Comparison of Standard Versus High Definition Colonoscopy for Polyp Detection: A Randomized Controlled Trial

Abstract

We sought to compare the performance of colonoscopy using a high-definition, wide-angle endoscope vs a standard colonoscope for the detection of polyps.
A total of 390 patients were prospectively randomized into high-definition colonoscopy group (HD, n = 193) and standard colonoscopy group (SC, n = 197).
Analysis demonstrated that there were significant differences between the two groups, as far as the overall rate of polyps (SC, 1.31 ± 1.90; HD, 1.76 ± 2.31; P = 0.03) and the rate of small hyperplastic polyps (size < 5 mm; SC, 0.10 ± 0.36; HD, 0.25 ± 0.61; P = 0.003) were concerned. No significant differences between the two groups were observed, regarding large polyps (size ≥ 10 mm; SC, 0.39 ± 0.89; HD, 0.48 ± 0.80; P = 0.10), medium polyps (10 mm > size ≥ 5 mm; SC, 0.60 ± 1.46; HD, 0.58 ± 1.25; P = 0.31) and small polyps (size < 5 mm; SC, 0.32 ± 0.86; HD, 0.71 ± 1.65; P = 0.09). Similarly, no significant differences were demonstrated in the detection rate of adenomas and hyperplastic polyps, large adenomas, medium adenomas, small adenomas and large and medium hyperplastic polyps.
High-definition colonoscopy led to a significant increase in the polyp detection.

Full text

This is an Accepted Article that has been peer-reviewed and approved for publication in the
Colorectal Disease, but has yet to undergo copy-editing and proof correction. Please cite this
article as an “Accepted Article”; doi: 10.1111/j.1463-1318.2009.02145.x
Received Date: 29-Jul-2009
Revised Date: 18-Sep-2009
Accepted Date: 29-Sep2009
Article Type: Original Article
404-2009
Comparison of standard versus high-definition, wide-angle
colonoscopy for polyp detection: A Randomized Controlled
Trial
G. Tribonias1, A. Theodoropoulou1, K. Konstantinidis1, E. Vardas1, K.
Karmiris1, N. Chroniaris2, G. Chlouverakis3 and G. A. Paspatis1
Departments of Gastrenterology1 and Pathology2, Benizelion General
Hospital, Heraklion, Crete, Greece
Department of Social Medicine3, University of Crete, Heraklion, Crete,
Greece
Correspondence to:
G. A. Paspatis M.D.
Benizelion General Hospital
Department of Gastroenterology
L.Knossou, Heraklion
Crete-Greece, 71409
Tel/Fax: + (30) (2810) 368017

E-Mail: paspati@admin.teiher.gr
Trial registration number: ISRCTN60128262
Abstract
Objective: We sought to compare the performance of colonoscopy using
a high definition, wide-angle endoscope versus a standard colonoscope
for the detection of polyps.
Method: A total of 390 patients were prospectively randomized into high
definition colonoscopy group (HD, n = 193) and standard colonoscopy
group (SC, n = 197).
Results: Analysis demonstrated that there were significant differences
between the two groups, as far as the overall rate of polyps (SC, 1.31 ±
1.90; HD, 1.76 ± 2.31; P=0.03) and the rate of small hyperplastic polyps
(size<5mm; SC, 0.10 ± 0.36; HD, 0.25 ± 0.61; P =0.003) were concerned.
No significant differences between the two groups were observed,
regarding large polyps (size≥10mm; SC, 0.39 ± 0.89; HD, 0.48 ± 0.80;
P=0.10), medium polyps (10mm>size≥5mm; SC, 0.60 ± 1.46; HD, 0.58 ±
1.25; P=0.31) and small polyps (size<5mm; SC, 0.32 ± 0.86; HD, 0.71 ±
1.65; P=0.09). Similarly, no significant differences were demonstrated in
the detection rate of adenomas and hyperplastic polyps, large adenomas,
medium adenomas, small adenomas and large and medium hyperplastic
polyps.

Conclusions: High definition colonoscopy led to a significant increase in
the polyp detection.
INTRODUCTION
Colonoscopy is the most commonly performed gastrointestinal
procedure due to its utility in colorectal cancer (CRC) screening. The
direct mucosal inspection of the entire colon and treatment by
polypectomy of precancerous adenomas play a vital role in reducing CRC
incidence and mortality. Several prospective studies regarding the
protective effect of colonoscopy against CRC have been performed.
Specifically in the Polyp Study Group[1], the incidence of CRC after
clearing colonoscopy was reduced by 76% to 90%. Another cohort study
[2] has shown substantial reduction in the risk of CRC during follow up
after a screening colonoscopy. However, not all studies have shown the
same level of protection [3-5], with conflicting data which call in
question the precision of colonoscopy in CRC screening.
This lack of complete accuracy is due to biological and technical
limitations. Short-term development of CRC with rapid growth of tumors,
inadequate bowel preparation, operator-dependent procedure and
sometimes an inadequate polypectomy are some of the factors that

explain the lack of total efficacy of colonoscopy [6]. It is, therefore,
essential to optimize the technique of colonoscopy to increase polyp
detection and to remove premalignant lesions to prevent the development
of CRC. New instruments may lead to improvement in the quality of the
image and may possibly therefore increase the diagnostic accuracy of
colonoscopy[7]. Chromoendoscopy enhances the detection of neoplasia
in the colon and rectum, but it is time consuming and impractical for all
cases [8]. Narrow Band Imaging (NBI) does not improve adenoma
detection on endoscopy [9-14]. High definition (HD) imaging provides
better quality of image, improving surface detail and contrast, and hence
may increase lesion detection.
There are few surveys of the effect of HD imaging to detect
adenomas. Pellise et al[15] compared the performance of colonoscopy
using a wide-angle HD endoscope versus the standard colonoscope for
detection of colorectal neoplasia. The results demonstrated that HD
colonoscopy did not result in better detection of adenomas. Similar data
resulted from another study performed by East et al [16], in which HD
endoscopy did not lead to a significant increase of adenoma or
hyperplasic polyp detection. It is noteworthy that the analyses of these
two studies showed a statistical trend towards a greater number of small
lesions (0-5mm) detected by HD colonoscopy.

We conducted a randomized controlled trial with the aim of comparing
HD versus a standard colonoscopy for the detection of polyps.
METHOD
The study was approved by the hospital ethics committee, and informed
consent was obtained from participating patients (Registration number:
controlled-trials.com/ ISRCTN60128262).
Study design
The study was conducted in patients undergoing a routine
colonoscopy at a large public county hospital in Greece. Patients were
enrolled between May 7 2008 and October 10 2008. All procedures were
performed by one gastroenterologist who had a known high detection rate
of polyps [17]. Patients were eligible if they were aged 50 years or more.
Exclusion criteria included polyposis syndromes, hereditary nonpolyposis
CRC, previous surgical resection of the colon or rectum, active
anticoagulation and inflammatory bowel disease.
Patients were randomly assigned to high definition colonoscopy (HD) or
standard colonoscopy (SC) using a SPSS-generated Bernouli sequence
with a "success" probability value equal to 0.05. The group was
concealed until the beginning of the endoscopy when the doctor

responsible for the survey (G.T.) opened an envelop which contained the
colonoscopy group.
Colonoscopy
The insertion and withdrawal time of colonoscopy were measured
using a stopwatch which was started when the first endoscopic view of
the rectum was obtained and stopped when the caecal pole was seen.
During insertion, the stopwatch ran continuously and was paused if a
decision was made to perform a polypectomy. It was restarted when the
insertion process recommenced. No attempt was made to examine for
polyps systematically during insertion. A careful examination technique
was used during extubation, pressing down folds and re-examining
flexures to try to maximize mucosal views. The vast majority of polyps
were removed during extubation. The withdrawal time started when the
caecum was examined and stopped when the colonoscope was withdrawn
from the anus. It lasted at least 6 min [18] with the stopwatch being
stopped during removal and retrieval of the polyps and also duting
periods of suction and irrigation of the colon and during the taking of
any biopsy. Thus, the measured withdrawal time reflected all the time
spent searching for polyps during withdrawal.
The location, size and number of each polyp were recorded. The polyp
size was estimated by placing the open biopsy forceps next to the lesion.
All visible lesions were resected. More specifically, polyps ≤5 mm were

resected using gold biopsy forceps combined with gold probe application
(Microvasive, Boston Scientific Corp., USA) [19] or cold snare, whereas
pedunculated or nonpedunculated polyps and flat lesions >5mm were
resected by polypectomy snare. Each polyp was retrieved separately for
histopathological examination.
In the SC group, a standard-resolution, standard-angle
videocolonoscope - Olympus (CF-Q165L, Tokyo, Japan) was used with a
high-definition 1080-line screen (Olympus [OEV191H, Tokyo, Japan]
and video processor Olympus [EVIS EXERA II CV-180, Tokyo,
Japan]). In the HD group colonoscopy was performed with a wide-angle
(170o) high-resolution videocolonoscope (Olympus [CFH180AL, Tokyo,
Japan]) with the same HD screen and video processor. Bowel preparation
was accomplished with four litres of polyethylene glycol solution.
Sedation and analgesia were achieved with midazolam and pethidine.
All colonoscopy reports were entered into an electronic database at
the time they were performed. The database included: gender, age,
indication for colonoscopy, time to caecum and time of withdrawal. In
addition, number, size, location and pathology of each polyp and the
method of polypectomy were recorded. The polyp morphology was
determined following the Paris classification[20].

Statistical analysis
The primary outcome measure of this study was to compare the
performance of colonoscopy using a HD colonoscope versus a standard
colonoscope for the detection of polyps. There were no pre-specified
secondary outcomes measured.
Sample size calculation showed that at least 182 patients were
needed in each group in order to achieve a statistical power of 80% and to
detect a 15% increase in the number of detected polyps between the two
groups at the 5% level of significance. Continuous data were compared
with Mann-Whitney test. Categorical variables were tested using
corrected chi-squared tests or two-sided Fischer’s exact tests, as
appropriate. The criterion for statistical significance was a probability
value of less than 0.05. The Bonferroni correction was used for multiple
comparisons. The SPSS version 10.0 statistical software package was
used.
RESULTS
A total of 424 consecutive patients who underwent an outpatient
colonoscopy fulfilled the inclusion criteria and were entered in the study.
Thirty-one had to be excluded owing to insufficient bowel preparation,
and three patients were excluded due to incomplete colonoscopy. The

study protocol was therefore completed by 390 patients (HD, 193; SC,
197; Figure 1).
Table 1 shows the patient characteristics in both arms of the study,
including age, gender, indication for the procedure, insertion time and
withdrawal time. There were no differences between the two arms in the
demographics, indications and procedure times. The mean age of the
study populations was 61 and 62 years (SC and HD groups respectivey)
Table 2 shows the total number of adenomas and hyperplastic
polyps of various sizes in the two arms of the study. There were 599
lesions identified in the entire study population and histopathological
examination was performed in all the lesions. Of these 482 (80%)were
adenomas, 102 (17%) hyperplastic polyps and 15(3%) lesions had other
pathology for example inflammatory.
Table 2 also summarizes the characteristics of endoscopic findings in
both arms of the study. Both studies detected a similar number of
adenomas and there were no differences in the distribution along the
colon for both adenomas and hyperplastic polyps. Two hundred and
one(34%) adenomas were ≤5 mm, whereas 230(38%) were of medium
size (>5 mm, <10 mm;) and 168 (28%) were large (≥10 mm;). A
statistically significant difference was found in the size of detected polyps
between SC and HD colonoscopy (P=0.001; Table 2). There was no

difference in either arm of the study regarding the number of flat polyps
[SC, 42(16%); HD, 40(12%); P =0.12]. Moreover, the proportion of large
hyperplastic polyps (≥1 cm) in the right colon was limited without a
statistical difference between the two groups [SC, 8(3%); HD, 7(2%)].
There was a significant difference between the two groups, regarding the
overall rate of polyp formation (SC, 1.31 ± 1.90; HD, 1.76 ± 2.31;
P=0.03).There was no difference between the two arms in the overall
detection rate of adenomas or of the rates of small polyps, medium polyps,
large polyps, small adenomas, medium adenomas, large adenomas,
medium hyperplastic and large hyperplastic polyps (Table 3).
In contrast, HD showed a significant increase in the detection of small
hyperplastic polyps (SC, 0.10 ± 0.36; HD, 0.25 ± 0.61; P =0.003).
Moreover HD detected a significantly greater number of hyperplastic
polyps than SC (SC, 0.19 ± 0.47; HD, 0.34 ± 0.67; P =0.02). This
observation lost its statistical significance when the Bonferroni correction
(p<0.0125) was applied in the group of hyperplastic polyps. Considering
the proportion of patients with at least one detected polyp, there was an
increase in the HD group that was statistically significant [SC, 104(53%);
HD, 123(64%); P =0.03]. In contrast, there was no statistically significant
difference in the number of patients with ≥ 1 adenoma [SC, 99(50%); HD,
111(58%); P =0.16] (Table 3).

DISCUSSION
Despite the fact that colonoscopy is the most effective diagnostic
and therapeutic tool for the prevention of CRC it is not infallible.
Combined data from studies examining the role of colonoscopy on the
CRC incidence rate showed a lower level of protection. Dietary
intervention trials [4,5] and chemo-prevention trials [3] have not only
showed higher incidence rates of CRC following clearing colonoscopy,
but have also demonstrated a protective effect of colonoscopy of around
50% for each of the first 5 years after the procedure. These differences
may reflect the variety of designs and end-points used in the various
studies, with the recognition that colonoscopy is an imperfect procedure.
Several studies have demonstrated missed lesion rates of 15%-
27% for small adenomas, 6%-12% for large adenomas (≥ 10mm) and 5%
for cancer [21-24]. An appropriate bowel preparation, a complete
colonoscopy and a thorough examination of the mucosa improve the
quality of the colonoscopy. Several methods such as extended withdrawal
time, chromoendoscopy, HD colonoscopy have been proposed to
maximize the rate of lesions detected in the mucosa. On the contrary, NBI
colonoscopy has not shown any superiority compared with the standard
procedure as far as the rate of detected colon polyps is concerned[9-14].
Indeed a certain rate of missed polyps has been reported in several studies.

Thus studies with these endpoints are meaningful. Moreover in UC
patients the rate of detected dysplasia was comparable between NBI
colonoscopy and SC[25].
The aim of the present study was to determine whether HD
colonoscopy could increase the number of detected polyps compared with
the standard examination. The primary outcome observed in the study
was that HD colonoscopy led to a significant increase in the detection of
polyps (per-patient based analysis). Moreover, a significant increase in
the proportion of patients with at least one polyp was observed. However,
no significant difference was observed in the overall detection rates of
adenomas or hyperplastic polyps. Indeed, there was a statistical trend for
more hyperplastic polyps in the HD colonoscopy group. The present
study also indicated that HD colonoscopy led to a significant increase in
the detection of small hyperplastic polyps. The great majority of
hyperplastic polyps was small and this fact influenced the overall number
of those polyps. Although no significant difference was observed, there
was a potentially clinically important increase in the number of small
adenomas. Indeed, the clinical significance of the higher detection of
small polyps via HD colonoscopy is questionable, since the great
majority of small polyps have a low rate of malignant transformation. On
the other hand, small polyps are of significant interest in high risk groups,

such as the members of hereditary non-polyposis colorectal cancer
families [26] .
Sample size calculation in the present study was different
compared with the two previous similar studies. East et al powered their
study to detect absolute differences of 21% and 25% in the proportion of
patients with at least one polyp or adenoma respectively. Moreover,
Pellise et al powered their study to establish a 30% significant increase in
the rate of adenoma detection in HD group. Based on their observations,
East et al recommended there should be a study which would be powered
to look for differences of less than 30%. The present study was powered
to detect a 15% increase in the number of detected polyps. Based on the
existing evidence that colon polyps other than adenomas such as
hyperplastic polyps in the right colon [27-29] might have malignant
process, we felt that this endpoint would be of significant interest among
endoscopists.
The analyses of the two previous studies showed a statistical trend
towards a greater number of small lesions (0-5mm) detected in HD
group[15,16]. Furthermore, the study of East et al demonstrated a
significantly higher number of non flat, diminutive (≤5 mm) lesions
detected with HD colonoscopy.
We sought to determine the possible effect of HD imaging on the
detection of polyps in an every day endoscopy setting, in a busy

endoscopy suite with an experienced endoscopist. To evaluate this, we
conducted a randomized controlled trial using a selected population of
higher mean age than the Spanish study (non selected population with
adult patients ≥ 18 years old) and comparable to the British. Furthermore,
our study was powered to establish a 15% significant increase in the rate
of polyp detection in the HD group, enrolling at least 182 patients in each
group. It is noteworthy that although Pellise et al included a larger study
population than our study, the number of detected polyps was lower.
Moreover, the study population and the number of lesions detected in the
study of East et al were lower compared with the present study. From an
epidemiological point of view, the lack of an authorized CRC screening
program in Greece, with subsequent negative colonoscopies, could
explain the higher proportion of colonoscopies with detected polyps.
Although the study was not stratified according to the indication for
colonoscopy, the patients had a high incidence of polyps (Table 1). In this
particular population, the comparison of HD and SC colonoscopy in the
detection of polyps would have been more accurate.
There are some limitations to our study. First it was performed in
the setting of one centre by one endoscopist and therefore the results are
difficult to generalize. Secondly it was not powered for adenomas which
tend to cause malignant transformation. Indeed our aim was to compare
generally the efficacy of HD colonoscopy for the detection of polyps

overall. Accepting this limitation, the study was powered for polyp
detection and the aim was to estimate the effectiveness of this new
technique in colonoscopy practice. Besides, there are certain polyps other
than adenomas which are potentially malignant.
The strength of the present study is that it was designed as a randomized
trial, similarly that of Pellise et al. On the contrary, the study of East et al
was a not randomized .
It should be pointed out that the endoscopist in the present study
was very experienced (>10.000 colonoscopies) with previous
documentation of a high adenoma detection rate using SD colonoscopy
[17]. This resulted in a high detection rate of adenomas in the present
study (HD group: 1.38 ± 1.83). Conversely, the procedures in the study of
East et al were carried out by an endoscopist who had completed more
than 500 colonoscopies at the start of the study. As far as the study of
Pellise et al is concerned, the procedures were performed by seven non
dedicated gastroenterologists which probably resulted in the lower
detection rates of adenomas (HD group: 0.43 ± 0.87).
In the present study, the number of large hyperplastic polyps
(≥1cm) in the colon was limited. This is in accordance with a previous
autopsy study performed by our group on a Cretan population[30]. The
small number of large hyperplastic polyps prevented speculation on the
effectiveness of HD colonoscopy in these polyps.

In conclusion, our data showed that HD colonoscopy led to a
significant increase in the detection of polyps. The clinical significance of
this finding is questionable. Randomized controlled multi-centre studies
to study this question further are needed.
References
[1] Winawer SJ, Zauber AG, Ho MN et al. Prevention of colorectal
cancer by colonoscopic polypectomy. The National Polyp Study
Workgroup. N Engl J Med 1993; 329(27):1977-81.
[2] Citarda F, Tomaselli G, Capocaccia R, Barcherini S, Crespi M.
Efficacy in standard clinical practice of colonoscopic polypectomy
in reducing colorectal cancer incidence. Gut 2001; 48(6):812-5.
[3] Robertson DJ, Greenberg ER, Beach M et al. Colorectal cancer in
patients under close colonoscopic surveillance. Gastroenterology
2005; 129(1):34-41.
[4] Schatzkin A, Lanza E, Corle D et al. Lack of effect of a low-fat,
high-fiber diet on the recurrence of colorectal adenomas. Polyp
Prevention Trial Study Group. N Engl J Med 2000; 342(16):1149-55.

[5] Alberts DS, Martinez ME, Roe DJ et al. Lack of effect of a high-
fiber cereal supplement on the recurrence of colorectal adenomas.
Phoenix Colon Cancer Prevention Physicians' Network. N Engl J
Med 2000; 342(16):1156-62.
[6] Levin B, Lieberman DA, McFarland B et al. Screening and
surveillance for the early detection of colorectal cancer and
adenomatous polyps, 2008: a joint guideline from the American
Cancer Society, the US Multi-Society Task Force on Colorectal
Cancer, and the American College of Radiology. Gastroenterology
2008; 134(5):1570-95.
[7] Rex D. Detection of neoplasia at colonoscopy: what next?
Endoscopy 2008; 40(4):333-5.
[8] Brown SR, Baraza W, Hurlstone P. Chromoscopy versus
conventional endoscopy for the detection of polyps in the colon and
rectum. Cochrane Database Syst Rev 2007;(4):CD006439.
[9] Adler A, Pohl H, Papanikolaou IS et al. A prospective randomised
study on narrow-band imaging versus conventional colonoscopy for
adenoma detection: does narrow-band imaging induce a learning
effect? Gut 2008; 57(1):59-64.

[10] Adler A, Aschenbeck J, Yenerim T et al. Narrow-band versus white-
light high definition television endoscopic imaging for screening
colonoscopy: a prospective randomized trial. Gastroenterology 2009;
136(2):410-6.
[11] East JE, Suzuki N, Saunders BP. Comparison of magnified pit
pattern interpretation with narrow band imaging versus
chromoendoscopy for diminutive colonic polyps: a pilot study.
Gastrointest Endosc 2007; 66(2):310-6.
[12] East JE, Suzuki N, Stavrinidis M et al. Narrow band imaging for
colonoscopic surveillance in hereditary non-polyposis colorectal
cancer. Gut 2008; 57(1):65-70.
[13] East JE, Suzuki N, Bassett P et al. Narrow band imaging with
magnification for the characterization of small and diminutive
colonic polyps: pit pattern and vascular pattern intensity. Endoscopy
2008; 40(10):811-7.
[14] Rex DK, Helbig CC. High yields of small and flat adenomas with
high-definition colonoscopes using either white light or narrow band
imaging. Gastroenterology 2007; 133(1):42-7.
[15] Pellise M, Fernandez-Esparrach G, Cardenas A et al. Impact of
wide-angle, high-definition endoscopy in the diagnosis of colorectal

neoplasia: a randomized controlled trial. Gastroenterology 2008;
135(4):1062-8.
[16] East JE, Stavrindis M, Thomas-Gibson S et al. A comparative study
of standard vs. high definition colonoscopy for adenoma and
hyperplastic polyp detection with optimized withdrawal technique.
Aliment Pharmacol Ther 2008; 28(6):768-76.
[17] Paspatis GA, Vardas E, Theodoropoulou A et al. Complications of
colonoscopy in a large public county hospital in Greece. A 10-year
study. Dig Liver Dis 2008; 40(12):951-7.
[18] Barclay RL, Vicari JJ, Doughty AS, Johanson JF, Greenlaw RL.
Colonoscopic withdrawal times and adenoma detection during
screening colonoscopy. N Engl J Med 2006; 355(24):2533-41.
[19] Paspatis GA, Vardas E, Charoniti I et al. Bipolar electrocoagulation
vs conventional monopolar hot biopsy forceps in the endoscopic
treatment of diminutive rectal adenomas. Colorectal Dis 2005;
7(2):138-42.
[20] The Paris endoscopic classification of superficial neoplastic lesions:
esophagus, stomach, and colon: November 30 to December 1, 2002
Gastrointest Endosc 2003; 58(6 Suppl):S3-43.

[21] Saini SD, Kim HM, Schoenfeld P. Incidence of advanced adenomas
at surveillance colonoscopy in patients with a personal history of
colon adenomas: a meta-analysis and systematic review.
Gastrointest Endosc 2006; 64(4):614-26.
[22] Rex DK, Cutler CS, Lemmel GT et al. Colonoscopic miss rates of
adenomas determined by back-to-back colonoscopies.
Gastroenterology 1997; 112(1):24-8.
[23] Bressler B, Paszat LF, Vinden C et al. Colonoscopic miss rates for
right-sided colon cancer: a population-based analysis.
Gastroenterology 2004; 127(2):452-6.
[24] Pickhardt PJ, Nugent PA, Mysliwiec PA, Choi JR, Schindler WR.
Location of adenomas missed by optical colonoscopy. Ann Intern
Med 2004; 141(5):352-9.
[25] Dekker E, van den Broek FJ, Reitsma JB et al. Narrow-band
imaging compared with conventional colonoscopy for the detection
of dysplasia in patients with longstanding ulcerative colitis.
Endoscopy 2007; 39(3):216-21.
[26] East JE, Suzuki N, Stavrinidis M et al. Narrow band imaging for
colonoscopic surveillance in hereditary non-polyposis colorectal
cancer. Gut 2008; 57(1):65-70.

[27] East JE, Saunders BP, Jass JR. Sporadic and syndromic hyperplastic
polyps and serrated adenomas of the colon: classification, molecular
genetics, natural history, and clinical management. Gastroenterol
Clin North Am 2008; 37(1):25-46, v.
[28] Harvey NT, Ruszkiewicz A. Serrated neoplasia of the colorectum.
World J Gastroenterol 2007; 13(28):3792-8.
[29] Spring KJ, Zhao ZZ, Karamatic R et al. High prevalence of sessile
serrated adenomas with BRAF mutations: a prospective study of
patients undergoing colonoscopy. Gastroenterology 2006;
131(5):1400-7.
[30] Paspatis GA, Papanikolaou N, Zois E, Michalodimitrakis E.
Prevalence of polyps and diverticulosis of the large bowel in the
Cretan population. An autopsy study. Int J Colorectal Dis 2001;
16(4):257-61.

Table 1. Demographics, indications and colonoscopy baseline
characteristics in both arms of the study
Standard
colonoscopy
High definition
colonoscopy
Patients, n 197 193
Age (y), mean (SD) 60.6 ± 11.0 62.4 ± 9.9
Male, n (%) 101 (51) 108 (56)
Indication n (%)
Polyp surveillance
Screening CRC
Abnormal bowel habit
Rectal bleeding
Abdominal pain
Anemia
Others
41 (21)
38 (19)
36 (18)
27 (14)
16 (8)
6(3)
33(17)
51 (26)
35 (18)
27 (14)
27 (14)
15 (8)
10(5)
28(15)
Time to caecum, min 5.81 ± 1.40 5.83 ± 1.68
Time for withdrawal, min 8.85 ± 1.35 8.94 ± 1.61

Table 2. Characteristics of Endoscopic Findings in Both Arms of the
study
Standard
colonoscopy
High definition
colonoscopy
P value
Evaluated lesions, n 259 340
Location, n (%)
Caecum
Ascending
Transverse
Descending
Sigmoid
Rectum
29 (11)
41 (16)
27 (10)
36 (14)
70 (27)
56 (22)
43 (13)
45 (13)
42 (12)
49 (14)
111 (33)
50 (15)
0.22
Pathology, n (%)
Adenoma
Hyperplastic
Others
216 (83)
37 (14)
6 (3)
266 (78)
65 (19)
9 (3)
0.27
Size, n (%)
≤5 mm (small)
>5 mm, <10 mm (medium)
≥10 mm (large)
64 (25)
119 (46)
76 (29)
137 (40)
111 (33)
92 (27)
<0.001
Morphology, n (%)
Flat
42 (16)
40 (12)
0.12

Table 3. Detection Rate of Lesions in Both Study Arms
(* = Expressed as mean value ± standard deviation / per patient)
Bonferroni adjusted-test for multiple comparisons (statistical differences
of less than 0.0125)
Standard
colonoscopy
High definition
colonoscopy
P value
Evaluated patients 197 193
Total small polyps *
Total medium polyps *
Total large polyps *
Total polyps *
0.32 ± 0.86
0.60 ± 1.46
0.39 ± 0.89
1.31 ± 1.90
0.71 ± 1.65
0.58 ± 1.25
0.48 ± 0.80
1.76 ± 2.31
0.091
0.307
0.096
0.03
Adenomas
≤5 mm *
>5 mm, <10 mm *
≥10 mm *
Total number *
0.19 ± 0.61
0.52 ± 1.24
0.38 ± 0.88
1.10 ± 1.58
0.41 ± 1.14
0.51 ± 1.07
0.46 ± 0.76
1.38 ± 1.83
0.123
0.315
0.102
0.10
Hyperplastic
≤5 mm *
>5 mm, <10 mm *
≥10 mm *
Total number *
0.10 ± 0.36
0.08 ± 0.33
0.01 ± 0.07
0.19 ± 0.47
0.25 ± 0.61
0.07 ± 0.29
0.02 ± 0.12
0.34 ± 0.67
0.003
0.707
0.306
0.02
Patients with ≥ 1 polyp, n (%)
Patients with ≥ 1 adenoma, n (%)
104 (53)
99 (50)
123 (64)
111 (58)
0.03
0.16

Figure 1. Enrollment of subjects
High-Definition Colonoscope
(HD group)
N=193
Standard Colonoscope
(SC group)
N = 197
Excluded patients
Poor bowel preparation
N=14 N=17
Incomplete colonoscopy
N=2 N=1
High-Definition Colonoscope
(HD group)
N=211
Standard Colonoscope
(SC group)
N = 213
Randomization 1:1
Eligible Patients
N = 424
Assesed for eligibility
N = 429 Excluded (N = 5)
Not meeting inclusion criteria
(N = 3)
Refused to participate
(N = 2)