Implementing endoscopic optical diagnosis into practice: a green light at the horizon

 

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Endoscopic optical diagnosis (EOD), which is a major aim of image-enhanced endoscopy, refers to endoscopic interpretation to make histologic diagnosis – using objective and validated criteria [1]. The use of objective and validated criteria is important, as it will allow EOD to be practiced at the same level as pathologic diagnosis. The thresholds that must be met in order for EOD to be considered on a par with pathology have been defined a priori by the American and European endoscopy societies [2] [3].

A number of studies have shown that real-time EOD of diminutive colorectal polyps in the academic settings has similar diagnostic operating characteristics to those of pathology. A recent meta-analysis showed that concordance between the surveillance interval recommendations that were calculated based on EOD and pathology was excellent, and the negative predictive value for polyps in the rectosigmoid colon was ≥ 90 % [4]. However, the application of EOD into clinical practice beyond the academic setting will require proof that the diagnostic accuracy also meets the thresholds that have been set forth by American Society for Gastrointestinal Endoscopy (ASGE) and/or European Society of Gastrointestinal Endoscopy (ESGE).

Paggi et al. from Valduce Hospital, a community-based hospital in Italy, are to be congratulated for showing that EOD of diminutive polyps can be performed with a diagnostic accuracy that surpasses the respective ASGE or ESGE thresholds [5]. They conducted a prospective observational study involving four endoscopists, who underwent periodic training on narrow-band imaging (NBI) assessment of polyp histology before and during the study. Endoscopist performance was audited, and periodic individual feedback was given to each endoscopist based on accuracy of the EOD diagnosis. Out of 284 outpatients enrolled, 656 polyps were detected, 465 (70.9 %) of which were diminutive and were included in the analysis. The accuracy of high-confidence NBI predictions for adenoma was 91.9 %; this predicted the correct surveillance interval in 95.8 % and 93.3 % of cases, according to European and American guidelines for the surveillance of colorectal neoplasia, respectively. The negative predictive value for adenoma in the rectosigmoid was 91.3 %.

The implementation of EOD of diminutive colon polyps involves a system redesign − a systematic change − in our approach to the management of diminutive polyps. The scope of such a change is enormous. If implemented, it may be considered to be a paradigm shift. Paggi et al. recognized the importance of following the key steps that are critical for a system redesign. They understood that learning EOD is experiential: “a cyclic process of doing, noticing, questioning, reflecting, exploring concepts and models (evidence), and then doing again” [6]. In contrast to their previous study [7], they implemented periodic training, audits, and feedbacks. Thus, presumably, the participating endoscopists were able to continue to learn and perhaps to improve during the study. They followed the Plan – Do – Study – Act cycle model for system redesign and surpassed the thresholds. In their previous study, they did not deploy the learning cycle and were unable to meet the thresholds.

The commitment shown by Paggi et al. gives credence to the notion that EOD studies can be successful when the participants are committed to change. The authors also proved that they were able to develop the knowledge and skills by self-learning, despite a presumably busy practice. In doing so, they confirmed that the required knowledge and skills to perform EOD for colorectal polyps are not innate.

The recent ESGE guideline appears to give a green light for Paggi et al. to implement EOD in their practice. Note, however, the strength of the guideline and the stringent criteria for its implementation. The guideline states: “ESGE suggest that virtual chromoendoscopy and conventional chromoendoscopy can be used, under strictly controlled conditions, for real-time optical diagnosis of diminutive (≤ 5 mm) colorectal polyps to replace histopathological diagnosis. The optical diagnosis has to be reported using validated scales, must be adequately photodocumented, and can be performed only by experienced endoscopists who are adequately trained and audited (weak recommendation, high quality of evidence)” [3]. The “weak” recommendation means that patients’ choices vary according to their values and preferences, and clinicians must ensure that individual care is in keeping with the values and preferences of the patient. Thus, at this time, they would need to assess patients’ values and preferences toward EOD or pathology diagnosis. In addition, the guideline states a requirement to obtain photodocumentation. Paggi et al. did not describe their photodocumentation process. This capability is important because, in addition to the value of photodocumentation for medicolegal purposes, it is necessary in order to continuously perform the Plan–Do–Study–Act cycle.

The green light for implementation of EOD for diminutive colorectal polyps at large can be seen at the horizon. The path, however, may be long and arduous. A change, let alone a paradigm shift, requires effort. In addition, there are potentially specific objections against the change. However, students of endoscopy need not be deterred. We need to continue to move forward through good research practice, including using standardized methodology and reporting. Thus, in due time, we can develop robust evidence to support the implementation of EOD in clinical practice [8]. The study by Paggi et al. is refreshing. It is a step in the right direction of continuing progress in endoscopy. We hope that many more similar studies will be conducted and published in the near future.

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