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.
