The binomial symptom index: toward an optimal method for the evaluation of symptom association in gastroesophageal reflux

Modern diagnosis of GERD: the Lyon Consensus

Clinical history, questionnaire data and response to antisecretory therapy are insufficient to make a conclusive diagnosis of GERD in isolation, but are of value in determining need for further investigation. Conclusive evidence for reflux on oesophageal testing include advanced grade erosive oesophagitis (LA grades C and D), long-segment Barrett's mucosa or peptic strictures on endoscopy or distal oesophageal acid exposure time (AET) >6% on ambulatory pH or pH-impedance monitoring. A normal endoscopy does not exclude GERD, but provides supportive evidence refuting GERD in conjunction with distal AET <4% and <40 reflux episodes on pH-impedance monitoring off proton pump inhibitors. Reflux-symptom association on ambulatory reflux monitoring provides supportive evidence for reflux triggered symptoms, and may predict a better treatment outcome when present. When endoscopy and pH or pH-impedance monitoring are inconclusive, adjunctive evidence from biopsy findings (histopathology scores, dilated intercellular spaces), motor evaluation (hypotensive lower oesophageal sphincter, hiatus hernia and oesophageal body hypomotility on high-resolution manometry) and novel impedance metrics (baseline impedance, postreflux swallow-induced peristaltic wave index) can add confidence for a GERD diagnosis; however, diagnosis cannot be based on these findings alone. An assessment of anatomy, motor function, reflux burden and symptomatic phenotype will therefore help direct management. Future GERD management strategies should focus on defining individual patient phenotypes based on the level of refluxate exposure, mechanism of reflux, efficacy of clearance, underlying anatomy of the oesophagogastric junction and psychometrics defining symptomatic presentations.

[The binomial symptom index for the evaluation of temporal association between cardiorespiratory symptoms and gastroesophageal reflux in neonates]

INTRODUCTION

The evaluation of symptom association between gastroesophageal reflux and cardiorespiratory events in preterm infants remains unclear. This paper describes a conservative approach to decision-making of anti-reflux surgery through symptom association analysis.

METHODS

Forty-three neonates with potentially reflux-related cardiorespiratory symptoms underwent synchronized esophageal impedance-pH and cardiorespiratory monitoring. Three indices were considered to evaluate symptom association, the symptom index (SI), the symptom sensitivity index (SSI) and the symptom association probability (SAP). A conservative strategy was adopted regarding the decision of anti-reflux surgery, and therefore, patients were scheduled for laparoscopic Nissen fundoplication if the three indices showed a positive assessment of symptom association. Retrospectively, these indices and the binomial symptom index (BSI) were contrasted against the decision of anti-reflux surgery using different windows of association.

RESULTS

Thirteen patients showed positive symptom association but only two underwent anti-reflux surgery. The SI and the SSI showed an increasing trend with the width of the window of association. The SAP was affected randomly by slightly altering the windowing parameters. The BSI showed the best performance with the two-minute window (κ =0.78) CONCLUSIONS: The pathology under study is known to improve with maturity. However, the severity of cardiorespiratory symptoms may threaten the neonate's life and therefore, in some occasions, invasive treatments must be considered to protect life. The BSI provides a good prediction of a combination of positive SI, SSI and SAP, which may improve clinical decisions. However, further clinical studies are required to prove the BSI as an optimal predictor of clinical outcomes.

Reflux monitoring in children

Recently, multichannel intraluminal impedance (MII) monitoring was added to the repertoire of tests to evaluate the (patho)physiology of gastroesophageal reflux (GER) in children. Its advantage above the sole monitoring of the esophageal pH lies in the ability of the detection of both acid and nonacid GER and to discern between liquid and gas GER. Currently, combined 24 h pH-MII monitoring is recommended for evaluation of gastro-esophageal reflux disease (GERD) and its relation to symptoms in infants and children, despite the lack of reference values in these age groups. There is new evidence in the current issue of this Journal supporting the role of pH-MII monitoring for the evaluation of children presenting with gastrointestinal symptoms suggestive of GERD and the prediction of the presence of reflux esophagitis. However, several issues should be taken into account when performing pH-MII clinically.

Association between gastroesophageal reflux and pathologic apneas in infants: a systematic review

BACKGROUND

In infants, apneas can be centrally mediated, obstructive or both and have been proposed to be gastroesophageal reflux (GER) induced. Evidence for this possible association has never been systematically reviewed.

PURPOSE

To perform a systematic review using PubMed, EMBASE and Cochrane databases to determine whether an association between GER and apnea in infants exists. Studies with n ≥ 10 infants, aged <12 months, were included. GER had to be studied by pH-metry or pH-impedancemetry. GER episodes were defined as pH <4 for ≥ 5 s and/or a drop of >50% of baseline in impedance signal in distal channels. An apneic event was defined as a cessation of breathing for >20 s, or ≥ 10 s with hypoxemia or bradycardia. An epoch of ≤ 2 min was used to define temporal relation between GER and apnea. Methodological quality of studies was assessed with Newcastle Ottawa Scale (NOS). Of 1959 abstracts found, 6 articles met the inclusion criteria. All studies had poor methodological quality. A total of 289 infants were included. The temporal association of GER followed by apnea was assessed in all studies, with epochs varying from 10 s to 2 min. One study found an increase of apneic events after GER, the remaining 5 studies did not find an association. Two studies assessed apnea followed by GER as well, but did not find sufficient evidence for association. This systematic review showed insufficient evidence for an association between GER and apneas in infants. High quality studies using uniform inclusion criteria, definitions according to accepted guidelines, and patient relevant outcome measures are needed.

Inter-reflux and bolus clearance times in non-pathologic pediatric patients: data support computational models

Previous contributions suggested that gastroesophageal reflux can be modeled in terms of a Poisson process. This study aims to provide empirical data to validate this statement in pediatric patients so that computational models can be broadly used as an alternative for research. A retrospective review of 63 pediatric patients who underwent 24-hour impedance-pH monitoring to discard gastroesophageal reflux disease was conducted in this study. Patients were grouped by age as preterm (21), infants (21), and children (21). All the tracings were analyzed by a trained physician who identified the reflux entry and the bolus clearance time of each episode. The time between reflux episodes was tested against three probability distributions (gamma, exponential and inverse Gaussian) whereas the bolus clearance time was tested against a normal probability distribution. Parameters were estimated using the maximum likelihood method. The Kolmogorov-Smirnov test and the Kullback-Leibler divergence were computed to evaluate the goodness of fit. One-way analysis of variance was applied to compare results along the three groups. Exponential fitting for inter-reflux time was successful in 90.48% of children older than 1 year. The overall reflux rate was 57.58 reflux episodes per day whereas the mean bolus clearance time ranged between 10.87 in preterm subjects and 12.05 in children, showing a good Gaussian fitting. The time between reflux episodes can be modeled in terms of a Poisson process in non tube-fed patients, whereas the bolus clearance time follows a normal distribution in all cases.

Association between reflux and symptoms during ambulatory reflux monitoring: pros and cons of existing methods

Ambulatory reflux monitoring provides information on the quantity of gastroesophageal reflux and, if symptoms are registered during the study, provides insights into the relation between symptoms and reflux. Several symptom-reflux association analysis indices have been developed to express the relationship between onset of symptom and reflux in a numerical way. One of these indices is the binomial symptom index, introduced by Ghillebert et al. in 1990. The binomial symptom index can be used to study the relationship between symptoms and acid reflux. In this issue of Neurogastroenterology and Motility Barriga-Rivera et al. describe the use of Monte Carlo simulations to investigate the effect of random changes in reflux rates and symptom occurrences on binomial symptom index outcome. Their analysis shows that this index can be used to measure the strength of reflux symptom association. Performing symptom-reflux association analysis is important as the outcome has been shown to be reproducible and can be used as a predictor to response to acid-suppressive treatment. Despite some limitations, use of symptom-reflux association analysis is a valuable clinical tool that can provide unique insights into the cause of a patient's symptoms.