Table 1:

Patient characteristics and follow-up data stratified by presence of PIPs

	PIPs n=462	No PIPs n=1120	P value*
Baseline and disease-related characteristics
Age at index colonoscopy (years), median (IQR)	45 (36 – 56)	45.5 (35 – 54)	0.43
Sex, n (%)			0.42
Male	238 (51.1)	597 (53.3)
Female	227 (48.9)	523 (46.7)
IBD type, n (%)			0.81
Ulcerative colitis	279 (60.4)	230 (53.6)
Crohn’s disease	170 (36.8)	181 (42.2)
IBD-unclassified	13 (2.8)	18 (4.2)
Incident PIPs, n (%)	162 (35.1)	-	-
Follow-up before first diagnosis of PIPs (years), median (IQR)	2.9 (2.0 – 4.7)
Family history of colorectal cancer, n (%)	29 (6.3)	64 (5.7)	0.67
Disease duration at index colonoscopy (years), median (IQR)	14 (10 – 22)	14 (10 – 22)	0.40
Dysplasia# at/before index colonoscopy, n (%)	70 (15.2)	163 (14.6)	0.41
Low-grade dysplasia	34 (7.4)	91 (8.1)
Indefinite for dysplasia	18 (3.9)	27 (2.4)
Unspecified	17 (3.7)	45 (4.0)
Extensive disease, n (%)	396 (88)	879 (83)	0.01
Primary sclerosing cholangitis, n (%)	38 (8.2)	196 (17.5)	<0.0005
Exposure to medication
5-Aminosalicylates	393 (85.1)	893 (79.7)	0.01
Thiopurines	265 (57.4)	475 (42.4)	<0.0005
Methotrexate	30 (6.5)	60 (5.4)	0.38
Biologicals	125 (27.1)	196 (17.5)	<0.0005
Colonoscopic Surveillance Details
Number of procedures/year, median (IQR)	0.7 (0.6 – 1.0)	0.7 (0.6 – 1.0)	0.49
Mean inflammation score
Endoscopic	1.50 (1.00 – 2.00)	1.41 (1.00 – 1.80)	0.001
Histologic	2.60 (2.00 – 3.00)	2.50 (2.00 – 3.00)	<0.0005
Cecum intubated, mean (SD) % of procedures	86.0 (22.3)	87.4 (22.3)	0.21
Adequate bowel preparation, mean (SD) % of procedures	97.6 (10.5)	98.1 (8.5)	0.09
Duration of follow-up (years), median (IQR)	5.4 (3.3 – 7.6)	4.5 (2.7 – 6.6)	<0.0005

Classification of PIPs in this table includes both prevalent and incident PIPs.

^*Significant at P <0.05 level. PIPs: Post-inflammatory polyps.

^#Patients with HGD at/before the index colonoscopy were excluded