Diagnostic performance of chromoendoscopy and narrow band imaging for colonic neoplasms: a meta-analysis

Diagnostic performance of Japan NBI Expert Team classification for differentiation among noninvasive, superficially invasive, and deeply invasive colorectal neoplasia

BACKGROUNDS AND AIMS

The Japan NBI Expert Team (JNET) classification is the first universal narrow-band imaging magnifying endoscopic classification of colorectal tumors. Considering each type in this classification, the diagnostic ability of Type 2B is the weakest. Generally, clinical behavior is believed to be different in each gross type of colorectal tumor. We evaluated the differences in the diagnostic performance of JNET classification for each gross type (polypoid and superficial) and examined whether the diagnostic performance of Type 2B could be improved by subtyping.

METHODS

We analyzed 2933 consecutive cases of colorectal lesions, including 136 hyperplastic polyps/sessile serrated polyps, 1926 low-grade dysplasias (LGDs), 571 high-grade dysplasias (HGDs), and 300 submucosal (SM) carcinomas. We classified lesions as polypoid and superficial type and compared the diagnostic performance of the classification system in each type. Additionally, we subtyped Type 2B into 2B-low and 2B-high based on the level of irregularity in surface and vessel patterns, and we evaluated the relationship between the subtypes and histology, as analyzed separately for polypoid and superficial types. We also estimated interobserver and intraobserver variability.

RESULTS

The diagnostic performance of JNET classification did not differ significantly between polypoid and superficial lesions. Ninety-nine percent of Type 2B-low lesions were LGDs, HGDs, or superficial submucosal invasive (SM-s) carcinomas. In contrast, 60% of Type 2B-high lesions were deep submucosal invasive (SM-d) carcinomas. The results were not different between each gross type. Interobserver and intraobserver agreements for Type 2B subtyping were good, with kappa values of .743 and .786, respectively.

CONCLUSIONS

Type 2B subtyping may be useful for identifying lesions that are appropriate for endoscopic resection. JNET classification and Type 2B sub classification are useful criteria, regardless of gross type.

Economic value of narrow band imaging versus white light endoscopy for the characterization of diminutive polyps in the colon: systematic literature review and cost-consequence model

AIMS

To demonstrate the economic implication of adopting narrow-band imaging (NBI) for the characterization of diminutive polyps in the colon from an English payer perspective.

MATERIALS AND METHODS

A decision-tree model was undertaken to perform a cost-consequence and budget impact analysis from the NHS England perspective in the UK, over a 7-year time horizon. Clinical inputs came from the published literature (both randomized controlled trials and meta-analyses) identified through a systematic literature review, and cost inputs came from national list prices and unpublished internal market data. Deterministic sensitivity analysis (DSA) was conducted on the budget impact results to assess their robustness.

RESULTS

Optical diagnosis with NBI offered cost savings vs white light endoscopy (WLE) over 7 years due to reductions in histological exams, resections, and associated adverse events, while having minimal impact on health outcomes. Budget impact analysis demonstrated annual cost savings of £141 192 057 over 7 years, with histological exams being the biggest cost driver. DSA showed these results to be robust, but most sensitive to the cost of tariff with and without biopsy, and the cost of histological exam. Break-even analysis to explore how changing the unit cost and number of biopsies per patient would change the budget impact found NBI consistently offered net savings, even if the cost of biopsy was £0.

LIMITATIONS

Although every effort was made to ensure robustness of results, as with any model, there were some limitations including a lack of published data for certain clinical inputs and potential variation between model inputs and real-life cost and market share values.

CONCLUSIONS

Optical diagnosis with NBI was found to be equally effective compared with the standard of care (WLE), while potentially enabling cost savings from the NHS England perspective.

Meta-analysis: The diagnostic efficacy of chromoendoscopy for early gastric cancer and premalignant gastric lesions

BACKGROUND AND AIM

Chromoendoscopy (CE) is widely used in the diagnosis of early gastric cancer (EGC) and premalignant gastric lesions (PGLs). We conducted a meta-analysis to evaluate the diagnostic efficacy of CE for EGC and PGLs.

METHODS

We searched PubMed/MEDLINE, EMBASE, and the Cochrane library to identify all eligible studies according to inclusion and exclusion standards. Publication bias was tested using Funnel plots and Egger's test. The possible sources of the heterogeneity were explored by performing a meta-regression analysis. Heterogeneity was assessed by the Q test and I(2) statistic.

RESULTS

Ten studies met the inclusion standards, including a total of 699 patients and 902 lesions. The pooled sensitivity, specificity, and area under the curve of CE were 0.90 (95% confidence interval, 0.87-0.92), 0.82 (95% confidence interval, 0.79-0.86), and 0.9464, respectively. In subgroup analysis of diagnostic accuracy, CE showed higher accuracy versus standard white light endoscopy for EGC (P = 0.005) and PGLs (P = 0.001).

CONCLUSION

Chromoendoscopy seems to have a high diagnostic efficacy and improve the detection of EGC and PGLs compared with standard white light endoscopy.

Advances in the removal of diminutive colorectal polyps

Diminutive polyps (<5 mm in diameter) represent the majority of polyps found during colonoscopy; about a half of them are adenomatous, with low risk of advanced neoplasia. Recent studies have demonstrated that cold polypectomy should be considered the recommended approach for resecting diminutive polyps and that cold snaring may be superior to cold forceps biopsy, at least for polyps of 4-5 mm. Recently, electronic chromoendoscopy has been applied to characterization of diminutive polyps to discriminate adenomatous from nonadenomatous lesions. Optical diagnosis of polyp histology could potentially exert huge cost savings by the 'resect and discard' strategy for diminutive polyps and 'leaving-in' for diminutive hyperplastic polyps in the recto-sigmoid colon. These policies represent the mainstay for adopting endoscopy-directed post-polypectomy surveillance strategies, endorsed by both American and European Endoscopy Societies. Accuracy of both histology and surveillance intervals predictions from academic centers have been encouraging, although the same performance has not been replicated in community practices.

Clinical competence in the surgery of rectal cancer: the Italian Consensus Conference

BACKGROUND AND AIM

The literature continues to emphasize the advantages of treating patients in "high volume" units by "expert" surgeons, but there is no agreed definition of what is meant by either term. In September 2012, a Consensus Conference on Clinical Competence was organized in Rome as part of the meeting of the National Congress of Italian Surgery (I Congresso Nazionale della Chirurgia Italiana: Unità e valore della chirurgia italiana). The aims were to provide a definition of "expert surgeon" and "high-volume facility" in rectal cancer surgery and to assess their influence on patient outcome.

METHOD

An Organizing Committee (OC), a Scientific Committee (SC), a Group of Experts (E) and a Panel/Jury (P) were set up for the conduct of the Consensus Conference. Review of the literature focused on three main questions including training, "measuring" of quality and to what extent hospital and surgeon volume affects sphincter-preserving procedures, local recurrence, 30-day morbidity and mortality, survival, function, choice of laparoscopic approach and the choice of transanal endoscopic microsurgery (TEM).

RESULTS AND CONCLUSION

The difficulties encountered in defining competence in rectal surgery arise from the great heterogeneity of the parameters described in the literature to quantify it. Acquisition of data is difficult as many articles were published many years ago. Even with a focus on surgeon and hospital volume, it is difficult to define their role owing to the variability and the quality of the relevant studies.

Investigation of publication bias in meta-analyses of diagnostic test accuracy: a meta-epidemiological study

Background

The validity of a meta-analysis can be understood better in light of the possible impact of publication bias. The majority of the methods to investigate publication bias in terms of small study-effects are developed for meta-analyses of intervention studies, leaving authors of diagnostic test accuracy (DTA) systematic reviews with limited guidance. The aim of this study was to evaluate if and how publication bias was assessed in meta-analyses of DTA, and to compare the results of various statistical methods used to assess publication bias.

Methods

A systematic search was initiated to identify DTA reviews with a meta-analysis published between September 2011 and January 2012. We extracted all information about publication bias from the reviews and the two-by-two tables. Existing statistical methods for the detection of publication bias were applied on data from the included studies.

Results

Out of 1,335 references, 114 reviews could be included. Publication bias was explicitly mentioned in 75 reviews (65.8%) and 47 of these had performed statistical methods to investigate publication bias in terms of small study-effects: 6 by drawing funnel plots, 16 by statistical testing and 25 by applying both methods. The applied tests were Egger’s test (n = 18), Deeks’ test (n = 12), Begg’s test (n = 5), both the Egger and Begg tests (n = 4), and other tests (n = 2). Our own comparison of the results of Begg’s, Egger’s and Deeks’ test for 92 meta-analyses indicated that up to 34% of the results did not correspond with one another.

Conclusions

The majority of DTA review authors mention or investigate publication bias. They mainly use suboptimal methods like the Begg and Egger tests that are not developed for DTA meta-analyses. Our comparison of the Begg, Egger and Deeks tests indicated that these tests do give different results and thus are not interchangeable. Deeks’ test is recommended for DTA meta-analyses and should be preferred.

Narrow band imaging: application for early-stage gastrointestinal neoplasia

Narrow-band imaging (NBI) is an imaging technique for endoscopy using optical filters to narrow the bandwidth of spectral transmittance. Through this narrow spectrum, NBI contrasts surface structure and microvascular architecture of various lesions. In this article we focus on the application of NBI for early-stage neoplasia in the esophagus, stomach and colon with a three-step strategy of endoscopic diagnosis: (i) the detection of abnormality; (ii) the differentiation between non-neoplasia and neoplasia; and (iii) staging for tumor extension and depth of invasion.

Endoscopic versus histological characterisation of polyps during screening colonoscopy

BACKGROUND

As screening colonoscopy becomes more widespread, the costs for histopathological assessment of resected polyps are rising correspondingly. Reference centres have published highly accurate results for endoscopic polyp classification. Therefore, it has been proposed that, for smaller polyps, the differential diagnosis that guides follow-up recommendations could be based on endoscopy alone.

OBJECTIVE

The aim was to prospectively assess whether the high accuracy for endoscopic polyp diagnosis as reported by reference centres can be reproduced in routine screening colonoscopy.

DESIGN

Ten experienced private practice endoscopists had initial training in pit patterns. Then they assessed all polyps detected during 1069 screening colonoscopies. Patients (46% men; mean age 63 years) were randomly assigned to colonoscopy with conventional or latest generation HDTV instruments. The main outcome measure was diagnostic accuracy of in vivo polyp assessment (adenomatous vs hyperplastic). Secondary outcome measures were differences between endoscopes and reliability of image-based follow-up recommendations; a blinded post hoc analysis of polyp photographs was also performed.

RESULTS

675 polyps were assessed (461 adenomatous, 214 hyperplastic). Accuracy, sensitivity and specificity of in vivo diagnoses were 76.6%, 78.1% and 73.4%; size of adenomas and endoscope withdrawal time significantly influenced accuracy. Image-based recommendations for post-polypectomy surveillance were correct in only 69.5% of cases. Post hoc analysis of polyp photographs did not improve accuracy.

CONCLUSIONS

In everyday practice, endoscopic classification of polyp type is not accurate enough to abandon histopathological assessment and use of latest generation colonoscopes does not improve this. Image-based surveillance recommendations after polypectomy would consequently not meet guideline requirements.

TRIALREGNO

NCT01297712.

Narrow band imaging to differentiate neoplastic and non-neoplastic colorectal polyps in real time: a meta-analysis of diagnostic operating characteristics

PURPOSE

Many studies have reported on the use of narrow band imaging (NBI) colonoscopy to differentiate neoplastic from non-neoplastic colorectal polyps. It has potential to replace pathological diagnosis of diminutive polyps. We aimed to perform a systematic review and meta-analysis on the real-time diagnostic operating characteristics of NBI colonoscopy.

METHODS

We searched PubMed, SCOPUS and Cochrane databases and abstracts. We used a two-level bivariate meta-analysis following a random effects model to summarise the data and fit hierarchical summary receiver-operating characteristic (HSROC) curves. The area under the HSROC curve serves as an indicator of the diagnostic test strength. We calculated summary sensitivity, specificity and negative predictive value (NPV). We assessed agreement of surveillance interval recommendations based on endoscopic diagnosis compared to pathology.

RESULTS

For NBI diagnosis of colorectal polyps, the area under the HSROC curve was 0.92 (95% CI 0.90 to 0.94), based on 28 studies involving 6280 polyps in 4053 patients. The overall sensitivity was 91.0% (95% CI 87.6% to 93.5%) and specificity was 82.6% (95% CI 79.0% to 85.7%). In eight studies (n=2146 polyps) that used high-confidence diagnostic predictions, sensitivity was 93.8% and specificity was 83.3%. The NPVs exceeded 90% when 60% or less of all polyps were neoplastic. Surveillance intervals based on endoscopic diagnosis agreed with those based on pathology in 92.6% of patients (95% CI 87.9% to 96.3%).

CONCLUSIONS

NBI diagnosis of colorectal polyps is highly accurate--the area under the HSROC curve exceeds 0.90. High-confidence predictions provide >90% sensitivity and NPV. It shows high potential for real-time endoscopic diagnosis.

Optical diagnosis of small colorectal polyp histology with high-definition colonoscopy using narrow band imaging

Optical diagnosis of polyp histology can potentially result in enormous cost savings by way of the "resect and discard" strategy for diminutive polyps and the "do not resect" strategy for diminutive hyperplastic polyps in the distal colon. Narrow Band Imaging (NBI) highlights the surface mucosal and vascular pattern on polyps and has been shown to accurately characterize adenomatous and hyperplastic polyps by experts. However, the results have been a little discouraging amongst lesser experienced endoscopists. Studies have also shown that using the NBI diagnosis of diminutive polyp histology, experts can accurately define the future surveillance colonoscopy intervals. However nonexperts in academic or community setting have as yet failed to achieve the recommended thresholds. The subjectivity in assessment by endoscopists leads to the variable accuracy rates and can be circumvented by computer based automated tools. Although initial experience with a few computer based algorithms have shown accuracies comparable to experts, further refinement and validation will be required before these can be implemented in clinical practice. Incorporation of optical diagnosis of diminutive polyps into clinical practice is bound to face several hurdles. But the potential for enormous cost saving makes it an attractive strategy that can make colonoscopy more cost effective.

Emerging endoscopic and photodynamic techniques for bladder cancer detection and surveillance

This review provides an overview of emerging techniques, namely, photodynamic diagnosis (PDD), narrow band imaging (NBI), Raman spectroscopy, optical coherence tomography, virtual cystoscopy, and endoscopic microscopy for its use in the diagnosis and surveillance of bladder cancer. The technology, clinical evidence and future applications of these approaches are discussed with particular emphasis on PDD and NBI. These approaches show promise to optimise cystoscopy and transurethral resection of bladder tumours.