Interendoscopist variability in proximal colon polyp detection is twice higher for serrated polyps than adenomas

Table 1 Observed polyp detection rates amongst the 18 colonoscopists

Endoscopist (No.)	Colonoscopies (n)	A.DR	DA.DR	PA.DR	PSP.DR
A	273	33.33%	29.67%	7.33%	4.40%
B	272	24.63%	19.49%	6.25%	5.51%
C	213	46.48%	38.97%	17.84%	19.25%
D	210	47.62%	38.10%	18.57%	6.19%
E	207	28.99%	25.12%	7.25%	5.31%
F	185	30.81%	27.57%	5.95%	2.70%
G	172	32.56%	29.07%	9.88%	7.56%
H	164	31.71%	28.05%	8.54%	8.54%
I	160	35.63%	30.00%	11.25%	3.13%
J	157	47.13%	35.67%	22.93%	15.92%
K	148	33.11%	29.05%	11.49%	2.03%
L	148	36.49%	31.76%	11.49%	10.14%
M	135	37.04%	25.19%	17.78%	4.44%
N	135	40.74%	31.11%	14.07%	5.93%
O	132	34.85%	33.33%	6.82%	2.27%
P	105	30.48%	19.05%	21.90%	15.24%
Q	85	38.82%	31.76%	12.94%	4.71%
R	78	32.05%	25.64%	11.54%	1.28%
N	18	18	18	18	18
mean	165.50	35.69%	29.37%	12.43%	6.92%
SD	54.65	6.41%	5.41%	5.36%	5.14%
Median	158.50	34.09%	29.37%	11.49%	5.41%
Q1-Q3	135-207	31.71%-38.82%	25.64%-31.76%	7.33%-17.78%	3.13%-8.54%
Min-Max	78-273	24.63%-47.62%	19.05%-38.97%	5.95%-22.93%	1.28%-19.25%

A.DR: Adenoma detection rate; DA.DR: Distal adenoma detection rate; PA.DR: Proximal adenoma detection rate; PSP.DR: Proximal serrated polyp detection rate.

Table 2 Comparison of polyp detection rates (%) between males and females amongst the 18 colonoscopists using the Wilcoxon test

		Males	Females	Total	P value
A.DR	n	18	18	18
	mean	46.3	24.5	35.7
	Median	44.9	23.7	34.1	< 0.0001
	Q1-Q3	40.7-50.0	20.0-27.7	31.7-38.8
	Min-Max	35.8-67.3	12.5-39.3	24.6-47.6
DA.DR	n	18	18	18
	mean	38.2	20	29.4
	Median	37.7	20.6	29.4	< 0.0001
	Q1-Q3	32.4-40.0	17.9-22.7	25.6-31.8
	Min-Max	27.9-54.8	11.0-29.2	19.0-39.0
PA.DR	n	18	18	18
	mean	17.8	7.1	12.4
	Median	15.3	6.6	11.5	< 0.0001
	Q1-Q3	11.0-22.4	3.6-10.8	7.3-17.8
	Min-Max	8.6-40.0	1.3-18.0	5.9-22.9
PSP.DR	n	18	18	18
	mean	8.3	5.3	6.9
	Median	7.0	4.3	5.4	0.06
	Q1-Q3	4.5-10.8	1.5-6.6	3.1-8.5
	Min-Max	2.2-25.6	0.0-16.9	1.3-19.2

A.DR: Adenoma detection rate; DA.DR: Distal adenoma detection rate; PA.DR: Proximal adenoma detection rate; PSP.DR: Proximal serrated polyp detection rate.

Table 3 Comparison of polyp detection rates (%) according to age groups amongst the 18 colonoscopists using the Wilcoxon test

		< 55	55-59	60-64	65-69	≥ 70	Total	P value
A.DR	n	18	18	18	18	18	18
	mean	29.5	28.6	36.7	42.3	42.2	35.7
	Median	28.5	29.6	38.8	43.5	43.0	34.1	< 0.0001
	Q1-Q3	24.4-34.8	21.4-33.3	29.4-41.4	28.6-50.0	37.5-45.5	31.7-38.8
	Min-Max	16.7-42.9	12.5-42.6	18.4-52.9	21.7-73.0	29.0-53.8	24.6-47.6
DA.DR	n	18	18	18	18	18	18
	mean	23.9	23.6	31.9	35.3	33.4	29.4
	Median	22.7	23.8	33.0	39.0	33.3	29.4	0.0003
	Q1-Q3	17.6-31.8	18.5-27.8	29.4-37.5	22.7-44.4	26.5-37.5	25.6-31.8
	Min-Max	11.1-35.3	12.5-36.8	14.3-42.9	13.6-54.1	23.1-51.6	19.0-39.0
PA.DR	n	18	18	18	18	18	18
	mean	9.1	8.8	11.7	15.9	17.4	12.4
	Median	8.3	9.5	9.1	17.5	15.9	11.5	0.0006
	Q1-Q3	5.9-9.3	4.3-11.8	5.0-18.2	11.9-20.0	12.5-20.6	7.3-17.8
	Min-Max	0-25.0	0-17.9	0-31.0	2.5-32.4	0-46.2	5.9-22.9
PSP.DR	n	18	18	18	18	18	18
	mean	6.1	6.5	6.2	8.1	8.6	6.9
	Median	5.0	4.7	1.8	5.8	8.0	5.4	0.37
	Q1-Q3	0.0-7.4	3.2-10.0	0.0-10.0	2.5-10.2	3.2-12.9	3.1-8.5
	Min-Max	0.0-20.9	0.0-21.4	0.0-23.1	0.0-26.5	0.0-20.6	1.3-19.2

A.DR: Adenoma detection rate; DA.DR: Distal adenoma detection rate; PA.DR: Proximal adenoma detection rate; PSP.DR: Proximal serrated polyp detection rate.

Table 4 Results of multilevel logistic regression analysis for assessing the interendoscopist variability

			Coefficient (standard error)	P value	OR	95%CI
Adenoma detection rate	Patient level	Constant	-2.37 (0.356)	< 0.0001
		Age	0.036 (0.006)	< 0.0001	1.037	1.025-1.048
		Gender (ref = male)	-1.019 (0.082)	< 0.0001	0.361	0.308-0.424
	Endoscopist level	σ2u01	0.070 (0.032)	0.03
Distal adenoma detection rate	Patient level	Constant	-2.498 (0.369)	< 0.0001
		Age	0.033 (0.006)	< 0.0001	1.033	1.022-1.045
		Gender (ref = male)	-0.932 (0.085)	< 0.0001	0.394	0.333-0.466
	Endoscopist level	σ2u01	0.044 (0.025)	0.08
Proximal adenoma detection rate	Patient level	Constant	-4.169 (0.538)	< 0.0001
		Age	0.041 (0.008)	< 0.0001	1.042	1.025-1.059
		Gender (ref = male)	-1.065 (0.127)	< 0.0001	0.345	0.269-0.442
	Endoscopist level	σ2u01	0.234 (0.101)	0.02
Proximal serrated polyp detection rate	Patient level	Constant	-4.049 (0.677)
		Age	0.025 (0.010)	0.02	1.025	1.004-1.046
		Gender (ref = male)	-0.498 (0.150)	< 0.001	0.608	0.453-0.816
	Endoscopist level	σ2u01	0.460 (0.199)	0.02

¹Variance of the endoscopist-level random effect representing the heterogeneity between endoscopists in terms of the outcome.