Worldwide, colorectal cancer (CRC) is the third most common cancer and the fourth
most common cause of cancer deaths [1]. Although treatments for CRC have advanced over the past decade, they have translated
into only a modest benefit for patients who have advanced and metastatic CRC, and
with significantly increased treatment costs [2]. The aim of national screening programs is to reduce the burden of CRC in the population.
Screening for CRC with colonoscopy has been shown to be cost-effective in detecting
and removing adenomas, which are the clinical precursors of CRC, and several large
studies have demonstrated that high quality colonoscopy can improve outcomes with
a substantial reduction in CRC rates [3]
[4]. However, the detection of precursor lesions and early CRC depends on a number of
factors, including adequate bowel preparation, and studies have shown that inadequate
bowel cleansing increases the risk that flat adenomas and other high risk lesions
will remain undetected [5]
[6].
The reasons for not adhering to bowel-cleansing instructions before colonoscopy are
likely to be multifactorial; both patient-related factors (e. g., limited mobility,
language barriers, illiteracy) and factors related to the bowel-cleansing agent itself
(e. g., unpalatability, the large volume that must be consumed, side effects such
as nausea and headache) are worth considering. Patient educational interventions are
thought to result in an improved quality of bowel preparation, and in practice they
should result in increased rates of adenoma detection.
In this month’s issue, a meta-analysis by Chang et al. summarizes the outcomes of
patients who receive educational intervention compared with the outcomes of those
who receive no intervention in regard to the quality of bowel preparation and the
polyp detection rate. Nine randomized controlled trials (RCTs) enrolling 2885 patients
were included in the meta-analysis. The educational interventions used were pamphlets,
booklets, videos, questionnaires, and visual aids in seven studies, and mobile phone
messages and telephone consultations in the remaining two studies. The authors reported
an overall significant improvement in the quality of bowel preparation in patients
who received educational intervention compared with those who did not, irrespective
of whether the intervention was conducted directly by health professionals (RR = 1.19;
95 %CI 1.08 – 1.32) or consisted of self-directed learning with provided materials
(RR = 1.22; 95 %CI 1.05 – 1.42). Perhaps disappointingly, the improvement in the quality
of bowel preparation did not translate into a significant improvement in the polyp
detection rate, although only three of the nine studies reported this particular outcome,
and as the authors state, the data were insufficient to allow any meaningful conclusions
for this outcome to be drawn. Furthermore, the polyp detection rate is likely to depend
on other factors not assessed in these studies, such as withdrawal time and colonoscopist
experience. A limitation of this meta-analysis was that the scales used to assess
the quality of bowel preparation, the types of bowel purgative, and the timing of
administration (single vs. split dose) differed among the included studies, resulting
in significant heterogeneity.
Educational intervention to ensure adequate bowel cleansing before colonoscopy is
likely to be most beneficial in a small but significant subset of “high risk” patients,
and identifying these patients and tailoring the intervention to their individual
needs remains the challenge. One size does not fit all! The use of electronic media,
such as smartphone applications and interactive online educational material, is attractive.
However, simple interventions, such as face-to-face consultations to overcome language
and educational barriers in high risk patients, may be just as important.
