Clinical Study of Real Time Colorectal Polyp Diagnosis During Colonoscopy - the VALID Colonoscopy Study

• Compare the number of accurate high confidence polyp histology predictions by the endoscopist in the two groups. [ Time Frame: 12 months ] [ Designated as safety issue: No ]
  Measure the number of accurate high confidence predictions by the endoscopist in the differentiation of neoplastic from non-neoplastic colorectal lesions, using the high definition narrow band imaging colonoscopy with and without close focus features.
  
  

• Cost [ Time Frame: 1 year ] [ Designated as safety issue: No ]
  Measure the cost of colonoscopy with macroscopic histopathologic diagnosis of colorectal lesions compared to colonoscopy with conventional microscopic histopathologic diagnosis, on the lesions that were managed based on an accurate endoscopic diagnosis.
  
  
• Diagnostic characteristics [ Time Frame: 12 months ] [ Designated as safety issue: No ]
  Compare the diagnostic characteristics (accuracy, sensitivity, specificity, positive predictive value and negative predictive value) using the high definition narrow band imaging colonoscopy with and without close focus features.
  
  
• Accuracy of predicted versus actual surveillance intervals [ Time Frame: 12 months ] [ Designated as safety issue: No ]
  Compare the accuracy of predicted versus actual surveillance colonoscopy interval recommendations
  
  
• Surveillance Colonoscopy Advanced Pathology Findings [ Time Frame: 5 years ] [ Designated as safety issue: No ]
  Compare the advanced pathology and colon cancer incidence at surveillance colonoscopy of the groups who underwent high definition narrow band imaging colonoscopy with and without close focus features, and more specifically who underwent macroscopic versus microscopic polyp management.
  
  
• Learning Curve [ Time Frame: 12 months ] [ Designated as safety issue: No ]
  Examine the impact of a learning curve (i.e. accuracy with low and high confidence at each of endoscopist's first 25% of exams versus last 25% exams)
  
  

A recent single arm prospective cohort study suggested that high definition colonoscopy with narrow band imaging is an acceptable strategy to diagnose polyp histology and determine future surveillance intervals. Endoscopic proficiency in macroscopic features to differentiate polyp histology can be attained in a relatively short time period. A new high definition colonoscope with close focus narrow band imaging features may further improve diagnostic accuracy for polyp differentiation, and can replace formal pathologic assessment in cases of high diagnostic confidence.

Primary Aim: Compare the diagnostic accuracy of high definition narrow band imaging colonoscopy with and without close focus features for the macroscopic differentiation of neoplastic and non-neoplastic colorectal lesions using histopathologic diagnosis as the reference standard.

Secondary Aims: Compare diagnostic characteristics of the colonoscopes, measure concordance of high confidence and accuracy, compare accuracy of predicted versus actual surveillance interval recommendations, perform a cost-effective analysis of endoscopic versus pathologic diagnoses, measure advanced pathology and colon cancer at surveillance, and measure complications.