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.

Fig. 1

Patient flow chart.

Fig. 2

Calculation of post-colonoscopy colorectal cancer (PCCRC).

Fig. 3

Bar chart of PCCRC rate according to patient, procedure, and tumor characteristics. Black bars indicate groups that differ significantly from the reference groups. Reference groups are defined as groups with the lowest a priori expected PCCRC (so the expected odds ratios are greater than 1).

Fig. 4

Differences in PCCRC rates among physicians with: left panel: different polyp detection rates (PDR); middle panel: different numbers of resections performed on a yearly basis; right panel: different numbers of full procedures performed on a yearly basis. Mean PCCRC (SE) rates indicated in gray differ significantly from those indicated in black, supporting a significantly higher PCCRC rate for physicians with PDR below 20 % (left panel), with less than 80 resections performed per year (middle panel), and with less than 225 full procedures performed per year (right panel).

Fig. 5

Funnel graph of: left panel: between-physician variation in PCCRC rates for physicians with more than 50 colonoscopies (TP + FN) (χ ²  = 476, degrees of freedom = 215, P  < 0.0001); right panel: between-hospital variation in PCCRC rates for hospitals with more than 100 colonoscopies (TP + FN) (χ ²  = 288, degrees of freedom = 91, P  < 0.0001). Solid and dashed lines reflect 95 % and 99 % prediction bands, respectively. The horizontal line represents the average PCCRC rate across all physicians (left) or hospitals (right).

Fig. 6

Conditional survival analysis (Kaplan – Meier curve uncorrected for other covariates ( Table 3 )) for all patients still alive 3 years after date of first colonoscopy (year 0 on x axis).