Gastroenterol Res

Gastroenterology Research, ISSN 1918-2805 print, 1918-2813 online, Open Access

Article copyright, the authors; Journal compilation copyright, Gastroenterol Res and Elmer Press Inc

Journal website http://www.gastrores.org

Original Article

Volume 11, Number 5, October 2018, pages 361-368

Hydrogen Breath Testing Predicts Bowel Preparation Quality Prior to Colonoscopy: A Systematic Review

**Table 1.** Study Characteristics
	Altomare group A (PEG only) [5]	Altomare group B (PEG + inulin) [5]	Mann et al (2003) [6]	Urita et al (2003) [7]	Meyer et al (2001) [9]	Meyer et al (2002) [8]
Study setting and design
Country	Italy	USA	Japan	USA	USA
Study design	Prospective
Colonoscopy indication	Screening, surveillance and diagnostic	Unstated	Diagnostic	Unstated	Unstated
Patient selection	Non-consecutive	Unstated	Consecutive	Unstated
Patient blinded?	Unstated
Endoscopist blinded?	Yes	Unstated
Breath tester blinded?	Yes	Unstated
Exclusion of H₂ non-producers?	Yes	No	Included, analyzed as subgroup	No	No
Inclusion criteria	Signs/symptoms of distal small intestinal diseases, screening or surveillance for colorectal cancer, follow up evaluation of IBD under medical therapy	Unstated	Diagnostic, non-emergent endoscopy	Unstated	Unstated
Exclusion criteria	History of liver, lung, heart, metabolic or neurological disease; lack of compliance, emergency colonoscopy, antibiotic or motility agent 1 month before endoscopy or recent smoking	Unstated	Renal insufficiency, ascites, heart failure, history of abdominal surgery, treatment prokinetics or antibiotics in 6 weeks before endoscopy	Unstated	Unstated
Breath testing protocol
Baseline (pre-preparation) HBT? If yes, timing	Yes, 5 min before preparation	No	Yes, before starting preparation after fasting	No	Yes, timing unstated
Timing of HBT relative to colonoscopy	5 min before colonoscopy	Unstated	Every 15 min for 4 h before colonoscopy	Unstated	Unstated
Non-hydrogen gases assessed?	No
Substrate used	None	Inulin	None	Lactulose	None	½ pt received 1,250 mg Fibercon the day before colonoscopy
Equipment used	LactoFAN	Bedfont Scientific EC 60 gastrolyzer	TGA-2000, Teramecs	MD-80 breath analyzer	Unstated
Colonoscopy protocol
Timing of colonoscopy	9 a.m.	Unstated	1 p.m.	Unstated
Bowel preparation scale	Excellent/fair/poor	Excellent/fair/poor	Excellent/fair/poor	1 - 5 (best to worst)	1 - 5 (best to worst)
Definition of “adequate preparation”	Unstated	Unstated	Excellent/fair considered “adequate”	Adequate=1 - 2, inadequate=3 - 5
Pre-colonoscopy dietary changes	12 h fast before colonoscopy	Clear-liquid diet the day before colonoscopy followed by overnight fast	“Usual diet” the day before procedure, then overnight fast before morning time preparation	Unstated
	Group A: 11 patients fasted 1 day before colonoscopy, 31 had carbohydrates without starches 1 day before, 54 pts had no restrictions Group B: No specific dietary changes
Purgative used	PEG	PEG	PEG	Unstated	Fleet’s phosphosoda, visicol or golytely
Single versus split dose preparation	Unstated	Single	Single	Unstated

Table 1. Study Characteristics

Altomare group A (PEG only) [5]

Altomare group B (PEG + inulin) [5]

Mann et al (2003) [6]

Urita et al (2003) [7]

Meyer et al (2001) [9]

Meyer et al (2002) [8]

Study setting and design

Country

Italy

USA

Japan

USA

Study design

Prospective

Colonoscopy indication

Screening, surveillance and diagnostic

Unstated

Diagnostic

Unstated

Patient selection

Non-consecutive

Unstated

Consecutive

Unstated

Patient blinded?

Unstated

Endoscopist blinded?

Yes

Unstated

Breath tester blinded?

Yes

Unstated

Exclusion of H₂ non-producers?

Yes

Included, analyzed as subgroup

Inclusion criteria

Signs/symptoms of distal small intestinal diseases, screening or surveillance for colorectal cancer, follow up evaluation of IBD under medical therapy

Unstated

Diagnostic, non-emergent endoscopy

Unstated

Exclusion criteria

History of liver, lung, heart, metabolic or neurological disease; lack of compliance, emergency colonoscopy, antibiotic or motility agent 1 month before endoscopy or recent smoking

Unstated

Renal insufficiency, ascites, heart failure, history of abdominal surgery, treatment prokinetics or antibiotics in 6 weeks before endoscopy

Unstated

Breath testing protocol

Baseline (pre-preparation) HBT? If yes, timing

Yes, 5 min before preparation

Yes, before starting preparation after fasting

Yes, timing unstated

Timing of HBT relative to colonoscopy

5 min before colonoscopy

Unstated

Every 15 min for 4 h before colonoscopy

Unstated

Non-hydrogen gases assessed?

Substrate used

None

Inulin

None

Lactulose

None

½ pt received 1,250 mg Fibercon the day before colonoscopy

Equipment used

LactoFAN

Bedfont Scientific EC 60 gastrolyzer

TGA-2000, Teramecs

MD-80 breath analyzer

Unstated

Colonoscopy protocol

Timing of colonoscopy

9 a.m.

Unstated

1 p.m.

Unstated

Bowel preparation scale

Excellent/fair/poor

1 - 5 (best to worst)

Definition of “adequate preparation”

Unstated

Excellent/fair considered “adequate”

Adequate=1 - 2, inadequate=3 - 5

Pre-colonoscopy dietary changes

12 h fast before colonoscopy

Clear-liquid diet the day before colonoscopy followed by overnight fast

“Usual diet” the day before procedure, then overnight fast before morning time preparation

Unstated

Group A:
11 patients fasted 1 day before colonoscopy, 31 had carbohydrates without starches 1 day before, 54 pts had no restrictions
Group B:
No specific dietary changes

Purgative used

PEG

Unstated

Fleet’s phosphosoda, visicol or golytely

Single versus split dose preparation

Unstated

Single

Unstated

**Table 2.** HBT Outcomes by Study
	Altomare group A (PEG only) [5]	Altomare group B (PEG + inulin) [5]	Mann et al. (2003) [6]	Urita et al. (2003) [7]	Meyer et al. (2001) [9]	Meyer et al. (2002) [8]
HBT outcomes	Patients did HBT once (inpatient and outpatient). H₂ level in excellent/fair versus poor was 1.4 ± 0.1 ppm versus 3.5 ± 0.2 ppm (P < 0.001). Patients did HBT twice (inpt only): H₂ level in excellent/fair versus poor was 1.2 ± 0.3 ppm versus 3.3 ± 0.1 ppm (P = 0.005)	Pre-prep to post-prep H₂ levels: 23.8 ± 2.9 ppm versus 2.3 ± 0.3 ppm (P < 0.001).	H₂ levels were lower in the fair-to-excellent prep group (2.2 ± 0.2 ppm) relative to the poor prep group (14.5 ± 1.5 ppm, P < 0.005)	No difference in baseline H₂ levels between the adequate and inadequate group At 90 min into preparation, the H₂ level in the adequate group (18 ppm) was lower than the inadequate group (32 ppm) but without a reported P value At 240 min into preparation, the H₂ level in the adequate group (1.6 ppm) was significantly lower than in the inadequate group (43.4 ppm, P < 0.01)	H₂ levels were lower in the adequately prepared group (1.56 ppm) relative to the inadequately prepared group (2.11 ppm, P < 0.05)	No difference between baseline H₂ levels and post-prep H₂ levels in the adequately prepared group relative to the inadequately prepared group

Table 2. HBT Outcomes by Study

Altomare group A (PEG only) [5]

Altomare group B (PEG + inulin) [5]

Mann et al. (2003) [6]

Urita et al. (2003) [7]

Meyer et al. (2001) [9]

Meyer et al. (2002) [8]

HBT outcomes

Patients did HBT once (inpatient and outpatient). H₂ level in excellent/fair versus poor was 1.4 ± 0.1 ppm versus 3.5 ± 0.2 ppm (P < 0.001).
Patients did HBT twice (inpt only): H₂ level in excellent/fair versus poor was 1.2 ± 0.3 ppm versus 3.3 ± 0.1 ppm (P = 0.005)

Pre-prep to post-prep H₂ levels: 23.8 ± 2.9 ppm versus 2.3 ± 0.3 ppm (P < 0.001).

H₂ levels were lower in the fair-to-excellent prep group (2.2 ± 0.2 ppm) relative to the poor prep group (14.5 ± 1.5 ppm, P < 0.005)

No difference in baseline H₂ levels between the adequate and inadequate group
At 90 min into preparation, the H₂ level in the adequate group (18 ppm) was lower than the inadequate group (32 ppm) but without a reported P value
At 240 min into preparation, the H₂ level in the adequate group (1.6 ppm) was significantly lower than in the inadequate group (43.4 ppm, P < 0.01)

H₂ levels were lower in the adequately prepared group (1.56 ppm) relative to the inadequately prepared group (2.11 ppm, P < 0.05)

No difference between baseline H₂ levels and post-prep H₂ levels in the adequately prepared group relative to the inadequately prepared group

**Table 3.** Statistical Analysis and Proposed Hydrogen Level Cutoffs for Poor Bowel Preparation
	Altomare group A (PEG only) [5]	Altomare group B (PEG + inulin) [5]	Mann et al (2003) [6]	Urita et al (2003) [7]	Meyer et al (2001) [9]	Meyer et al (2002) [8]
H₂ cutoff value suggested (ppm)	3	3	5	10 at 90 and 240 min into prep ingestion	Unstated	N/a since no difference was found
Sensitivity (%)	72	83	96.7	100
Specificity (%)	93	87	87.5	100
NPV (%)	93	93	77.8	100
PPV (%)	72	69	98.3	100
AUROC/c-statistic	Not available	0.93	Not available	Not available

Table 3. Statistical Analysis and Proposed Hydrogen Level Cutoffs for Poor Bowel Preparation

Altomare group A (PEG only) [5]

Altomare group B (PEG + inulin) [5]

Mann et al (2003) [6]

Urita et al (2003) [7]

Meyer et al (2001) [9]

Meyer et al (2002) [8]

H₂ cutoff value suggested (ppm)

10 at 90 and 240 min into prep ingestion

Unstated

N/a since no difference was found

Sensitivity (%)

96.7

100

Specificity (%)

87.5

100

NPV (%)

77.8

100

PPV (%)

98.3

100

AUROC/c-statistic

Not available

0.93

Not available

**Table 4.** QUADAS-2 [10] Assessment
	Altomare et al (both studies) [5]	Mann et al (2003) [6]	Urita et al (2003) [7]	Meyer et al (2001) [9]	Meyer et al (2002) [8]
Overall QUADAS-2 rating	Low risk of bias	Medium risk of bias	Low risk of bias	Medium risk of bias	Medium risk of bias
Domain 1 (patient selection)	Unclear if selection introduced bias; overall low concern that included patients did not match the review question	Unclear if selection introduced bias; overall low concern that included patients did not match the review question	Low risk of selection introducing bias; overall low concern that included patients did not match the review question	Unclear if selection introduced bias; overall low concern that included patients did not match the review question	Unclear if selection introduced bias; overall low concern that included patients did not match the review question
Domain 2 (index test)	Low risk that conduction or interpretation of the index test could have introduced bias; low concern that the index test, its conduct or interpretation differed from the review question	Low risk that conduction or interpretation of the index test could have introduced bias; low concern that the index test, its conduct or interpretation differed from the review question	Low risk that conduction or interpretation of the index test could have introduced bias; low concern that the index test, its conduct or interpretation differed from the review question	Low risk that conduction or interpretation of the index test could have introduced bias; low concern that the index test, its conduct or interpretation differed from the review question	Low risk that conduction or interpretation of the index test could have introduced bias; unclear concern that the index test, its conduct or interpretation differed from the review question
Domain 3 (reference standard)	Low risk that the reference standard, its conduct or interpretation could have introduced bias; low concern regarding the target condition matching the review question	Unclear risk that the reference standard, its conduct or interpretation could have introduced bias; low concern regarding the target condition matching the review question	Unclear risk that the reference standard, its conduct or interpretation could have introduced bias; low concern regarding the target condition matching the review question	Unclear risk that the reference standard, its conduct or interpretation could have introduced bias; low concern regarding the target condition matching the review question	Unclear risk that the reference standard, its conduct or interpretation could have introduced bias; low concern regarding the target condition matching the review question
Domain 4 (flow and timing)	Low risk that patient flow introduced bias	Unclear risk that patient flow introduced bias	Low risk that patient flow introduced bias	Unclear risk that patient flow introduced bias	Unclear risk that patient flow introduced bias

Table 4. QUADAS-2 [10] Assessment

Altomare et al (both studies) [5]

Mann et al (2003) [6]

Urita et al (2003) [7]

Meyer et al (2001) [9]

Meyer et al (2002) [8]

Overall QUADAS-2 rating

Low risk of bias

Medium risk of bias

Low risk of bias

Medium risk of bias

Domain 1 (patient selection)

Unclear if selection introduced bias; overall low concern that included patients did not match the review question

Low risk of selection introducing bias; overall low concern that included patients did not match the review question

Unclear if selection introduced bias; overall low concern that included patients did not match the review question

Domain 2 (index test)

Low risk that conduction or interpretation of the index test could have introduced bias; low concern that the index test, its conduct or interpretation differed from the review question

Low risk that conduction or interpretation of the index test could have introduced bias; unclear concern that the index test, its conduct or interpretation differed from the review question

Domain 3 (reference standard)

Low risk that the reference standard, its conduct or interpretation could have introduced bias; low concern regarding the target condition matching the review question

Unclear risk that the reference standard, its conduct or interpretation could have introduced bias; low concern regarding the target condition matching the review question

Domain 4 (flow and timing)

Low risk that patient flow introduced bias

Unclear risk that patient flow introduced bias

Low risk that patient flow introduced bias

Unclear risk that patient flow introduced bias