Quality indicators for colonoscopy: Current insights and caveats

Table 1 Quality indicators and their shortcomings

Quality indicator	Proposed standard	Unresolved issues
Bowel preparation	Each endoscopy report should state the quality of the bowel preparation[18,19] ≥ 90% of patients undergoing colonoscopy should have had a bowel preparation rated as excellent or at least adequate[19,20]	No evidence to support a cut-off of ≥ 90% No clear and generally accepted definition of adequate bowel preparation Unclear what bowel preparation quality is the absolute minimum to detect relevant findings and prevent interval cancers No clear policy on how to proceed in case of inadequate bowel preparation
Cecal intubation rate	Overall cecal intubation rate of ≥ 90%[18-20] Adjusted cecal intubation rate of ≥ 95%[18,19] Cecal intubation rate of ≥ 95% in all screening colonoscopies[18,19]	No robust scientific evidence to support a cut-off of ≥ 90% No evidence supporting an association between cecal intubation rate and the occurrence of interval CRC
Withdrawal time	≥ 6 min on withdrawal from cecal pole to anus[18-20]	Conflicting reports on the association between withdrawal time and the number of detected polyps Interventions directed at optimizing withdrawal time have yielded conflicting results No evidence supporting an association between withdrawal time and the occurrence of interval CRC Better endoscopic withdrawal technique is not necessarily associated with withdrawal time An indirect measure to quantify the proportion of the colonic mucosa that is adequately visualized
Adenoma detection rate	≥ 25% in men and ≥ 15% in women over 50 yr[18] ≥ 35% of all screening colonoscopies in patients with a positive fecal occult blood testing[19]	The only quality indicator that has been shown to be directly associated with interval CRC Does not discriminate between subjects in whom the endoscopist detects one vs more than one adenoma Does not optimally differentiate between high- and low-performing endoscopists
Patient comfort and sedation	Routinely reporting and monitoring of patient comfort scores and sedation dosages[19,20]	Until recently no validated patient comfort score was available Not yet clear what patient comfort scores are considered acceptable The endoscopist, the nurse and the patient may have different opinions about the level of comfort during the procedure No gold standard regarding sedation during colonoscopy No validated score to assess the level of sedation during colonoscopy
Complication rate	Perforation in < 1:1000 colonoscopies[18-20] Post-polypectomy bleeding in < 1:100 colonoscopies with polypectomy[18,19]	Consensus based Complication rate is mainly dependent on the number of therapeutic colonoscopies, which may vary between screening strategies (colonoscopic screening of the entire population vs selection of high-risk individuals through fecal occult blood testing)

CRC: Colorectal cancer.

Table 2 Potential measures to improve performance per quality indicator

Quality indicator	Potential intervention to improve performance	Strength of scientific evidence
Bowel preparation	Split dose bowel preparation Last ingested dose of PEG-solution 3-5 h before colonoscopy	Meta-analysis of randomized controlled trials Observational, prospective studies
Cecal intubation rate	Additional training and use of auxiliary endoscopic instruments (e.g., pediatric colonoscope)	Expert opinion
Adenoma detection rate	Endoscopy nurse participation as a second observer Perform colonoscopy in the morning or in half-day blocks High definition colonoscopy (compared to standard video colonoscopy, marginal effect) Cap-assisted colonoscopy (marginal effect) Third-Eye Retroscope Full Spectrum Endoscopy	Randomized, multicenter studies Retrospective studies Meta-analysis Meta-analysis of randomized controlled trials Randomized, multicenter study Randomized, multicenter study
Complication rate	Cold snaring of small, non-pedunculated polyps may prevent bleeding	Prospective, multicenter, observational study and small single center randomized controlled study
	Submucosal injection with saline and epinephrin prevents immediate bleeding	Randomized study
	Prophylactic placement of a detachable snare around the stalk of a pedunculated polyp prevents bleeding	Randomized studies
	Prophylactic closure of the polypectomy site with metallic clips after removal of large (> 2 cm) sessile or flat lesions may prevent bleeding	Retrospective study