Guideline on the evaluation of drugs for the treatment of Gastrooesophageal reflux disease
Draft Agreed by Efficacy Working Party
Adoption by CHMP for release for consultation
17 December 2009
End of consultation (deadline for comments)
30 June 2010
Agreed by the Gastroenterology Drafting Group
Adoption by CHMP
17 March 2011
Date for coming into effect
01 October 2011
Gastro-oesophageal Reflux Disease (GORD), Reflux Oesophagitis, Non-Erosive Reflux Disease (NERD)
Guideline on the evaluation of drugs for the treatment of Gastro-oesophageal reflux disease
Table of contents
1. Introduction (background)
1.1. Definition of GORD
1.2. GORD in children
3. Legal basis
4. Disease classification/possible claims
4.1. “Disease classes” possibly leading to treatment claims
4.1.1. Subdivision based on endoscopic findings
4.1.2. Further Subdivision/claims based on the response to acid suppressive medication, especially PPIs
4.2. “Disease classes” not leading to treatment claims
4.2.1. Typical and atypical GORD
4.2.2. Functional heartburn
5. Possible targets of treatment
6. Clinical Study Design
6.1. Patient selection
6.1.1. Inclusion criteria
6.1.2. Exclusion criteria
6.2. Diagnostic methods/Methods to assess efficacy
6.2.1. Methods for the investigation of pharmacodynamics of drug candidates
6.2.2. Endoscopic imaging
6.2.3. Quantification of symptoms
6.2.4. Quality of Life
6.3. Design of Clinical Trials
6.3.1. Pharmacokinetic documentation
6.3.2. Pharmacodynamic trials/phase 1 and 2
6.3.3. Main therapeutic trial
7. Studies in children and adolescents
7.1. PK/PD studies
7.2. Phase III studies in children
7.2.1. Studies in erosive GORD
7.2.2. Studies in symptomatic GORD
8. Safety References
LIST of abbreviations
Gastro-oesophageal Reflux Disease
GERD Symptom Questionnaire
Irritable Bowel Syndrome
Infant Gastro-oesophageal Reflux Questionnaire
Infant Gastro-oesophageal Reflux Questionnaire Revised
Los Angeles Classification of reflux oeosophagitis
Lower Oesophageal Sphincter
Non-Erosive Reflux Disease
Over The Counter
pH monitoring and Impedance monitoring
Proton pump inhibitors
Patient Reported Outcome
Transient Lower Oesophageal Sphincter Relaxations
This guideline intends to address the EU regulatory position on the main topics of the clinical development of new medicinal products in the treatment of patients with gastro-oesophageal reflux disease (GORD).
1. Introduction (background)
1.1. Definition of GORD:
Gastro-oesophageal reflux disease (GORD) has been identified as the most common gastrointestinal diagnosis in outpatient clinics. Estimations suggest that up to 20% of adults are affected (weekly complaints over an observation period of 1 year).1 Over the last 2 decades there has been an overall increase in GORD, with trends indicating further increases still.
According to the most recent consensus definition of GORD, the disease is defined as a condition which develops when the reflux of stomach contents causes troublesome symptoms and/or complications. According to this definition, “troublesome” symptoms are those that adversely affect an individual’s well-being. Typical symptoms (such as heartburn and acid regurgitation) and their frequency in order to be “troublesome” have also been defined.
Other, earlier definitions put the focus quite similarly on complications (including oesophagitis) but also on the impairment of Quality of Life.
The typical symptoms, heartburn and acid regurgitation have been defined by consensus only and do currently lack adequate validation. Accompanying symptoms are regarded to be epigastric pain, sleep disturbances, dyspepsia, dysphagia, odynophagia, nausea, vomiting and others.
The main complications of GORD can be regarded to be reflux oesophagitis, the development of strictures, Barrett’s oesophagus (intestinal metaplasia and dysplasia) and oesophageal adenocarcinoma. In rare cases, oesophagitis may also lead to clinically significant bleeding and/or perforation.
However, despite the possible serious consequences, GORD usually presents as a relatively benign condition, not leading to a relevant increase in mortality. GORD has traditionally been seen as a non-progressive disease (as regards the progression from non-erosive to erosive disease, to more severe erosive disease and to Barrett’s oesophagus and other complications), with progression occurring in only a small proportion of patients. However, conflicting evidence is available on this topic, indicating higher progression rates than previously thought7.
The pathophysiological factors causing GORD can be divided into those inducing greater exposure of the oesophagus to stomach contents, and those providing increased mucosal damage or increased perception of reflux. Key elements representing these factors have been identified to be transient lower oesophageal sphincter relaxations, and oesophageal hypersensitivity as a result of visceral neural pathways dysfunction. Risk factors associated with the development of GORD have been identified to be largely environmental/demographic in nature, such as smoking and alcohol consumption, age and high body mass index. Although it has long been known that family history is significantly associated with GORD, the search for genetic susceptibility and identification of specific loci has only just begun8
1.2. GORD in children
The current knowledge of the epidemiology and natural history of GORD in children and adolescents is limited. Physiological gastro-oesophageal reflux (GOR) is found in up to 70% of healthy newborns and infants resolving without intervention in 95% of cases by 12-14 months of age. After the first year of life, the incidence decreases up to the age of 12 and increases again during adolescence.910 Prevalence of oesophagitis is low at infancy and early childhood, increasing to adult values only during adolescence. It is important to distinguish between GOR and GORD in infants, as medical treatment is seldom warranted in the former and thus it is not expected that GOR would be the focus of drug development.
The definition of GORD in children is not consistent. A recent consensus document, however, defined GORD in the paediatric population based on troublesome symptoms in a similar way as adult GORD, i.e. reflux symptoms that are not troublesome should not be diagnosed as GORD11. Definition of “troublesome”, however, remains a challenge, particularly in infants and for this age-group, GORD is defined by the presence of complications as well. Symptoms associated with GORD in the younger paediatric population range from regurgitation, vomiting, abdominal pain, arching and irritability, to feeding refusal, and/or poor growth. Extra-oesophageal symptoms, e.g. respiratory symptoms, occur in children as well as adults. Children with secondary GORD (i.e. associated with underlying disorders such as neurodevelopmental delay or congenital abnormalities) form a separate sub-group of the paediatric GORD population as they are more prone to severe and chronic forms of GORD with complications.
Conservative management of mild GORD in infants consists of positioning and feeding changes. Pharmacological options for moderate to severe GORD include acid inhibitory agents and prokinetic agents. Surgical treatment is usually reserved for special circumstances, such as children with oesophageal atresia.
This Guideline is intended to assist applicants during the development of products for the treatment of GORD in adults and children, where no current regulatory guidance exists in the EU.
The Guideline does not address drug development in the functional gastrointestinal disorders, including functional oesophageal disorders, which are defined differently from GORD or eosinophilic oesophagitis. It does not address the specific requirements for the development of OTC products in the treatment of symptomatic GORD or heartburn and it does also not address generic drug development in GORD.
It is only guidance; any deviation from guidelines should be justified.
3. Legal basis
This guideline has to be read in conjunction with the introduction and general principles (4) and Part I and II of the Annex I to Directive 2001/83 as amended. Applicants should also refer to other relevant European and ICH guidelines (in their current version):
• Note for Guidance on General Considerations for Clinical Trials (CPMP/ICH/291/95)
• Note for Guidance on Good Clinical Practice (CPMP/ICH/135/95)
• Note for Guidance on Dose Response Information to support Drug Registration (CPMP/ICH/378/95)
• Note for Guidance on Statistical Principles for Clinical Trials (CPMP/ICH/363/96)
• Note for Guidance on Choice of Control Group in Clinical Trials (CPMP/ICH/364/96)
• Reflection paper on the extrapolation of results from clinical studies conducted outside Europe to the EU-population (Draft; CHMP/EWP/692702/08)
• Note for Guidance on the Investigation of Drug Interactions (CPMP/EWP/560/95) (Along with: Concept Paper/Recommendation on the need for revision of (CHMP) Note for guidance on the investigation of drug interactions (CHMP/EWP/297931/08).
• Note for Guidance on Clinical Investigation of Medicinal Products in the Paediatric Population (CHMP/ICH/2711/99)
• Note for Guidance on Population Exposure: The Extent of Population Exposure to assess Clinical Safety (CHMP/ICH/375/95)
• Reflection Paper on the regulatory guidance for the use of Health-Related Quality of Life (HRQL) measures in the evaluation of medicinal products (CHPM/EWP/139391/04)
• Guideline on the Choice of the Non-Inferiority Margin (CHMP/EWP/2158/99)
• Guideline on conduct of pharmacovigilance for medicines used by the paediatric population (CHMP/PhVWP/235910/05)
4. Disease classification/possible claims
The following paragraph describes several “disease classes” into which GORD has been subdivided. However, not all of these subgroups are considered suitable to base indication labelling claims upon.
4.1. “Disease classes” possibly leading to treatment claims:
4.1.1. Subdivision based on endoscopic findings:
The development of acid-suppressive agents has been based on the primary evaluation of reflux oesophagitis patients, followed later by the inclusion of non-erosive disease, based on symptomatic evaluations “only”. This “traditional” subdivision is still considered valid, as it expresses the severity of the disease, not in terms of severity of symptoms and impairment of quality of life, but severity regarding acid exposure and the risk of pre-malignant and malignant changes in the oesophageal mucosa.
The possible indication claims are therefore erosive disease (“reflux oesophagitis”) and “Non-Erosive GORD”. The indication “Symptomatic GORD” is also possible and may include mild forms of reflux oesophagitis, see below. A global indication “GORD” may be possible if the two distinct populations are both studied in pivotal trials. However, the two populations should be tested in separate trials (see 184.108.40.206.).
Erosive disease (reflux oesophagitis):
Reflux oesophagitis has to be diagnosed by endoscopy, using the best validated classification, which is, at the moment, the Los Angeles classification. The L.A. classification is described in the following table:
Table 1. Los Angeles classification of reflux oesophagitis
One (or more) mucosal break(s) no longer than 5 mm, that does not extend between the tops of two mucosal folds
One (or more) mucosal break(s) more than 5 mm long, that does not extend between the tops of two mucosal folds
One (or more) mucosal break(s) that is continuous between the tops of two or more mucosal folds, but which involve(s) less than 75% of the oesophageal circumference
One (or more) mucosal break(s) which involve(s) at least 75% of the oesophageal circumference
The use of other classifications is no longer recommended, but may be justified on a case by case basis. The presence of mucosal breaks in these patients is therefore regarded to be the main disease feature.
Non-erosive disease is by definition a “diagnosis of exclusion” based on the absence of mucosal breaks. Non-erosive disease is basically not distinct in terms of symptom pattern and severity from reflux oesophagitis, but has a lower frequency in patients with hiatal hernia, lower acid exposure, and higher rates of “functional comorbidity”, like functional dyspepsia, IBS, and psychological disorders12. Diagnosis based on further criteria, such as micro-endoscopic diagnosis, has currently not been established and can therefore not be recommended for the purpose of drug registration trials.
If studies in this patient population are conducted, data on endoscopic diagnosis (exclusion of mucosal breaks) are required before inclusion (see 6.1.1.).
The condition “Symptomatic Gastro-oesophageal Reflux Disease” is slightly different from pure “non-erosive disease” because mild reflux oesophagitis (defined as grade A of L.A classification) has traditionally been included in trials in the “non-erosive” population leading to the claim “symptomatic GORD” or “symptomatic treatment of GORD”.
The inclusion of mild oesophagitis patients and subsequent claim of “Symptomatic Gastro-oesophageal Reflux Disease” is considered acceptable on the basis of adequate justification.
4.1.2. Further Subdivision/claims based on the response to acid suppressive medication, especially PPIs:
In recent years, there have been a growing number of reports suggesting that about 30% of GORD patients treated with PPI are partially or completely unresponsive to standard dose and duration of PPI therapy.13,14,15,16 For these patients, it is usually suggested – as a first step – to increase (usually double) the dose and duration of therapy with a PPI.17,18 The recommendation, however, is based on expert opinion only, and not supported by clinical data.
For the inclusion of patients with typical symptomatology while on PPI therapy into clinical trials, it is therefore considered likewise acceptable that patients are included on the basis of a non-response or insufficient response to PPIs and to standard dose or to double-dose PPI. The insufficient response should always be documented during a run-in period with a duration of at least 4 weeks in patients with non-erosive, and 8 weeks in those with erosive disease. This period should emphasise and carefully document the compliance with PPI therapy as non-compliance is an important cause of PPI failure. The final evaluation should include an evaluation of the correlation of historical insufficient response, the response achieved during the run-in phase, and the response achieved during the randomised phase of the trials.
It is not considered necessary that all patients take the same PPI for the inclusion into such trials, as reasonable homogeneity of such a population can be assumed. On the other hand, the choice of one particular PPI may have influence on the final labelling.
PPI partial responders:
Partial responders should be defined analogously to the general inclusion criteria, meaning that, by history taking, the presence of both, heartburn and acid regurgitation, should have been present in
these patients at the time of primary diagnosis. Partial response should also be based on medical history, indicating a reduction in typical symptoms with an adequate course of PPI therapy.
However, both typical symptoms of GORD might be influenced differentially by the “partial response” to PPIs. Also, acid regurgitation may remain as a symptom, although no longer being acid-related. This means that a significant symptom burden should exist for either heartburn or regurgitation (or both) that is considered to be troublesome by the patient at inclusion (see also 6.1.1.).
The definition of PPI non-responders may be difficult, as this requires a standardised comparison of symptom burden before and after PPI therapy, which is usually not available in clinical practice. Therefore, a group of “primary” non-responders may not be reliably identifiable unless a second treatment trial with a PPI (with standardised symptom recording at inclusion during and after end of therapy) is performed.
Similarly, the clear identification of patients initially (partly) responding to PPI therapy and subsequently experiencing a complete relapse of symptoms (“secondary failures”), may be as difficult as for the “primary” failures.
However, if “non-response” can be accurately demonstrated, the creation of such a subgroup of patients with additional indication claims may be possible.
It is therefore recommended that an indication claim may – aside from the indication mentioned above - include terms such as “only partially responsive to PPI” or “insufficiently responsive to PPI”.
It is assumed that the treatment will be an “add-on” to existing PPI therapy.
For these subpopulations – apart from the patients with “residual” oesophagitis – the requirements for clinical trials for the “non-erosive” disease population will be applicable (see 6.3.).
4.2. “Disease classes” not leading to treatment claims: 4.2.1. Typical and atypical GORD
This subdivision based on the characteristics of symptoms has been introduced more recently. However, in the following, it is shown why this distinction is – at the moment – not considered suitable for labelling claims. It is considered that only a “typical GORD” population can lead to one of the indications mentioned in chapter 4.1.
The typical symptoms of GORD according to scientific literature are considered to be heartburn and acid regurgitation. However, the attempt of the Montreal process, to define an overall sensitivity and specificity of the two symptoms for the diagnosis of GORD, has failed19, for the most part due to the lack of a gold standard and non-homogeneity of the trials. Therefore, the diagnosis of typical GORD and its definition by its main symptoms is only based on expert consensus. However, in the situation with an overwhelming consensus and the lack of practicable alternatives, this definition of a “typical” symptom spectrum is considered to be acceptable for the purpose of development of new compounds in the therapeutic area.
As heartburn and acid regurgitation translate poorly into several languages, the symptoms have to be defined with a description. This description should be included in all studies requiring the recruitment of GORD patients based on symptoms only.
Other symptoms, such as dysphagia, epigastric pain, or features of “atypical GORD” may or may not be present in the patient populations included, however, at a lower level than the main symptoms (see also 6.1.1.)
Syndromes considered to be associated with or caused by gastro-oesophageal reflux (disease) are considered to be the following:
- Non-cardiac chest pain (or “reflux chest pain syndrome”);
- Chronic cough (especially nocturnal cough);
- Chronic laryngitis;
The association of these symptoms/syndromes with the symptoms of GORD or with endoscopic or pH-metric diagnosis of GORD is usually relatively weak. Likewise, the treatment success of acid suppressive medication in these syndromes appears to be rather modest20,21,22 or is mainly based on the suppression of oesophageal symptoms only.23 Therefore, reflux (disease) is usually seen as an “aggravating” factor of the underlying condition only.
The investigation and subsequent claim of treatment of “atypical GORD” would therefore need to comprise a rather elaborate diagnostic work-up, showing that (acid or other) reflux is present to a pathological extent and is associated with the respective symptoms in the patients to be investigated.
On the other hand, the treatment of these complaints would have to show that not only the reflux related symptoms are positively influenced but that also the “atypical” symptoms get better in a consistent manner (and, needless to say, both “parts” of the disease should be shown to improve in a statistically significant and clinically relevant manner).
Therefore, the conduct of trials for regulatory purposes with the goal to claim an indication other than GORD, by defining a sub-population based on the nature of such “atypical” symptoms, can currently not be recommended. For such development programs, companies should seek Scientific Advice in order to receive individual feedback/guidance.
The investigation of patients suffering mainly from associated symptoms (such as asthma, chest pain, chronic cough, or laryngitis) without proof of a relevant “typical” symptom burden or clear pathological (acid) reflux cannot not lead to labelling claims for GORD.
Further research, including the possible links between disease and symptoms, pathophysiology and mechanisms of disease interplay appear to be warranted before regulatory decisions can be taken on these issues.
4.2.2. Functional heartburn
Based on the outcome of pH-monitoring, NERD patients have been further subdivided into “true” NERD (with pathological increased acid exposure in the oesophagus) and those with normal acid exposure in pH testing, subsequently diagnosed to be suffering from “functional heartburn”. Functional heartburn (FH) has been included into the list of functional GI disorders in the Rome III criteria24, and is, in these criteria, defined as
1. Burning retrosternal discomfort or pain,
2. Absence of evidence that gastro-oesophageal acid reflux is the cause of the symptom and
3. Absence of histopathology-based motility disorders.
This definition, referring to acid reflux only, is, however, in conflict to the Montreal definition of GORD, which includes FH into GORD, as the pH of the refluxate is not a criterion for diagnosis. The exact diagnosis of FH patients would therefore have to be based on exclusion of mucosal breaks, exclusion of pathological acid exposure and the exclusion of symptom associations (e.g. impedance investigations).25,26 More recent studies have defined FH as absence of all reflux (acidic and non-acidic) that is not the cause of the symptoms (as diagnosed by combined pH-impedance monitoring with symptom association evaluation).27
As the inclusion of patients into GORD therapeutic trials is usually only based on nature and severity of symptoms (see 6.1.1.), the inclusion of this kind of patients into clinical trials in non-erosive disease or “symptomatic GORD” appears to be inevitable to some extent and is regarded as acceptable.
Any claim for the treatment of FH for an investigational product is however, currently not considered acceptable because of insufficient validation of this concept at the present time.
5. Possible targets of treatment:
Acid suppressive agents, particularly PPIs are currently the mainstay of therapy in GORD, with good efficacy and tolerability. However, a need to optimise acid suppression with regard to the daily course of acid secretion, especially during the night, has been identified.28 Also, higher healing rates of the more severe forms of reflux oesophagitis or a faster onset of full treatment effects may constitute a further potential for optimisation. Therefore, attempts to develop compounds with a longer duration of action (i.e. longer half-life, different release characteristics, and different way of binding to the proton pump) or a faster onset of action are under way.29,30 Whether these will lead to clinically relevant improvements in efficacy, however, is currently unclear.31,32,33,34 It is considered self-evident that, even if superiority to existing PPIs can be shown in specific features (such as night-time reflux complaints, better control in on-demand medication), this will most likely not lead to a different indication in the labelling, as the disease to be treated will essentially not change.
Agents influencing motility
Agents acting on the basal lower oesophageal sphincter (LOS) pressure, on transient lower oesophageal sphincter relaxations (TLOSR) frequency and magnitude/duration, and concurrently on gastric emptying are regarded as potential candidates for drug development in GORD.35,36 These agents would usually be developed in an “add-on” setting to existing acid suppressive medication for the “symptomatic GORD” indication. Such claims would therefore be mainly based on symptoms rather than mucosal healing. This is considered acceptable, even if patients with remaining (mild) reflux oesophagitis are included in the studies. However, in these circumstances, patients with reflux oesophagitis should be endoscoped at inclusion (or an appropriate result of endoscopy within a certain time frame be known). If unhealed mucosa is found, this should be included as a secondary endpoint. If the influence on mucosal injury can sufficiently and reliably be characterised within the early development of the compound, confirmatory trials may also be conducted in a more “naturalistic setting” without further endoscopy.
If a high proportion of patients with reflux oesophagitis is included and/or the claim is “healing of reflux oesophagitis”, the primary endpoint should, however, be endoscopic healing (see 6.3.3).
Modulation of visceral pain has been suggested to be a possible further option for the optimisation of therapy, based on the similarities and associations of GORD with the functional syndromes IBS and
functional dyspepsia regarding visceral hypersensitivity. Because hypersensitivity has been shown to be involved in the generation of symptoms in GORD, this approach may be promising.
Further options may include agents for mucosal protection. Other mechanisms and targets such as TRPV 137, ASIC 1-338, P2X 1-7, and others have been discussed as a potential mechanisms to enter clinical development.
It is expected that the same requirements as for the agents influencing motility regarding the inclusion of reflux oesophagitis patients and the conduct of endoscopies would apply to these cases.
6. Clinical Study Design
6.1. Patient selection
6.1.1. Inclusion criteria
Patients may be included on the presence of mucosal breaks if the indication “reflux oesophagitis” or “erosive reflux disease” is being proposed. The phase III trials should include a relevant proportion of all severities, unless a restriction of the indication (e.g. to less severe inflammation, or most severe inflammation only) is being sought. For endoscopic grading, the Los Angeles classification should be used (see 4.1.1. and 6.2.2.).
For substances where a “symptomatic claim” only is being sought, endoscopic status should nevertheless be documented. To this end, either pre-inclusion endoscopy results should be available, which should not be older than 1 year, or – in pre-treated patients (e.g. as “add-on” to acid suppressive therapy), previously diagnosed reflux oesophagitis should be re-checked for healing at the time of inclusion, and if unhealed, also be followed-up after the end of the trial. For the requirements for patients with mild reflux oesophagitis included in such trials, see 4.1.1.
As the cardinal symptoms of GORD are regarded to be heartburn and acid regurgitation, the presence of both symptoms are required for inclusion of GORD patients in clinical trials in which recruitment of patients is based on symptoms only, no matter whether the primary endpoint refers to endoscopy or symptoms only.
Both acid regurgitation and heartburn, have displayed a relatively weak performance in the stringent sense of diagnostic accuracy.39 However, the gold standard for these comparisons (endoscopic diagnosis) has not been the most adequate. An adequate gold standard may be lacking completely. Therefore, in the absence of an accurately defined gold standard, consensus definitions are considered acceptable for the time being. The proposed requirement of both symptoms to be present is expected to increase the diagnostic accuracy.40
The selection of “typical” GORD patients should be based on the evaluation of overall severity. This may be done with either the criterion of rating “troublesomeness” or severity on a global level, or with defining and rating the symptoms with a validated scale by frequency and severity41 at the time of inclusion.
Typical GORD patients should have the greatest troublesomeness and/or highest symptom burden on one of the two symptoms heartburn or acid regurgitation (to be defined in the protocol) as opposed to other concurrent symptoms, and both symptoms should be present.
For inclusion, in addition to the requirement of both symptoms having to be present it should furthermore be required that the overall severity and frequency of all symptoms as well as the severity and frequency of at least one of the typical symptoms are above a certain threshold to be defined in advance, and which may depend on the instrument used (see also 6.2.3.).
Slightly different criteria will have to be applied in a population that has experienced an insufficient response to PPI treatment (see 4.1.2.).
Health related quality of life:
As it has been shown that a relevant symptom burden indeed decreases quality of life, inclusion criteria defining a qualification of patients based on the evaluation of a certain degree of decrease of quality of life is not warranted.
6.1.2. Exclusion criteria
Patients with so-called “alarm features” in symptomatology, like odynophagia, severe dysphagia, bleeding, weight loss, anaemia, and blood in stool, pointing to a possible malignant disease of the GI tract should be excluded from clinical trials in GORD. Exclusion can be based on symptoms only. Patients displaying “alarm symptoms” additionally to the “typical” GORD symptoms may be included based on endoscopic exclusion of malignancy.
Eosinophilic oesophagitis is a clinical entity increasingly diagnosed in adults as well as in children.42 The main features of the disease are the missing response to acid suppressive therapy, the presence of eosinophilia in histological probes of the oesophageal mucosa (although the overall validity is unclear43), and a normal pH profile of the distal oesophagus. It is typically associated with the symptoms of dysphagia and food impaction. The exclusion of patients based on a predominance of the “typical” eosinophilic oesophagitis symptoms only (as above) is considered acceptable. However, in patients with a predominance of “typical” symptoms and co-existing significant dysphagia and food impaction, the syndrome should be excluded by endoscopy with biopsy.44
6.2. Diagnostic methods/Methods to assess efficacy
6.2.1. Methods for the investigation of pharmacodynamics of drug candidates
220.127.116.11. pH Monitoring
PH monitoring (including wireless pH monitoring) can be done on an ambulatory basis and is therefore considered suitable for an outpatient setting. Usually 24 hour (or 48 hour) recordings of the pH are used and a maximum time for which pH is allowed to fall below the threshold of 4 is defined as being pathologic. Thresholds (for percentage of time pH<4) and duration of observation should be defined and justified in advance.45,46,47
The method is suitable to detect acid reflux only.
The method is recommended for the documentation of the pharmacodynamics of acid suppressive substances or those influencing the LOS/oesophageal pressure in phase I and II of the development, when a full elucidation of pharmacodynamics and dose response is required. In a situation where acid suppression is used as basal therapy, and additional substances are used in addition, the method may not be fully appropriate and is therefore not recommended.
pH monitoring may be used as inclusion criterion for clinical trials but is not regarded to be compulsory due to high diagnostic burden on the patients.
18.104.22.168. Impedance monitoring
pH and impedance monitoring can be combined, which is the preferred method in a highly experimental setting. Whereas pH monitoring can only detect acid reflux, impedance pH-monitoring is a technique that can be used to detect all types of GORD (acidic, weakly acidic, and weakly alkaline).
Impedance monitoring or pH-impedance monitoring is considered to be the method of choice in patients unresponsive or only partly responsive to acid suppressive therapy. The method is recommended for use especially in substances which aim to influence the motility and/or pressure of the oesophagus/oesophageal sphincter in order to fully document the pharmacodynamic properties and dose response in phase I and II of the clinical development (in addition to the documentation of the pressure changes).
An inclusion of the technique for inclusion or assessment of treatment response in phase III trials is not recommended for reasons of impracticability.
22.214.171.124. Pressure monitoring and other motility assessment methods
Methods to measure oesophageal pressure (including sphincter pressure) have traditionally been used to evaluate patients with symptoms of oesophageal obstruction (“swallowing disorders”) or atypical symptoms, such as non-cardiac chest pain or in the pre-operative work-up for patients undergoing antireflux surgery.48,49
The evaluation by manometry is currently not sufficiently standardised, and should be justified on an individual basis.
Combination with impedance and pH-impedance monitoring is possible.
Manometry is especially considered useful and necessary for substances aiming at altering the motility of the oesophagus. However, as certain manometrically diagnosed abnormalities might also be influenced by substances reducing the symptom burden by a different mechanism of action (e.g. acid suppression, influence on mucosal sensitivity), manometry may also add to the full elucidation of pharmacodynamic properties in other substance classes.
A routine performance of manometry studies in phase III of the drug development will not be required.
126.96.36.199. Bile reflux monitoring:
A method to detect bile reflux may be especially useful in the evaluation of patients with persisting symptoms despite adequate PPI therapy.50 It may provide additional information in patients diagnosed with non-acidic reflux during impedance pH measurements. Bile reflux monitoring may be useful in the full elaboration of pharmacodynamic properties of a new substance.51 Validated methods to prove exposure of the oesophageal mucosa to bile acids, however, are currently not available.
6.2.2. Endoscopic imaging
The use of the “Los Angeles classification” is recommended for inclusion or exclusion of patients and as efficacy criterion in clinical trials for erosive disease (see 4.1).52
A truly sensitive and simple diagnostic tool remains an unmet need for NERD.
Magnification endoscopy53, narrow band imaging54, and confocal laser endomicrosopy have been proposed to be used as diagnostic tools for non-erosive reflux disease. However, these methods can currently not be recommended to reliably differentiate patients suffering from reflux related symptomatology from those with “normal” exposure to gastric contents of the oesophageal mucosa.
Development of a new and fully validated tool for the diagnosis of NERD55,56 remains an important task. Further research on such tools is encouraged to be part of the development programmes of new drugs in the field. It is, however, considered undesirable that validation of diagnostic or efficacy tools and their use as outcome measures takes place in the same trial (see also 6.2.3).
6.2.3. Quantification of symptoms
The evaluation and quantification of symptoms of GORD is the main tool for the selection of patients and for the evaluation of efficacy. Therefore, whenever patients are included or evaluated based on symptoms, a thoroughly and sufficiently validated tool for the assessment of symptoms should be used.
Symptoms should always be assessed by the patients themselves because symptom evaluation by physicians/investigators is considered less reliable57. However, symptom assessment done by the investigator may be useful as a secondary endpoint.
Symptom response should be used for evaluation of the properties of possible drug candidates at relatively early stages of development in order to relate the pharmacodynamic response (e.g. acid suppression, change in motility or sensitivity) to symptomatic response at the time when a substantial diagnostic workup (see 188.8.131.52. to 184.108.40.206) is required.
For the later phases of drug development (phase IIb and phase III), symptom based evaluation forms the primary basis of proof of efficacy, if the claim is not related to endoscopic healing of (concurrent) inflammation of the oesophageal mucosa.
In the absence of specific European regulatory guidance on patient reported outcomes, sponsors are encouraged to involve patients during instrument development and to record symptom frequency and severity using tools that assure accurate data collection and minimise recall bias.
For GORD, a substantial number of partly, or even almost fully validated symptom based outcome measures/scales do exist.58,59,60 It is recommended to use fully validated GORD specific instruments that are focused on symptom evaluation only. The assessment of Quality of Life should be kept separate from symptom assessment. Symptom evaluation should include severity and frequency of symptoms. Availability and validity in different languages is to be considered crucial for the use in multi-national trials. Part of the validation work of symptom questionnaires might be done during the development programme of possible drug candidates. This may also concern subgroups of patients (e.g. PPI non-responders) that were insufficiently included in earlier validation studies. However, confirmative clinical trials should not be used for the validation of such a tool.
The symptom questionnaires should use VAS or several point Likert scales for different domains of complaints. The number of rating points (in the Likert scales) within these scales may vary between the tools, however, they should include at least 5 points. The main symptoms of GORD, identified as heartburn and acid regurgitation should be included in the scales.
Symptom scales open to deterioration are preferred to dichotomous modes of answers (e.g. like “satisfactory relief” or “adequate relief”) as the latter have not been validated nor used in GORD.
The primary analysis of efficacy should be established on a responder analysis based on the evaluation of the two cardinal symptoms of reflux disease, heartburn and acid regurgitation, ideally based on the evaluation of severity and frequency. The protocol should define clearly a treatment responder, i.e. amount of improvement that is considered to be clinically relevant. Complete resolution of symptoms is also considered to be acceptable as primary endpoint.
If not used as primary endpoint, the evaluation of freedom from the main reflux symptoms, heartburn and acid regurgitation, or freedom from all reflux-related symptoms, should be included as secondary endpoint(s).
A minimal clinically relevant change in the overall symptom scale (and its definition) should be included in the validation of such scales and a minimally clinically relevant change in responder rates should be pre-defined.
6.2.4. Quality of Life
In reflux disease, it has been shown that Health-Related Quality of Life is significantly impaired61. The impact of GORD on Quality of Life has found to be similar to other chronic diseases such as ischemic heart disease.
Quality of Life has therefore to be regarded as an important secondary endpoint in trials not explicitly investigating the healing of oesophagitis (where the symptom evaluation is the main secondary endpoint).
Only validated health-related quality of life questionnaire should be used. Partly or even fully validated scales are already available62. For validation the same rules do apply as for the symptom questionnaires.
To be used as a main secondary endpoint, disease specific questionnaires are preferred to generic instruments.
For claims derived from the evaluation of Quality of Life, reference is made to the Reflection Paper on Health-Related Quality of Life” (EMEA/CHMP/EWP/139391/2004).
For both “Quality of Life” and symptom evaluation scales, a global, generic scale of change (e.g. CGI-I) is recommended to be used as internal validation measure during the trials.
6.3. Design of Clinical Trials
6.3.1. Pharmacokinetic documentation:
The general recommendations for exploration of pharmacokinetics in humans also apply for products intended to be developed for the treatment of GORD. However, due to the high prevalence of the disease and a high probability that patients will be taking concomitant medications, careful evaluation of potential drug-drug interactions should be conducted. A risk based approach based on in-vitro and animal data and the assessment of prescription data of (co-(prescribed)) drugs is recommended. Regarding drug-drug interactions, the “Note for Guidance on the investigation of drug interactions” (CPMP/EWP/560/95 and CHMP/EWP/297931/08) should be taken into account.
6.3.2. Pharmacodynamic trials/phase 1 and 2
As mentioned earlier, early phase trials should investigate the pharmacodynamic properties of the drug with a variety of diagnostic tools, usually in comparison to placebo. In case of acid suppressive drugs,
active comparators may be included additionally. The correlation of the pharmacodynamic parameters with the change of symptoms should also be explored at this early phase of the development.
6.3.3. Main therapeutic trials
220.127.116.11. Trial duration, endpoints and general design issues:
The treatment of GORD, being chronic in nature, can be subdivided into acute treatment during which healing of oesophageal lesions or primary symptom control is the aim, and a maintenance phase, during which the maintenance of healing and/or symptom control should be achieved.
Large randomised, double-blind treatment trials are required for the proof of efficacy.
Prior to the start of trials that include patients pre-treated with acid-suppressive medication, usually an appropriate wash-out period should be part of the protocol (e.g. one week in case of H2-antagonists, and 4 weeks in the case of PPIs). However, this is not applicable in case an add-on indication to acid suppressives is investigated. In these cases, a run-in period under active treatment is required (see 4.1.2 and 6.1.1.)
A possible rebound effect after the end of treatment should be evaluated during an appropriate follow-up period.
The treatment duration in these trials has traditionally been 4-8 weeks. A trial duration of 8 weeks will be regarded as the minimum requirement for the documentation of healing of reflux oesophagitis.
The primary endpoint is the complete healing of all mucosal breaks (see also 6.2.2.) at the end of the trial period.
Other endpoints, such as “complete remission”,63 which is a composite of a validated symptom questionnaire and mucosal healing may be acceptable, depending on justification.
Trial durations in non-erosive GORD have traditionally been shorter, in the range of 2-4 weeks. However, treatment durations shorter than 8 weeks will only be acceptable in the future, if either efficacy in repeated cycles of treatment, maintenance treatment, or in the so-called “on-demand” treatment can be shown at the same time. The choice of the length of this primary treatment cycle (and possible further treatment cycles) should be based on the pharmacodynamic properties and the success rates achieved in phase II, which might bring up the need to explore different treatment durations.
A possible rebound effect after the end of the trials should also be evaluated during an appropriate follow-up period. This not only applies to acid suppressive agents, but also to those with other mechanism of action.
The primary analysis of efficacy should be established on a responder analysis based on the evaluation of the two cardinal symptoms of reflux disease, heartburn and acid regurgitation (see also 6.2.3.). The time course of response should be sufficiently taken into consideration with regular assessment of symptoms (e.g. weekly). Responders would be defined by two criteria: A level of symptom improvement and the time course of the response (e.g. in the example given above: being a responder e.g. 75% of all weeks).
If patients with erosive disease (grade A) are included into trials focusing on symptomatic treatment only, full documentation of mucosal healing should in these cases be included as secondary endpoint (in the subgroup).
The duration of trials in maintenance therapy should be at least 6 months to sufficiently document long-term efficacy. At least one year treatment data are, however, necessary to appropriately document safety for new chemical entities for which no prior human long-term safety data are available (see section 8.).
Possible rebound effect after long-term use may also be considered an issue and should be investigated.
If the maintencance of effect in patients with previous erosive disease is investigated, the endpoint should be the maintenance of complete oesophageal healing over the complete duration of the study.
For maintenance treatment in non-erosive disease, the maintenance of “response” (according to the definition used in the acute studies) over the whole duration of the trial is proposed as the primary endpoint.
The corresponding time-related endpoints (time to “failure”) are considered to be a main secondary endpoint.
“On-demand” treatment or “repeated treatment cycles”:
On demand treatment (take the medication whenever symptoms occur) has been documented for PPIs and other acid suppressant medication64,65 for patients suffering from non-erosive disease and mild oesophagitis and is regarded to be an appropriate mode of handling the chronic nature of the disease, where symptoms fluctuate.
The problem with the assessment of these trials has been identified to be two-fold:
Firstly, the chosen endpoint (“willingness to continue treatment” in most of the trials) was not validated and not directly related to the symptom burden of the patients. It is furthermore obvious, that patients waiting for symptoms to re-occur and in which the symptoms do indeed re-occur is per definition worse-off than those treated continuously in which a continuous freedom from symptoms is maintained.
Secondly, the problem of worsening disease over time and eventually developing reflux oesophagitis has also not been widely addressed by these studies.
Therefore, it is recommended for these studies, either to use a newly developed validated primary endpoint, or to use Quality of Life evaluations and/or treatment satisfaction as an additional primary endpoint that might outweigh the anticipated increased symptom burden. Furthermore, at least one study in a development programme for this treatment regimen should document the exclusion of the development of reflux oesophagitis. In this special case, when continuous (active) treatment is compared to an on-demand or intermittent (also active) treatment, blinded studies might be too difficult to conduct and open studies are considered acceptable. However, blinded evaluation of the endoscopies is mandatory in this case.
Repeated treatment cycles (otherwise called “intermittent treatment”) may form the alternative basis of approval. This may be considered for appropriate patient populations with a more “undulating” nature of their disease course, with longer periods of “off symptoms”. It is not recommended for patients with a history of frequent relapse (be it symptomatic or endoscopic). At least two treatment
cycles should be documented for repeated short term treatments of 4 weeks. For shorter periods, an appropriate higher number of treatment cycles are recommended. The need for long-term safety data should appropriately be considered.
18.104.22.168. Choice of comparator:
Studies in Reflux oesophagitis:
In reflux oesophagitis a specific medication with high success rates (around 85-90% of the patients are expected to have healed oesophageal mucosa after 8 weeks) and acceptable tolerability is available for the treatment of typical reflux disease. Therefore, the use of placebo in the investigation of a typical GORD population appears ethically not justifiable and an appropriate PPI should be used as comparator.
For candidate drugs being investigated in comparison to PPIs proposing similar efficacy the non-inferiority margin chosen should not only take into account the magnitude of superiority of the PPIs to placebo, but also to other substances used in the treatment of GORD (e.g. H2-antagonists).
Studies in non-erosive disease:
Trials in “non-erosive” reflux disease should be conducted in comparison to placebo. This can be justified by the lower response rate of acid suppressive medication in NERD in comparison to erosive disease66, and the benign, and, mainly non-progressive nature of the disease entity. However, before inclusion in such trials, the existence of erosive disease should be excluded, e.g. by historic endoscopy/current endoscopy combined (for the inclusion of Grade A LA classification oesophagitis: see chapter 6.2.2.).
For such a programme in non-erosive disease, the (possible) development of reflux oesophagitis in relevant numbers of patients while on active treatment should be properly investigated and excluded during phase II. Otherwise this would have to be documented in phase III. Appropriate rescue procedures (medication and facilitated trial exit) should be in place.
Possible other classifications:
For other subgroups of patients, the comparison to a placebo group is generally considered to be mandatory, especially in those patients insufficiently treated with proton-pump inhibitors, for which the medication is given in addition to PPI treatment.
Whereas the above relates to the drug development in the acute treatment, a differentiation for erosive and non-erosive disease is not necessary for the maintenance parts of the clinical trials regarding the comparator. For the maintenance parts, placebo is the recommended comparator throughout. An active comparator may be included in addition.
7. Studies in children and adolescents
Age-classification is according to the NfG on clinical investigation of medicinal products in the paediatric population (CPMP/ICH/2711/99).
Studies in the paediatric population are encouraged. The need to develop appropriate formulations for children is emphasized.
As there are important differences between GORD in infants and in older children and adolescents and due to different pharmaceutical formulations, drug development in these different age-groups will be addressed separately.
As the (symptom and pathophysiological) differences between adult GORD and paediatric GORD decrease with the increasing age of the paediatric population and the relative prevalence of secondary GORD also becomes lower with increasing age, the extrapolation of adult efficacy data to the adolescent population may be possible. In these situations, the efficacy and safety of the substance in adults should be well-established, and possible specific safety problems (e.g. with long-term use) should be addressed.
7.1. PK/PD studies
As pharmacokinetics may be different in children with GORD, separate PK studies in the different age-groups are required. Dose-finding has to be performed and a supportive rationale provided in children as well.
For pharmacodynamic studies of acid suppressive agents, pH monitoring is currently recommended as gold standard. Adding impedance monitoring to standard pH monitoring improves the accuracy of reflux-symptom associations.67,68,69,70 Especially in infants oesophageal acid exposure is a poor marker of symptomatic GORD. Therefore, in infants and younger children, combined pH monitoring and impedance monitoring (pH/IMP) are recommended. In addition, patients should have an observed clinical association of symptoms and reflux episodes in order to be defined as suffering from symptomatic reflux. Typical symptoms can be quantified during an 8-24 hour observational study. Scales for severity should be based on the number of symptom episodes determined at baseline and follow up. Event reporting by combined pH/IMP datalogger (marked by parent and child reporting) is considered adequate. For infants a video-based system may be more accurate.71,72 If pH/IMP monitoring - symptom association has been explored sufficiently during phase II, this may spare the pH/IMP related co-primary endpoint in the phase III studies (see 7.2.).
The design of studies depends on the mode of action of the investigational drug.
Acid inhibitors: For PK/PD studies with acid suppressive agents, 24-hour pH monitoring is sufficient to assess reduction in acid reflux. Measurement of intragastric and oesophageal pH should be performed in relation to dose finding. Combined pH/IMP monitoring will improve the quality and is recommended, see above.
Pro-motility drugs: For other treatment modalities that target the frequency of GOR episodes impedance monitoring and manometry should be used in PK/PD studies for the assessment of a pharmacodynamic effect on the frequency of bolus reflux and transient lower oesophageal sphincter relaxation episodes. When a drug has an effect on gastric emptying, this should be studied as well.
7.2. Phase III studies in children
For the indication of paediatric GORD, clinical efficacy and safety data are needed in addition to PK/PD data. Confirmatory studies should be double-blind, randomised controlled trials (RCT).
7.2.1. Studies in erosive GORD
Oesophagitis is rare in younger children making a separation from purely symptomatic disease, impractical for drug research in this age-group, unless healing of oesophagitis is the specific target of the drug. There is an unmet medical need to study secondary GORD in children with underlying disorders such as neurodevelopmental delay or congenital abnormalities. These should preferably be studied in separate trials or alternatively, it has to be ensured that sufficient proportions of patients are represented in studies combining primary and secondary GORD in order to allow meaningful interpretation of results for the sub-populations. Stratification is recommended.
The primary endpoint should be complete healing of the oesophageal mucosa. Endoscopy is needed to confirm the presence and severity of erosive oesophagitis and to exclude other diseases. Healing should likewise be confirmed by endoscopy. When a drug is targeting both healing of oesophagitis and symptom reduction, inclusion should be based on a positive association of symptoms with pH/IMP results, and endoscopy results should be combined with pH/IMP - symptom association as co-primary endpoint, unless this has previously been done during phase II development. If this has sufficiently been explored in phase II, symptom reduction alone should be the co-primary endpoint.
Especially in infants, symptom severity does not correlate with presence of oesophagitis. No specific and validated classification for evaluation of erosive oesophagitis in children exists. The Hetzel and Dent classification is commonly used but also the LA classification. Both are acceptable.
Secondary endpoints include symptom assessments. Currently there are no validated symptom questionnaires for erosive GORD in children and development of such a tool during the earlier phases of development are strongly encouraged, see also symptomatic GORD below. Future questionnaires that might result in a reduction of the need to perform control endoscopies in this population would be welcomed.
Microscopic oesophagitis and the value of histology in paediatric GORD have been questioned recently and therefore biopsies should be taken during any endoscopy as long as this issue is not resolved.
Recommended duration of trials is 8-12 weeks with 2-4 weeks of follow-up. Relapses are assumed to be uncommon following successful healing of erosive oesophagitis in children and therefore, studies on maintenance treatment would normally not be required, with the exception of children with secondary GORD with oesophagitis, where maintenance treatment should be addressed in the developmental programme.
7.2.2. Studies in symptomatic GORD
22.214.171.124. Studies in older children and adolescents (12-17 years)
In children with typical symptoms of adult GORD where heartburn and regurgitation are the predominant symptoms, drug development could basically follow the same recommendations as for adults.
In trials for the symptomatic treatment of GORD in children, erosive oesophagitis and eosinophilic oesophagitis should be excluded by previous or baseline endoscopy, a test for Helicobacter pylori (Hp) should be performed at baseline and children with Hp associated gastroduodenal disease should not be included in the trial. Children with alarm symptoms such as bilious vomiting should be excluded.
The primary endpoint should be symptom based, measuring change in frequency and severity of symptoms. However, there is a lack of a globally accepted validated symptom-based questionnaire for older children and adolescents.
Studies in younger children (2-11 years)
As children in this age group cannot reliably report typical symptoms of adult GORD, heartburn and regurgitation as the predominant symptoms, drug development needs a different design compared to studies in adults.
Enrolment based on clinical symptoms and endoscopic findings without confirmation of a link between symptoms and reflux is unacceptable if symptom benefit is claimed, therefore, inclusion of patients should be based on the combined pH/IMP monitoring - symptom association results. Oesophagitis should preferably be excluded prior to inclusion. The very low prevalence of oesophagitis in this age group, however, challenges the necessity of baseline or previous endoscopy for trials in symptomatic GORD. Absence of endoscopy may thus be acceptable with justification.
The primary endpoint should be symptom based, measuring change in frequency and severity of symptoms.
If the association of symptoms with pH/IMP has not or only insufficiently been explored in phase II, pH/IMP changes have to be used as co-primary endpoint. Having proven a symptom association, the measuring change in frequency and severity of symptoms can be used to quantify a therapeutic effect. Secondary endpoints proposed include individual PRO items as well as investigators assessment and use of rescue medication.
It is acknowledged that at the time of writing this guideline, much work has to be done as regards the development of good patient reported outcome questionnaires for children with GORD. Questionnaires for parents are also needed - see studies in infants and younger children below.
There is a lack of a globally accepted validated symptom-based questionnaire for children above the age of 4 years. Furthermore, in general PRO measures may not be reliable in younger children, i.e. below the age of 8 years.
Studies with active comparators, in preference to placebo, should be performed, when they are available. For a first-line, monotherapy indication, placebo controlled trials are acceptable.
For ‘add on’ indication, design with PPI’s as the background treatment is recommended.
Recommended trial duration is at least 8 weeks. A follow-up evaluation period of 2-4 weeks off treatment is recommended.
126.96.36.199. Studies in infants (0- <2 years)
Physiological GOR is common in the age-group below 2 years and should not be the target of drug development. Efforts should be made to exclude these patients from trials in GORD. Diagnosis of GORD should be made using validated symptom-based questionnaires, such as the I-GERQ with the addition - especially important in this low age group - of combined pH/IMP monitoring with symptom association. It is, however, acknowledged that the I-GERQ may not be an optimal tool (especially as outcome measure) as it has primarily been evaluated to measure change and more research is needed for the development of a reliable diagnostic tool in this age-group.
Only those children in whom changes in feeding and positioning have not resulted in a satisfactory reduction of symptoms should be included in trials of new drugs for GORD. Eosinophilic oesophagitis and food allergy (e.g. cow milk) should be excluded clinically and/or endoscopically.
The primary endpoint should be symptom-based. The I-GERQ/I-GERQ-R has been partly validated for infants below the age of 1 year and the GSQ for children 1-4 year of age, but especially the I-GERQ/I-GERQ-R needs additional validation.
As regards individual components of questionnaires, especially for vomiting and respiratory symptoms, the association with GORD is highly variable.
Reliable parent-reported outcome measures need to be developed.
A co-primary endpoint of pH/IMP change is likewise needed in this age group, if the relationship between symptoms and combinedpH/IMP has not been sufficiently clarified during phase II.
Secondary endpoints include individual symptoms such as episodes of regurgitation/vomiting and irritability. Testing the reduction in symptoms as primary endpoint in infants should be associated with a co-primary endpoint: reduction of reflux if the relationship has not been established in phase II.
For comparators and trial duration, the same recommendations apply as for children between 2-11years of age.
GORD is a non life-threatening disease. Therefore, the safety of any therapeutic intervention is regarded to be of utmost importance. Sufficiently safe and efficacious medications are already available for a substantial number of GORD patients. The requirements of the ICH E1 guideline for symptomatic benign disorder will be applicable, as GORD is regarded as a chronic disease and this makes it necessary to appropriately document the long-term safety of such compounds (see also. 188.8.131.52.).
Depending on the results of pre-clinical evaluations and on the overall safety profile, a comparison of long-term pharmacological treatment with surgery based methods of the treatment of GORD post-approval is recommended.
Safety data collected in sub-populations may not necessarily support the authorisation in a wider patient population.
The risk for GI infections following profound acid inhibition with new acid suppressive agent is an issue that is a special concern in infants.
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