Validity for calculating ADR for all indications correlates well with the standard of the screening ADR in the Australian population

Abstract

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 organisations. 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 10 family history of colorectal cancer <55 years 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 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 Assess if the ADR in the screening population correlates significantly with the overall ADR for all indications.

Method 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 FOBT 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 with IBD, polyposis syndromes, and preoperative cancer, with inadequate bowel prep, an anastomosis, or obstructive mass, or the caecum was unable to be intubated or aged <50 were excluded. Endoscopists were included in the analysis if they had completed at least 200 colonoscopies in the study period.

Results 6315 colonoscopies by 14 endoscopists were analysed. Table 1 shows the ADR for each indication and overall ADR. 51% of procedures completed were for diagnostic indications, then screening (25%) and surveillance (24%).Screening ADR was higher than diagnostic ADR for all endoscopists. 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 mixed gender population > 50 years, all endoscopists exceeded this target for all indication groupings individually and using the combined ADR.

Discussion 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.