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American Journal of Gastroenterology ISSN 0002-9270C 2006 by Am. Coll. of Gastroenterology doi: 10.1111/j.1572-0241.2006.00630.x
Published by Blackwell Publishing
CME
The Montreal Definition and Classification of
Gastroesophageal Reflux Disease: A Global
Evidence-Based Consensus
Nimish Vakil, M.D., F.A.C.G.,1 Sander V. van Zanten, M.D.,2 Peter Kahrilas, M.D.,3 John Dent, M.D.,4 Roger
Jones, M.D.,5 and the Global Consensus Group
1
University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin and Marquette University
College of Health Sciences, Milwaukee, Wisconsin; 2 Dalhousie University, Halifax, Nova Scotia, Canada;
3
Northwestern University, Chicago, Illinois; 4 University of Adelaide, Adelaide, Australia; and 5 Kings College,
London, United Kingdom
OBJECTIVES: A globally acceptable definition and classification of gastroesophageal reflux disease (GERD) is
desirable for research and clinical practice. The aim of this initiative was to develop a consensus
definition and classification that would be useful for patients, physicians, and regulatory agencies.
METHODS: A modified Delphi process was employed to reach consensus using repeated iterative voting. A
series of statements was developed by a working group of five experts after a systematic review of
the literature in three databases (Embase, Cochrane trials register, Medline). Over a period of 2 yr,
the statements were developed, modified, and approved through four rounds of voting. The voting
group consisted of 44 experts from 18 countries. The final vote was conducted on a 6-point scale
and consensus was defined a priori as agreement by two-thirds of the participants.
RESULTS: The level of agreement strengthened throughout the process with two-thirds of the participants
agreeing with 86%, 88%, 94%, and 100% of statements at each vote, respectively. At the final vote,
94% of the final 51 statements were approved by 90% of the Consensus Group, and 90% of
statements were accepted with strong agreement or minor reservation. GERD was defined as a
condition that develops when the reflux of stomach contents causes troublesome symptoms and/or
complications. The disease was subclassified into esophageal and extraesophageal syndromes.
Novel aspects of the new definition include a patient-centered approach that is independent of
endoscopic findings, subclassification of the disease into discrete syndromes, and the recognition of
laryngitis, cough, asthma, and dental erosions as possible GERD syndromes. It also proposes a new
definition for suspected and proven Barrett’s esophagus.
CONCLUSIONS: Evidence-based global consensus definitions are possible despite differences in terminology and
language, prevalence, and manifestations of the disease in different countries. A global consensus
definition for GERD may simplify disease management, allow collaborative research, and make
studies more generalizable, assisting patients, physicians, and regulatory agencies.
(Am J Gastroenterol 2006;101:1900–1920)
INTRODUCTION has led some authorities to combine these entities in pri-
mary care management strategies (10). There is also uncer-
A number of guidelines and recommendations for the di- tainty about the extraesophageal manifestations of GERD,
agnosis and management of gastroesophageal reflux disease coupled with an expanding list of putative extraesophageal
(GERD) have been published in different countries, but a uni- disorders, resulting in both over- and underdiagnosis
versally accepted definition of GERD and its various symp- of the disease. Finally, the definition of Barrett’s esophagus
toms and complications is lacking (1–9). Reflux symptoms varies in different regions of the world, causing confusion
are common in primary care and GERD is frequently diag- in the assessment of risk and the appropriate use of surve-
nosed based on symptoms alone, but there is no consensus illance.
on the distinction of GERD from dyspepsia, so that these The aim of this international Consensus Group was to de-
terms may lead to confusion in primary care settings. This velop a global definition and classification of GERD, us-
To access a continuing medical education exam for this article, please visit
ing rigorous methodology, that could be used clinically by
www.acg.gi.org/journalcme. primary care physicians and that embraces the needs of
1900
, The Montreal Definition and Classification of GERD 1901
physicians, patients, researchers, and regulatory bodies from China, Denmark, France, Germany, Hong Kong, Italy, Japan,
different parts of the world. Mexico, Netherlands, Peru, Sweden, United Kingdom, and
the United States.
METHODS Systematic Searches
A modified Delphi process was used to develop the con- Systematic literature reviews, with defined inclusion and
sensus definition of GERD (11–13). The Delphi pro- exclusion criteria, were conducted to identify and grade
cess is a method for developing consensus that has been the available evidence to support each statement. Literature
used for complex problems in medicine and industry. A searches were conducted of English language publications in
novel aspect of this endeavor was the combination of the Medline, Embase, and the Cochrane trials register, in human
principles of evidence-based medicine, supported by sys- subjects from 1980 onwards. Searches of meeting abstracts
tematic literature reviews, with the Delphi process. A key (American College of Gastroenterology, American Gastroen-
element of the Delphi process is the use of anonymous vot- terological Association, British Society of Gastroenterology,
ing, which allows a change of views from a previously held United European Gastroenterology Week) and review arti-
position without embarrassment, together with controlled cles were limited to the preceding 2 yr. A number of search
feedback regulated by a nonvoting chairman that prevents strings were used that are too numerous to list in the arti-
the process from being hijacked by a vocal minority. Sys- cle. A complete list of the search strings may be obtained by
tematic literature reviews were chosen to support the ev- communicating with the lead author of this article. Due to the
idence base as this orientates the consensus process away large number of citations retrieved on each of the topics, the
from clinical opinion to methodologically sound evidence. primary reviewer reviewed each of the abstracts and selected
Multiple iterations of the statements that make up the def- articles and meeting abstracts for further review. The review
inition and classification were created until consensus was was qualitative and the primary reviewer reached an assess-
reached. ment on the grade assigned to the statement that was then
The principal steps in the process were: (1) Selection of reviewed in the Working Group. Quantitative meta-analyses
the Consensus Group and development of draft statements by were not performed. The references cited in this article are
a Working Group; (2) Systematic literature reviews to iden- a fraction of the articles reviewed in each area and were se-
tify the evidence to support each statement; (3) Grading of lected to amplify the statements and the discussion in the
the evidence; (4) Voting discussion and repeated anonymous Working Group.
voting on a series of iterations of the statements until a con-
sensus was reached. Each of these steps is described in more Grades of Evidence
detail below. Assignment of the grade of evidence for each statement,
where applicable, employed the GRADE system, which takes
Consensus Group Selection into account the type of evidence while increasing or decreas-
Members of the Consensus Group were selected using several ing the grade depending on the quality of the study and data
criteria: (14). The final grade provides a practical indication of the
1. Demonstrated knowledge/expertise in GERD by publi- likely impact of further research on confidence in the esti-
cation/research or participation in national or regional mate of effect. The grading of evidence is as follows:
GERD consensus guidelines or an interest in guideline r High: Further research is unlikely to change our confidence
development and dissemination.
in the estimate of effect.
2. Geographical considerations: individuals who met the cri- r Moderate: Further research is likely to have an important
teria under (1) were then invited to provide broad repre-
sentation of different regions of the world (North America, impact on our confidence in the estimate of effect and may
change the estimate.
South America, Asia, Europe, Australia) that have differ- r Low: Further research is likely to have an important impact
ences in prevalence and manifestation.
3. Diversity of views and expertise related to GERD (includ- on our confidence in the estimate of effect and is very likely
to change the estimate.
ing experts in Barrett’s esophagus, surgeons, and primary r Very low: Any estimate of effect is uncertain.
care physicians).
The Consensus Group was led by a nonvoting chairman An initial assessment of grade was made by the primary
(NV). The Working Group, who are the primary authors of reviewer of the topic from within the Working Group. The as-
this article, developed the initial statements and prepared and signed grade was then discussed within the Working Group
reviewed the evidence to support the statements that were pre- and a final determination of grade was made. Assignment
sented to the Consensus Group. The Consensus Group, which of grade was not voted upon in the broader Consensus
included the Working Group, consisted of 44 experts from Group. A grade of not applicable was chosen for defini-
18 countries: Argentina, Australia, Belgium, Brazil, Canada, tions or statements that cannot be influenced by research. For
, 1902 Vakil et al.
example a cluster of symptoms that is defined as a syndrome Endorsement by the World Organization of
is an arbitrary designation and cannot be altered by re- Gastroenterology
search. The final document was endorsed by the World Organization
of Gastroenterology (WGO-OMGE) as “an important devel-
opment in a critical area of gastroenterology worldwide.”
Voting “Montreal” is in the title because the results of the study were
The entire process lasted 2 yr and the Consensus Group voted first presented at the World Congress of Gastroenterology in
on four iterations of the statements. Between each of the Montreal.
four votes, statements were revised by the Working Group
based on feedback from the Consensus Group and additional
literature reviews. All votes were anonymous. RESULTS AND DISCUSSION
1. A first vote (baseline) was conducted for the entire Con- Overview of the Voting on Statements
sensus Group electronically (by e-mail), without expla- A total of 57 statements were presented for the baseline Vote
nation or justification of the statements, and the results 1 and, following discussion of the supporting evidence, for
were collated (Vote 1). Feedback on the statements was Vote 2. The statements were subsequently revised and consol-
solicited. idated, providing 53 statements for Vote 3. Further discussion
2. A meeting of the entire Consensus Group was held to and modification at the final Consensus Group meeting re-
discuss suggested modifications based on feedback from sulted in 51 statements for the final Vote 4.
the first vote and to review and discuss the evidence to The level of consensus increased with each round of vot-
support specific statements. Subsequently, a second vote ing, with a high level of consensus in the fourth and final
was held, using electronic keypads to ensure anonymity vote (Fig. 1). At each of the four votes, there was consen-
(Vote 2). sus (agreement by ≥67% of the group) on 86%, 88%, 94%,
3. Focus subgroups were created within the Consensus and finally 100% of statements, respectively. Over 90% of
Group to address controversies in Barrett’s esophagus the group agreed with 94% (48) of the 51 final statements.
and extraesophageal syndromes. Statements were again Moreover the strength of agreement was very high by the final
revised, this time with input from the focus subgroups. A vote, as illustrated by the average percentage vote across the
third electronic vote was conducted by e-mail (Vote 3). final 51 statements at each level of the 6-point Likert scale
4. A final Consensus Group meeting was held and the com- (Table 1). Following the final vote it became apparent that
plete results of the previous votes were reviewed, followed one statement had become redundant as it was already ad-
by an open discussion of all statements, including focused dressed in a preceding statement. Consequently, statements
presentations on those statements where there was still and accompanying commentary are given for 50 rather than
lack of consensus. This culminated in the fourth and final 51 statements.
vote, using keypads (Vote 4).
Voting on the Process and Sponsor Influence
Regulatory agencies were invited to the initiative and the Anonymous votes were also obtained on the Delphi process
European Medicines Agency was represented by a nonvoting and the influence of the sponsor on the outcome. Ninety per-
observer at the final Consensus Group meeting. cent of participants agreed that the voting process was fair
For the first two votes, a simple 2-point scale and that they had a chance to input adequately. Ninety-two
(agree/disagree) was used in order to rapidly identify areas
where consensus/lack of consensus existed. For the third and
fourth votes, a 6-point Likert scale was used: 1, agree strongly % 100
(A+); 2, agree with minor reservation (A); 3, agree with 90
major reservation (A−); 4, disagree with major reservation 80
(D−); 5, disagree with minor reservation (D); 6, disagree
70
strongly (D+). Agreement with a statement (A+, A, or A−)
60 >67% agreement
by two-thirds (i.e., ≥67%) of the group was defined a priori >75% agreement
50
as consensus. The level of agreement in the final vote is given >85% agreement
40
for each statement, expressed as the percentage vote at each >90% agreement
point on the Likert scale. 30
20
10
Funding Sources 0
Vote 1 Vote 2 Vote 3 Vote 4
The process was funded by an unrestricted grant from Astra-
Zeneca Research and Development. The European Medicines Figure 1. Percentage of statements at each level of agreement at
Agency was responsible for the costs of their observer. each vote.
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