Introduction
A good bowel preparation (BP) plays an important role in ensuring an accurate, complete,
and safe colonoscopy examination. Despite its importance, bowel cleansing for colonoscopies
has been reported to be poor in up to 20 – 40 % of cases [1 ], which can compromise patient care and outcomes. Poor bowel cleansing leads to increased
risks of complications, longer procedure times, and increased rates of missed lesions,
including colorectal polyps and cancers [2 ]
[3 ]
[4 ]. Inadequate bowel cleansing is also a common reason for early repeat procedures.
BP conducted the day before a colonoscopy clears fecal material from the colon [5 ]. However, after the fecal material has been cleared, more material – including new
fecal material, mucus, secretions – begins to re-enter the colon [6 ]
[7 ]. Thus, preparation starts to deteriorate as time passes from the administration
of the bowel preparation. This is the primary reason why a split-dose bowel preparation
(SDBP), in which the second dose is taken close to the timing of the colonoscopy,
was suggested over 20 years ago [8 ]. Another reason to split the dose, frequently unrecognized, is to increase patient
tolerance [1 ]
[9 ]
[10 ]. Patient tolerance of SDBP may be higher due to individuals needing to consume a
lower amount of the laxative at a time, contributing to fewer nocturnal awakenings
or less intense bowel movements [11 ].
Evidence supporting improved bowel cleansing with SDBP compared with a day-before
preparation has been overwhelming [12 ]
[13 ]
[14 ]
[15 ]
[16 ]
[17 ]. A meta-analysis of 29 randomized controlled trials suggested an absolute rate difference
of 22 % more adequate cleansing with SDBP (85 %) than with non-SDBP (63 %) [15 ]. It is recommended that the colonoscopy should be performed within 4 hours of the
last dose of the SDBP [15 ]
[17 ]. European and North American guidelines now strongly recommend the use of SDBP for
all colonoscopies [1 ]
[3 ]
[4 ]
[5 ]
[18 ]
[19 ].
Despite the guidelines and the evidence of benefits of SDBP, many endoscopists are
reluctant to ask their morning colonoscopy patients to take SDBP because they believe
that patients will not agree to waking early to take the second part of the laxative
[20 ]
[21 ]
[22 ]. There are limited data from routine clinical practices on patients’ willingness
to wake early in the morning for BP and predictors of reluctance. A study from a tertiary
care center limited to patients undergoing colonoscopy for average risk CRC screening
reported that 15 % were not compliant with SDBP [23 ]. A study from Italy gave patients an information sheet on the benefits of SDBP [20 ]. Patients were then provided the option of day before or SDBP and 38 % chose day
before preparation. Predictors of choosing day before preparation included colonoscopy
appointment before 1000 h, travel time > 1 hour, low education level, and female gender.
In that study, all patients used 4 L of polyethylene glycol (PEG) BP, and all were
undergoing their first colonoscopy. Many patients undergo repeat colonoscopies and
use of low volume BP is common. Hence, it is important to assess the opinions of those
with varying numbers of previous colonoscopies and colonoscopy preparation experiences
to identify factors that may be modified in instructing patients about bowel preparation.
In this study, we assessed in usual clinical practice, colonoscopy patients’ opinions
about waking up for BP early in the morning, and evaluated factors associated with
reluctance to conduct early morning BP.
Methods
Study population
A self-administered anonymous survey (see Supplementary Fig. 2 ) was distributed between August 2015 and June 2016 to adult patients immediately
before their outpatient colonoscopy in six hospitals and two ambulatory care centers
in Winnipeg, Manitoba, Canada. Approximately 85 % of the colonoscopies in Winnipeg
are performed in the six hospitals in the city and their affiliated endoscopy units,
and the rest in two ambulatory care centers.
Participants were invited into the study if there was enough time before their procedure
to complete the survey. Inclusion criteria included patients’ willingness to complete
the self-administered survey while sitting in the waiting room, and the ability to
read and respond in English. The colonoscopy centers were frequently busy and the
survey was only distributed when staff had adequate time to explain the survey to
patients waiting for their procedure.
The survey
The survey included items on demographic characteristics, reason for the current colonoscopy,
previous experience with colonoscopy, whether or not the patient was going directly
to endoscopy (i. e. meeting the endoscopist for the first time on the day of the procedure),
BP procedure used, anxiety about the colonoscopy, knowledge/information needs around
colonoscopy and how willing the patient would be to wake early in the morning to complete
the BP for their next colonoscopy. The question about willingness to wake early used
the example of waking at 0400 h to take BP for a colonoscopy at 0800 h. The survey
took about 10 to 20 minutes to complete. The questionnaire was first pilot tested
among eight patients experienced with colonoscopies and eight endoscopists.
Three self-reported anxiety scores were obtained from each respondent using visual
analogue scales [24 ]
[25 ]: anxiety about the BP, anxiety about the colonoscopy procedure, and anxiety about
the colonoscopy results. Each score was obtained by asking the respondent to assess
their level of anxiety by placing a mark such as the one below:
The mark was then translated into a score from 0 to 100 by measuring placement of
the line on the scale.
Statistical analysis
Background characteristics of the respondents are described. Patients indicated whether
they were very willing, willing, neutral, reluctant, or very reluctant to wake up
early in the morning for BP. In the analysis, willing and very willing responses were
combined, as were reluctant and very reluctant responses. The proportion of patients
willing, neutral, or reluctant to wake early in the morning for BP was described for
each potential predictor in the subsequent analyses. Multivariable logistic regression
analyses were performed to determine predictors of reluctance to use early morning
BP. In separate logistic regression analysis models, those who were reluctant to use
early morning BP were compared to people who were willing, people who were neutral,
and people who were willing or neutral toward use of early morning BP.
In some analyses, the continuous anxiety scales were dichotomized. A score of 70 or
more was chosen to indicate a high level of anxiety, because this score represented
approximately the top quartile of the anxiety score among all patients.
Our main response variable was ordered from reluctant to neutral to willing to wake
up early morning for BP. As such, in addition to ordinary logistic regression, we
assessed whether our conclusions would be the same using ordinal logistic regression.
These results are provided as supplementary material.
The odds from our logistic regressions were transformed into probabilities using the
formula:
Probability = Odds/(1 + Odds) [26 ]
To visually inspect the importance of different variables in predicting the likelihood
of being reluctant to undergo early morning BP, we graphed the probabilities of being
reluctant, neutral, or willing to undergo BP early in the morning, given different
levels of the independent variables in the ordinal logistic regression model. In total,
16 permutations of levels of the independent variables were graphed, and probabilities
of being reluctant, neutral, or willing to undergo early morning BP were compared.
Ethical approval
This study was approved by the University of Manitoba Health Research Ethics Board.
Results
At two of the hospitals, the survey was distributed and collected by clinical staff
and the response rate could be assessed; it was 86 % at both locations. The other
locations were not able to collect response rate information as staff were too busy
to document the number of persons who refused to complete the surveys, but all locations
indicated that the survey was well accepted. Of the 1336 respondents, 52.2 % were
women and the median age was 57 years (IQR 49 – 65). Participant ages ranged from
16 to 91 years. Just over one-quarter (26.5 %) were reluctant or very reluctant to
complete BP in the early morning, 24.0 % were neutral, and 49.5 % were willing or
very willing ([Table 1 ]).
Table 1
Characteristics of the study respondents by proportion reluctant, neutral, and willing
to do an early morning bowel preparation (%).
Reluctant (n = 354)
Neutral (n = 321)
Willing (n = 661)
Survey location (n = 1336)
25
25
50
26
24
50
32
21
47
Gender (n = 1301)
[1 ]
21
24
54
31
24
44
Age (n = 1293)
56.7
55.8
56.0
58
57
57
Education (n = 1212)
25
27
47
26
29
45
28
23
49
24
20
56
Marital status (n = 1293)
25
24
51
31
25
44
33
19
48
31
26
43
How much bowel prep info received (n = 1258)
36
16
48
25
24
51
28
26
46
33
7
60
Clarity of bowel prep info (n = 1300)
[1 ]
46
16
38
33
24
43
24
25
51
Split prep for current colonoscopy (n = 1304)
[1 ]
21
22
57
30
25
45
Anxiety scores (on scale of 0 to 100)
Bowel prep anxiety (n = 1303)[1 ]
23
25
52
43
19
38
Colonoscopy procedure anxiety (n = 1302)
24
25
51
31
24
45
Colonoscopy results anxiety (n = 1301)
25
25
50
29
23
48
Purpose of colonoscopy (n = 1301)
22
25
53
26
25
49
29
23
48
Time of colonoscopy (n = 1331)
28
22
49
29
24
27
23
26
51
Number of previous colonoscopies (n = 1322)
24
23
53
27
25
48
29
25
46
Type of bowel prep (multiple responses allowed)
31
22
47
23
26
51
25
23
51
35
26
39
When last saw scope doctor (n = 1315)
25
25
50
28
22
49
25
27
48
Finished laxative for current colonoscopy (n = 1320)
25
23
51
34
28
38
1
P value for group differences < 0.01.
Although type of BP used for the current colonoscopy was based on advice from their
endoscopist, those who used SDBP (morning or afternoon) were less likely to be reluctant
to do early morning BP for a subsequent colonoscopy than those who used day before
BP (21.2 % versus 29.5 % reluctant respectively, P < 0.001). Furthermore, among those who used SDBP for their current colonoscopy, 33.3 %
thought that waking early in the morning for BP would be difficult or very difficult,
while 46.5 % of those who had conducted day before BP thought that an early morning
BP would be difficult or very difficult (P value for difference < 0.001).
Predictors of reluctance to wake early for bowel preparation
In a model that excluded those who were neutral toward early morning waking for BP
([Table 2, ]Model 1), the respondent characteristics associated with reluctance to wake early
were female gender (OR 1.65), number of previous colonoscopies (OR 1.20 per colonoscopy),
receiving unclear BP information (OR 1.86), having a BP anxiety score > 70 (OR 2.02),
indication for current colonoscopy being symptoms (OR 1.40), using 4 L of PEG laxative
(OR 1.45), not having used SDBP for the current colonoscopy (OR 1.96), and not having
finished the laxative for the current colonoscopy (OR 1.66). Reluctance increased
with increasing number of prior colonoscopies; for example, a respondent who had had
three previous colonoscopies was estimated to be 1.73 times more likely (95 %CI 1.23 – 2.46)
to be reluctant than willing ([Table 2, ]Model 1) to perform an early morning BP than one whose current colonoscopy was their
first one. This estimate is derived by raising the OR for previous colonoscopies to
the power of 3 (1.203 = 1.73). In a model comparing reluctant to neutral, the associations were similar
to those found in the model described above, but less strong; that is, although the
odds ratios were similar, fewer potential predictors were statistically significant
([Table 2, ]Model 2).
In ordinal logistic regression modeling (Supplementary Table1 , right column), both the statistically significant predictors, as well as the odds
ratios, were similar to those found in the ordinary logistic regression modeling.
Under numerous permutations of the different levels of the statistically significant
predictors from the ordinal logistic regression model, we have displayed, in Supplementary Fig. 1a,b , the probability of being reluctant, neutral, or willing to undergo early morning
BP, depending on the level of each of the following significant predictors from the
ordinal logistic regressions: gender, clarity of BP information, having conducted
a SDBP, having finished their laxative, and their BP anxiety score. As an example,
under almost all permutations of the different levels of independent variables (e. g.,
female versus male, having received clear versus unclear bowel preparation information,
having split the dose for the current colonoscopy versus having conducted a single-dose
preparation, etc.), the probability of being willing to wake early for BP was higher
than the probability of being reluctant, at low levels of anxiety about the bowel
preparation. A notable exception was among women who received unclear BP information,
had not conducted an SDBP for their current colonoscopy, and had not finished the
laxative for their current colonoscopy (Supplementary Fig. 1a , panel 8). Among this group, even those with very low levels of anxiety had a relatively
high probability of reluctance. The probability of reluctance among this group was
almost the same as the probability of willingness when anxiety about the BP was near
0, and it increased to almost 75 % when anxiety about the BP was near its highest
possible score of 100. Other variables in Supplementary Fig. 1 are also in line with results from the logistic regression. For example, all else
being equal, people who received unclear BP information had a higher probability of
reluctance to wake early for BP, women were more likely to be reluctant than men,
and those who had not finished their laxative were more likely to be reluctant than
those who had finished their laxative.
Table 2
Predictors of reluctance to use early morning bowel preparation – adjusted logistic
regression analysis.
Model 1:
Reluctant vs. Willing
(n = 772), Odds ratio (95 %CI)
Model 2:
Reluctant vs. Neutral
(n = 515), Odds ratio (95 %CI)
Demographic of respondent
Female
1.65 (1.19 – 2.29)[2 ]
1.46 (0.99 – 2.16)
Age, years (reference = 16 – 39 years)
0.87 (0.51 – 1.49)
1.16 (0.64 – 2.11)
1.00 (0.57 – 1.76)
1.30 (0.69 – 2.45)
Married
1.03 (0.71 – 1.50)
0.94 (0.61 – 1.43)
Post-secondary education
0.99 (0.70 – 1.40)
1.48 (1.00 – 2.21)
Prep information received and anxiety of respondent
Number of previous colonoscopies[3 ]
1.20 (1.07 – 1.35)[2 ]
1.13 (0.99 – 1.29)
Received “Right” amount of prep info
0.95 (0.67 – 1.34)
0.93 (0.62 – 1.38)
Bowel prep information was unclear[4 ]
1.86 (1.21 – 2.85)[2 ]
1.70 (1.04 – 2.77)[1 ]
Bowel preparation anxiety score > 70
2.02 (1.35 – 3.02)[2 ]
2.18 (1.34 – 3.55)[2 ]
Scope procedure anxiety score > 70
1.24 (0.85 – 1.80)
1.06 (0.68 – 1.65)
Scope results anxiety score > 70
0.94 (0.65 – 1.37)
1.07 (0.69 – 1.67)
Details of respondent’s current colonoscopy
Purpose is symptoms
1.40 (0.99 – 1.97)[1 ]
1.62 (1.10 – 2.38)[1 ]
Appointment is after 1200 h
0.90 (0.62 – 1.31)
0.72 (0.47 – 1.10)
Type of laxative is 4 L of PEG
1.45 (1.02 – 2.06)[1 ]
1.57 (1.03 – 2.39)[1 ]
Adjunctive agent in laxative
0.95 (0.68 – 1.31)
0.92 (0.63 – 1.34)
Direct to scope
0.97 (0.70 – 1.36)
0.76 (0.52 – 1.11)
No split bowel preparation
1.96 (1.31 – 2.93)[2 ]
1.42 (0.88 – 2.27)
Did not finished laxative
1.66 (1.01 – 2.73)[1 ]
0.85 (0.49 – 1.47)
1
P value < 0.05.
2
P value < 0.01.
3 Odds ratio is per previous colonoscopy. For example, an individual with 3 previous
colonoscopies is estimated to be 1.203 = 1.73 times more likely than an individual with 0 previous colonoscopies to be reluctant
than willing to undergo SDBP.
4 This refers to people who stated that the information they received was either “somewhat
clear” or “confusing”, as opposed to “clear”.
The respondent behavior that had the largest impact on reluctance to wake early for
BP was not having finished the laxative for their current colonoscopy (panels 2, 4,
and 6 among women, and 2, 4, and 6 among men, Supplementary Fig. 1 ). Among those who did not finish their laxative, the probability of feeling reluctant
approached the probability of willingness as anxiety about the BP increased, and,
in some cases, the probability of feeling reluctant surpassed the probability of being
willing.
Discussion
Among patients who were about to undergo a colonoscopy, approximately three-quarters
were willing or neutral to wake early for BP for repeat colonoscopy. On the one hand,
this indicates a significant proportion of patients who suggest that they would comply
with SDBP if their endoscopists advised it. That said, one-quarter would be reluctant
to conduct SDBP even if it were requested by their endoscopist; so we assessed determinants
of reluctance.
In our study, there was a striking similarity in odds ratios in the model predicting
reluctant
versus willing to undergo early morning BP ([Table 2, ]Model 1), and that predicting reluctant versus willing or neutral (Supplementary Table 1 , Model 3); this suggests that people who state that they are neutral toward early
morning BP would likely behave similarly to those who state that they are willing
to conduct an early morning BP. The predictors of reluctance were female gender, higher
number of previous colonoscopies, high levels of anxiety about BP, perceived inadequacy
of received BP information, the purpose of the current colonoscopy being symptoms,
having used 4 L of PEG laxative for the current colonoscopy, not having split the
BP for the current colonoscopy, and not having finished the laxative. Importantly,
age, lower education level, presenting directly for colonoscopy without a prior visit
with the endoscopist, and the timing of the current colonoscopy had no association
with reluctance to wake up early for BP for a subsequent colonoscopy. An understanding
of these predictors may help in developing approaches to increase the use of SDBP
and the early waking that this requires of some patients.
There are a number of approaches that could be taken to reduce reluctance to wake
early for BP. As suggested in previous studies [21 ]
[27 ], we found that high anxiety about the BP was consistently associated with reluctance
to wake early in the morning to complete BP. There has been limited research on interventions
to reduce anxiety around colonoscopy. Although some randomized controlled trials suggest
that providing more user friendly written materials and videos explaining how to conduct
the BP appear to be effective in lowering anxiety [28 ]
[29 ]
[30 ], the effects have not been consistent [31 ], which may be related to the content of the information provided. Another suggestion
is to allow more time with the patient before the colonoscopy [32 ]. More work exploring ways to mitigate anxiety may result in an increased likelihood
that patients would be willing to wake early for BP.
Respondents who had undergone previous colonoscopies were more reluctant to wake early
for BP for their next colonoscopy, and the reluctance increased with each prior colonoscopy.
It is possible that they had not used SDBP previously and had a “successful” colonoscopy
so did not feel that early morning waking for the second dose of SDBP was necessary.
More widespread use of SDBP is relatively recent and people with previous colonoscopies
likely used the day before method for prior colonoscopies. However, the quality of
colon cleansing has not been routinely documented [33 ] or communicated to patients until recently and therefore it is possible that some
of the patients with prior colonoscopies had inadequate prior examination leading
to early repeat colonoscopy.
It is notable that 30 % of respondents indicated that they did not receive enough
information before the colonoscopy and a further 4 % indicated that they received
no information ([Table 1 ]). Improved information sharing and educational resources, developed with assistance
from patients experienced with colonoscopy, may help to reduce problems with instructions
that are not clear to some patients. Although the amount of information received was
not associated with reluctance to undergo early morning SDBP, improved messages to
patients about the advantages of split dose, integrated with instructions about BP,
may also decrease reluctance.
Reluctance to wake up early in the morning for BP was higher among individuals who
used large volume BP laxative for a colonoscopy. One could anticipate this reluctance
as it takes longer to consume large volume BP, which then would leave either shorter
travel time to the endoscopy unit or the need to wake up even earlier. In this regard,
the results of the recent Italian study where 38 % of the study participants did not
take the SDBP even though they were informed about the benefits of SDBP, likely do
not apply to settings using lower volume BP [20 ].
The results of our study are consistent with those of randomized controlled trials,
which have reported higher willingness to repeat colonoscopy with the same method
among those undergoing SDBP than day before BP [17 ]. In our study in routine clinical practice, those who had split their bowel preparation
for the current colonoscopy were more likely to be willing to undergo early morning
BP for their next colonoscopy. It is possible that this is a result of selection bias – those
who would be willing to undergo early morning BP in the future were also willing (and
did) to undergo SDBP for their current colonoscopy. It may also suggest that the fear
of the unknown may be a greater barrier to administering a morning BP than is the
actual discomfort of the morning BP. An educational tool, such as a video with narratives
from colonoscopy patients who had conducted SDBP and not found it too difficult, may
help those who have never undergone SDBP to be comfortable with a suggestion of waking
early for BP.
The documented benefits of SDBP [12 ]
[13 ]
[14 ]
[15 ]
[16 ]
[17 ]
[19 ] suggest that it would be helpful to consider what administrative changes might encourage
increased use of SDBP for morning colonoscopies. One approach might be to ask at the
stage of the referral whether the patient would accept a morning colonoscopy that
would involve early wakening to complete the BP. Our survey suggests that many people
would accept this option. For some, this may even be a preferred option since early
morning colonoscopies allow individuals to resume their normal diet earlier in the
day. Those who indicated a preference not to have early appointments would be scheduled
for later appointments. If many people chose later day appointments, there might be
a longer wait for these appointments than for early in the day appointments. The offer
to schedule later day appointments could be prioritized; for example, depending on
the demand, it could be restricted to those advised to have frequent colonoscopies,
such as those with Lynch syndrome and IBD patients with prior documented dysplasia.
Limitations and strengths
The results of this study should be considered in the context of strengths and limitations.
To ensure the survey length remained reasonable for completion, we limited the number
of questions asked about waking early for a morning colonoscopy. We did not explore
reasons for reluctance with direct questions, or explore options for reducing reluctance
in this study. Furthermore, some respondents would have had to travel some distance
to the colonoscopy location on the day of the procedure and this may have been a factor
for these patients. We did not gather information about the time required to travel
to the colonoscopy location. Similar to other survey studies, this study is potentially
subject to socially desirable response bias and opinions may or may not reflect future
behavior. Our results show associations between various patient characteristics and
reluctance to conduct early morning BP, and these should be interpreted cautiously;
associations differ from cause and effect. Although we know the characteristics of
those who participated in this study, we do not know the characteristics of those
who did not participate. We were therefore unable to assess whether those who participated
differed from those who did not in a way which may have impacted the generalizability
of our results.
The strengths of this study include a large and diverse sample recruited from routine
city-wide
clinical practices. Participants had a range of previous experience with colonoscopy
and a
variety of different indications for the procedure and this is typical of clinical
practice. Our multiple analyses provided consistent results: in addition to the ordinary
logistic regression, we assessed the assumptions for, and then conducted, an ordinal
logistic regression. In both methods of logistic regression, results were nearly the
same (compare [Table 2 ] with Supplementary Table 1 ), strengthening the reliability of our findings.
Conclusions
The majority of respondents to our survey indicated that they were neutral toward
or willing to administer an early morning BP; however, a substantial proportion (approximately
one-quarter) would be reluctant to undertake a SBDP. As the advantages of an SDBP
are strong and most patients would be willing to undertake a SDBP if asked to, endoscopists
and family physicians should not hesitate to suggest splitting the dose to their patients,
even if the colonoscopy will be early in the morning. It will also be important to
develop strategies to improve acceptance of early morning wakening for BP among those
who continue to be reluctant. Addressing modifiable factors, such as improving BP
information, allaying BP-related anxiety and use of low volume BP may increase acceptance
of SDBP among patients and colonoscopists for early morning colonoscopies.
