ORIGINAL CONTRIBUTION Randomized Clinical Trial: A Normocaloric Low-Fiber Diet the Day Before Colonoscopy Is the Most Effective Approach to Bowel Preparation in Colorectal Cancer Screening Colonoscopy Marco A. Alvarez-Gonzalez, M.D., Ph.D.1,2 • Miguel A. Pantaleon, M.D.1,2 Juana A. Flores-Le Roux, M.D., Ph.D.2,3 • Diana Zaffalon, M.D.1 • Jaume Amorós4 Xavier Bessa, M.D., Ph.D.1,2 • Agustin Seoane, M.D.1 • Juan Pedro-Botet, M.D., Ph.D.2,3 On behalf of the PROCOLON group* 1 Department of Digestive Diseases, Hospital del Mar, Barcelona, Spain 2 Department of Medicine, Universitat Autònoma de Barcelona, Spain 3 Department of Endocrinology and Nutrition, Hospital del Mar, Barcelona, Spain 4 Faculty of Psychology and Educational Sciences, Universitat Oberta de Catalunya, Spain BACKGROUND: Clinical guidelines recommend either SETTINGS: The study was conducted at a tertiary care a clear-liquid diet or a low-fiber diet for colonoscopy center. preparation. Participants in a screening program are PATIENTS: A total of 276 consecutive participants of usually motivated healthy individuals in which a good the Barcelona colorectal cancer screening program were tolerability is important to improve adherence to included. potential surveillance colonoscopies. INTERVENTION: Participants were randomly assigned to OBJECTIVE: Our aim was to assess whether or not a a clear-liquid diet or a normocaloric low-fiber diet the normocaloric low-fiber diet followed the day before a day before the colonoscopy. Both groups received 4 L of screening colonoscopy compromises the efficacy of bowel polyethylene glycol in a split-dose regimen. cleansing and may improve the tolerability of bowel MAIN OUTCOME MEASURES: Primary outcome was preparation. the adequate bowel preparation rate measured with the DESIGN: This is a randomized, endoscopist-blinded, Boston bowel preparation scale. Secondary outcomes noninferiority clinical trial. included tolerability, fluid-intake perception, hunger, side effects, and acceptability. RESULTS: Participants in both groups were similar in Funding/Support: None reported. baseline characteristics. Adequate bowel preparation was Financial Disclosure: None reported. achieved in 89.1% vs 95.7% in clear-liquid diet and low- fiber diet groups, showing not only noninferiority, but also *Members of the PROCOLON research group are listed in the Acknowl- superiority (p = 0.04). Low-fiber diet participants reported edgments. less fluid-intake perception (p = 0.04) and less hunger (p = 0.006), with no differences in bloating or nausea. Correspondence: Marco A. Alvarez-Gonzalez, M.D., Ph.D., Diges- tive Endoscopy Unit, Hospital del Mar, Passeig Marítim, 25-29, 08003 LIMITATIONS: The single-center design of the study ­Barcelona, Spain. E-mail: marcoalgo@gmail.com could limit the external validity of the results. The present findings may not be comparable to other clinical settings. Dis Colon Rectum 2019; 62: 491–497 CONCLUSION: A normocaloric low-fiber diet the day DOI: 10.1097/DCR.0000000000001305 before a screening colonoscopy achieved better results Copyright © 2019 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Society of Colon and Rectal Surgeons. than a clear-liquid diet in terms of adequate colon This is an open-access article distributed under the terms of the Crea- preparation. Moreover, it also improved the perception tive Commons Attribution-Non Commercial-No Derivatives License of hunger and excessive fluid intake. Registered at 4.0 (CCBY-NC-ND), where it is permissible to download and share the clinicaltrials.gov: NCT02401802. See Video Abstract at work provided it is properly cited. The work cannot be changed in any http://links.lww.com/DCR/A829. way or used commercially without permission from the journal. DISEASES OF THE COLON & RECTUM VOLUME 62: 4 (2019) 491 492 ALVAREZ-GONZALEZ ET AL: DIET ADVICE FOR SCREENING COLONOSCOPY KEY WORDS: Bowel preparation; Colonoscopy; Hospital del Mar, Barcelona (4870/l). It was registered on Colorectal cancer screening. March 17, 2015 at clinicaltrials.gov (NCT02401802) B owel preparation is essential for the success of colon- Study Population oscopy; however, it is usually perceived as an extremely The study was performed at the Hospital del Mar, Bar- unpleasant part of the procedure and one of the ma- celona. Consecutive participants of the Barcelona CRC jor drawbacks for repeating the colonoscopy.1 Furthermore, screening program with a positive fecal blood immuno- a patient-perceived negative experience with bowel prepara- chemical test attending a protocol study appointment were tion is a predictor of both lower-quality bowel preparation invited to participate. Detailed data on the Barcelona CRC and a lower rate of polyp detection.2 General population screening program and the screening process has been de- acceptance of a screening colonoscopy depends on per- ception of its relative risks and benefits. Colorectal cancer scribed elsewhere.13 Exclusion criteria were: unwillingness (CRC) screening programs have raised the quality standards to participate, inability to follow instructions, incomplete on bowel preparation, demanding not only a high-quality colonoscopies for technical reasons or contraindicated by bowel cleansing, but also a good tolerability. The wide im- the endoscopist, and IBD. plementation of these programs has increased the expec- tations of participants who are healthy and asymptomatic; Treatment Allocation and Masking therefore, achieving optimum tolerability in the bowel prep- The allocation sequence was obtained by using a computer- aration process is mandatory to increase adherence to fol- generated block randomization table with a 1:1 allocation low-up colonoscopies and to promote general population rate. A research nurse randomly assigned consenting pa- uptake of the CRC screening program. Current guidelines tients to CLD or LFD, according to a randomization table, are very challenging in their recommendations for the rate assigned the bowel preparation diet, and facilitated self- of adequate bowel preparations in screening colonoscopy, administered questionnaires. At the time of the appointed suggesting rates of at least 90%. Nevertheless, the optimum colonoscopy, a researcher collected the questionnaires and diet recommendation for achieving this high standard in interviewed the participants. Five skilled endoscopists bowel preparation efficacy is not yet established.3 (>10,000 colonoscopies each) performed the colonosco- Traditionally, bowel preparation included a low-res- pies blinded to randomization. Endoscopists underwent a idue diet for several days, followed by a clear-liquid diet calibration exercise before the study in the use of the Bos- (CLD) the day before colonoscopy. Several recent ran- ton bowel preparation scale (BBPS) to improve consensus. domized clinical trials (RCTs) showed that a low-residue diet the day before the procedure may be as effective as a Interventions CLD, with slightly better tolerance.4–12 All participants were instructed by nurses on the impor- However, there were 2 main limitations in the pro- tance of bowel preparation and received verbal and written posed intervention in those RCTs. First, the amount of instructions on diet recommendations and laxative intake. fiber included in the proposed “low-residue diet” was ei- ther not specified or inadequate. Second, the dietary rec- All participants were given a dietary plan with a normo- ommendations given were usually hypocaloric and none caloric LFD, developed by an endocrinologist and a nutri- included a 5-meal balanced diet. tionist, to be started 4 days before the colonoscopy. In that Our study aimed to ascertain whether or not a nor- period they were also required to stop all fiber-based laxa- mocaloric, well-defined low-fiber diet (LFD) taken the day tives, allowing them to take other sorts of laxatives. The before a screening colonoscopy compromises the efficacy LFD was calculated to provide up to 2000 kcal/day with a of bowel cleansing and may improve the tolerability of mean dietary fiber content <10 g (Table 1). The LFD group bowel preparation. received instructions on continuing the LFD plan the day before the colonoscopy and were allowed to eat 5 meals, including breakfast, midmorning snack, lunch, midafter- PATIENTS AND METHODS noon snack, and dinner (Table 1), whereas CLD subjects Study Design received instructions on following a strict CLD 24 hours A randomized, single-blind, parallel group, noninferiority- before the procedure. controlled trial was conducted to compare the efficacy of a All study participants received 4 L of polyethylene gly- normocaloric LFD with a CLD the day before CRC screen- col solution in a split-dose fashion: 2 L in the evening of ing colonoscopy. The study protocol followed the Decla- the day before colonoscopy and 2 L in the morning start- ration of Helsinki ethical guidelines and was approved ing 5 hours before the procedure. All colonoscopies were on January 12, 2015 by the local ethics committee of the performed during the morning. DISEASES OF THE COLON & RECTUM VOLUME 62: 4 (2019) 493 TABLE 1. Barcelona diet plan for the day before colonoscopy: low-fiber diet group Meal Carbohydrate Protein Dairy products Breakfast 80 g of white bread or refined cereals Turkey breast (120 g) or ham (120 g) 1 glass (250 mL) milk or 2 full-fat (60 g) or 3 slices of white toast or cheese (60 g) yogurts (coffee at will is allowed) Snack 1 glass (250 mL) milk or 2 full-fat yogurts Lunch White rice (130 g) or plain white pasta Lean meat: beef (100 g) or pork or 1 full-fat yogurt (200 g) or peeled potatoes (fried, poultry (160 g) or fish (200 g) or baked, or boiled) (300 g) eggs (2 units) Snack 1 glass (250 mL) milk or 2 full-fat yogurts Dinner (6 P.M.) White rice (130 g) or plain white pasta Lean meat: beef (100 g) or pork or 1 full-fat yogurt (200 g) or peeled potatoes (fried, poultry (160 g) or fish (200 g) or baked, or boiled) (300 g) eggs (2 units) Choose 1 item of each group. (The maximum allowed quantity is indicated.) In each meal, 2 tablespoons of vegetable oil or an equivalent amount of butter are allowed. Outcome Measures A ­noninferiority margin of 6% was established to main- Our primary outcome was the rate of adequate bowel tain adequate bowel preparation with an LFD over 90%, as preparation measured with the BBPS.14 Adequacy was de- recommended in the clinical guidelines.3 The sample size fined as a colonoscopy with a score of 2 or 3 points in all resulted in 138 subjects per arm, with an α-risk of 0.05, colon segments.15 80% power, and an expected loss to follow-up of 5%. This Secondary outcomes were the adequate bowel prep- sample size calculation was estimated to provide noninfe- aration rate in the different segments of the BBPS (right, riority of LFD to CLD while achieving the recommended left, and transverse colon) and other colonoscopy quality minimum of 90% of adequate preparations for a screen- variables, tolerability, acceptability, and compliance with ing colonoscopy. the laxative intake. Other indicators of colonoscopy qual- All randomly assigned patients were included in the ity included cecal intubation rate, and whole, proximal, intention-to-treat (ITT) analysis. Missing efficacy data and distal colon polyp and adenoma detection rate in the were imputed as failures. Patients who fulfilled the bowel whole, proximal, or distal colon (related to the splenic preparation protocol and underwent the colonoscopy flexure). Tolerability of the bowel preparation was meas- were included in the per protocol (PP) analysis. ured rating hunger and patient volume perception, which For the primary outcome, a noninferiority test was were quantified using a 1 to 10 visual analogue scale (1 = performed. It was proven if the 1-sided 95% lower con- excellent and 10 = unbearable), and also with self-report- fidence limit for the difference between treatments was ed nausea or vomiting and bloating. We defined accept- ≥–6%. If noninferiority was met, a superiority test was ability as the patient´s willingness to use the same bowel performed. preparation protocol in a hypothetical new procedure. As for the secondary outcomes, the qualitative vari- Compliance was evaluated as mean laxative intake in liters ables were compared between groups by the Pearson χ2 and also as the proportion of patients imbibing at least 3 L test or Fisher test when appropriate. Quantitative variables (75%) of laxative. were compared using the Student t test for independent samples. Two-tailed p values of <0.05 were considered sta- Data Collection tistically significant. A research statistician performed the Information on age, sex, history of constipation (accord- analysis using Stata software version 13 (StataCorp, Col- ing to Rome III criteria), Charlson Comorbidity Index,16 lege Station, TX). and the endoscopist who performed the procedure were gathered in a personal interview and from medical charts. The participants completed self-administered question- RESULTS naires on hunger, volume perception, nausea, vomiting, The study was conducted between March 17 and June 30, and bloating during the bowel preparation process, and 2015. Figure 1 shows the flow diagram of patient recruit- acceptability and compliance with laxative intake. ment. All 276 eligible candidates were randomly assigned and included in the ITT analysis for efficacy. For the PP Statistical Analysis analysis, 9 participants (3%) were excluded after random- The sample size was calculated for a noninferiority test. ization: 6 in the CLD group and 3 in the LFD group, all Estimating 96% of adequate bowel preparation with for nonappearance at the colonoscopy appointment. Self- CLD was based on our previous data with our current administered questionnaires were collected in 249 cases CLD bowel preparation protocol (unpublished data). (90%). Both groups had comparable baseline character- 494 ALVAREZ-GONZALEZ ET AL: DIET ADVICE FOR SCREENING COLONOSCOPY Study flow chart 276 eligible candidates 276 randomly assigned 138 138 Liquid diet Low-fiber diet 6 Nonappearance for 3 Nonappearance for colonoscopy colonoscopy 132 135 Completed the study Completed the study FIGURE 1. Consolidated Standards of Reporting Trials flow diagram. istics and patients were equally distributed among endos- over the –6% considered for noninferiority. Furthermore, copists. Men accounted for 52% of participants (48% in the rate of adequate bowel preparation with LFD also at- CLD and 56% in LFD, p = 0.19) with a mean age of 59.9 tained statistical superiority, p = 0.04. years (60.1 in the CLD group and 59.9 in the LFD group, In the PP analysis, the rate of adequate bowel prepara- p = 0.83). The mean Charlson Comorbidity Index was 2.4 tion in the CLD group was 93.2% (95% CI, 87.5%–96.4%) (2.4 in CLD and 2.4 in LFD groups, p = 0.87), and 5.5% and 97.8% (95% CI, 93.7%–99.2%) in LFD participants. had a history of chronic constipation (6% in CLD and 5% The risk difference was 4.6% (CI 95%, –0.6% to 10.4%). LFD, p = 0.8). Noninferiority was proven as the lower confidence limit of the risk difference (–0.6%) that was over the –6% consid- Primary Outcome ered for noninferiority. The superiority test for LFD in the In the ITT analysis, the adequate bowel preparation rate PP analysis was not proven (p = 0.07). was 89.1% (95% CI, 82.8–93.3) in the CLD group and There were no statistically significant differences in 95.7% (95% CI, 90.8–98) in the LFD group (Table 2). The the adequacy scoring between endoscopists (Fisher exact lower CI limit for adequate bowel preparation was >90% test, p = 0.393). in the LFD group but not in the CLD group. The risk dif- ference between groups was 6.5% (95% CI, 0.2%–13.2%). Secondary Outcomes Noninferiority was demonstrated for LFD since the lower Both ITT and PP analyses showed no statistical differences confidence limit of the risk difference was 0.2%, which was in adequate bowel preparation in the different segments TABLE 2.   Primary and secondary efficacy outcome measures: intention-to-treat analysis CLD group LFD group Risk difference Variable n = 138 n = 138 % (95% CI) p Adequate bowel preparation, n (%) 123 (89) 132 (96) 6.5 (0.2 to 13.2) 0.041 BBPS ≥2, n (%)  Right colon 126 (91) 132 (96) 4.3 (–1.6 to 10.7) 0.144  Transverse colon 131 (95) 133 (96) 1.4 (–4 to 6.9) 0.56  Left colon 126 (91) 133 (96) 5.1 (–0.8 to 11.3) 0.08 Cecal intubation rate, n (%) 131 (95) 133 (96) 1.4 (–3.8 to 6.9) 0.56 Whole-polyp detection rate, n (%) 86 (62) 100 (72) 10.1 (–0.9 to 20.9) 0.07 Proximal colon polyp detection rate, n (%) 60 (43) 65 (47) 3.6 (–8 to 15.3) 0.545 Distal colon polyp detection rate, n (%) 58 (42) 72 (52) 10.1 (–1.6 to 21.5) 0.091 Overall adenoma detection rate, n (%) 69 (50) 82 (59) 9.4 (–2.3 to 20.8) 0.116 Proximal adenoma detection rate, n (%) 49 (36) 49 (36) 0 (–11.1 to 11.1) 1 Distal adenoma detection rate, n (%) 43 (31) 58 (42) 10.9 (–0.5 to 21.8) 0.061 CLD = clear-liquid diet; LFD = low-fiber diet; BBPS = Boston bowel preparation scale. Bolded values are statistical significant. DISEASES OF THE COLON & RECTUM VOLUME 62: 4 (2019) 495 TABLE 3.   Tolerability, acceptability, and compliance CLD group LFD group Variable n = 138 n = 138 p Hunger, VAS, mean (95% CI) 4.5 (4.1–5) 3.5 (3.1–4) 0.003 Excessive volume perception, VAS, mean (95% CI) 6.9 (6.5–7.3) 6.2 (5.7–6.7) 0.03 Bloating, VAS, mean (95% CI) 3.3 (2.9–3.8) 3.3 (2.8–3.7) 0.8 Nausea or vomiting, VAS, mean (95% CI) 2.3 (1.9–2.7) 1.6 (1.2–2) 0.02 Acceptability, n (%) 106 (86) 112 (89) 0.5 Laxative intake, liters, mean (95% CI) 3.2 (3.1–3.4) 3.4 (3.3–3.6) 0.07 Laxative intake ≥3 L, n (%) 96 (78) 110 (88) 0.037 CLD = clear-liquid diet; LFD: = low-fiber diet; BBPS = Boston bowel preparation scale; VAS = visual analogue scale (1 = excellent, 10 = unbearable). Bolded values are statistical significant. of the BBPS, cecal intubation rate, adenoma detection rate lished RCTs, the amount of fiber in the recommended diet (ADR), and polyp detection rate in the whole, proximal, and was not specified.4,5,7–12 Only 1 RCT indicated the amount distal colon. Table 2 shows the results of the ITT analysis. of fiber included in the diet; however, the quantity is 32 g/ Hunger, volume perception, and nausea/vomiting day, well above the 10-g limit recommendation.6 It should scores were significantly lower in the LFD group. No dif- be pointed out that the fiber content in our proposed diet ferences were found in bloating or acceptability. Regarding plan was <10 g/day. compliance, a slight increase was observed in mean laxative On the other hand, all the proposed diets were hy- intake in the LFD group, but without achieving statistical pocaloric, ranging from 1000 to 1200 kcal/day. The rec- significance (p = 0.07); however, the number of patients ommended caloric intake for a middle-aged adult varied completing at least 3 L (75%) of laxative was higher in the between 1800 and 2100 kcal/day, as calculated with the LFD group than in the CLD group (p = 0.04) (Table 3). Harris-Benedict formula.19 In the present study, a full diet with a mean caloric intake of up to 2000 kcal/day was in- cluded. A normocaloric diet could facilitate patient adher- DISCUSSION ence to the recommendations. In a randomized trial conducted within an organized CRC Another significant flaw of most of the published screening program, a normocaloric LFD the day before co- RCTs is the lack of information on what truly defines lonoscopy achieved not only noninferior efficacy, but also “adequacy.” Guidelines define adequate bowel prepara- superiority for adequate bowel preparation compared with tion if the endoscopist is able to identify polyps >5 mm.20 a CLD. In addition, our dietary intervention associated A study by Clark et al15 aimed at quantifying adequate improved tolerability with less hunger and volume percep- bowel cleansing for surveillance or screening colonoscopy tion. No differences were found in other quality parameters concluded that those with BBPS scores ≥2 for every co- of colonoscopy, such as cecal intubation rate, polyp detec- lon segment have adequate bowel preparation. Six of the tion rate, or ADR in whole colon or right-sided colon. studies did not use the BBPS, which is the most rigorously A normocaloric LFD the day before colonoscopy validated bowel preparation scale.4–8,11 Furthermore, the 3 achieved a higher quality of bowel preparation than a CLD. RCTs that used the BBPS either did not report a minimum The efficacy of an LFD versus a CLD the day before colon- score for the definition of adequate preparation,9 or used oscopy has been evaluated in previous studies, but their an overall score without establishing a minimum score for results were dissimilar. In this respect, 8 RCTs found no each colon segment.10,12 significant differences in terms of efficacy,4–6,8–12 whereas Finally, the use of a split-dose protocol was systemat- 1 RCT reported better efficacy with LFD.7 Nevertheless, ically used in only 4 studies.4,9,10,12 The split-dose regimen that study had an unacceptably low rate of adequate bowel is the only intervention that has been demonstrated to im- preparation in the CLD group (52%). prove both bowel preparation quality and ADR.21 Those RCTs had several limitations that should be Another salient aspect of the present study was the mentioned. On the one hand, the definition of LFD varied recruited population. Earlier RCTs focused on a mixed across studies. Most referred to a low-residue diet instead population of symptomatic, screening, and surveillance of a LFD. Recently, the term low-residue diet has been re- colonoscopies. The analysis of 8 previous studies of an moved from nutritional clinical guidelines given the lack unselected population4,5,7–12 shows that 87% (629/723) of consensus in its quantitative definition.17 Because the of participants in the LFD group had an adequate bowel only component of fecal residue present in the diet is preparation, compared with 83% (586/704) of participants dietary fiber, it has been proposed to substitute the term in the CLD group. Although there may be a slight trend to- low-residue diet with LFD and to quantitatively define a ward a better efficacy in the LFD group, in the pooled a- maximum of 10 g fiber/day for an LFD.18 In 8 of the 9 pub- nalysis there were no statistically significant differences in 496 ALVAREZ-GONZALEZ ET AL: DIET ADVICE FOR SCREENING COLONOSCOPY efficacy between both groups.22 Our study included only Our study was not limitation-free. First, the single- participants in an organized colorectal screening program center design of the study could limit the external validity based on fecal immunochemical testing (FIT). The ran- of the results. Nevertheless, the selection criteria for this domized setting, coupled with the highly controlled and trial were not restrictive and the results may thus apply homogeneous population included, also brought the in- to any FIT-based screening program population. Further- itial findings on such an association shown in previous more, the present findings may not be generalizable to studies to a higher level of evidence. Moreover, in a CRC other clinical settings. We did not measure participant’s screening program, the need for a high standard of bowel compliance with the proposed diet. Finally, we used a non- cleanliness is crucial because the findings of the index co- validated questionnaire for symptoms, a common limita- lonoscopy will determine the interval for the follow-up tion in most studies on bowel preparation. colonoscopy. It should be pointed out that a previous study demon- strated that an LFD adapted to diabetic patients, together CONCLUSIONS with an educational intervention before colonoscopy, im- This trial showed that a normocaloric LFD the day before proved bowel cleanliness.23 a screening colonoscopy achieves better results in terms Fecal residue is composed from nonabsorbable fi- of adequate colon preparation and tolerability than a ber as well as dead cells, mucus, and bacteria. During the CLD. We conclude that a LFD the day before colonoscopy bowel preparation process, all that matter has to be re- should be considered the most effective approach to bowel moved from the colon. There are some explanations that preparation in CRC screening colonoscopy. may justify why patients on a LFD the day before the co- lonoscopy achieve better cleansing. First, a strict CLD is difficult to follow and compli- ACKNOWLEDGMENTS ance may be suboptimal; nevertheless, we did not meas- We thank as contributors all the registered nurses who partic- ure patient´s compliance in study groups and we cannot ipated in the study: Gemma Casals, Montserrat Bonilla and confirm this hypothesis. Second, a strict CLD may im- Ines Ibañez. We also thank as contributor Dr Agnés Fernán- pair bowel peristalsis, resulting in ineffective evacuation dez-Clotet who was involved in critical revision for intellec- of fecal residue. In fact, because an LFD adds little fecal tual content of the manuscript. We thank Christine O’Hara residue, another possible complementary explanation for review of the English version of the manuscript. is that the total balance of fecal evacuation is improved PROCOLON is a group of investigators conducting re- with this diet. search in the frame of the Barcelona colorectal cancer screen- Although efficacy is the leading factor in bowel prep- ing program, and includes the following members: Rafael aration, patient tolerability is also important. Participants Abós-Herrándiz, Jaume Grau, Eva Abril, Marta Aldea, Cris- in the LFD group reported less hunger, perception of ex- tina Álvarez, Marco Antonio Alvarez-Gonzalez, Montserrat cessive volume intake, and nausea or vomiting, and bet- Andreu, Isis Araujo, Josep M. Augé, Anna Aymar, Guillermo ter compliance with the laxative intake. In the setting of a Bagaria, Francesc Balaguer, Xavier Bessa, Montserrat Bonilla, screening colonoscopy, tolerability is a major concern be- Andrea Burón, Sabela Carballal, Xavier Castells, Antoni Cas- cause participants are asymptomatic, relatively young, and tells, Rosa Costa, Míriam Cuatrecasas, Maria Pellisé, Mercè apparently healthy, and patient experience is important Comas, Josep M. Dedeu, Imma Garrell, Maria Estrada, Jordi for both general uptake of the program and compliance Gordillo, Rafael Guayta, Mar Iglesias, Leticia Moreira, Cris- with future follow-up colonoscopies. tina Hernández, Laura Llovet, María López-Cerón, Francesc We found no differences in other colonoscopy quality Macià, Lorena Moreno, Gemma Navarro, Teresa Ocaña, Mer- parameters, such as ADR and the cecal intubation rate, al- cè Pintanell, Àngels Pozo, Cristina Rodríguez, Teresa Puig, though a tendency toward a higher polyp detection rate, in Faust Riu, Liseth Rivero-Sánchez, Maria Sala, Ariadna Sán- particular, for distal polyps and adenomas, was observed. chez, M. Francisca Murciano, Antoni Trilla, Agustín Seoane, Note the high yield of ADR in our population, which is Judit Sivilla, Anna Serradesanferm, Isabel Torà. in accordance with other FIT-positive average screening population studies.24 Several studies with a large sample size found that bowel cleanliness increased ADR, although REFERENCES the present study was underpowered to detect differences 1. Ko CW, Riffle S, Shapiro JA, et al. Incidence of minor compli- in ADR.25,26 cations and time lost from normal activities after screening or To our knowledge, this is the largest clinical trial surveillance colonoscopy. Gastrointest Endosc. 2007;65:648–656. evaluating a well-structured dietary intervention in bowel 2. Holt EW, Yimam KK, Ma H, Shaw RE, Sundberg RA, Verhille preparation for colonoscopy. Moreover, it is also the only MS. Patient tolerability of bowel preparation is associated with clinical trial including a very homogeneous population polyp detection rate during colonoscopy. 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