Results
Patient Characteristics
A total of 145 patients was consented for the trial from September 2010 to April 2013. Of these, 94 patients (64.8%) had at least one visible colorectal polyp and were included in the final analysis. Patient demographics are detailed in Table 1. Eighty percent of patients were undergoing a screening colonoscopy while twenty percent of patients had a history of polyps and were undergoing surveillance colonoscopy. Almost 9% had a history of colorectal cancer. Forty-eight patients (51.1%) had one polyp, twenty-eight patients (29.8%) had two polyps, thirteen patients (13.8%) had three polyps, and five patients (5.3%) had more than three polyps. No patient reported any adverse events.
Polyp Characteristics
A total of 171 polyps was detected by WLE, imaged by HRME, and evaluated histologically. The average size of the polyps was 7.6 mm. Forty-five percent (n=77) were neoplastic, with the majority being tubular adenomas. Of the non-neoplastic lesions, 52% were hyperplastic. Table 2 details the polyp characteristics.
HRME and WLE Performance Characteristics of All Polyps
Table 3 describes the performance characteristics of HRME in differentiating neoplastic from non-neoplastic colorectal polyps compared with WLE for all 171 polyps. Although sensitivity for neoplasia is not different between the two modalities, HRME has a significantly higher specificity and accuracy compared with WLE. The PPV of HRME is also significantly greater than that of WLE, whereas the NPV is not statistically different.
HRME and WLE Performance Characteristics of Small and Diminutive Polyps
Table 4 and Table 5 describe the performance characteristics of HRME compared with WLE for small and diminutive polyps. Small polyps were defined as polyps estimated to be less than or equal to 10 mm. Diminutive polyps were defined as polyps estimated to be less than or equal to 5 mm. Although sensitivity is not different between the two modalities, HRME has a significantly higher specificity and accuracy compared with WLE for the differentiation of both small and diminutive neoplastic polyps. Similarly, PPV is significantly greater in HRME for both small and diminutive polyps, whereas there is no statistical difference in PPV compared with WLE for either polyp size.