Variation in post-colonoscopy colorectal cancer across colonoscopy providers in English National Health Service: population based cohort study

Abstract

Objectives: To quantify post-colonoscopy colorectal cancer (PCCRC) rates in England by using recent World Endoscopy Organisation guidelines, compare incidence among colonoscopy providers, and explore associated factors that could benefit from quality improvement initiatives.

Design: Population based cohort study.

Setting: National Health Service in England between 2005 and 2013.

Population: All people undergoing colonoscopy and subsequently diagnosed as having colorectal cancer up to three years after their investigation (PCCRC-3yr).

Main outcome measures: National trends in incidence of PCCRC (within 6-36 months of colonoscopy), univariable and multivariable analyses to explore factors associated with occurrence, and funnel plots to measure variation among providers.

Results: The overall unadjusted PCCRC-3yr rate was 7.4% (9317/126 152), which decreased from 9.0% in 2005 to 6.5% in 2013 (P<0.01). Rates were lower for colonoscopies performed under the NHS bowel cancer screening programme (593/16 640, 3.6%), while they were higher for those conducted by non-NHS providers (187/2009, 9.3%). Rates were higher in women, in older age groups, and in people with inflammatory bowel disease or diverticular disease, in those with higher comorbidity scores, and in people with previous cancers. Substantial variation in rates among colonoscopy providers remained after adjustment for case mix.

Conclusions: Wide variation exists in PCCRC-3yr rates across NHS colonoscopy providers in England. The lowest incidence was seen in colonoscopies performed under the NHS bowel cancer screening programme. Quality improvement initiatives are needed to address this variation in rates and prevent colorectal cancer by enabling earlier diagnosis, removing premalignant polyps, and therefore improving outcomes.

Fig 1

Trends in unadjusted rates of post-colonoscopy colorectal cancer within three years of investigation (PCCRC-3yr) for each year of colonoscopy. Top panel: all colonoscopies, “non-surveillance,” and UK bowel cancer screening programme (BCSP). Bottom panel: colonoscopies in people with an admission code for inflammatory bowel disease. “Non-surveillance” colonoscopies are those in people not diagnosed as having inflammatory bowel disease and those not performed within the BCSP

Fig 2

Unadjusted variation in rates of post-colonoscopy colorectal cancer within three years of investigation (PCCRC-3yr) by provider for 2005-07, 2008-10, and 2011-13. In funnel plots each dot represents an individual colonoscopy provider. Dashed lines represent 95% and 99.8% control limits outside national PCCRC-3yr rate (solid line). X axis is number of detected cancers plus PCCRC-3yr cancers diagnosed in the period. Yellow dots indicate providers who diagnosed less than 96 cancers in the given period. Hollow dots represent independent colonoscopy providers

Fig 3

Adjusted variation in rates of post-colonoscopy colorectal cancer within three years of investigation (PCCRC-3yr) by provider for 2005-07, 2008-10, and 2011-13. In funnel plots each dot represents an individual colonoscopy provider. Dashed lines represent 95% and 99.8% control limits outside national PCCRC-3yr rate (solid line). X axis is number of detected cancers plus PCCRC-3yr cancers diagnosed in the period. Adjusted for non-modifiable risk factors: year of colonoscopy, age group at colonoscopy, sex, index of multiple deprivation income category (fifths), comorbidity score, previous Hospital Episode Statistics coded diagnosis of inflammatory bowel disease or diverticular disease, previous colorectal cancer, previous colonoscopy, and whether the colonoscopy was within English NHS bowel cancer screening programme or by independent provider. Yellow dots indicate providers who diagnosed less than 96 cancers in the given period. Hollow dots represent independent colonoscopy providers