Elsevier

Gastrointestinal Endoscopy

Volume 81, Issue 3, March 2015, Pages 502.e1-502.e16
Gastrointestinal Endoscopy

ASGE technology committee systematic review and meta-analysis
ASGE Technology Committee systematic review and meta-analysis assessing the ASGE PIVI thresholds for adopting real-time endoscopic assessment of the histology of diminutive colorectal polyps

https://doi.org/10.1016/j.gie.2014.12.022Get rights and content

Abstract

In vivo real-time assessment of the histology of diminutive (≤5 mm) colorectal polyps detected at colonoscopy can be achieved by means of an “optical biopsy” by using currently available endoscopic technologies. This systematic review and meta-analysis was performed by the American Society for Gastrointestinal Endoscopy (ASGE) Technology Committee to specifically assess whether acceptable performance thresholds outlined by an ASGE Preservation and Incorporation of Valuable endoscopic Innovations (PIVI) document for clinical adoption of these technologies have been met. We conducted direct meta-analyses calculating the pooled negative predictive value (NPV) for narrow-band imaging (NBI), i-SCAN, and Fujinon Intelligent Color Enhancement (FICE)–assisted optical biopsy for predicting adenomatous polyp histology of small/diminutive colorectal polyps. We also calculated the pooled percentage agreement with histopathology when assigning postpolypectomy surveillance intervals based on combining real-time optical biopsy of colorectal polyps 5 mm or smaller with histopathologic assessment of polyps larger than 5 mm. Random-effects meta-analysis models were used. Statistical heterogeneity was evaluated by means of I2 statistics. Our meta-analyses indicate that optical biopsy with NBI, exceeds the NPV threshold for adenomatous polyp histology, supporting a “diagnose-and-leave” strategy for diminutive predicted nonneoplastic polyps in the rectosigmoid colon. The pooled NPV of NBI for adenomatous polyp histology by using the random-effects model was 91% (95% confidence interval [CI], 88–94). This finding was associated with a high degree of heterogeneity (I2 = 89%). Subgroup analysis indicated that the pooled NPV was greater than 90% for academic medical centers (91.8%; 95% CI, 89-94), for experts (93%; 95% CI, 91-96), and when the optical biopsy assessment was made with high confidence (93%; 95% CI, 90-96). Our meta-analyses also indicate that the agreement in assignment of postpolypectomy surveillance intervals based on optical biopsy with NBI of diminutive colorectal polyps is 90% or greater in academic settings (91%; 95% CI, 86-95), with experienced endoscopists (92%; 95% CI, 88-96) and when optical biopsy assessments are made with high confidence (91%; 95% CI, 88-95). Our systematic review and meta-analysis confirms that the thresholds established by the ASGE PIVI for real-time endoscopic assessment of the histology of diminutive polyps have been met, at least with NBI optical biopsy, with endoscopists who are expert in using this advanced imaging technology and when assessments are made with high confidence.

Introduction

The majority of colorectal polyps found at screening colonoscopy are diminutive (≤5 mm). These polyps seldom harbor advanced histological features (villous features or high-grade dysplasia) and very rarely harbor cancer. However, based on current management guidelines, endoscopists encountering diminutive polyps are obliged to remove them and submit them to histopathology to determine the next surveillance colonoscopy interval based on the histology of these polyps (adenomatous vs hyperplastic).1, 2 The costs associated with resection and pathology evaluation of these diminutive polyps add substantially to the total cost of colonoscopy, especially in countries such as the United States, where colonoscopy is a common modality for colorectal cancer screening.3

If a sufficiently accurate in vivo assessment of the histology of these diminutive polyps can be achieved by means of an “optical biopsy,” this may allow for a paradigm shift in the assessment and management of these polyps, which could significantly reduce the total cost of colonoscopy without affecting its efficacy in reducing future risk of colorectal cancer. This paradigm shift would incorporate the adoption of a “diagnose-and-leave” strategy, in which the endoscopist leaves in situ diminutive rectosigmoid hyperplastic polyps, and a “resect-and-discard” strategy, in which diminutive adenomatous polyps are resected after endoscopic assessment of histology to allow determination of surveillance colonoscopy intervals, but not submitted for histopathology evaluation.

Several in vivo endoscopic technologies exist that allow for real-time characterization of diminutive colorectal polyps that are superior to that achievable with white-light endoscopy. Electronic chromoendoscopy technologies facilitate polyp characterization by enhancing the surface pit pattern and highlighting the microvasculature of these polyps. These technologies include narrow-band imaging (NBI) (Olympus, Tokyo, Japan), i-SCAN (Pentax, Tokyo, Japan), and Fujinon Intelligent Color Enhancement (FICE) (Fujinon Inc, Saitama, Japan).4 Confocal laser endomicroscopy (CLE) has also been evaluated for this purpose.

The American Society for Gastrointestinal Endoscopy (ASGE) created a new initiative in 2011 entitled Preservation and Incorporation of Valuable endoscopic Innovations (PIVI). The key objectives of the PIVI initiative are to identify important clinical questions related to endoscopy and to establish a priori, diagnostic, and/or therapeutic thresholds for endoscopic technologies designed to resolve these clinical questions. The ASGE has identified endoscopic polyp characterization as a key area for new endoscopic technologies and has outlined in a PIVI document entitled “The ASGE PIVI on Real-Time Endoscopic Assessment of the Histology of Diminutive Colorectal Polyps” the performance thresholds that these technologies should meet before adoption into clinical practice.5 Two thresholds have been established in this PIVI document:

  • 1

    For a technology to be used to guide the decision to leave suspected rectosigmoid hyperplastic polyps 5 mm or smaller in place (without resection), the technology should provide a 90% or greater negative predictive value (NPV) (when used with high confidence) for adenomatous histology.

  • 2

    For colorectal polyps 5 mm or smaller to be resected and discarded without pathologic assessment, endoscopic technology (when used with high confidence) used to determine histology of these polyps, when combined with the histopathologic assessment of polyps larger than 5 mm, should provide 90% or greater agreement in assignment of postpolypectomy surveillance intervals when compared with decisions based on pathology assessment of all identified polyps.

The systematic review and meta-analyses were performed by the ASGE Technology Committee to specifically assess whether these PIVI thresholds have been met, based on the existing literature. Input was also sought from the chair (D.K.R.) of the ASGE Committee that wrote the original PIVI document.

Section snippets

Data sources and search strategies

A comprehensive search of several English-language databases was conducted for studies published between January 1, 1980 and May 14, 2014. The databases included Ovid MEDLINE In-Process & Other Non-Indexed Citations, Ovid MEDLINE, Ovid Embase, Ovid Cochrane Central Register of Controlled Trials, Ovid Cochrane Database of Systematic Reviews, and Web of Science. The search strategy was designed and conducted by an experienced librarian with input from the study team. Controlled vocabulary

Results

The search results are summarized in Figure 1. The literature search captured a total of 771 citations for NBI and 159 citations for i-SCAN and FICE. Review for citation duplication eliminated 377 citations for NBI and 85 citations for i-SCAN and FICE. Of the 74 remaining citations for i-SCAN and FICE, 39 citations were for FICE and 35 citations were for i-SCAN. Title reviews led to the exclusion of 244 citations for NBI, 13 citations for FICE, and 11 citations for i-SCAN. Of the subsequently

Discussion

The PIVI document on real-time endoscopic assessment of the histology of diminutive colorectal polyps5 was created by the ASGE to promote and facilitate a potential paradigm shift in the management of diminutive colorectal polyps by using optical biopsy with endoscopic technologies rather than histopathology for polyp characterization and for decision making regarding polyp management as well as assigning surveillance intervals. The PIVI document established performance thresholds that needed

Disclosures

The following authors disclosed financial relationships relevant to this article: Dr Banerjee has received research funding from Pentax. Dr Konda has received honoraria from Manua Kea Technologies and grant support from Olympus. Dr Wallace has received research funding from Olympus. Dr Rex has received research support and is a consultant for Olympus. All other authors disclosed no financial relationships relevant to this article.

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    This document was developed by the ASGE Technology Committee. This document was reviewed and approved by the governing board of the American Society for Gastrointestinal Endoscopy (ASGE).

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