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BACKGROUND AND STUDY AIM: High quality colonoscopy requires low complication rates. However in quality assurance, evaluation of individual colonoscopist complication rates is limited because complications are relatively rare events and there is variation in average procedure complexity. The aim of the study was to develop a quality system that adjusted for procedure complexity to monitor bleeding adverse events at both the screening center and colonoscopist levels. METHODS: The study examined the risk factors for post-procedure bleeding from 130 831 colonoscopies conducted between August 2006 and January 2012. Binomial and logistic regression models were used to examine the risk of events against explanatory variables including age, sex, polyps resected, and polyp size. The models were used to produce a procedure-adjusted standardized adverse event ratio (PASAER) based on the ratio of the observed to expected number of adverse events. The primary outcome of interest was to identify centers that were outside a funnel plot outlier level of 99.8 % (3 SDs). RESULTS: Mulivariate models showed that the risk of bleeding was associated with largest resected polyp size, sex, polyp location, and degree of co-morbidity. These variables were used to calculate PASAERs for the 59 screening centers and 286 colonoscopists. The method highlighted one center with a high PASAER of 3.08 (32 observed compared with 10.4 expected events) and one with a low PASAER of 0.34 (10 observed compared with 29.8 expected events), which merited further investigation. CONCLUSIONS: The PASAER provided additional certainty that a crude adverse event rate was not confounded by procedure complexity, thus objectively identifying centers or colonoscopists that required further performance evaluation.

Original publication




Journal article



Publication Date





910 - 916


Aged, Clinical Competence, Colonic Polyps, Colonoscopy, Female, Follow-Up Studies, Humans, Incidence, Male, Postoperative Hemorrhage, Quality Indicators, Health Care, Retrospective Studies, Risk Assessment, Risk Factors, United Kingdom