Factors affecting adenoma detection rate in a national flexible sigmoidoscopy screening programme: a retrospective analysis

A national colorectal cancer screening programme started in England in 2013, offering one-off flexible sigmoidoscopy to all men and women aged 55 years in addition to the biennial faecal occult blood testing programme offered to all individuals aged 60–74 years. We analysed data from six pilot flexible sigmoidoscopy screening centres to examine factors affecting the adenoma detection rate (ADR). We did a retrospective analysis of flexible sigmoidoscopy screening procedures performed in individuals aged 55 years at six pilot sites in England as part of the National Health Service Bowel Scope Screening programme. ADR (number of procedures in which at least one adenoma was removed or biopsied, divided by total number of procedures) was calculated for each site and each endoscopist. Multiple regression models were used to examine the variation in ADR with withdrawal time and extent of examination, and the effect of other factors including comfort and bowel preparation on extent of examination. The analysis included 8256 procedures done between May 7, 2013, and May 6, 2014. The overall ADR was 9·1% (95% CI 8·5–9·8; 755 of 8256 procedures), varying from 7·4% (6·2–8·9) to 11·0% (9·1–13·4) by screening centre. The ADR was 11·5% (95% CI 10·6–12·5; 493 of 4299 procedures) in men and 6·6% (5·9–7·4; 262 of 3957 procedures) in women (p