Post-colonoscopy colorectal cancer in Belgium: characteristics and influencing factors

Abstract

Background and study aims Post-colonoscopy colorectal cancer (PCCRC) is an important quality parameter of colonoscopy. Most studies have shown that the risk for colorectal cancer is reduced after an index colonoscopy for screening or diagnostic purposes with or without polypectomy. In this study, we aimed to quantify and describe PCCRC in Belgium, including the possible relationships with patient, physician, and colonoscopy characteristics. Patients and methods Reimbursement data on colorectal related medical procedures from the Intermutualistic Agency (IMA-AIM) were linked with data on clinical and pathological staging of colorectal cancer (CRC) available at the Belgian Cancer Registry (BCR) over a period covering 9 years (2002 – 2010). Results In total, 63 518 colorectal cancers were identified in 61 616 patients between 2002 and 2010. We calculated a mean PCCRC rate of 7.6 %. PCCRC was significantly higher in older people and correlated significantly with polyp detection rate and the number of resections and procedures performed per year per physician. Conditional observed survival, given still alive 3 years since first colonoscopy, for PCCRC was worse than for CRC. Older patients and patients with invasive carcinomas had a worse outcome. Conclusions Although no quality register exists in Belgium, we were able to demonstrate that PCCRC in Belgium is directly related to the experience of the physician performing the procedure. In the absence of a quality register, utilization of population-based data sources proved to be a valuable tool to identify quality parameters.

Causes of Post-Colonoscopy Colorectal Cancers Based on World Endoscopy Organization System of Analysis

“…To account for lead-time bias, survival should be calculated from the date of index colonoscopy and not PCCRC diagnosis; however, there is an additional potential bias: immortal time bias. 5 Patients with PCCRC must survive in the interval between index colonoscopy and the diagnosis of PCCRC to be available for survival analysis. For example, if a patient has a false negative colonoscopy at time 0, and then dies for an unrelated reason at 1 year (before being diagnosed with PCCRC) he or she will not be included in PCCRC mortality data calculated from the index colonoscopy.…”

“…This would lead to falsely improved survival times in PCCRC cases. To avoid this "immortal time" bias, and to provide direct comparison with the results of the Belgium PCCRC study, 5 survival was calculated in patients still alive at 3 years and 4 years after index colonoscopy…”

“…Immortal time bias and lead-time bias were accounted for by ignoring deaths within 3 and 4 years of the index colonoscopy 5,19 : 1-year survival at 3 and 4 years from index colonoscopy was 76 (80%) of 95 and 59 (69.4%) of 85, respectively.…”

National post-colonoscopy colorectal cancer data challenge services to improve quality of colonoscopy

“…The World Endoscopy Organisation (WEO) has recently published a consensus paper on the taxonomy, investigation and reporting of PCCRC 2 aimed at both colonoscopy services and investigators. In the linked paper, Macken et al report national level data of PCCRC in Belgium, exploring characteristics of PCCRCs and factors associated with their development 3 . The Belgian investigators should be applauded for resisting the temptation to invent a new method of analyzing PCCRC rates.…”

Unacceptable variation in screening colonoscopy

“…Burr and colleagues highlight concerning heterogeneity in the quality of colonoscopies, as evidenced by differences in the incidence of post-colonoscopy cancers among patients using private and NHS providers 3. This heterogeneity is likely to affect outcomes,4 and will be of concern to patients, clinicians, and providers. The inconsistencies seem linked to training and accreditation processes and are therefore amenable to improvement.…”