Table 3.

Adjusted¹ OR and 95% CI for metachronous findings by index colonoscopy findings characterized by low risk adenoma and serrated polyp (size and histology) among 4,616 NHCR participants with 2 colonoscopies (1/2004 – 6/2015)

	Metachronous
		HRA N = 292 (6.3%)	SP ≥ 1 cm N = 55 (1.2%)
	Total N= 4,616	Adjusted	Adjusted
Index findings	N (col %)	OR (95% CI)	OR (95% CI)
Classification based on size of serrated polyps on index colonoscopy
Low risk adenoma (N = 1,418)
SP ≥ 1 cm	22 (0.5)	1.83 (0.41–8.11)	22.28 (5.50–90.34)
SP < 1 cm	272 (5.9)	2.09 (1.32–3.31)	2.59 (0.93–7.17)
Unknown SP Size	133 (2.9)	2.90 (1.53–5.48)	2.90 (0.64–13.16)
No SP	991 (21.5)	1.93 (1.41–2.62)	0.31 (0.07–1.37)
No adenoma (N = 3,198)
SP ≥ 1 cm	65 (1.4)	0.83 (0.20–3.49)	14.57 (5.19–40.88)
SP < 1 cm	452(9.8)	0.73 (0.42–1.28)	1.20 (0.40–3.62)
Unknown SP Size	285 (6.2)	0.70 (0.28–1.76)	4.82 (1.72–13.53)
No SP	2,396 (51.9)	Reference	Reference
Classification based on histology of serrated polyps on index colonoscopy
Low risk adenoma (N = 1,418)
STSA	49 (1.1)	2.88 (1.67–7.13)	9.33 (2.47–32.28)
HP Only	378 (8.2)	2.19 (1.45–3.31)	2.80 (1.13–6.97)
No SP	991 (21.5)	1.93 (1.41–2.62)	0.31 (0.07–1.37)
No adenoma (N = 3,198)
STSA	104 (2.3)	0.83 (0.26–2.70)	10.29 (3.91–27.13)
HP Only	698 (15.1)	0.72 (0.43–1.19)	1.96 (0.83–4.61)
No SP	2,396 (51.9)	Reference	Reference

Abbreviations: OR = odds ratio, CI = confidence interval, NHCR = New Hampshire Colonoscopy Registry, HRA=high risk adenoma, SP = serrated polyp, STSA = sessile and traditional serrated adenoma, HP = hyperplastic polyp

¹Adjusted for patient age, gender, smoking status, BMI and median time between the 2 colonoscopies