Case-mix adjustment to compare colonoscopy performance between endoscopy centers: a nationwide registry study

Abstract

Background: Non-modifiable patient and endoscopy characteristics might influence colonoscopy performance. Differences in these so-called case-mix factors are likely to exist between endoscopy centres. This study aims to examine the importance of case-mix adjustment when comparing performance between endoscopy centres. Methods: Prospectively collected data recorded in the Dutch national colonoscopy registry between 2016-2019 were retrospectively analyzed. Performance on cecal intubation rate (CIR) and adequate bowel preparation rate (ABPR) were studied. Additionally, polyp detection rate (PDR) was studied in fecal immunochemical test (FIT)-positive screening colonoscopies. Variation in case-mix factors between endoscopy centres and expected outcomes for each performance measure were calculated per endoscopy centre, based on their case-mix factors (sex, age, ASA score, indication), using multivariable logistic regression. Results: In total, 363,840 colonoscopies were included from 51 endoscopy centres. The mean percentages per endoscopy centre were significantly different for age > 65 years, male patients, ASA > III and diagnostic colonoscopies (all p < 0.001). In the FIT-positive screening population, significant differences were observed per endoscopy centre for age > 65 years, male patients and ASA > III (all p value < 0.001). The expected CIR, ABPR and PDR ranged from 95.0% to 96.9%, from 93.6% to 96.4% and from 76.2% to 79.1%, respectively. Age, sex, ASA classification and indication were significant case-mix factors for CIR and ABPR. In the FIT-positive screening population, age, sex and ASA classification were significant case-mix factors for PDR. Conclusion: Our findings emphasize that when comparing colonoscopy performance measures between endoscopy centres, case-mix adjustment should be considered.

Quality assurance in colonoscopy: is case mix a problem?

“…There are concerns that case-mix differences may lead to erroneous categorization of performance of endoscopy centers and individual endoscopists. In this issue of Endoscopy , Nass et al report on case-mix adjustments in a national registry study from the Netherlands, including 51 endoscopy centers and more than 363 000 colonoscopies (approximately 183 000 diagnostic, 100 000 surveillance, and 80 000 work-up colonoscopies after a positive fecal immunochemical test [FIT]) 7 . Patient age and sex, American Society of Anesthesiology (ASA) classification, and indication for colonoscopy were significant case-mix factors for CIR and ABPR, and they varied between centers.…”