Reply to Chiu et al. and Lasa et al.

We thank Dr. Chiu et al. for their thoughtful comments on the classification of flat polyps in our large, nationwide screening colonoscopy study [1]. As stated in our discussion, we agree that a major limitation of the study was the lack of further more detailed classification of flat polyps to distinguish between flat depressed and other flat polyps. Nevertheless, the flat polyp detection rate included depressed polyps, as the endoscopists were asked to classify flat and depressed lesions (Paris 0-IIa, 0-IIb, 0-IIc) together. Therefore, these lesions were indeed not described separately and statistically evaluated, but neither were they neglected. As discussed, the aim of the study was to estimate the risk of all flat polyps with regard to high grade dysplasia in screening colonoscopy, irrespective of their location. Furthermore, as we have pointed out in the paper, the macroscopic classification of a lesion is based on the endoscopist’s interpretation and remains subjective. Regarding the training of the participants, only endoscopists who were performing at least 100 colonoscopies and 10 polypectomies per year participated in the project. The goal of the study was not to show the effects of training in the detection of flat lesions, but to evaluate “the real life” data from screening colonoscopy. In our opinion, most of the screening colonoscopies in Europe are performed in general, rather than specialized centers, or in private practice. Thus, we think that the study design, in particular, has a strong advantage; the study included 52 000 patients, which provides the opportunity to present a representative overview of colonoscopy in daily practice. We consider our results to therefore be a valuable contribution to epidemiology data and screening colonoscopy outcome.

We would also like to thank Dr. Lasa et al. for very clear comments on our paper. In our study the correlation of flat polyp detection rate (FPDR) with adenoma detection rate was weak (r = 0.24), but nonetheless significant. Further studies are certainly needed to test Lasa’s assumption of FPDR as a practical quality index and we hope that our data can serve as one of the first steps towards the definition of a minimum flat adenoma detection rate as a quality control parameter. In this context we would also greatly appreciate more investigations that define and evaluate colonoscopy quality parameters, as it is now obvious that quality controlled procedures represent a major step forward in the detection of (pre-)malignant lesions in order to reduce the morbidity and mortality from colorectal cancer [2].

• References

• 1 Reinhart K, Bannert C, Dunkler D et al. Prevalence of flat lesions in a large screening population and their role in colonoscopy quality improvement. Endoscopy 2013; 45: 350-356
• 2 Kaminski MF, Regula J, Kraszewska E et al. Quality indicators for colonoscopy and the risk of interval cancer. N Engl J Med 2010; 362: 1795-1803