Pump down the prep to pump up the uptake: dream or nightmare?Referring to Pisera A et al. p. 227–236
26.Februar 2019 (online)
Colorectal cancer (CRC) screening of average-risk individuals represents one of the most universal and strongest recommendations adopted in any national or international guideline . Unexpectedly, a substantial proportion of the target population does not participate in screening programs . It could be argued that this is not specific for CRC screening and that it is related to personal disbelief in the risk of developing cancer and the efficacy of the recommended interventions, or to attitudes such as fatalism, denial of CRC risk, and a low socio-economic status. Several interventions aimed at removing these barriers by engaging and motivating nonadherent individuals have been recommended, with variable and generally disappointing results .
“...before implementing a low-volume regimen in an organized program … a pragmatic verification of its effectiveness by monitoring and auditing the main quality indicators is necessary in a real-life setting…”
For CRC screening, however, there is a unique barrier that relates to the endoscopy community. Colonoscopy is still perceived as an invasive, painful screening procedure, generating irrational fears. Indeed, uptake is much higher for nonendoscopic (immunochemical fecal test) primary tests . Implementation of sedation protocols to reduce pain can address this barrier, as illustrated by the high uptake of primary screening colonoscopy in the United States that was associated with a boost of anesthesiologist-assisted colonoscopies .
A second major barrier to uptake in a colonoscopy-based screening program is poor tolerability of bowel preparation. This is directly related to the large volume of an isotonic agent (polyethylene glycol [PEG]) that is necessary to achieve adequate cleansing of the colon without causing electrolyte and volume imbalances. This question has been studied in this issue of Endoscopy by a nationwide randomized trial in Poland. The study compared the uptake of primary screening colonoscopy when a high- vs. low-volume preparation regimen was offered to average-risk eligible individuals who had not previously undergone colonoscopy . By analyzing 13 497 randomized individuals within the Polish screening program, the authors failed to show any increase in uptake between the group offered an ultra-low volume (300 mL sodium picosulfate/magnesium citrate) non-PEG solution and the group offered the high-volume 4 L PEG regimen, with participation rates of 16.6 % and 15.5 %, respectively .
This study clearly indicates that the volume of the bowel preparation in patients who have not undergone colonoscopy before is not the main determining factor in their decision to participate in a screening program. Thus, factors other than the volume of the cleansing regimens are responsible for the fact that approximately 85 % of the eligible Polish population actually refused participation . This does not necessarily preclude any effect between tolerability and screening uptake for surveillance endoscopy, but rather suggests the existence of a hierarchy between other technical and nontechnical factors and acceptability. For instance, an unexpected 30 % of colonoscopy-associated pain has been reported by Polish patients undergoing screening colonoscopy . These data are much more likely to affect the acceptability of colonoscopy than the volume of laxative. Secondly, the mail-based invitation system of the Polish program may be insufficient to address psychological or organizational barriers that prevent many people from accepting the recommended intervention. For instance, older age, male sex, and travel distance from the screening center appeared to predict participation, irrespectively of the chosen regimen . It is also important to emphasize that the Polish data did not assess acceptability of the bowel preparation as such. It is conceivable that this may be a crucial factor in the uptake of follow-up colonoscopy, as indicated in clinical trials . It would also be interesting to assess patients’ preferences when oral instructions are given and patients are offered a choice of bowel preparations.
The lack of increased uptake in the Polish trial does not mean that low-volume bowel preparations have not contributed to the evolution of colonoscopy. Meta-analysis of well-conducted randomized trials has shown improved tolerability for low-volume regimens, with equal efficacy and safety . Thus, if not a facilitator for screening participation, volume reduction is still a technical improvement with a positive impact on the patient experience, which is one of the European Society of Gastrointestinal Endoscopy (ESGE) key performance measures for colonoscopy and endoscopy services . The current study, however, underlines the difference between well-controlled and -monitored randomized trials, during which patients are given clear instructions on the use of a product, and a real-life situation where asymptomatic individuals receive written instructions for their procedure. In view of the evidence of the trials, it emphasizes the importance of giving clear instructions to motivate patients and also to select the correct patients for the correct bowel preparation. Indeed, chronic constipation is often an exclusion criterion for trials, but has a high prevalence in the general population.
With regard to quality of colonoscopy, the second main result of this Polish study is the difference in the quality of cleansing and the adenoma detection rates between high- and low-volume regimens when pragmatically implemented in a population-based screening program . Unexpectedly, the study showed clear inferiority of the low-volume regimen in the level of adequate cleansing (79.0 % vs. 86.4 %, respectively) . Benchmarked against an ESGE threshold of 90 %, the low-volume regimen is too far off target . In addition, the level of optimal cleansing, as rated by the highest values of the Boston Bowel Preparation Scale, appeared to be better for the high-volume arm . Even more worrisome, although less clear, is a higher detection rate, especially for proximal lesions, including advanced adenomas and serrated lesions, in favor of the high-volume bowel preparation . These data overall indicate that before implementing a low-volume regimen in an organized program based on the results of high-quality randomized trials, a pragmatic verification of its effectiveness by monitoring and auditing the main quality indicators is necessary in a real-life setting, where patients receive less rigid instructions and can be constipated.
In conclusion, the study by Pisera et al. indicates that in colonoscopy-naïve patients who are only informed by written instructions, the volume of the bowel preparation is not the main factor determining whether they proceed with screening colonoscopy . The low uptake of CRC screening in several European countries is unlikely to be reversed by a mere technical improvement of colonoscopy, but requires long-lasting complex and multidimensional interventions at the different levels of the national or regional health system.
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