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Original article
Telephone-based re-education on the day before colonoscopy improves the quality of bowel preparation and the polyp detection rate: a prospective, colonoscopist-blinded, randomised, controlled study
  1. Xiaodong Liu1,
  2. Hui Luo1,
  3. Lin Zhang1,
  4. Felix W Leung2,3,
  5. Zhiguo Liu1,
  6. Xiangping Wang1,
  7. Rui Huang1,
  8. Na Hui1,
  9. Kaichun Wu1,
  10. Daiming Fan1,
  11. Yanglin Pan1,
  12. Xuegang Guo1
  1. 1Xijing Hospital of Digestive Diseases, Fourth Military Medical University, Xi'an, Shannxi, China
  2. 2Sepulveda Ambulatory Care Center, Veterans Affairs Greater Los Angeles Healthcare System, North Hill, California, USA
  3. 3David Geffen School of Medicine, UCLA, Los Angeles, California, USA
  1. Correspondence to Professor Xuegang Guo or Yanglin Pan, Xijing Hospital of Digestive Diseases, Fourth Military Medical University, 169 Changle West Road, Xi'an, Shannxi 710032, China; xuegangguo{at}gmail.com or panyanglin@gmail.com

Abstract

Background Despite advances in bowel preparation methods, the quality of bowel preparation in some patients undergoing colonoscopy remains unsatisfactory. The effect of telephone re-education (TRE) on the day before colonoscopy on the quality of bowel preparation and other outcome measures had not been studied.

Methods A prospective colonoscopist-blinded study was conducted. All patients received regular instructions during a visit to discuss colonoscopy. Those scheduled for colonoscopy were randomly assigned to receive TRE on the day before colonoscopy (TRE group) for bowel preparation or no TRE (control group). The primary outcome was the rate of adequate bowel preparation. The secondary outcomes included polyp detection rate (PDR), non-compliance with instructions, and willingness to repeat bowel preparation.

Results A total of 605 patients were randomised, 305 to the TRE group and 300 to the control group. In an intention-to-treat analysis of the primary outcome, adequate preparation was found in 81.6% vs 70.3% of TRE and control patients, respectively (p=0.001). PDR was 38.0% vs 24.7% in the TRE and control group, respectively (p<0.001). Among patients with successful colonoscopy, the Ottawa scores were 3.0±2.3 in the TRE group and 4.9±3.2 in the control group (p<0.001). Fewer patients who showed non-compliance with instructions were found in the TRE group (9.4% vs 32.6%, p<0.001). No significant differences were observed between the two groups with regard to willingness to have a repeat bowel preparation (p=0.409).

Conclusions TRE about the details of bowel preparation on the day before colonoscopy significantly improved the quality of bowel preparation and PDR.

  • COLONOSCOPY

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Significance of this study

What is already known on this subject?

  • Colonoscopy is currently the gold standard in luminal diagnosis of lesions of the colorectum. The success of colonoscopy depends on high-quality bowel preparation.

  • Inadequate bowel preparation results in more incomplete visualisation of the colon, missed lesions (22–48%), procedural difficulties, prolonged procedure time and reduced interval to follow-up.

  • Several methods have been tried to enhance patient education and compliance with instructions for bowel preparation. However, the results are inconsistent.

What are the new findings?

  • Telephone re-education (TRE) about the details of bowel preparation on the day before colonoscopy increases the quality of bowel preparation and the rate of detection of polyps.

  • The day before colonoscopy is an appropriate time to intervene to ensure better compliance with bowel preparation instructions.

How might it impact on clinical practice in the foreseeable future?

  • No matter which method of bowel preparation is chosen, better quality bowel preparation, more detection of lesions and fewer difficulties during the procedure would be achieved during colonoscopy through telephone-based re-education on the day before colonoscopy.

  • More adequate bowel preparation through TRE might increase the efficacy of the colonoscopy screening programme and decrease overall colonoscopy cost.

Introduction

Despite advances in bowel preparation methods,1 bowel preparation is inadequate in up to one-third of all colonoscopies in reported series.2–6 Inadequate bowel cleansing results in negative consequences for the examination,7 including incomplete visualisation of the colon,8 missed lesions (22–48%),9 ,10 procedural difficulties, prolonged procedure time and reduced time interval until follow-up, and an estimated 12–22% increase in overall colonoscopy cost.11

The adequacy of a bowel preparation is closely linked to patient compliance with both dietary and purge instructions. Previous work has shown that 18–23.5% of the patients with poor preparation had failed to follow preparation instructions.12 ,13 The rate may have been even higher because it is ‘socially undesirable’ to report failure. One study performed in Asia showed that non-compliance with bowel preparation instructions, lower education level, and a long wait for the colonoscopy appointment were independent risk factors for poor bowel preparation.4 Non-compliance had the highest OR (4.76). A survey among doctors showed that gastroenterologists with the highest number of patients with inadequate bowel preparation believed that patients are unwilling to follow preparation instructions, struggle with the prescribed diet, and are unable to tolerate the full course of purgative.14 It is reasonable to hypothesise that efforts to improve education and maximise patient compliance during the preparatory period will enhance the efficacy of bowel preparation.15–17

Several methods had previously been tried to enhance patient education and compliance with instructions for bowel preparation. Results were inconsistent. Nurse-delivered education with brochures,18 instructions plus educational pamphlet,19 a novel designed patient educational booklet,15 and education with cartoon visual aids20 increased the quality of bowel preparation. However, other interventions, such as photographs of ‘clean’ and ‘dirty’ colons in addition to written instructions,21 or instructions plus a question and answer session to provide additional information based on responses to a questionnaire failed to improve bowel preparation quality.22

We hypothesised that telephone re-education (TRE) on the day before colonoscopy, reminding the patients of the detailed information related to bowel preparation, would improve the compliance of patients and ultimately improve bowel preparation quality during colonoscopy. The purpose of this study was to evaluate the effect of intervention with TRE on the quality of bowel preparation during colonoscopy and its impact on clinically relevant outcomes, such as polyp detection rates (PDRs).

Methods

Patients

This is a prospective, colonoscopist-blinded, randomised, controlled study with consecutive outpatients undergoing colonoscopy at the Endoscopy Center of Xijing Hospital of Digestive Diseases in China. The study protocol and informed consent form were approved by the institutional review board of Xijing Hospital, and the study was registered with ClinicalTrials.gov (NCT01584817).

Outpatients aged 18–75 years undergoing colonoscopy who had provided written informed consent were eligible for participation in the study. Exclusion criteria included: (1) history of colorectal surgery; (2) severe colonic stricture or obstructing tumour; (3) dysphagia; (4) compromised swallowing reflex or mental status; (5) significant gastroparesis or gastric outlet obstruction or ileus; (6) known or suspected bowel obstruction or perforation; (7) severe chronic renal failure (creatinine clearance<30 ml/min); (8) severe congestive heart failure (New York Heart Association class III or IV); (9) uncontrolled hypertension (systolic blood pressure>170 mm Hg, diastolic blood pressure>100 mm Hg); (10) toxic colitis or megacolon; (11) dehydration; (12) disturbance of electrolytes; (13) pregnancy or lactation; (14) unable to give informed consent; and (15) haemodynamically unstable.

Written informed consent was obtained from all the patients. Patients were randomised to either the TRE or control group at the time of appointment for colonoscopy by opening a sealed opaque envelope. The envelopes were randomised by using computer-generated random numbers generated by one of the investigators (HR) who kept the randomisation key locked until the inclusion of the last patient. At least two telephone numbers for all patients or their relatives living together were recorded in case of failure to contact. All patients were instructed not to tell colonoscopists, nurses and investigators before, during and after the procedure about their preparation method and when they received instructions.

Education on bowel preparation

All patients received regular instructions at the time of their appointment to discuss colonoscopy. One nurse provided education about colonoscopy, including the importance of bowel preparation, the side effects of the agents used, and the exact preparation instructions. Then a booklet with clear, written instructions was given to all patients. Although sodium phosphate has been withdrawn from many markets as a bowel preparation agent because of possible side effects, it is still widely used for bowel preparation in China. We followed local community practice in this study, which was approved by the institutional review board of Xijing Hospital. Patients were prescribed polyethylene glycol electrolyte powder (PEG-ELP, each sachet containing 59 g polyethylene glycol 4000, 1.46 g sodium chloride, 5.68 g sodium sulfate, 0.74 g potassium chloride, 1.68 g sodium bicarbonate; WanHe Pharmaceutical Co, Shenzhen, China) or sodium phosphate (Fleet Phospho-soda; CB Fleet Company, Switzerland) for bowel preparation. Baseline demographic and clinical characteristics of all the patients were recorded.

The preparation method has previously been reported with acceptable cleansing rate and tolerance.23–25 Briefly, all patients were instructed to have a regular meal for lunch and only clear liquids for dinner the day before the colonoscopy. They were asked to drink two sachets of PEG-ELP dissolved in 2 litres of water, or 90 ml sodium phosphate dissolved in 1.5 litres of water at 04:00–05:00 h within 2 h on the day of colonoscopy. Patients were encouraged to drink more clear liquids after purgatives for adequate hydration before colonoscopy. All colonoscopies were performed at 09:00–13:00 h.

For the patients allocated to the TRE group, a TRE was conducted by one investigator (LH) at 09:00–11:00 h on the day before colonoscopy. The importance of bowel preparation, the directions for use and side effects of purgatives, the proper food type, and the start time were especially emphasised. Patients were given a telephone number and were encouraged to contact the investigator if they had any questions about bowel preparation. Patients in the control group received education and a booklet on the day of the appointment only. They did not receive TRE on the day before colonoscopy. In this study, the information delivered by different education interventions, including education by the nurse at the time of the appointment, the booklet the patients received, and the TRE conducted by the investigator, had the same content on bowel preparation.

Data collection and colonoscopy

On the day of colonoscopy, before the procedure, all enrolled patients were interviewed by one investigator (LZG) who was not involved in the endoscopic procedure. Details of how purgatives were used, the food type, the start time of bowel preparation, side effects, sleeping quality and willingness to repeat bowel preparation were recorded. Colonoscopies were carried out by one of four colonoscopists (ZLH, WXP, PYL and GXG) each with a minimum experience of 2000 colonoscopies. The Fujinun colonoscope (CV-240, Japan) was used for each procedure. All examinations were conducted without conscious sedation.

Quality of bowel preparation, caecal intubation time, withdrawal time and colonoscopic findings for all patients were recorded by only one investigator (LXD), who was blinded to the timing of instructions and methods of bowel preparation.

Outcome measures

The primary outcome was the rate of adequate bowel preparation defined as total Ottawa score <6 at the time of colonoscopy. Bowel preparation was considered inadequate if one or more of the following was met: (1) inadequate visualisation on colonoscopy defined by Ottawa score ≥6; (2) the colonoscopy was cancelled because of poor bowel preparation or personal reasons; (3) incomplete colonoscopy. The secondary outcomes included PDR, rate of non-compliance with instructions, willingness to repeat bowel preparation, caecal intubation rate, caecal intubation time, and withdrawal time.

The quality of bowel cleansing in successful colonoscopy was evaluated using the Ottawa scale.26 Each section of the colon—that is, right, transverse and left—is rated for level of cleansing according to a five-point scale (0=‘excellent’, 1=‘good’, 2=‘fair’, 3=‘poor’, and 4=‘inadequate’). In addition, the overall colonic fluid is rated according to a three-point scale (0=small, 1=moderate, 2=large). As a result, the total score ranges from 0 to 14 (lower is better). Non-compliance with bowel preparation was defined as incorrect start time for taking purgatives, non-adherence to dietary restrictions, admitted failure to follow instructions including insufficient volume of bowel preparation solution taken, duration within which the bowel preparation solution should be completed, and adequate hydration. Sleeping quality was defined as excellent or good (the same as usual), fair or bad (worse than usual), as reported previously.27

Calculation of sample size

At the beginning of the study, a sample size calculation was performed, assuming a 10% difference in the rate of colonic cleansing. The rate of adequate bowel preparation in our endoscopic centre was ∼80%. To detect the difference with a significance level (α) of 0.05 and a power of 80% with a two-tailed test, we calculated that at least 398 patients were needed for the study. However, from our previous experience, ∼10% of patients may cancel their colonoscopy or have a failed colonoscopy, so we estimated that a total of 600 patients would be sufficient to detect a significant difference in the primary outcome.

Statistical analysis

Intention-to-treat (ITT) analysis was used to assess primary outcome and colonoscopic findings from all evaluable patients. Categorical variables were analysed using χ2 tests or Fisher’s exact test, as appropriate. Continuous variables were expressed as means with SD and analysed with Student's t test. To assess factors associated with inadequate bowel preparation (Ottawa score ≥6), multivariate analysis was performed using variables with p values of <0.1 in the univariate analysis. Analyses were performed with SPSS software V.19.0 for Windows. A p value of <0.05 was considered significant.

Results

Patient characteristics

From February to July 2012, 1127 outpatients aged 18–75 years undergoing unsedated colonoscopy were assessed for inclusion: 522 were excluded (348 met exclusion criteria and 174 were unwilling to participate in the study); 605 were randomised to the TRE group (n=305) and the control group (n=300). After randomisation, 29 subjects in the TRE group and 27 in the control group cancelled their colonoscopy appointments because of ‘bad’ bowel preparation (2 vs 6, p=0.174) or personal reasons (27 vs 21, p=0.399). Finally, 276 subjects in the TRE group and 273 in the control group underwent unsedated colonoscopy. The subject flow is detailed in figure 1. All baseline characteristics were well balanced between the two groups (table 1).

Table 1

Baseline characteristics of the study patients

Figure 1

Flowchart of the study.

Outcomes of bowel preparation and colonoscopy

In an ITT analysis of the primary outcome (table 2), adequate preparation was found in 81.6% vs 70.3% of TRE and control patients, respectively (p=0.001). PDR was 38.0% vs 24.7% in the TRE and control group, respectively (p<0.001). More diverticula were found in the TRE group (p=0.048). Colonoscopy failed in 14 subjects in the TRE group and 40 in the control group (p<0.001). Incomplete colonoscopy due to inadequate preparation was 1.8% vs 10.6% in the TRE and control group, respectively (p<0.001). Incomplete colonoscopy due to technical difficulty or stricture was not significantly different (p=0.619). The caecal intubation rate was higher in the TRE group (94.9% vs 85.4%, p<0.001). Among patients with successful colonoscopy, the Ottawa scores were 3.0±2.3 in the TRE group and 4.9±3.2 in the control group (p<0.001). No significant differences were observed between the two groups with regard to the mean time to reach the caecum (p=0.806). However, a shorter withdrawal time was used in the TRE group than the control group (6.2±2.3 vs 7.8±2.8 min, p<0.001).

Table 2

Effect of telephone re-education on the outcome of bowel preparation and colonoscopy

Procedure of bowel preparation

The effect of TRE on the procedure of bowel preparation is shown in table 3. The rate of non-compliance with instructions was significantly lower in the TRE group than the control group (9.4% vs 32.6%, p<0.001). Significant differences were found with regard to incorrect start time of bowel preparation (12 vs 34, p<0.001) and incorrect diet restriction (11 vs 58, p<0.001) between TRE and control groups, while the difference in failure to follow purgative instruction (including proper volume, duration and adequate hydration) between the two groups was not significant (p=0.811). More patients reported excellent or good sleep quality in the TRE group than in the control group (214 vs 177, p=0.002). No significant differences were observed between the two groups in side effects (p=0.573) and willingness to have a repeat bowel preparation (p=0.409).

Table 3

Effect of telephone re-education on the procedure of bowel preparation

Factors associated with inadequate bowel preparation

Logistic regression analyses were performed to identify any significant factors for inadequate bowel preparation (table 4). The factors analysed were age, gender, body mass index, history of surgery, bowel preparation and constipation, interval from appointment to colonoscopy, indication for colonoscopy, purgative type, TRE, and patient compliance with instructions. The univariate analysis indicated that constipation (OR 1.99, p=0.013), interval from appointment to colonoscopy (OR 1.97, p=0.036), regular instruction without TRE (OR 3.54, p<0.001), incorrect start time of bowel preparation (OR 6.68, p<0.001) and incorrect diet restriction (OR 4.21, p<0.001) were significantly associated with poor bowel preparation for colonoscopy defined by Ottawa score ≥6. The multivariate analysis revealed that constipation (OR 1.96, p=0.026), regular instruction without TRE (OR 2.43, p=0.002), incorrect start time of bowel preparation (OR 3.50, p<0.001) and incorrect diet restriction (OR 2.65, p=0.009) were factors significantly associated with poor bowel preparation for colonoscopy.

Table 4

Univariate and multivariate analysis of factors associated with poor bowel preparation (Ottawa score ≥6)

Discussion

Salient features of this study are tabulated alongside those of earlier reports on interventions aimed at improving bowel preparation in online supplementary tables S1 and S2. Our study group produced a greater reduction in Ottawa score (1.9) than the only other study using ITT analysis (0.7).15 The rate of adequate bowel preparation in our study group (81.6%) falls within the range of other studies (56% to 96.1%).15 ,19–22 The reduction in non-compliance rate of 23.2% is considerably better than that of 7% found in an earlier study.22 The increase in PDR of 13.3% exceeds those of 0%21 and 0.2%20 reported by earlier studies that also focused on this variable. The caecal intubation rate of 94.9% in our study group is higher than those of 90%18 and 90.1%19 in earlier studies. The lowest cancellation rate of 9.5% is achieved compared with previous reports of 10%18 and 35.2%.21 Intubation and withdrawal times are of comparable order of magnitude (7–11 min) to those in earlier studies.20 ,21

Chan et al4 found that a long wait for a colonoscopy appointment was an independent risk factor for poor bowel preparation, which was confirmed by the present study by univariate analysis, although the wait was relatively short in our centre (table 4). This study, to our knowledge, is the first trial to focus on the day before colonoscopy for better patient education on bowel preparation.

Nearly half of all patients (42/87, 48.3%) who had inadequate bowel preparation failed to comply with bowel preparation instructions in the present study. Among factors associated with non-compliance with instructions, incorrect start time and incorrect diet restriction rather than failure to follow purgative instruction were independent factors of inadequate bowel preparation. Through TRE the day before colonoscopy, patient compliance with diet restriction and the time to start drinking purgative was significantly enhanced, which could be the main reason for improved bowel preparation. As a convenient way to improve the quality of bowel preparation, better patient compliance could be further achieved by handout materials, training videos, self-help websites, or follow-up telephone calls to address questions.14 ,20

The same-day bowel preparation method was used in this study, which has been reported to have acceptable tolerance, preparation cleansing rate and lesion detection rate.23–25 ,28 ,29 However, comparisons between same-day and split-dose regimens are lacking. The latter is widely endorsed by many physicians, despite some patients experiencing inconvenience.29 It is likely that TRE might also enhance the efficacy of split-dose regimens just as has been demonstrated for same-day preparation. Future research should evaluate the impact of TRE on split-dose regimens.

There are several limitations to this study. First, TRE is not as good as face-to-face consultation. It may provide less opportunity for additional questions, leading to lower satisfaction levels and inferior participation rates.30 However, as face-to-face consultation on the day before colonoscopy is impractical, a TRE programme is a reasonable alternative for reminding patients how to prepare their bowel correctly. Second, although PDR was significantly increased from 24.7% to 38.0% after TRE, it is not known whether TRE could further reduce cancer incidence in the future. Longer-term studies are needed to address this question. Third, the indication for screening or surveillance was found in only ∼15% in the present study, so polyp detection is hard to interpret, particularly as it is difficult to know if the ‘diagnostic’ group indications are equally represented. The PDRs in diagnostic patients with different symptoms are listed in table 5, which shows that the PDRs in the TRE arm were consistently higher than those in the control arm for all the diagnostic groups. Fourth, the variation in compliance with the instruction on bowel preparation is relatively small in our study. Only 12.5% (34/273) of patients began bowel preparation at the incorrect time (not taken at 04:00–05:00). The lowest cancellation rate of 9.5% is achieved compared with previous reports of 10%18 and 35.2%.21 The reason may be the high rate (85.2%) of diagnostic colonoscopy and short interval (∼3.5 days) between clinic visit and colonoscopy in our endoscopic centre. Patients with symptoms undergoing diagnostic colonoscopy may be more compliant with the instructions than those undergoing screening colonoscopy. Patients tend to be more aware and more compliant with education information on bowel preparation when the interval between the clinic visit and colonoscopy is short. The intervention of TRE may be even more effective in countries with longer than average intervals. The effect of TRE on bowel preparation in different settings, such as centres with more patients undergoing screening colonoscopy and longer average intervals, requires further investigation. Finally, the present study was performed on unsedated patients in one tertiary care referral centre. The results need further confirmation through multicentre trials with larger groups of patients including those undergoing sedated colonoscopy.

Table 5

PDR in diagnostic patients with different main symptoms

In conclusion, TRE about the details of bowel preparation on the day before colonoscopy increases the quality of bowel preparation and the rate of detection of polyps. Plausible explanations include a reduction in the rate of non-compliance with the start time and diet restriction. The day before colonoscopy is an appropriate time point to intervene to ensure better compliance with bowel preparation instructions.

Acknowledgments

We thank the nurse, Jing Li, for patient education on bowel preparation, and Subesh Kumar Dahal for preparation of the manuscript. This work was supported in part by the National Natural Science Foundation of China (81172288). Support was also received by YP from the Science Foundation of the Ministry of Education.

References

View Abstract

Supplementary materials

  • Supplementary Data

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Footnotes

  • XL, HL and LZ contributed equally.

  • Contributors Conception and design: XL, HL, LZ, ZL, RH, XW, NH, YP, XG. Analysis and interpretation of the data: XL, HL, LZ, YP, FWL. Drafting of the article: HL, YP, FWL. Critical revision of the article for important intellectual content: YP, FWL, KW, DF. Final approval of the article: XG, KW, DF.

  • Competing interests None.

  • Patient consent Obtained.

  • Ethics approval This study was conducted with the approval of the institutional review board of Xijing Hospital.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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