Correlation between adenoma detection rate and polyp detection rate at endoscopy in a non-screening population

It is understood that colorectal adenomas progress to colonic adenocarcinoma. Adenoma detection rate (ADR) at endoscopy has been used as a key performance indicator at endoscopy and is inversely associated with diagnosis of interval colorectal cancer. As most endoscopy reporting systems do not routinely incorporate histological assessment, ADR reporting is a cumbersome task. Polyp Detection Rate (PDR) has therefore been adopted as a surrogate marker for ADR. A prospectively maintained database of colonoscopies performed between July 2015 and July 2017 was analysed. This was cross referenced with a histological database. Statistical analysis was performed using IBM SPSS, version 24. Inferential procedures employed included the Pearson's correlation coefficient (r) and Binomial logistic regression. Of 2964 procedures performed by 8 endoscopists, overall PDR was 27% and ADR was 19%. The PDR, ADR, adenoma to polyp detection rate quotient (APDRQ) and estimated ADR (PDR x APDRQ group average=0.72) was calculated for each individual. There was a strong positive linear correlation between PDR and ADR,r(8)=0.734, p=0.038 and between PDR and estimated ADR, r(8)=0.998, p<0.001. Adenoma detection rate strongly correlated with estimated ADR, r(8)=0.720, p=0.044. With the exclusion of a moderate outlier, these correlations increased in both strength and significance. There was a stronger correlation between PDR and ADR,r(7)=0.921, p=0.003 and between ADR and estimated ADR, r(7)=0.928, p=0.003.