Initiatives to increase colonoscopy capacity - is there an impact on polyp detection? A UK National Endoscopy Database analysis.

Background Mismatch between routine endoscopy capacity and demand means centres often implement initiatives to increase capacity, such as weekend working or using locums/agency staff (insourcing). There are concerns about whether increasing workload to meet demand could negatively impact quality. We investigated polyp detection, a key quality metric, in weekend vs weekday and insourced vs standard procedures using data from the UK National Endoscopy Database (NED). Methods We conducted a national retrospective cross-sectional study of diagnostic colonoscopies undertaken 01/01-04/04/2019. The primary outcome was mean number of polyps (MNP) and the secondary, polyp detection rate (PDR). Multi-level mixed-effect regression, fitting endoscopist as a random effect, was used to examine associations between procedure day (weekend/weekday) and type (insourced/standard) and these outcomes, adjusting for patient age, sex and indication. Results 92,879 colonoscopies (weekends: 19,977 (21.5%); insourced: 9,909 (10.7%)) were performed by 2,496 endoscopists. For weekend colonoscopies, patients were more often female and less often having screening-related procedures; for insourced colonoscopies, patients were younger and less often attending for screening-related procedures (all p<0.05). Case-mix adjusted MNP was significantly lower for weekend vs weekday (IRR=0.86, (95%CI 0.83-0.89)) and for insourced vs standard procedures (IRR=0.91, (95%CI 0.87-0.95)). MNP was highest for weekday standard procedures and lowest for weekend insourced procedures, but there was no interaction between procedure day and type. Similar associations were found for PDR. Conclusions Strategies to increase colonoscopy capacity may have adverse effects on polyp detection. Routine quality monitoring should be undertaken following such initiatives. Meantime, reasons for this unwarranted variation require investigation.