Follow-up after colorectal polypectomy: a benefit-risk analysis of German surveillance recommendations

For colorectal screening patients a mean gain of life time was previously calculated of about 30-50 days. Different recommendations for recognising at-risk groups and defining surveillance intervals after an initial finding of colorectal adenomas have been published. However, no benefit-risk analysis regarding to specific long-term effects of follow-up has been reported to date.

A Markov model based on time-dependent transition possibilities was developed to perform a benefit-risk analysis of the risk-related surveillance recommendations based on the Erlangen Registry of Colorectal Polyps (ERCRP) in comparison with the recommendation of the German Society of Gastrointestinal Diseases and Nutrition (DGVS). The outcome was calculated for a 50-year-old patient with 30 years of follow-up after initial polypectomy. The data used in this model were taken from different sources, namely the ERCRP, the German Study Group of Colorectal Cancer, the German Statistical Yearbook, and from meta-analyses of studies reporting data on complications and sensitivity of colonoscopy.

Patients under surveillance have a mean lifetime gain of 98 (ERCRP) and 110 (DGVS) days compared with those who do not come for surveillance. 84% and 94% of deaths from colorectal carcinoma (CRC) could be prevented if patients were followed up according to the recommendations of the ERCRP and the DGVS, respectively. Less colonoscopies are needed to prevent one death from CRC following the recommendations of the ERCRP (221) than those of the DGVS (283). The risk of death due to colonoscopy for patients during follow-up is about 0.05% lifetime risk. Sensitivity analysis showed the stability of the results under a wide range of reasonable variations of relevant parameters. In a pessimistic one-way sensitivity analysis regarding compliance, effectiveness was reduced to one third.

Surveillance using colonoscopy is an effective tool for preventing CRC after colorectal polypectomy, especially if a good compliance is assumed. The effectiveness is higher following the recommendations of the DGVS, but more colonoscopies are needed.