0.166
High-risk adenoma DR, %	8.4	9.8	13.5	< 0.001
CSSP DR, %	7.8	9.5	10.3	< 0.001
SSL DR, %	3.2	3.7	3.9	0.064
Number of adenomas, mean (SD), n	0.74 (1.16)	0.81 (1.25)	1.03 (1.44)	< 0.001
Number of SSLs, mean (SD), n	0.04 (0.22)	0.05 (0.26)	0.05 (0.26)	0.553

¹There were 22065005 and 19833488 combinations of increasing and decreasing trends, respectively.

P values were calculated using Cochran–Armitage trend test and Jonckheere-Terpstra test for categorical and continuous variables, respectively. SD: Standard deviation; DR: Detection rate; CSSP: Clinically significant serrated polyp; SSL: Sessile serrated lesion.

Table 3 Multivariate analysis of the effect on polyp detections

	Odds ratio	95% confidence interval	DOF	P value
Adenoma
Looping1	1.13	1.06-1.20	1	< 0.001
Age	1.05	1.04-1.05	1	< 0.001
Male sex	1.39	1.28-1.50	1	< 0.001
Insertion time	0.94	0.92-0.96	1	< 0.001
Withdrawal time	1.14	1.13-1.15	1	< 0.001
Endoscopist experience	1.68	1.53-1.85	1	< 0.001
High-risk adenoma
Looping1	1.25	1.13-1.38	1	< 0.001
Age	1.05	1.05-1.06	1	< 0.001
Male sex	1.527	1.33-1.74	1	< 0.001
Insertion time	0.90	0.87-0.93	1	< 0.001
Withdrawal time	1.20	1.18-1.21	1	< 0.001
Endoscopist experience	3.91	3.17-4.82	1	< 0.001
Clinically significant serrated polyp
Looping1	1.14	1.04-1.26	1	0.007
Age	1.00	0.99-1.01	1	0.999
Male sex	0.60	0.52-0.68	1	< 0.001
Insertion time	0.92	0.88-0.95	1	< 0.001
Withdrawal time	1.16	1.14-1.17	1	< 0.001
Endoscopist experience	2.04	1.71-2.43	1	< 0.001

¹No, mild, and severe looping were scored 0, 1, and 2, respectively.

P value was calculated using binomial logistic regression model. DOF: Degree of freedom.

Table 4 Multivariate analysis of the effect on polyp detections in the sub-analysis of experienced endoscopists

	Odds ratio	95% confidence interval	DOF	P value
Adenoma
Looping1	1.14	1.07-1.23	1	< 0.001
Age	1.05	1.05-1.05	1	< 0.001
Male sex	1.42	1.29-1.56	1	< 0.001
Insertion time	0.93	0.91-0.95	1	< 0.001
Withdrawal time	1.13	1.11-1.14	1	< 0.001
High-risk adenoma
Looping1	1.27	1.14-1.41	1	< 0.001
Age	1.05	1.05-1.06	1	< 0.001
Male sex	1.56	1.35-1.81	1	< 0.001
Insertion time	0.89	0.85-0.92	1	< 0.001
Withdrawal time	1.18	1.16-1.20	1	< 0.001
Clinically significant serrated polyp
Looping1	1.15	1.04-1.28	1	0.008
Age	1.00	1.00-1.01	1	0.627
Male sex	0.66	0.57-0.77	1	< 0.001
Insertion time	0.92	0.89-0.96	1	< 0.001
Withdrawal time	1.13	1.11-1.15	1	< 0.001

¹No, mild, and severe looping were scored 0, 1, and 2, respectively.

P value was calculated using binomial logistic regression model. DOF: Degree of freedom.