Purpose: Although screening colonoscopy has significantly reduced the incidence of colorectal cancer due to removal of clinically significant adenomatous polyps, the clinical benefit of removing micro adenomas is of unclear benefit. As a result basing the value of increasing withdrawal time on adenoma detection rate may not be a good surrogate quality indicator for colonoscopic cancer screening. The aim of this study was to compare colonoscopic screening prior to and after full implementation of 6 minute withdrawal time. Specifically assess polyp detection rate (PDR) and adenoma detection rate (ADR) during both time frames and the incidence of interval cancers in the earlier study population.
Methods: Data from all out-patient screening colonoscopies during the first 6 months of 2006 (pre 6 minute withdrawal) and 2009 (post 6 minute withdrawal) were reviewed. Pathology reports were correlated with endoscopic findings. A retrospective chart review was performed on all screening colonoscopies from 2006 to evaluate for primary diagnosis of colorectal cancer in the 3 year period after there screening. Chi-square and T-test was used for quantitative and categorical data respectively. Confidence interval was used to compare difference in proportions and repeated measures ANOVA for data with Poisson distribution. P value was set at 0.05
Results: 900 screening colonoscopies were performed during the first 6 months of ‘06 and 750 in ‘09. Mean age 58.7 vs 57.7 years (p<0.05). Cecal intubation rate 96.6% vs 97% (p>0.05). Visualization was documented as good in over 99.5% of screening colonoscopies in both years. Neither PDR 14.9% vs 13.9% nor ADR 7.2% vs 9.6% were statistically significant between pre and post 6 minute withdrawal time, (p>0.05). Interval colorectal cancer rate at 3 years was 0%.
Conclusion: The data indicate that implementation of the 6 minute withdrawal time did no significantly alter PDR or ADR. Importantly there was no incidence of interval colon cancer in the 3 years following a screening colonoscopy in the pre 6 minute withdrawal group. These results occurred in a population with a high rate of cecal intubation and removal of clinically significant adenomatous lesions. Therefore the optimal quality measure may be interval colon cancer incidence rather than reliance on surrogate measures not clearly tied to the desired outcome.
Session: Podium Presentation
Program Number: S092
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