Virtual chromoendoscopy for the real-time assessment of colorectal polyps in vivo: a systematic review and economic evaluation

Abstract

BackgroundCurrent clinical practice is to remove a colorectal polyp detected during colonoscopy and determine whether it is an adenoma or hyperplastic by histopathology. Identifying adenomas is important because they may eventually become cancerous if untreated, whereas hyperplastic polyps do not usually develop into cancer, and a surveillance interval is set based on the number and size of adenomas found. Virtual chromoendoscopy (VCE) (an electronic endoscopic imaging technique) could be used by the endoscopist under strictly controlled conditions for real-time optical diagnosis of diminutive (≤ 5 mm) colorectal polyps to replace histopathological diagnosis.ObjectiveTo assess the clinical effectiveness and cost-effectiveness of the VCE technologies narrow-band imaging (NBI), flexible spectral imaging colour enhancement (FICE) and i-scan for the characterisation and management of diminutive (≤ 5 mm) colorectal polyps using high-definition (HD) systems without magnification.DesignSystematic review and economic analysis.ParticipantsPeople undergoing colonoscopy for screening or surveillance or to investigate symptoms suggestive of colorectal cancer.InterventionsNBI, FICE and i-scan.Main outcome measuresDiagnostic accuracy, recommended surveillance intervals, health-related quality of life (HRQoL), adverse effects, incidence of colorectal cancer, mortality and cost-effectiveness of VCE compared with histopathology.Data sourcesElectronic bibliographic databases including MEDLINE, EMBASE, The Cochrane Library and Database of Abstracts of Reviews of Effects were searched for published English-language studies from inception to June 2016. Bibliographies of related papers, systematic reviews and company information were screened and experts were contacted to identify additional evidence.Review methodsSystematic reviews of test accuracy and economic evaluations were undertaken in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Meta-analyses were conducted, where possible, to inform the independent economic model. A cost–utility decision-analytic model was developed to estimate the cost-effectiveness of VCE compared with histopathology. The model used a decision tree for patients undergoing endoscopy, combined with estimates of long-term outcomes (e.g. incidence of colorectal cancer and subsequent morbidity and mortality) derived from University of Sheffield School of Health and Related Research’s bowel cancer screening model. The model took a NHS perspective, with costs and benefits discounted at 3.5% over a lifetime horizon. There were limitations in the data on the distribution of adenomas across risk categories and recurrence rates post polypectomy.ResultsThirty test accuracy studies were included: 24 for NBI, five for i-scan and three for FICE (two studies assessed two interventions). Polyp assessments made with high confidence were associated with higher sensitivity and endoscopists experienced in VCE achieved better results than those without experience. Two economic evaluations were included. NBI, i-scan and FICE are cost-saving strategies compared with histopathology and the number of quality-adjusted life-years gained was similar for histopathology and VCE. The correct surveillance interval would be given to 95% of patients with NBI, 94% of patients with FICE and 97% of patients with i-scan.LimitationsLimited evidence was available for i-scan and FICE and there was heterogeneity among the NBI studies. There is a lack of data on longer-term health outcomes of patients undergoing VCE for assessment of diminutive colorectal polyps.ConclusionsVCE technologies, using HD systems without magnification, could potentially be used for the real-time assessment of diminutive colorectal polyps, if endoscopists have adequate experience and training.Future workFuture research priorities include head-to-head randomised controlled trials of all three VCE technologies; more research on the diagnostic accuracy of FICE and i-scan (when used without magnification); further studies evaluating the impact of endoscopist experience and training on outcomes; studies measuring adverse effects, HRQoL and anxiety; and longitudinal data on colorectal cancer incidence, HRQoL and mortality.Study registrationThis study is registered as PROSPERO CRD42016037767.FundingThe National Institute for Health Research Health Technology Assessment programme.

Incomplete endoscopic resection of colorectal polyps: a prospective quality assurance study

“…Improved polypectomy technique is clearly needed, and the results from the Italian EMR study [15] indicate that cold snare polypectomy may be a good choice for these polyps and should be tested in randomized trials. Furthermore, modern technology such as computer-assisted technology, snare tip soft coagulation, and chromoendoscopy [21][22][23] may also be helpful in identifying and completely removing SSA/Ps, as well as in determining their extent in the colon mucosa.…”

Rediscovering histology: what is new in endoscopy for inflammatory bowel disease?

“…Furthermore, with the introduction of new advanced endoscopic modalities, such as VCE, most dysplastic lesions are visible and a smaller number of biopsy specimens is required, making surveillance less cumbersome for both patients and clinicians. 53 , 87 Among image enhancement techniques, the available evidence suggests that dye-less chromoendoscopy is not inferior to the gold standard DCE in terms of neoplastic lesions detection. 48 , 53 , 54 , 59 Moreover, dye-less chromoendoscopy modalities offer the advantage of requiring less procedure time without additional spray-agent costs (median withdrawal time: 15 versus 20 min with VCE and DCE, respectively).…”

Prediction of the histology of colorectal neoplasm in white light colonoscopic images using deep learning algorithms

“…However, these techniques are not available in many medical centers, especially in community-based hospitals, and endoscopists who are equipped with these endoscopes require training or education, as long as 6 months, to reach certain levels of competence and accuracy in using them 34 , 35 . To be able to use these techniques, there are clear diagnostic thresholds and requirements 36 . Our study was designed to overcome these disadvantages and maximize our model’s clinical use by using solely unmagnified white light colonoscopic images.…”