Narrow Band Imaging in the Prediction of Surveillance Intervals After Polypectomy in Community Practice: Ready for (a European) Prime Time
Condition: Resect and Discard Strategies for Colonoscopy
Study type: Observational

Summary: 
      Several reports have suggested that an endoscopic diagnosis of adenoma, by means of narrow
      band imaging (NBI), might allow the determination of polyp management and surveillance
      interval, particularly in patients with diminutive polyps (< 5mm), in which the advanced
      histological features are uncommon and the prevalence of invasive cancer is negligible (1).
      On this basis, the American Society of Gastrointestinal Endoscopy (ASGE) has set an
      initiative evaluating the applicability of real-time endoscopic polyp assessment in clinical
      practice (1), which states that:

        1. for diminutive polyps to be resected and discarded without pathologic assessment,
           endoscopic technology (when used with high confidence) used to determine histology of
           polyps < 5mm in size, when combined with the histopathologic assessment of polyps >5 mm
           in size, should provide a > 90% agreement in assignment of post-polypectomy surveillance
           intervals when compared to decisions based on pathology assessment of all identified
           polyps.

        2. In order for a technology to be used to guide the decision to leave suspected
           rectosigmoid hyperplastic polyps <5 mm in size in place (without resection), the
           technology should provide > 90% negative predictive value (when used with high
           confidence) for adenomatous histology

      This strategy could potentially exert a significant impact on colonoscopy practice, by
      decreasing at some extent pathology-associated costs, although those related to histological
      analysis of >5mm polyps is maintained.

      In a recent study performed in our Centre (2), we restricted the application of the resect
      and discard strategy to patients with small or diminutive polyps only, achieving an
      accordance between endoscopy-directed and histology-directed surveillance strategy of about
      85% in both populations. This approach, where decisions on patient management are driven only
      by the "in vivo" endoscopic assessment, provides on one hand a slightly lower accordance than
      the threshold of 90% set by the PIVI, but on the other one it allows the complete spare of
      pathology related costs, although for a smaller proportion of patients. Moreover we observed
      a negative predictive value of 86% for the presence of adenoma within the diminutive polyps
      cohort, although a separate analysis for left sided ones was not performed.

      AIms of this single center, prospective, observational study:

        1. To prospectively evaluate the accordance between the endoscopy-directed and
           histology-directed surveillance strategies by applying the resect and discard strategy
           for diminutive polyps according to the PIVI statements

        2. To assess the economic impact of the resect and discard strategy when applied either
           according to the PIVI statements or to restrictedly to subjects with diminutive polyps
           only

        3. To provide a temporary validation of diagnostic performances of the resect and discard
           strategy for our group and the potential presence of a learning effect for the
           methodology

        4. Accordance between endoscopists' and nurses' categorization of adenomas according to
           standardized criteria (see below)
    


Observational model: Cohort
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Consecutive adult (18-80 yrs) outpatients undergoing colonoscopy for routine indications
        (screening, symptoms, surveillance).

        Exclusion criteria:

          -  patients with CRC history or hereditary polyposis syndromes or hereditary
             non-polyposis colorectal cancer

          -  patients with inadequate bowel preparation

          -  patients in which cecal intubation was not achieved or scheduled for partial
             examinations

          -  polyps could not be resected due to ongoing anticoagulation or could not be retrieved
             for pathologic assessment