Introduction
The use of colonoscopy has been increasing continuously worldwide [1]
[2]. Colonoscopy is universally accepted as the preferred option for screening and surveillance
of people who are at high risk of developing colorectal cancer (CRC), as well as for
following up results of other screening tests [3]. Successful visualization and identification of lesions during colonoscopy is contingent
on adequate bowel preparation [4]. Unfortunately, bowel cleansing for colonoscopies has been reported to be suboptimal
in up to 20 %–40 % of cases [5]. Poor bowel cleansing can lead to repeat colonoscopies at shorter intervals [6], increased costs to the healthcare system [7], an increased risk of complications, longer procedure times, and a higher likelihood
of missed lesions [5]
[8].
Traditionally, people undergoing a colonoscopy have been advised to complete a bowel
preparation regimen the day before the procedure (i. e. they were instructed to consume
the bowel preparation laxatives, most commonly 4 L polyethylene glycol [PEG] [9], entirely the day before their colonoscopy). Randomized controlled trials (RCTs)
have demonstrated that splitting the volume into two 2-L doses on the day before and
morning of the colonoscopy, referred to as split-dose bowel preparation (SDBP), provides
better bowel cleansing than the day-before bowel preparation approach [10]
[11]
[12]. SDBP with 3 L or more of PEG has been reported to yield greater bowel cleanliness
than lower volume split-dose regimens on intention-to-treat (ITT) analysis [10], so continues to be used by many practices.
There have however been concerns raised about the generalizability of the current
RCT findings to the general population undergoing colonoscopies [13]. For example, the RCTs do not specifically evaluate early morning colonoscopies,
include volunteer participants who may be more adherent to a challenging bowel preparation
regimen (e. g. middle of the night intake of bowel preparation for the early morning
procedures with SDBP), and involve research personnel who can provide more support
and intensive instructions to those undergoing bowel preparation than is feasible
in usual clinical practice. Therefore, there continues to be reluctance in using SDBP
for early morning colonoscopies owing to concerns regarding patient compliance and
the effectiveness of SDBP in unselected patients in clinical practice [14]
[15].
Healthcare providers are worried that routinely splitting the dose for early morning
colonoscopies may: (i) discourage patients from undergoing colonoscopy in the early
morning owing to a fear of sleep interruption; (ii) risk noncompletion of the bowel
preparation prior to transit to the endoscopy facility; (iii) accumulate extra work
in terms of patient phone calls about their concerns regarding the procedure, rebooking,
and late cancellations; (iv) lead to a lack of adequate adherence to the bowel preparation
regimen. As a result, the day-before bowel preparation regimen is still commonly used
for early morning colonoscopies. Many practices (including our citywide practice across
six busy sites) continue to give patients a choice of SDBP or day-before bowel preparation
(optional SDBP) for morning colonoscopies, with the belief that this optional SDBP
does not lead to overall markedly worse bowel preparation for early or late morning
colonoscopies.
As such, we compared the effectiveness of optional SDBP with mandatory SDBP protocols
for morning colonoscopies in a noninferiority pragmatic RCT. We aimed to assess, and
powered the study to evaluate, noninferiority (optional SDBP is not substantially
worse than mandatory SDBP) for early morning colonoscopies (8:00 AM–10:30 AM) and
separately for late morning colonoscopies (10:30 AM–12:00 PM), in two parallel RCTs.
Methods
Study population
Adult patients undergoing outpatient morning colonoscopies (before 12:00 PM) between
20 June 2018 and 8 October 2020 in usual clinical practice, performed by any of the
four gastroenterologists at a single center, were included in a pragmatic single-blinded
RCT. Patients were randomized by the central booking office into two groups, using
a computer-generated randomization schedule (1:1 randomization in blocks of 10) and
were sent written instructions on bowel preparation for either: (i) mandatory SDBP
or (ii) optional SDBP (choice between SDBP or day-before bowel preparation). The 1:1
randomization was stratified according to early morning (8:00 AM–10:30 AM) and late
morning (10:30 AM–12:00 PM) colonoscopies.
Both SDBP groups (mandatory and optional) received standardized information regarding
pre-procedure diet, medication use, and the sedatives and colonoscopy. Both groups
were encouraged to visit an informative online platform (https://mycolonoscopy.ca), which provides validated patient-education materials focused on SDBP [16]. Patients were aware of the bowel preparation instructions, but the endoscopists
were unaware of the bowel preparation instructions that had been provided to the patients.
Mandatory split-dose bowel preparation
Written instructions sent to the mandatory group instructed patients to take their
bowel preparation (4 L PEG) split into two doses of 2 L each (split dose). The instructions
required the first 2 L to be taken at 6:00 PM on the day before the colonoscopy, and
the second dose to be started 4–5 hours prior to the scheduled time of the colonoscopy.
Patients were instructed to ingest aliquots from each of the 2-L doses every 10–15
minutes in 250-mL increments (1 cup) over a 2-hour timespan.
The European and North American guidelines highly recommend the use of SDBP for all
colonoscopies [5]
[17]
[18], so mandatory SDBP was used as the reference for noninferiority hypothesis testing.
Optional split-dose bowel preparation
The instructions sent to the optional group advised patients on the SDBP (as per the
mandatory option), but also included instructions for day-before bowel preparation,
in which the bowel preparation is taken entirely during the day before. In the latter
case, patients were instructed to start drinking the 4 L PEG in 250-mL increments
every 10–15 minutes, beginning at 6:00 PM and finishing within a 4-hour timespan.
The instructions highlighted that the SDBP was the optimal and preferred preparation
for cleansing the bowel and for visualization of lesions, but that the patient could
choose the day-before bowel preparation over the SDBP if they preferred.
Patient experience with bowel preparation (survey data)
On the day of the procedure, a sample of patients were asked to participate in a survey
regarding their experiences with the preparation for colonoscopy. The survey was administered
when there was time between check-in and the procedure, and when staff were available
to distribute the survey. Those who gave their consent completed the survey prior
to their procedure. Patient experience factors included: ability to follow and clarity
of instructions, anxiety about the bowel preparation and colonoscopy, willingness
to do the same preparation in the future, tolerability, sleep, and incontinence experiences.
Patients were also asked whether they agreed to link their survey responses to their
procedural data (colonoscopy bowel cleanliness, procedure details, pathology).
Demographic, procedural, and pathologic characteristics
Demographic characteristics included: age; known inflammatory bowel disease (IBD);
and indication for colonoscopy (diagnostic, to assess IBD activity, screening, surveillance).
Procedure characteristics included: withdrawal and total procedure times; completeness
of colonoscopy (cecal or ileal intubation); need for repeat colonoscopy because of
poor bowel preparation; and lesions detected, such as polyps, suspected/definitive
tumor, suspected/definitive IBD, and diverticulosis. The histologic analysis (pathology)
of the polyps was categorized as advanced adenomas (villous, high grade dysplasia,
≥ 1 cm in size), hyperplastic, serrated lesions, or other.
Primary end point and secondary outcomes
The primary end point for noninferiority hypothesis testing was adequate quality of
bowel cleanliness measured by the Boston Bowel Preparation Scale (BBPS) score. The
BBPS is recommended as the preferred standard [4], having been validated [19] and used in many studies in order to measure adequate bowel cleanliness [20]
[21]
[22]. The total BBPS score ranges from 0 to 9, with each colon segment receiving a “segment
score” from 0 to 3. Adequate cleansing was defined a priori as a BBPS score ≥ 2 in
all segments [23]
[24] (i. e. a total BBPS score ≥ 6 among individuals with no prior colonic resection).
The total BBPS and segment scores were analyzed continuously as secondary outcomes,
whereas adequate BBPS was analyzed as a binary variable (adequate vs. inadequate)
and considered the primary end point.
The Ottawa Bowel Preparation Scale (OBPS), although not as frequently used, has also
been validated [25] when assessing the quality of bowel cleanliness [26]
[27]. The total OBPS score ranges from 0 (excellent) to 14 (inadequate), based on three
segment scores of 0 to 4, plus a total colon score for fluid quantity of 0 to 2. Adequate
cleanliness was defined as a total OBPS score ≤ 7 [16]. OBPS was analyzed continuously (total and segment scores) and categorically (adequate
vs. inadequate). Although the OBPS measures bowel cleanliness at the onset of the
procedure, the score is not routinely recorded at our center, so it was decided a
priori that its documentation would not be compulsory, in contrast to the BBPS; the
OBPS was considered a secondary outcome.
Other secondary outcomes included: laxative intake completion; any phone calls received
from patients about the bowel preparation; and procedure measures, including withdrawal
and total procedure time, and the polyp and adenoma detection rates.
Statistical analysis
Sample size calculations for the primary outcome (adequate bowel cleanliness) for
both the early and late morning colonoscopy groups were based on previous literature
[15]. To detect noninferiority for a preset absolute difference of 5 % or less, with
a power of 0.80 and a P value of 0.025 (one-sided) for the comparisons of the optional group (80 %) with
the mandatory group (85 %), a total of 356 patients (178/group) were required, which
increased to 418 patients (n = 209/group) after adding a subject withdrawal rate of
15 %.
If a patient was randomized to the mandatory group and ended up ingesting the bowel
preparation entirely the day before, they were still analyzed as part of the mandatory
group as per ITT. The proportion of missed colonoscopies and BBPS scores not recorded
were determined and compared between the two groups. A sensitivity analysis was conducted,
assuming all missing BBPS scores were inadequate. All missing colonoscopy procedures
and unrecorded BBPS scores were excluded from the final analysis, and therefore the
comparisons were analyzed as a modified ITT (mITT) analysis. Demographic characteristics
(age, sex, known IBD) were compared between the randomized and non-missing data.
All analyses were conducted for early morning (8:00 AM–10:30 AM) and late morning
(10:30 AM–12:00 PM) colonoscopies separately. Descriptive statistics are presented
as mean (SD) and proportions. The secondary outcomes and potential predictors are
presented using point estimates and 95 %CIs around the point estimates.
We assessed the association between SDBP groups and secondary outcomes using bivariate
analysis. We also assessed the association between nonrandomized laxative timing (split
dose or day before) and adequate bowel cleanliness, and the secondary outcomes listed
in the methods section, among those assigned to the optional group. The nonrandomized
laxative intake timing was defined by whether a patient actually took the laxative
as a split dose or on the day before.
Lastly, we conducted planned subgroup analyses assessing whether the patient experiences
of the bowel preparation (survey data) differed: (i) between the mandatory and the
optional SDBP groups; and (ii) for nonrandomized split-dose compared with day-before
bowel preparation for those assigned to the optional group. Post hoc exploratory multivariable
logistic regression analysis was performed to identify possible predictors for choosing
day-before bowel preparation among the optional group.
Noninferiority hypothesis testing is presented using the absolute risk difference
(aRD) in the proportions (optional SDBP proportion – mandatory SDBP proportion) and
95 %CIs for the primary end point (adequate BBPS). Secondary outcomes and potential
predictors of choosing day-before bowel preparation were assessed using Fisher’s exact
test for categorical variables, and t test or Wilcoxon signed-rank test for continuous variables, depending on the distribution
of the data. P values of < 0.05 were considered as statistically significant.
In the analysis of bowel cleanliness in the colonic segments, the Bonferroni correction
was used with P < 0.0125 for four comparisons (BBPS in the three colonic segments and continuous
total score) and P < 0.01 with five comparisons (OBPS scores). When assessing the many factors regarding
patient experiences (survey data) between the SDBP groups, we used the point estimates
and 95 %CIs; statistical significance between groups was determined if the 95 %CIs
did not overlap. Analyses were conducted using SAS V9.4 (SAS Institute Inc., Cary,
North Carolina, USA).
This study was approved by the Health Research Ethics Board at the University of Manitoba.
Results
Out of 1050 randomized patients, approximately 50 % were randomized to each of the
SDBP groups: mandatory (n = 523) and optional (n = 527) ([Fig. 1]). The proportions of patients who missed a colonoscopy were similar between the
two groups (21.0 % for the mandatory compared with 20.5 % for the optional group)
and they were excluded from the final analysis. Among patients who underwent a colonoscopy,
over 90 % in both the mandatory and optional groups had completed BBPS scores. The
sensitivity analysis that included unrecorded BBPS observations as inadequate BBPS
had no effect on the noninferiority analysis (data available upon request) and therefore
these were also excluded from the final analysis. Patient demographic characteristics
were similar between: (i) patients who attended a colonoscopy compared with patients
who did not attend a colonoscopy, and (ii) patients who attended a colonoscopy and
had their BBPS recorded vs. those who did not have their BBPS recorded (Table 1 s, see online-only Supplementary material).
Fig. 1 Flow chart showing patients randomized to optional or mandatory split-dose bowel preparation
(SDBP) with complete Boston Bowel Preparation Scale (BBPS) scores who were included
in the overall analysis.
After exclusion of incomplete data, there was a total of 770 randomized patients included:
for early morning colonoscopies, 267 mandatory SDBP and 265 optional SDBP patients;
for late morning colonoscopies, 120 mandatory SDBP and 118 optional SDBP patients.
Demographic and clinical characteristics were similar between the two randomized SDBP
groups, among both early and late morning colonoscopies ([Table 1]).
Table 1
Patient and clinical characteristics for the mandatory and optional split-dose bowel
preparation (SDBP) groups, stratified by early vs. late morning colonoscopies (n = 770).
|
Early morning (8:00 AM–10:30 AM)
|
Late morning (10:30 AM–12:00 PM)
|
|
Mandatory (n = 267)
|
Optional (n = 265)
|
Mandatory (n = 120)
|
Optional (n = 118)
|
|
Patient
|
|
Sex, female, n (%)
|
134 (50.2)
|
139 (52.5)
|
59 (49.2)
|
64 (54.2)
|
|
Age, mean (SD), years
|
53.2 (15.6)
|
54.9 (16.1)
|
55.2 (16.2)
|
54.5 (16.6)
|
|
Known IBD, n (%)[1]
|
62 (24.5)
|
52 (20.8)
|
29 (25.4)
|
21 (18.6)
|
|
Indication, n (%)
|
|
|
128 (47.9)
|
148 (55.8)
|
61 (50.8)
|
56 (47.5)
|
|
|
34 (12.7)
|
36 (13.6)
|
19 (15.8)
|
9 (7.6)
|
|
|
46 (17.2)
|
43 (16.2)
|
19 (15.8)
|
19 (16.1)
|
|
|
81 (30.3)
|
61 (23.0)
|
26 (21.7)
|
40 (33.9)
|
|
Procedure
|
|
Withdrawal time, mean (SD), minutes[2]
|
9.7 (5.9)
|
9.4 (6.7)
|
9.2 (5.5)
|
8.4 (4.8)
|
|
Total procedure time, mean (SD), minutes[3]
|
17.6 (7.6)
|
18.2 (9.0)
|
17.3 (7.2)
|
17.4 (7.4)
|
|
Intubation (cecal or ileal), n (%)
|
261 (97.8)
|
258 (97.4)
|
117 (97.5)
|
113 (95.8)
|
|
Need to repeat colonoscopy, n (%)[4]
|
11 (4.1)
|
14 (5.3)
|
9 (7.5)
|
13 (11.0)
|
|
Lesions, n (%)
|
|
|
75 (28.1)
|
72 (27.2)
|
41 (34.2)
|
35 (29.7)
|
|
|
3 (1.1)
|
4 (1.5)
|
1 (0.8)
|
–
|
|
|
28 (10.5)
|
13 (4.9)
|
10 (8.3)
|
3 (2.5)
|
|
|
55 (20.6)
|
56 (21.1)
|
22 (18.3)
|
20 (16.9)
|
|
|
119 (44.6)
|
127 (47.9)
|
53 (44.2)
|
62 (52.5)
|
|
Pathology of polyps, n (%)[5]
|
|
Adenoma detection rate
|
41 (15.4)
|
40 (15.1)
|
22 (18.3)
|
21 (17.8)
|
|
|
4 (1.5)
|
4 (1.5)
|
2 (1.7)
|
2 (1.7)
|
|
Hyperplastic
|
15 (5.6)
|
23 (8.7)
|
7 (5.8)
|
8 (6.8)
|
|
Serrated
|
3 (1.1)
|
9 (3.4)
|
5 (4.2)
|
4 (3.4)
|
|
Other
|
24 (9.0)
|
20 (7.5)
|
17 (14.2)
|
8 (6.8)
|
|
|
16 (6.0)
|
9 (3.4)
|
13 (10.8)
|
7 (5.9)
|
|
Bowel preparation, n (%)
|
|
Laxative intake completed[7]
|
192 (87.3)
|
183 (83.9)
|
80 (87.9)
|
69 (90.8)
|
|
When did the subject take the laxative?[8]
|
|
|
179 (74.3)
|
58 (24.7)
|
78 (70.3)
|
37 (38.1)
|
|
|
59 (24.5)
|
172 (73.2)
|
28 (25.2)
|
57 (58.8)
|
|
|
3 (1.2)
|
5 (2.1)
|
5 (4.5)
|
3 (3.1)
|
|
Phone calls made by patient
|
24 (9.0)
|
16 (6.0)
|
7 (5.8)
|
7 (5.9)
|
IBD, inflammatory bowel disease.
Note: there were no statistically significant differences between the groups except
for “when the subject took the laxative,” so P values are not shown.
1 Missing data: early (n = 29), late (n = 11).
2 Missing data: early (n = 58), late (n = 22).
3 Missing data: early (n = 47), late (n = 19).
4 Need to repeat colonoscopy owing to inadequate bowel preparation according to endoscopist
opinion.
5 Includes multiple responses as patients may have more than one polyp.
6 Defined as adenomas (tubular, villous, tubulovillous) with high grade dysplasia,
villous or tubulovillous adenoma, or size ≥ 1 cm.
7 Missing data: early (n = 94), late (n = 71).
8 Missing data: early (n = 56), late (n = 30).
Given the choice (optional SDBP group), patients were more likely to choose to complete
the laxative intake entirely on the day before: 73.2 % for early and 58.8 % for late
morning colonoscopies. There were no differences in the procedure measures, including
withdrawal or procedure times, polyp or adenoma detection rates, completion of laxative
intake, or phone calls received by the secretarial team from patients in the mandatory
compared with the optional SDBP groups for either early or late morning colonoscopies
([Table 2]).
Table 2
Comparison of the primary end point (adequate Boston bowel preparation scale [BBPS]
score) and secondary outcomes between the mandatory and optional split-dose bowel
preparation (SDBP) groups, for early and late morning colonoscopies (n = 770).
|
Early morning colonoscopies
(8:00 AM –10:30 AM)
|
Late morning colonoscopies
(10:30 AM –12:00 PM)
|
|
Mandatory (n = 267)
|
Optional (n = 265)
|
P value
|
Mandatory (n = 120)
|
Optional (n = 118)
|
P value
|
|
Primary end point
|
|
Adequate BBPS, n (%)[1]
|
240 (89.9 %)
|
209 (78.9 %)
|
|
100 (83.3 %)
|
90 (76.3 %)
|
|
|
|
11.0 % (5.9 % to 16.1 %)
|
|
7.1 % (−1.5 % to 15.6 %)
|
|
|
Secondary outcomes
|
|
BBPS score, mean (95 %CI)
|
|
|
7.9 (7.7 to 8.1)
|
7.3 (7.0 to 7.5)
|
< 0.001[3]
|
7.4 (6.9 to 7.8)
|
6.9 (6.4 to 7.3)
|
0.06
|
|
|
2.6 (2.5 to 2.7)
|
2.4 (2.3 to 2.5)
|
0.004[3]
|
2.4 (2.3 to 2.6)
|
2.2 (2.0 to 2.3)
|
0.02
|
|
|
2.7 (2.6 to 2.8)
|
2.5 (2.4 to 2.6)
|
< 0.001[3]
|
2.5 (2.4 to 2.7)
|
2.4 (2.2 to 2.5)
|
0.08
|
|
|
2.7 (2.6 to 2.8)
|
2.5 (2.4 to 2.6)
|
< 0.001[3]
|
2.5 (2.4 to 2.7)
|
2.4 (2.2 to 2.5)
|
0.06
|
|
Procedure times, mean (95 %CI), minutes
|
|
Withdrawal[4]
|
9.7 (8.9 to 10.4)
|
9.4 (8.5 to 10.3)
|
0.59
|
9.2 (8.2 to 10.3)
|
8.4 (7.5 to 9.4)
|
0.25
|
|
Total procedure[5]
|
17.6
(16.7 to 18.6)
|
18.2
(17.0 to 19.3)
|
0.47
|
17.3
(16.0 to 18.7)
|
17.4
(16.0 to 18.8)
|
0.94
|
|
OBPS score, mean (95 %CI)[6]
|
|
|
4.6 (4.2 to 5.1)
|
5.6 (5.1 to 6.1)
|
0.008[7]
|
5.8 (5.0 to 6.6)
|
7.2 (6.4 to 8.1)
|
0.01
|
|
|
1.1 (1.0 to 1.2)
|
1.3 (1.2 to 1.4)
|
0.02
|
1.3 (1.2 to 1.5)
|
1.5 (1.3 to 1.6)
|
0.14
|
|
|
1.0 (0.8 to 1.1)
|
1.3 (1.1 to 1.4)
|
0.01
|
1.4 (1.2 to 1.7)
|
1.8 (1.5 to 2.1)
|
0.05
|
|
|
1.4 (1.3 to 1.6)
|
1.7 (1.6 to 1.9)
|
0.003[7]
|
1.7 (1.4 to 1.9)
|
2.0 (1.8 to 2.3)
|
0.02
|
|
|
1.1 (0.9 to 1.2)
|
1.4 (1.2 to 1.5)
|
0.01
|
1.4 (1.2 to 1.7)
|
1.8 (1.6 to 2.1)
|
0.03
|
|
Adequate OBPS score, n (%) [95 %CI][6]
,
[8]
|
152 (56.9)
[51.0 to 62.9]
|
133 (50.2)
[44.1 to 56.2]
|
0.01[9]
|
57 (47.5)
[38.5 to 56.5]
|
36 (30.5)
[22.1 to 38.9]
|
0.02*
|
|
Polyp detection rate, n (%) [95 %CI]
|
75 (28.1)
[22.7 to 33]
|
72 (27.2)
[21.8 to 33]
|
0.85
|
41 (34.2)
[25.6 to 43]
|
35 (29.7)
[21.4 to 38]
|
0.49
|
|
Adenoma detection rate, n (%) [95 %CI]
|
41 (15.4)
[11.0 to 20]
|
40 (15.1)
[10.8 to 19]
|
> 0.99
|
22 (18.3)
[11.4 to 25]
|
21 (17.8)
[10.8 to 25]
|
> 0.99
|
|
Laxative intake completed, n (%) [95 %CI][10]
|
192 (87.3)
[82.9 to 91.7]
|
183 (83.9)
[79.1 to 88.8]
|
0.34
|
80 (87.9)
[81.1 to 94.7]
|
69 (90.8)
[84.2 to 97.4]
|
0.62
|
|
Phone calls made by patient, n (%) [95 %CI]
|
24 (9.0)
[5.5 to 12.4]
|
16 (6.0)
[3.2 to 8.9]
|
0.25
|
7 (5.8)
[1.6 to 10.1]
|
7 (5.9)
[1.6 to 10.2]
|
> 0.99
|
aRD, absolute risk difference; OBPS, Ottawa Bowel Preparation Scale.
1 Defined as ≥ 2 in all colonic segments.
2 Defined as: percentage adequate BBPS in optional group – percentage adequate BBPS
in mandatory group.
3
P < 0.0125 using Bonferroni correction with four comparisons.
4 Missing data: early (n = 58), late (n = 22).
5 Missing data: early (n = 47), late (n = 19).
6 Missing data: early (n = 147), late (n = 73).
7
P < 0.01 using Bonferroni correction with five comparisons.
8 Defined as a score ≤ 7.
9
P < 0.05.
10 Missing data: early (n = 94), late (n = 71).
Bowel cleanliness for early morning colonoscopies
Among early morning (8:00 AM–10:30 AM) colonoscopies, the optional SDBP group had
inferior bowel cleanliness compared with the mandatory SDBP group: proportion of adequate
BBPS 78.9 % vs. 89.9 %; aRD 11.0 %, 95 %CI 5.9 % to 16.1 % ([Table 2]). The lower end of the 95 %CI of the aRD exceeded the predefined 5 % noninferiority
margin ([Fig. 2]), therefore the difference is statistically significant and clearly demonstrates
inferiority.
Fig. 2 Absolute risk difference and 95 %CIs for adequate Boston Bowel Preparation Scale
(BBPS) score in the mandatory vs. optional split-dose bowel preparation (SDBP) groups
for early morning and late morning colonoscopies.
Similarly, adequate OBPS was less frequent in the optional SDBP group (50.2 %, 95 %CI
44.1 % to 56.2 %) than in the mandatory SDBP group (56.9 %, 95 %CI 51.0 % to 62.9 %;
P = 0.01). The mean BBPS and OBPS total scores showed lower adequacy in the optional
group compared with the mandatory group (a lower score being better with the OBPS)
([Table 2]).
Bowel cleanliness for late morning colonoscopies
The proportion of patients with adequate BBPS for late morning (10:30 AM–12:00 PM)
colonoscopies was lower in the optional group (76.3 %) vs. the mandatory group (83.3 %)
([Table 2]); however, the 95 %CI for the aRD included the predefined noninferiority margin
([Fig. 2]) and was therefore not statistically different, and did not reject the noninferior
hypothesis: aRD 7.1 %, 95 %CI −1.5 % to 15.6 %. Adequate OBPS was however less frequent
with optional SDBP (30.5 %, 95 %CI 22.1 % to 38.9 %) compared with mandatory SDBP
(47.5 %, 95 %CI 38.5 % to 56.5 %; P = 0.02).
Among the optional group, patient characteristics and study outcomes were similar
for those individuals who took the bowel preparation the day before compared with
those who took the laxative as SDBP for both early and late morning colonoscopies
([Table 3]).
Table 3
Associations with split-dose vs. day-before laxative intake (nonrandomized analyses)
among those assigned to the optional group for early morning and late morning colonoscopies.
|
Early morning (n = 230)
|
Late morning (n = 94)
|
|
Day before (n = 172)
|
Split dose
(n = 58)
|
P
[1]
|
Day before (n = 57)
|
Split dose
(n = 37)
|
P[1]
|
|
Demographic data, n (%) [95 %CI][2]
|
|
Sex, female, n (%) [95 %CI]
|
96 (55.8)
[48.3 to 63.3]
|
28 (48.3)
[35.3 to 61.2]
|
0.36
|
33 (57.9)
[44.8 to 71.0]
|
23 (62.2)
[46.2 to 78.1]
|
0.83
|
|
Age, mean (95 %CI), years
|
54.9
(52.3 to 57.4)
|
54.8
(50.8 to 58.7)
|
0.97
|
55.0
(50.9 to 59.1)
|
53.3
(47.8 to 58.8)
|
0.62
|
|
Known IBD[3]
|
39 (24.2)
[17.6 to 30.9]
|
9 (16.1)
[6.4 to 25.8]
|
0.21
|
11 (19.6)
[9.0 to 30.3]
|
6 (18.2)
[4.8 to 31.6]
|
0.54
|
|
Indication
|
|
Diagnostic
|
93 (54.1)
[46.6 to 61.6]
|
32 (55.2)
[42.3 to 68.1]
|
> 0.99
|
27 (47.4)
[34.2 to 60.6]
|
20 (54.1)
[37.7 to 70.4]
|
0.67
|
|
Assess IBD activity
|
27 (15.7)
[10.2 to 21.2]
|
9 (15.5)
[6.1 to 24.9]
|
> 0.99
|
4 (7.0)
[0.3 to 13.8]
|
5 (13.5)
[2.3 to 24.7]
|
0.31
|
|
Screening
|
29 (16.9)
[11.2 to 22.5]
|
10 (17.2)
[7.4 to 27.0]
|
> 0.99
|
10 (17.5)
[7.5 to 27.6]
|
6 (16.2)
[4.1 to 28.3]
|
> 0.99
|
|
Surveillance
|
40 (23.3)
[16.9 to 29.6]
|
14 (24.1)
[13.0 to 35.2]
|
0.86
|
19 (33.3)
[20.9 to 45.8]
|
9 (24.3)
[10.2 to 38.4]
|
0.49
|
|
Primary outcome, n (%) [95 %CI]
|
|
Adequate BBPS
|
139 (80.8)
[74.9 to 86.7]
|
46 (79.3)
[68.8 to 89.8]
|
0.85
|
39 (68.4)
[56.1 to 80.7]
|
30 (81.1)
[68.2 to 93.9]
|
0.23
|
|
Secondary outcomes, n (%) [95 %CI]
[2]
|
|
Adequate OBPS[4]
|
86 (68.3)
[60.0 to 76.5]
|
29 (67.4)
[53.3 to 81.6]
|
> 0.99
|
15 (38.5)
[22.8 to 54.2]
|
12 (52.2)
[31.2 to 73.2]
|
0.43
|
|
Laxative intake completed[5]
|
135 (84.9)
[79.3 to 90.5]
|
46 (82.1)
[72.0 to 92.3]
|
0.67
|
43 (95.6)
[89.4 to 100]
|
25 (86.2)
[73.4 to 99.1]
|
0.20
|
|
Phone calls made by patient
|
9 (5.2)
[1.9 to 8.6]
|
5 (8.6)
[1.3 to 15.9]
|
0.35
|
3 (5.3)
[0.0 to 11.2]
|
4 (10.8)
[0.6 to 21.0]
|
0.43
|
|
Withdrawal time, mean (95 %CI), minutes[6]
|
9.2
(8.0 to 10.4)
|
9.7
(8.3 to 11.1)
|
0.60
|
8.3
(6.9 to 9.7)
|
8.9
(7.2 to 10.5)
|
0.60
|
|
Total procedure time, mean (95 %CI), minutes[7]
|
17.7
(16.3 to 19.2)
|
19.2
(16.6 to 21.7)
|
0.31
|
18.1
(15.9 to 20.3)
|
17.2
(15.1 to 19.3)
|
0.58
|
|
Polyp detection rate
|
49 (28.5)
[21.7 to 35]
|
14 (24.1)
[13.0 to 35]
|
0.61
|
18 (31.6)
[19.3 to 44]
|
11 (29.7)
[14.7 to 45]
|
> 0.99
|
|
Adenoma detection rate
|
27 (15.7)
[10.2 to 21]
|
8 (13.8)
[4.9 to 23]
|
> 0.99
|
11 (19.3)
[8.9 to 30]
|
6 (16.2)
[4.1 to 28]
|
0.79
|
IBD, inflammatory bowel disease; BBPS, Boston Bowel Preparation Scale; OBPS, Ottawa
Bowel Preparation Scale.
1 Statistical significance at P < 0.05
2 Unless otherwise specified.
3 Missing data: early (n = 13), late (n = 5).
4 Missing data: early (n = 61), late (n = 32).
5 Missing data: early (n = 15), late (n = 20).
6 Missing data: early (n = 29), late (n = 11).
7 Missing data: early (n = 18), late (n = 8).
Patient experiences with bowel preparation (survey data)
Demographic and clinical characteristics for the patient experiences with bowel preparation
(survey) data are presented in [Table 4]. A total of 444 patients (58.0 %) participated in the survey and agreed to link
their responses to their procedural data. The proportions with adequate BBPS for the
optional compared with the mandatory SDBP group were similar to the proportions found
for the entire cohort. The patient demographic characteristics were similar between
the groups (data available upon request).
Table 4
Patient experiences for mandatory compared with optional split-dose bowel preparation
(SDBP) groups for early and late morning colonoscopies for those who responded to
the survey (n = 444).
|
Early morning
(8:00 AM–10:30 AM)
|
Late morning
(10:30 AM–12:00 PM)
|
|
Mandatory (n = 160)
|
Optional (n = 159)
|
Mandatory (n = 66)
|
Optional (n = 59)
|
|
Adequate scores, n (%) [95 %CI]
|
|
BBPS[1]
|
130 (90.9)
[86.2 to 95.7]
|
104 (77.0)
[69.9 to 84.2]
|
53 (85.5)
[76.6 to 94.4]
|
39 (73.6)
[61.5 to 85.6]
|
|
OBPS[2]
|
78 (77.2)
[69.0 to 85.5]
|
64 (64.6)
[55.1 to 74.1]
|
32 (71.1)
[57.6 to 84.6]
|
16 (42.1)
[26.1 to 58.1]
|
|
Survey questions, n (%) [95 %CI][3]
|
|
Demographic data
|
|
Sex, female
|
87 (54.7)
[46.9 to 62.5]
|
85 (53.5)
[45.7 to 61.3]
|
33 (50.8)
[38.4 to 63.1]
|
37 (62.7)
[50.2 to 75.2]
|
|
Age (years), mean (95 %CI)
|
53.7
(51.4 to 56.0)
|
54.1
(51.6 to 56.6)
|
54.0
(49.9 to 58.2)
|
54.0
(49.9 to 58.0)
|
|
Education
|
|
|
22 (13.9)
[8.5 to 19.4]
|
31 (19.5)
[13.3 to 25.7]
|
7 (10.8)
[3.1 to 18.4]
|
5 (8.8)
[1.3 to 16.2]
|
|
|
136 (86.1)
[80.6 to 91.5]
|
128 (80.5)
[74.3 to 86.7]
|
58 (89.2)
[81.6 to 96.9]
|
52 (91.2)
[83.8 to 98.7]
|
|
Marital status
|
|
|
43 (27.0)
[20.1 to 34.0]
|
62 (39.0)
[31.4 to 46.6]
|
12 (18.5)
[8.9 to 28.0]
|
22 (38.6)
[25.8 to 51.4]
|
|
|
116 (73.0)
[66.0 to 79.9]
|
97 (61.0)
[53.4 to 68.6]
|
53 (81.5)
[72.0 to 91.1]
|
35 (61.4)
[48.6 %-74.2]
|
|
Previous colonoscopy
|
|
|
65 (58.6)
[49.3 to 67.8]
|
58 (55.2)
[45.7 to 64.8]
|
25 (59.5)
[44.3 to 74.7]
|
22 (59.5)
[43.3 to 75.6]
|
|
|
46 (41.4)
[32.2 to 50.7]
|
47 (44.8)
[35.2 to 54.3]
|
17 (40.5)
[25.3 to 55.7]
|
15 (40.5)
[24.4 to 56.7]
|
|
Clinical questions
|
|
How were you able to follow the instructions for bowel prep?
|
|
|
44 (27.5)
[20.5 to 34.5]
|
52 (32.7)
[25.4 to 40.0]
|
18 (27.3)
[16.4 to 38.2]
|
14 (23.7)
[12.7 to 34.7]
|
|
|
116 (72.5)
[65.5 to 79.5]
|
107 (67.3)
[60.0 to 74.6]
|
48 (72.7)
[61.8 to 83.6]
|
45 (76.3)
[65.3 to 87.3]
|
|
How clear were the instructions for the bowel prep?
|
|
|
100 (62.9)
[55.3 to 70.4]
|
109 (68.6)
[61.3 to 75.8]
|
46 (69.7)
[58.5 to 80.9]
|
40 (67.8)
[55.7 to 79.9]
|
|
|
39 (24.5)
[17.8 to 31.3]
|
33 (20.8)
[14.4 to 27.1]
|
11 (16.7)
[7.6 to 25.8]
|
15 (25.4)
[14.2 to 36.7]
|
|
|
20 (12.6)
[7.4 to 17.8]
|
17 (10.7)
[5.9 to 15.5]
|
9 (13.6)
[5.2 to 22.0]
|
4 (6.8)
[0.3 to 13.3]
|
|
How worried were you about the bowel prep?
|
|
|
122 (76.3)
[69.6 to 82.9]
|
128 (80.5)
[74.3 to 86.7]
|
55 (83.3)
[74.2 to 92.4]
|
49 (83.1)
[73.3 to 92.8]
|
|
|
38 (23.8)
[17.1 to 30.4]
|
31 (19.5)
[13.3 to 25.7]
|
11 (16.7)
[7.6 to 25.8]
|
10 (16.9)
[7.2 to 26.7]
|
|
How worried were you about the colonoscopy?
|
|
|
121 (75.6)
[68.9 to 82.3]
|
130 (81.8)
[75.7 to 87.8]
|
55 (83.3)
[74.2 to 92.4]
|
48 (81.4)
[71.3 to 91.4]
|
|
|
39 (24.4)
[17.7 to 31.1]
|
29 (18.2)
[12.2 to 24.3]
|
11 (16.7)
[7.6 to 25.8]
|
11 (18.6)
[8.6 to 28.7]
|
|
How worried were you about the results of the colonoscopy?
|
|
|
129 (80.6)
[74.5 to 86.8]
|
132 (83.0)
[77.2 to 88.9]
|
58 (87.9)
[79.9 to 95.9]
|
48 (81.4)
[71.3 to 91.4]
|
|
|
31 (19.4)
[13.2 to 25.5]
|
27 (17.0)
[11.1 to 22.8]
|
8 (12.1)
[4.1 to 20.1]
|
11 (18.6)
[8.6 to 28.7]
|
|
Tolerability
|
|
Please indicate if the following symptoms were moderate or severe:
|
|
|
57 (35.6)
[28.2 to 43.1]
|
61 (38.4)
[30.8 to 46.0]
|
23 (34.8)
[23.2 to 46.5]
|
19 (32.2)
[20.1 to 44.3]
|
|
|
24 (15.0)
[9.4 to 20.6]
|
13 (8.2)
[3.9 to 12.5]
|
3 (4.5)
[0.0 to 9.6]
|
6 (10.2)
[2.3 to 18.0]
|
|
|
30 (18.8)
[12.7 to 24.8]
|
33 (20.8)
[14.4 to 27.1]
|
11 (16.7)
[7.6 to 25.8]
|
13 (22.0)
[11.3 to 32.8]
|
|
|
12 (7.5)
[3.4 to 11.6]
|
13 (8.2)
[3.9 to 12.5]
|
6 (9.1)
[2.1 to 16.1]
|
3 (5.1)
[0.0 to 10.8]
|
|
|
15 (9.4)
[4.8 to 13.9]
|
21 (13.2)
[7.9 to 18.5]
|
6 (9.1)
[2.1 to 16.1]
|
6 (10.2)
[2.3 to 18.0]
|
|
|
13 (8.1)
[3.9 to 12.4]
|
17 (10.7)
[5.9 to 15.5]
|
4 (6.1)
[0.2 to 11.9]
|
4 (6.8)
[0.3 to 13.3]
|
|
|
28 (17.5)
[11.6 to 23.4]
|
27 (17.0)
[11.1 to 22.8]
|
13 (19.7)
[10.0 to 29.4]
|
8 (13.6)
[4.7 to 22.4]
|
|
|
5 (3.1)
[0.4 to 5.8]
|
9 (5.7)
[2.0 to 9.3]
|
1 (1.5)
[0.0 to 4.5]
|
2 (3.4)
[0.0 to 8.1]
|
|
|
52 (32.5)
[25.2 to 39.8]
|
41 (25.8)
[18.9 to 32.6]
|
16 (24.2)
[13.8 to 34.7]
|
13 (22.0)
[11.3 to 32.8]
|
|
|
34 (21.3)
[14.9 to 27.6]
|
30 (18.9)
[12.8 to 25.0]
|
9 (13.6)
[5.2 to 22.0]
|
12 (20.3)
[9.9 to 30.8]
|
|
|
45 (28.1)
[21.1 to 35.1]
|
45 (28.3)
[21.3 to 35.3]
|
18 (27.3)
[16.4 to 38.2]
|
16 (27.1)
[5.6 to 38.6]
|
|
If required future colonoscopy, would you be willing to use the same bowel prep instructions
again?
|
|
|
20 (12.5)
[7.3 to 17.7]
|
19 (11.9)
[6.9 to 17.0]
|
8 (12.3)
[4.2 to 20.4]
|
9 (15.5)
[6.1 to 25.0]
|
|
|
104 (65.0)
[57.6 to 72.4]
|
108 (67.9)
[60.6 to 75.2]
|
44 (67.7)
[56.2 to 79.2]
|
34 (58.6)
[45.8 to 71.5]
|
|
|
36 (22.5)
[16.0 to 29.0]
|
32 (20.1)
[13.9 to 26.4]
|
13 (20.0)
[10.1 to 29.9]
|
15 (25.9)
[14.4 to 37.]
|
|
Tolerance, mean (95 %CI)[4]
|
7.3
(6.9 to 7.7)
|
6.9
(6.5 to 7.3)
|
7.6
(7.03 to 8.1)
|
7.0
(6.3 to 7.7)
|
|
Tolerance scale
|
|
|
41 (25.6)
[18.8 to 32.4]
|
52 (32.7)
[25.4 to 40.0]
|
13 (20.0)
[10.1 to 29.9]
|
18 (31.0)
[19.0 to 43.1]
|
|
|
119 (74.4)
[67.6 to 81.2]
|
107 (67.3)
[60.0 to 74.6]
|
52 (80.0)
[70.1 to 89.9]
|
40 (69.0)
[56.9 to 81.0]
|
|
Sleep, mean (95 %CI)
|
|
|
2.6
(2.1 to 3.1)
|
2.5
(2.1 to 2.9)
|
2.5
(2.0 to 3.1)
|
2.6
(1.9 to 3.2)
|
|
|
1.8
(1.4 to 2.1)
|
2.1
(1.7 to 2.5)
|
2.1
(1.5 to 2.6)
|
2.2
(1.5 to 2.8)
|
|
|
1.4
(1.2 to 1.6)
|
1.3
(1.1 to 1.5)
|
1.4
(1.0 to 1.7)
|
1.3
(1.0 to 1.6)
|
|
|
4.1
(3.9 to 4.4)
|
4.5
(4.2 to 4.8)
|
5.1
(4.6 to 5.5)
|
4.9
(4.5 to 5.4)
|
|
|
7.1
(6.9 to 7.3)
|
7.1
(6.9 to 7.3)
|
6.8
(6.4 to 7.1)
|
7.2
(6.9 to 7.5)
|
|
Bowel movement information
|
|
How much time before colonoscopy was your last bowel movement?
|
|
|
38 (23.8)
[17.1 to 30.4]
|
28 (17.8)
[11.8 to 23.9]
|
14 (21.5)
[11.4 to 31.7]
|
10 (18.5)
[8.0 to 29.0]
|
|
|
70 (43.8)
[36.0 to 51.5]
|
76 (48.4)
[40.5 to 56.3]
|
25 (38.5)
[26.5 to 50.5]
|
22 (40.7)
[27.4 to 54.0]
|
|
|
22 (13.8)
[8.4 to 19.1]
|
28 (17.8)
[11.8 to 23.9]
|
10 (15.4)
[6.5 to 24.3]
|
12 (22.2)
[11.0 to 33.5]
|
|
|
30 (18.8)
[12.7 to 24.8]
|
25 (15.9)
[10.2 to 21.7]
|
16 (24.6)
[14.0 to 35.2]
|
10 (18.5)
[8.0 to 29.0]
|
|
Stopped for bowel movement during travel to clinic/hospital
|
7 (4.4)
[1.2 to 7.6]
|
7 (4.4)
[1.2 to 7.6]
|
4 (6.3)
[0.2 to 12.3]
|
7 (12.1)
[3.6 to 20.6]
|
|
Urgent bowel movement[5]
|
113 (70.6)
[63.5 to 77.7]
|
114 (71.7)
[64.7 to 78.7]
|
46 (71.9)
[60.7 to 83.0]
|
42 (72.4)
[60.7 to 84.1]
|
|
Incontinence[6]
|
27 (17.0)
[11.1 to 22.8]
|
27 (17.0)
[11.1 to 22.8]
|
11 (17.2)
[7.8 to 26.6]
|
15 (26.3)
[14.7 to 37.9]
|
BBPS, Boston Bowel Preparation Scale; OBPS, Ottawa Bowel Preparation Scale.
Note: bold values indicate that the 95 %CIs between the two groups do not overlap.
1 Calculated for those with complete BBPS data who agreed to link to retrospective
data: total early (n = 278); mandatory early (n = 143) optional early (n = 135); total
late (n = 115); mandatory late (n = 62); optional late (n = 53).
2 Calculated for those with complete OBPS data who agreed to link to retrospective
data: total early (n = 200); mandatory early (n = 101); optional early (n = 99); total
late (n = 83); mandatory late (n = 45); optional late (n = 38).
3 Unless otherwise stated.
4 Scale 1 (not tolerated at all) to 10 (totally tolerated).
5 In the time period between starting to take the bowel preparation medication and
the colonoscopy, did you have one or more times when you had an urgent bowel movement?
6 Did you have any incontinence (accident) episodes between the start of taking the
first dose of bowel preparation liquid and the time of your colonoscopy?
Factors associated with choosing day-before bowel preparation over SDBP in the optional
group are presented in Table 2 s. Among the 209 patients in the optional group, day-before bowel preparation was chosen
by 104/153 (68.0 %) for early morning colonoscopies and 34/56 (60.7 %) for late morning
colonoscopies. There were no differences in the patient experiences related to the
bowel preparation (ability to follow/clarity of instructions, anxiety, tolerability,
sleep, incontinence). Multivariable logistic regression analysis identified no significant
predictors associated with choosing day-before bowel preparation over SDBP among early
morning colonoscopies (Table 3 s).
Discussion
We found that optional SDBP was inferior to mandatory SDBP in providing adequate bowel
cleanliness (adequate BBPS) for early morning (8:00 AM–10:30 AM) colonoscopies. It
also numerically less frequently provided adequate bowel cleanliness (measured by
the BBPS) among late morning (10:30 AM–12:00 PM) colonoscopies, although the difference
for late morning colonoscopies did not reach statistical significance. The data collection
period extended partially into the COVID-19 pandemic, which meant we stopped the study
before we had reached the intended sample size (n = 209) for both the mandatory and
optional SDBP groups for late morning colonoscopies, which may have influenced statistical
significance. Adequate OBPS for late morning procedures was significantly less frequent
in the optional SDBP group compared with the mandatory SDBP group. Giving patients
a choice (optional SDBP) did not improve patient experiences of bowel preparation
compared with the mandatory SDBP group for early or late morning colonoscopies.
The literature continues to provide evidence to support SDBP being a better regimen
than the day-before bowel preparation approach [10]
[11]
[12]
[28]
[29], yet endoscopists have been hesitant to mandate SDBP for early morning procedures
owing to concerns regarding patient compliance, comfort [15], and efficacy in clinical practice [30]. A study that surveyed trusts in the UK [31] suggested most did not provide instructions optimizing the timing (split dose) of
bowel preparation prior to colonoscopy procedures, which resulted in an increased
rate of inadequate cleansing. As many centers use day-before rather than split-dose
regimens for early morning colonoscopies, patients may be unaware and lack knowledge
of the advantages that split dosing provides. Therefore, in these centers, the uptake
of split dosing for early morning colonoscopies is likely to be even lower than the
25 % uptake observed in our study. Consequently, the rate of inadequate bowel preparation
may be higher than we have reported.
When we compared those who took the laxative as a split dose versus those who took
the laxative the day before among those assigned to the optional group, we found no
differences in the clinical characteristics for either early or late morning procedures.
However, the sample size was limited, so more research is needed to identify any patient
factors that predict patients’ choice of day-before bowel preparation.
We have shown that, regardless of whether procedures are early or late morning, when
given a choice (optional SDBP), patients are more likely to choose to take the laxative
entirely the day before. This finding is not surprising as we have previously shown
in a survey of 1336 respondents that unclear bowel preparation information (odds ratio
[OR] 1.86, 95 %CI 1.21–2.85) and high bowel preparation anxiety (OR 2.02, 95 %CI 1.35–3.02)
are predictors of patient reluctance to use early morning bowel preparation [32]. Our studies suggest the need to provide additional information to patients, highlighting
the benefits of SDBP. We have recently reported how the use of an informative online
platform is associated with an increased use of SDBP [33].
Our previous study that assessed patients’ opinions about waking early for bowel preparation
[32] found that almost three-quarters of patients did not express reluctance to get up
early for bowel preparation; however, 27 % did. Results from another study, consistent
with our findings, assessing patients’ willingness to undergo SDBP for early morning
procedures, scheduled between 7 AM and 9 AM, found that a substantial minority of
patients do not comply with SDBP [34] (85 % stated they would be willing to get up, with 78 % actually awakening early
to take the second dose). Additional efforts should be made to reduce the likelihood
of patients continuing to be reluctant to take laxatives early in the morning, although
acknowledging SDBP may not be feasible for those travelling long distances on the
day of their colonoscopy [35].
Dissemination of our current study results could allay some of the patient anxiety
associated with the early morning intake of bowel preparation. In our current study,
we found that there was no difference in patient experiences relating to anxiety (worried
about bowel preparation, colonoscopy, results of the colonoscopy), tolerability, sleep,
or incontinence between the mandatory and optional SDBP groups, or between those who
chose day-before bowel preparation over SDBP for early morning colonoscopies.
Our study provides evidence that optional SDBP is inferior to mandatory SDBP in terms
of adequate bowel cleanliness for early morning colonoscopies, and possibly also for
late morning procedures. In addition, the mandatory SDBP group did not show a higher
proportion of missed colonoscopies, workload in terms of phone calls for nurses, or
proportion of incomplete laxative intake, or differ in the procedural measures compared
with the optional SDBP group for early or late morning procedures. These findings
should be reassuring to centers that have switched to or are considering switching
to mandatory SDBP for morning colonoscopies. As a net result of this study, our regional
citywide endoscopy program is now moving toward mandatory SDBP for most patients;
we believe other jurisdictions who are still using optional SDBP or day-before bowel
preparation should do so as well.
The greatest advantage of our study is its adoption of a pragmatic (i. e. real world)
setting, as it is more generalizable to usual practice [36]. As a result of this, we did have a high proportion of incomplete colonoscopies
and some unrecorded BBPS scores. Other studies have reported similar or lower rates
of attendance for colonoscopies [37]
[38]
[39]. Patient characteristics (including survey response results) and subgroup analysis
suggest robustness of our results. A further limitation is that, among the mandatory
SDBP group, 25 % of patients ingested the bowel preparation entirely the day before
rather than in two split doses. We did not ask patients why they did not complete
the intended SDBP; however, it has been previously reported that 15 %–22 % of patients
do not comply with SDBP [15]
[34]. In addition, high volume PEG is not considered the standard in many countries,
which may limit the external validity of our study findings. Similarly to other studies,
our secondary end points and post-hoc analysis are exploratory and should be interpreted
with caution. This was also a single-center study, albeit from a center that provides
care to a wide spectrum of patients. In addition, sample size was small in many of
the subgroup analyses.
Our study suggests that patients undergoing morning colonoscopy should not be offered
the option of day-before high volume PEG, as an alternative to split-dose high volume
PEG. Patients reasoning and the predictors for ingesting the bowel preparation laxatives
entirely on the day before when mandatory SDBP instructions have been provided need
further investigation. Facilitators of SDBP use in usual clinical practice should
be assessed and implemented. The implications of our study findings in settings where
low volume bowel preparation is the standard needs evaluation.
In conclusion, our study results suggest bowel preparation quality is inferior with
optional compared with mandatory SDBP for early morning (8:00 AM–10:30 AM) and possibly
for late morning (10:30 AM–12:00 PM) colonoscopies. Patient experience, compliance
for colonoscopies, and workload for clinical staff in terms of phone calls, rescheduling,
and cancellations does not differ between these groups. Given the choice, the majority
of patients choose the day-before bowel preparation method, which results in inferior
cleanliness. Our study results suggest that the day-before option needs to be eliminated
and the mandatory SDBP regimens need to be promoted for most patients, including those
undergoing early morning colonoscopies. Switching to mandatory SDBP will need to be
optimized through appropriate physician and patient education.
