Computed tomography colonography versus colonoscopy for the diagnosis of colorectal cancer: a systematic review and meta-analysis

Figures & data

Figure 1 Study selection flowchart.

Abbreviations: CRC, colorectal cancer; CTC, computed tomography colonography; OC, optical colonoscopy.

Table 1 Rate of participation

Study	CTC P/E (%)	OC P/E (%)
Sali et al^Citation24	1,286/4,825 (26.6)	153/1,036 (14.7)
Stoop et al^Citation25	982/2,920 (33.6)	1,276/5,924 (21.5)
Scott et al^Citation26	65/359 (18.1)	57/350 (16.2)

Abbreviations: CTC, computed tomography colonography; E, number of eligible patients; OC, optical colonoscopy; P, number of patients who agreed to participate.

Figure 2 Forest plot: rate of participation.

Abbreviations: CTC, computed tomography colonography; OC, optical colonoscopy.

Table 2 Positive test results and follow-up

Positive test results
Study	Definition	CTC, N (%)	CTC and OC (N)
Sali et al^Citation24	All with colonic masses or one or more polyp >6 mm	129 (10)	126
Stoop et al^Citation25	One or more lesions ≥10 mm	84 (9)	82
Scott et al^Citation26	One or more polyp ≥6 mm or two or more polyps of any size	26 (29.2)	26
			234

Abbreviations: CTC, computed tomography colonography; OC, optical colonoscopy.

Table 3 Rate of detection per participant

Study	CTC	OC
Sali et al^Citation24	67/1,286 (5.2%)	11/153 (7.1%)
Stoop et al^Citation25	60/982 (6.1%)	111/1,276 (8.6%)
Scott et al^Citation26	8/89 (8.9%)	8/95 (8.4%)

Notes: In the fractions, the numerator is the number of patients with ACN and the denominator is the number of patients who underwent the procedure. The percentages in parentheses, after fractions, refer to the rate of detection of ACN per participant.

Abbreviations: ACN, advanced colorectal neoplasia; CTC, computed tomography colonography; OC, optical colonoscopy.

Figure 3 Forest plot: rate of detection of ACN per participant.

Abbreviations: ACN, advanced colorectal neoplasia; CTC, computed tomography colonography; OC, optical colonoscopy.

Figure 4 Forest plot: rate of detection of ACN per invitee.

Abbreviations: ACN, advanced colorectal neoplasia; CTC, computed tomography colonography; OC, optical colonoscopy.

Table 4 Positive predictive value

	CTC participants (positive test result) who underwent OC (N)	ACN (N)	PPV (%)
Sali et al^Citation24	126	67	53.2
Stoop et al^Citation25	82	60	73.1
Scott et al^Citation26	26	8	30.7

Abbreviations: ACN, advanced colorectal neoplasia; CTC, computed tomography colonography; OC, optical colonoscopy; PPV, positive predictive value.

Table S1 Characteristics of the studies as per the PICOS strategy

PICOS
Study	Participants	Interventions	Comparisons	Outcomes	Study design
Sali et al^Citation1	Asymptomatic, age 54–65 years	1) R-CTC 2) F-CTC 3) FIT	Colonoscopy	–Rate of participation in the different procedures –Rate of detection of polyps/CRC	RCT
Stoop et al^Citation2	Asymptomatic, age 50–75 years	CT colonography	Colonoscopy	–Rate of participation in the different procedures –Rate of detection of polyps/CRC	RCT
Scott et al^Citation3	Asymptomatic, age 50–70 years	CT colonography	Colonoscopy	–Rate of participation in the different procedures –Rate of detection of polyps/CRC	RCT

Abbreviations: CT, computed tomography; CRC, colorectal cancer; F-CTC, full-preparation computed tomography colonography; FIT, fecal immunochemical test; PICOS, patient, intervention, comparison intervention, outcome, study design; R-CTC, reduced-preparation computed tomography colonography; RCTs, randomized clinical trials.

Table S2 Quality assessment of all included studies using QUADAS-2

Quality assessment of all included studies using QUADAS-2	Sali et al^Citation1	Stoop et al^Citation2	Scott et al^Citation3
Judgments on bias and applicability
Domain 1 – patient selection
A. Risk of bias
Was the patient recruitment through random sampling?	Yes	Yes	Yes
Was a case-control design avoided?	Yes	Yes	Yes
Did the study avoid inappropriate exclusions?	Yes	Yes	Yes
Outcome – could the selection of patients have introduced bias?	Low	Low	Low
B. Concerns about applicability
Are there concerns that the patients included do not correspond to the research question?	Low	Low	Low
Domain 2 – test index
A. Risk of bias
Were the index test results interpreted without the results of the reference standard?	Yes	Yes	Yes
If a threshold for positivity was used, was it prespecified?	Yes	Yes	Yes
Outcome – could the conducting or interpretation of the index test have introduced bias?	Higha	Higha	Higha
B. Concerns about applicability
Are there concerns that the index test, its conduct, or its interpretation differ from the research question?	Higha	Higha	Higha
Domain 3 – reference standard
A. Risk of bias
Is the reference standard likely to correctly classify the target condition?	Yes	Yes	Yes
Were the reference standard results interpreted without knowledge of the results of the index test?	Nob	Nob	Nob
Outcome – could the reference standard, its conduct, or its interpretation have introduced bias?	Highb	Highb	Highb
B. Concerns about applicability
Are there concerns that the target condition, as defined by the reference standard, does not correspond to the research question?	Low	Low	Low
Domain 4 – flow and timing
A. Risk of bias
Was there an appropriate interval between the index test and the reference standard?	Yesc	Yesc	Yesc
Did all patients receive a reference standard?	Nod	Nod	Nod
Did all patients receive the same reference standard?	Yes	Yes	Yes
Were all patients included in the analysis?	Noe	Noe	Noe
Outcome – could the patient flow have introduced bias?	High	High	High

Notes:

a The different interpretation of the index test meant that not all tests were conducted in the same way (the reference test was not always performed).

b The patients who underwent the reference test already had known positive index tests.

c Interval <3 months.

d Only patients who had a positive index test received the reference test.

e Only those who received a positive index test.

Abbreviation: QUADAS, quality assessment of diagnostic accuracy studies.

Table S3 Tabular application of results of QUADAS-2 for the included studies

Study	Risk of bias				Applicability
	Patient selection	Index test	Reference standard	Flow and timing	Patient selection	Index test	Reference standard
Sali et al^Citation1	[img]	[img]	[img]	[img]	[img]	[img]	[img]
Stoop et al^Citation2	[img]	[img]	[img]	[img]	[img]	[img]	[img]
Scott et al^Citation3	[img]	[img]	[img]	[img]	[img]	[img]	[img]

Notes: The frowns correspond to a high risk of bias and low applicability, whereas smiles correspond to a low risk of bias and high applicability.

Abbreviation: QUADAS, quality assessment of diagnostic accuracy studies.

Table S4 Patients

Patients
Study	Age (years)		N
			Invited (I)				Eligible (E)				Participants (P)
	Range	Mean	R-CTC	F-CTC	OC	CTC + OC	R-CTC	F-CTC	OC	CTC + OC	R-CTC	F-CTC	OC	CTC + OCb
Sali et al^Citation1	54–65	59	2,617	2,625	1,106	6,348	2,395	2,430	1,036	5,861	674	612	153	1,439
Stoop et al^Citation2	50–75	OC =60.8 CTC =60.9	2,920		5,924	8,844	2,920		5,924	8,844	982		1,276	2,258
Scott et al^Citation3	50–70	N/A	480		469	1,400 CTC =480 OC =469 Choice =451 16,592a	359		350	1,064 CTC =359 OC =350 Choice =355	89 CTC =65 Choice =24		95 OC =57 Choice =38	184 3,881

Notes:

a Total number of patients invited to perform CTC or OC.

b Total number of patients who performed CTC or OC in each study.

Abbreviations: CTC, computed tomography colonography; F-CTC, full-preparation computed tomography colonography; OC, optical colonoscopy; R-CTC, reduced-preparation computed tomography colonography.

SaliLMascalchiMFalchiniMSAVE study investigatorsReduced and full-preparation CT colonography, faecal immunochemical test, and colonoscopy for population screening of colorectal cancer: a randomized trialJ Natl Cancer Inst20151082pii:djv319

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StoopEMde HaanMCde WijkersloothTRParticipation and yield of colonoscopy versus non-cathartic CT colonography in population-based screening for colorectal cancer: a randomised controlled trialLancet Oncol2012131556422088831

 PubMed Web of Science ®Google Scholar

ScottRGEdwardsJTFritschiLFosterNMMendelsonRMForbesGMCommunity-based screening by colonoscopy or computed tomographic colonography in asymptomatic average-risk subjectsAm J Gastroenterol20049961145115115180739

 PubMed Web of Science ®Google Scholar

SaliLMascalchiMFalchiniMSAVE study investigatorsReduced and full-preparation CT colonography, faecal immunochemical test, and colonoscopy for population screening of colorectal cancer: a randomized trialJ Natl Cancer Inst20151082pii:djv319

 Google Scholar

StoopEMde HaanMCde WijkersloothTRParticipation and yield of colonoscopy versus non-cathartic CT colonography in population-based screening for colorectal cancer: a randomised controlled trialLancet Oncol2012131556422088831

 PubMed Web of Science ®Google Scholar

ScottRGEdwardsJTFritschiLFosterNMMendelsonRMForbesGMCommunity-based screening by colonoscopy or computed tomographic colonography in asymptomatic average-risk subjectsAm J Gastroenterol20049961145115115180739

 PubMed Web of Science ®Google Scholar