Validation of serrated polyps (SPs) in Swedish pathology registers

Soran R Bozorg,Mingyang Song,Louise Emilsson,Jonas F Ludvigsson

doi:10.1186/s12876-019-1134-6

Abstract

BackgroundLittle is known about the natural history of serrated polyps (SPs), partly due to the lack of large-scale epidemiologic data. In this study, we examined the validity of SP identification according to SNOMED (Systematised Nomenclature of Medicine) codes and free text from colorectal histopathology reports.MethodsThrough the ESPRESSO (Epidemiology Strengthened by histoPathology Reports in Sweden) study, we retrieved data on SPs from all pathology departments in Sweden in 2015–2017 by using SNOMED codes and free-text search in colorectal histopathology reports. Randomly selected individuals with a histopathology report of SPs were validated against patient charts using a structured, retrospective review.ResultsSPs were confirmed in 101/106 individuals with a histopathology report of SPs, yielding a positive predictive value (PPV) of 95% (95%CI = 89–98%). By year of diagnosis, the PPV was 89% (95%CI = 69–97%), 96% (95%CI = 81–99%) and 97% (95%CI = 89–99%) for individuals diagnosed before 2001 (n = 19), between 2001 and 2010 (n = 26) and after 2010 (n = 61), respectively. According to search method, the PPV for individuals identified by SNOMED codes was 100% (95%CI = 93–100%), and 93% (95%CI = 86–97%) using free-text search. Recorded location (colon vs. rectum) was correct in 94% of all SP histopathology reports (95%CI = 84–98%) identified by SNOMED codes. Individuals with SPs were classified into hyperplastic polyps (n = 34; 32%), traditional serrated adenomas (n = 3; 3%), sessile serrated adenomas/polyps (SSA/Ps) (n = 70; 66%), unspecified SPs (n = 3, 3%), and false positive SPs (n = 5, 5%). For individuals identified by SNOMED codes, SSA/Ps were confirmed in 49/52 individuals, resulting in a PPV of 94% (95%CI: 84–98%). In total, 57% had ≥2 polyps (1: n = 44, 2–3: n = 33 and ≥ 4: n = 27). Some 46% of SPs (n = 71) originated from the proximal colon and 24% were ≥ 10 mm in size (n = 37). Heredity for colorectal cancer, intestinal polyposis syndromes, or both was reported in seven individuals (7%). Common comorbidities included diverticulosis (n = 45, 42%), colorectal cancer (n = 19, 18%), and inflammatory bowel disease (n = 10, 9%).ConclusionColorectal histopathology reports are a reliable data source to identify individuals with SPs.

Highlights

Little is known about the natural history of serrated polyps (SPs), partly due to the lack of large-scale epidemiologic data
Serrated polyp (SP) were confirmed in 101/106 individuals with a histopathology report of SPs, yielding a positive predictive value (PPV) of 95% (95%Confidence interval (CI) = 89–98%)
Individuals with SPs were classified into hyperplastic polyps (n = 34; 32%), traditional serrated adenomas (n = 3; 3%), sessile serrated adenomas/polyps (SSA/Ps) (n = 70; 66%), unspecified SPs (n = 3, 3%), and false positive SPs (n = 5, 5%)

Summary

Introduction

Little is known about the natural history of serrated polyps (SPs), partly due to the lack of large-scale epidemiologic data. Colorectal cancer (CRC) is the third most common cancer and the third leading cause of cancer death worldwide. It kills over 600,000 people annually, accounting for 8% of cancer-related deaths [1]. The serrated pathway to CRC is mainly believed to originate from SSA/ Ps, which are estimated to represent up to 20% of all SPs [3, 5]. Even though the adenoma-carcinoma pathway still accounts for the majority of the CRC burden, a recent study comparing the risk of CRC development found that the increased risk of CRC in individuals with SPs is similar or higher than that seen in individuals with conventional adenomas [7]

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