Validity for calculating adenoma detection rate (ADR) for all indications correlates well with the standard of the screening ADR in the Australian population

Abstract

Introduction: Determining adenoma detection rate (ADR) is important to ensure quality colonoscopy. The minimum standard of 25% in screening patients aged >50 years is recommended by professional organizations. Despite reasonable uptake of the National Bowel Cancer Screening Program, most patients in Australian endoscopy units are symptomatic (diagnostic) or have a personal history of polyps (surveillance). While patients with a first‐degree family member diagnosed with colorectal cancer at <55 years of age fit screening criteria, due to overwhelming referrals of symptomatic patients, pure family history screening numbers are very low. Thus, screening colonoscopies are less representative of the actual work carried out by Australian endoscopists. Rex (2017) demonstrated that the combination of screening, surveillance, and diagnostic ADR correlated well with pure screening ADR. However, as this novel review was based at one site, it needs replication.

Aim: Our aim was to assess if the ADR in the screening population correlates significantly with the overall ADR for all indications.

Methods: Colonoscopy records from July 2014 to September 2017 were retrospectively examined at two regional hospital endoscopy units in Australia. All procedures were allocated to screening (positive fecal occult blood test result or familial history of cancer), surveillance (previous history of colonic polyps or cancer), or diagnostic (symptomatic). If patients had more than one indication, diagnostic indications took precedence over surveillance indications, which took precedence over pure screening indications. Additionally, patients were excluded if they had inflammatory bowel disease, polyposis syndromes, preoperative cancer, inadequate bowel preparation, an anastomosis, or obstructive mass, or if the cecum was unable to be intubated or they were aged <50 years. Endoscopists were included in the analysis if they had completed at least 200 colonoscopies in the study period.

Results: A total of 6315 colonoscopies performed by 14 endoscopists were analyzed. Table 1 shows the ADR for each indication and overall ADR. A majority of procedures (51%) were completed for diagnostic indications, followed by screening (25%) and surveillance (24%). Screening ADR was higher than diagnostic ADR for all endoscopists, and 38% of endoscopists had a higher screening ADR than surveillance ADR. Screening ADR was positively correlated with all ADR (r = 0.8178, P = 0.0003). Using the minimum recommendation of 25% for a mixed‐sex population aged >50 years, all endoscopists exceeded this target for all indication groupings individually and using the combined ADR.

Conclusion: Despite the surveillance ADR being slightly below the screening ADR in this population, overall findings correlate with the Rex (2017) study. This supports expansion of ADR calculations to include all procedures. Additionally, it makes calculation of ADR simpler, efficient, and more representative for endoscopists who work in units with proportionally high numbers of diagnostic colonoscopies.