Reflex mechanisms in gastroesophageal reflux disease and asthma

Gastroesophageal reflux disease and the risk of respiratory diseases: a Mendelian randomization study

BACKGROUND

Observational studies have suggested a suspected association between gastroesophageal reflux disease (GERD) and respiratory diseases, but the causality remains equivocal. The goal of this study was to evaluate the causal role of GERD in respiratory diseases by employing Mendelian randomization (MR) studies.

METHODS

We conducted Mendelian randomization analysis based on summary data of genome-wide association studies (GWASs) and three MR statistical techniques (inverse variance weighted, weighted median and MR-Egger) were employed to assess the probable causal relationship between GERD and the risk of respiratory diseases. Sensitivity analysis was also carried out to ensure more trustworthy results, which involves examining the heterogeneity, pleiotropy and leave-one-SNP-out method. We also identified 33 relevant genes and explored their distribution in 26 normal tissues.

RESULTS

In the analysis, for every unit increase in developing GERD, the odds ratio for developing COPD, bronchitis, pneumonia, lung cancer and pulmonary embolism rose by 72% (ORIVW = 1.72, 95% CI 1.50; 1.99), 19% (ORIVW = 1.19, 95% CI 1.11; 1.28), 16% (ORIVW = 1.16, 95% CI 1.07; 1.26), 0. 3% (ORIVW = 1.003, 95% CI 1.0012; 1.0043) and 33% (ORIVW = 1.33, 95% CI 1.12; 1.58), respectively, in comparison with non-GERD cases. In addition, neither heterogeneity nor pleiotropy was found in the study. This study also found that gene expression was higher in the central nervous system and brain tissue than in other normal tissues.

CONCLUSIONS

This study provided evidence that people who developed GERD had a higher risk of developing COPD, bronchitis, pneumonia, lung cancer and pulmonary embolism. Our research suggests physicians to give effective treatments for GERD on respiratory diseases. By exploring the gene expression, our study may also help to reveal the role played by the central nervous system and brain tissue in developing respiratory diseases caused by GERD.

Asymptomatic Esophageal Eosinophilia in an 11-Year-Old with Severe Persistent Asthma

Asymptomatic esophageal eosinophilia (aEE) is a rare presentation, where patients have increased eosinophils in esophageal mucosa but lack any esophagus-related symptoms. Cases of aEE have only been documented in adults, and little is known about its clinical significance and whether treatment is warranted. We report a case of an 11-year-old patient with uncontrolled severe persistent asthma who underwent flexible bronchoscopy and upper endoscopy as a part of complete aerodigestive evaluation. Elevated intraepithelial eosinophils in the esophageal mucosa were noted, suggesting an aEE-like presentation. This case documents a pediatric patient with aEE and highlights the importance of combined aerodigestive assessment with pulmonology and gastroenterology teams for the evaluation of severe asthma.

The link between airway reflux and non-acid reflux in children: a review

OBJECTIVE

Airway reflux, a member of extra-esophageal reflux, has been linked to countless respiratory pathologies amongst children. The advent of novel instrumentation has enabled the discovery of non-acid reflux which was postulated as the main culprit of airway reflux. The objective of this review is to outline the association between non-acid reflux and airway reflux in children.

METHODS

A comprehensive review of recent literature on non-acid reflux and airway reflux in children was conducted. Studies ranged from January 2010 till November 2021 were searched over a period of a month: December 2021.

RESULTS

A total of eleven studies were identified. All studies included in this review revealed a strong link between non-acid reflux and airway reflux in children. 6 of the included studies are prospective studies, 3 retrospective studies, 1 cross-section study, and type of study was not mentioned in 1 study. The most common reported respiratory manifestation of non-acid reflux in children was chronic cough (7 studies). Predominant non-acid reflux was noted in 4 studies. The total number of children in each study ranges from 21 to 150 patients. MII-pH study was carried out in all studies included as a diagnostic tool for reflux investigation.

CONCLUSION

Non-acid reflux is the culprit behind airway reflux as well as other myriads of extra-esophageal manifestations in children. Multicentre international studies with a standardized protocol could improve scientific knowledge in managing non-acid reflux in airway reflux amongst children.

Relationship Between COPD and GERD: A Bibliometrics Analysis

Purpose

A growing body of evidence links chronic obstructive pulmonary disease (COPD) to gastroesophageal reflux disease (GERD). In spite of the lack of understanding of the specific cause-effect relationship between COPD and GERD, GERD has been shown to be a significant predictor of acute exacerbations of COPD. In this study, we examined the evolution of the relationship between COPD and GERD over the past decades and provided valuable insights into this topic.

Methods

The Web of Science Core Collection (WoSCC) was searched since its inception until 19 August 2022 to obtain publications related to COPD and GERD. The data was analyzed in Microsoft Excel (version 2021), HisCite (version 2.1), Scimago Graphica (version 1.0.23), VOSviewer (1.6.17), and CiteSpace (version 5.8.R3).

Results

We extracted 545 documents from the WoSCC database. Since 2002, there have been rapid increases in publications. Among countries and institutions, the United States and the University of Manchester were most prolific. The most cited journal was Chest, while Respiratory Medicine had the most publications. Among 2870 related authors, Hasenfuss, Gerd, Lange, Peter, and Martinez, Gerd were the top 3 contributing authors in this field. Aside from "gastroesophageal reflux disease" and "chronic obstructive pulmonary disease", the terms "quality of life", "cough", and "inflammation" were frequently occurred in the title and abstract of articles. Keywords co-occurrence overlay visualization indicated that "refractory chronic cough" was hot topics in recent years.

Conclusion

Research on COPD and GERD has flourished, and its content topics have become more in-depth over time. In the future, this hot topic deserves more attention.

Impact of gastroesophageal reflux on longitudinal lung function and quantitative computed tomography in the COPDGene cohort

Rationale

Gastroesophageal reflux disease (GERD) is a common comorbidity in chronic obstructive pulmonary disease (COPD) and has been associated with increased risk of acute exacerbations, hospitalization, emergency room visits, costs, and quality-of-life impairment. However, it remains unclear whether GERD contributes to the progression of COPD as measured by lung function or computed tomography.

Objective

To determine the impact of GERD on longitudinal changes in lung function and radiographic lung disease in the COPDGene cohort.

Methods

We evaluated 5728 participants in the COPDGene cohort who completed Phase I (baseline) and Phase II (5-year follow-up) visits. GERD status was based on participant-reported physician diagnoses. We evaluated associations between GERD and annualized changes in lung function [forced expired volume in 1 s (FEV₁) and forced vital capacity (FVC)] and quantitative computed tomography (QCT) metrics of airway disease and emphysema using multivariable regression models. These associations were further evaluated in the setting of GERD treatment with proton-pump inhibitors (PPI) and/or histamine-receptor 2 blockers (H₂ blockers).

Results

GERD was reported by 2101 (36.7%) participants at either Phase I and/or Phase II. GERD was not associated with significant differences in slopes of FEV₁ (difference of − 2.53 mL/year; 95% confidence interval (CI), − 5.43 to 0.37) or FVC (difference of − 3.05 mL/year; 95% CI, − 7.29 to 1.19), but the odds of rapid FEV₁ decline of ≥40 mL/year was higher in those with GERD (adjusted odds ratio (OR) 1.20; 95%CI, 1.07 to 1.35). Participants with GERD had increased progression of QCT-measured air trapping (0.159%/year; 95% CI, 0.054 to 0.264), but not other QCT metrics such as airway wall area/thickness or emphysema. Among those with GERD, use of PPI and/or H₂ blockers was associated with faster decline in FEV₁ (difference of − 6.61 mL/year; 95% CI, − 11.9 to − 1.36) and FVC (difference of − 9.26 mL/year; 95% CI, − 17.2 to − 1.28).

Conclusions

GERD was associated with faster COPD disease progression as measured by rapid FEV₁ decline and QCT-measured air trapping, but not by slopes of lung function. The magnitude of the differences was clinically small, but given the high prevalence of GERD, further investigation is warranted to understand the potential disease-modifying role of GERD in COPD pathogenesis and progression.

Clinical trials registration

NCT00608764.

Associations between the severity of reflux esophagitis in children and changes in oxidative stress, serum inflammation, vasoactive intestinal peptide and motilin

Changes in the levels of serum oxidative stress indexes, gastrointestinal hormones and inflammatory factors in children with different severity of reflux esophagitis (RE) were detected. Sixty child patients diagnosed with gastroesophageal reflux disease (GERD) via gastroscopy were selected and divided into non-erosive reflux disease group (NERD group, n=12) and RE group (n=48) according to whether there was esophageal mucosal injury. In RE group, the patients were further divided into grade I RE group (n=15), grade II RE group (n=18) and grade III RE group (n=15) based on the severity of mucosal injury. None of the child patients took PPI and domperidone within 2 weeks before enrollment. The content of malondialdehyde (MDA) and total superoxide dismutase (T-SOD) in the esophageal mucosa was detected. The changes in the levels of serum vasoactive intestinal peptide (VIP), motilin, interleukin-1β (IL-1β), IL-8 and tumor necrosis factor-α (TNF-α) were determined. The DeMeester score was the highest in grade III RE group, followed by grade II RE group, grade I RE group and NERD group (P<0.05). The content of MDA in the esophageal mucosa was higher in RE group than that in NERD group, and the T-SOD activity declined with the increased severity of injury (P<0.05). In the three RE groups, the level of plasma VIP was significantly higher, while the motilin level was remarkably lower than those in NERD group (P<0.05). With the increased severity of disease, the expression levels of serum IL-1β, IL-8 and TNF-α in RE group were gradually raised (P<0.05). RE patients have strong oxidative stress and inflammatory response, an increased level of serum VIP, a regulator of gastrointestinal motility, and a decreased level of motilin. Controlling the changes in the above factors using effective treatment means can improve the development of GERD.

Dorsal Vagal Complex Modulates Neurogenic Airway Inflammation in a Guinea Pig Model With Esophageal Perfusion of HCl

Neurogenic airway inflammation in chronic cough and bronchial asthma related to gastroesophageal reflux (GER) is involved in the esophageal–bronchial reflex, but it is unclear whether this reflex is mediated by central neurons. This study aimed to investigate the regulatory effects of the dorsal vagal complex (DVC) on airway inflammation induced by the esophageal perfusion of hydrochloric acid (HCl) following the microinjection of nuclei in the DVC in guinea pigs. Airway inflammation was evaluated by measuring the extravasation of Evans blue dye (EBD) and substance P (SP) expression in the airway. Neuronal activity was indicated by Fos expression in the DVC. The neural pathways from the lower esophagus to the DVC and the DVC to the airway were identified using DiI tracing and pseudorabies virus Bartha (PRV-Bartha) retrograde tracing, respectively. HCl perfusion significantly increased plasma extravasation, SP expression in the trachea, and the expression of SP and Fos in the medulla oblongata nuclei, including the nucleus of the solitary tract (NTS) and the dorsal motor nucleus of the vagus (DMV). The microinjection of glutamic acid (Glu) or exogenous SP to enhance neuronal activity in the DVC significantly potentiated plasma extravasation and SP release induced by intra-esophageal perfusion. The microinjection of γ-aminobutyric acid (GABA), lidocaine to inhibit neuronal activity or anti-SP serum in the DVC alleviated plasma extravasation and SP release. In conclusion, airway inflammation induced by the esophageal perfusion of HCl is regulated by DVC. This study provides new insight for the mechanism of airway neurogenic inflammation related to GER.

Respiratory manifestations of gastro-oesophageal reflux in children

Gastro-oesophageal reflux disease (GORD) is a complex problem in children. Suspected respiratory manifestations of GORD, such as asthma, chronic cough and laryngitis, are commonly encountered in the paediatric practice, but continue to be entities with more questions than answers. The accuracy of diagnostic tests (ie, pH or pH-impedance monitoring, laryngoscopy, endoscopy) for patients with suspected extraoesophageal manifestations of GORD is suboptimal and therefore whether there is a causal relationship between these conditions remains largely undetermined. An empiric trial of proton pump inhibitors can help individual children with undiagnosed respiratory symptoms and suspicion of GORD, but the response to therapy is unpredictable, and in any case what may be being observed is spontaneous improvement. Furthermore, the safety of these agents has been called into question. Poor response to antireflux therapy is an important trigger to search for non-gastro-oesophageal reflux causes for patients' symptoms. Evidence for the assessment of children with suspected extraoesophageal manifestations of GORD is scanty and longitudinal studies with long-term follow-up are urgently required.

Improved control of hypertension following laparoscopic fundoplication for gastroesophageal reflux disease

This study aims to determine whether successful laparoscopic fundoplication for gastroesophageal reflux disease (GERD) can improve the control of hypertension. We conducted an observational study of GERD patients with hypertension. The esophageal and gastroesophageal symptoms of these patients were successfully treated with laparoscopic fundoplication, as measured by the reduced GERD symptoms and proton pump inhibitor consumption. A hypertension control scale was used to classify the use of antihypertensive medications and the quality of blood pressure control before and after anti-reflux surgery.Wilcoxon signed-ranks test was used for the statistical analyses. Seventy GERD patients were included in the analysis and followed up for a mean period of 3.5 ± 1.4 years. Prior to surgery, all participating patients were taking at least one class of antihypertensive medication, and 56 patients (80%) had intermittently high blood pressure. After surgery, the mean number of antihypertensive medication classes per patient was significantly reduced from 1.61 ± 0.77 pre-procedure to 1.27 ± 0.88 post-procedure (P < 0.001). The blood pressure of 48 of the 56 cases (86%) with preoperative intermittent high blood pressure returned to normal post procedure. A total of 50 patients (71%) recorded improvements on the hypertension control scale, with the overall mean score decreasing from 3.1 ± 1.0 preprocedure to 1.4 ± 1.0 post-procedure (P < 0.001). Therefore, successful laparoscopic fundoplication may result in better blood pressure control in some hypertensive GERD patients. This result suggests a possible connection between gastroesophageal reflux and hypertension.

Gastroesophageal reflux disease in COPD: links and risks

COPD is a long-term condition associated with considerable disability with a clinical course characterized by episodes of worsening respiratory signs and symptoms associated with exacerbations. Gastroesophageal reflux disease (GERD) is one of the most common gastrointestinal conditions in the general population and has emerged as a comorbidity of COPD. GERD may be diagnosed by both symptomatic approaches (including both typical and atypical symptoms) and objective measurements. Based on a mix of diagnostic approaches, the prevalence of GERD in COPD ranges from 17% to 78%. Although GERD is usually confined to the lower esophagus in some individuals, it may be associated with pulmonary microaspiration of gastric contents. Possible mechanisms that may contribute to GERD in COPD originate from gastroesophageal dysfunction, including altered pressure in the lower esophageal sphincter (which normally protect against GERD) and changes in esophageal motility. Proposed respiratory contributions to the development of GERD include respiratory medications that may alter esophageal sphincter tone and changes in respiratory mechanics, with increased lung hyperinflation compromising the antireflux barrier. Although the specific cause and effect relationship between GERD and COPD has not been fully elucidated, GERD may influence lung disease severity and has been identified as a significant predictor of acute exacerbations of COPD. Further clinical effects could include a poorer health-related quality of life and an increased cost in health care, although these factors require further clarification. There are both medical and surgical options available for the treatment of GERD in COPD and while extensive studies in this population have not been undertaken, this comorbidity may be amenable to treatment.

Upper aerodigestive tract disorders and gastro-oesophageal reflux disease

A wide variety of symptoms and diseases of the upper aerodigestive tract are associated to gastro-oesophageal reflux disease (GORD). These disorders comprise a large variety of conditions such as asthma, chronic otitis media and sinusitis, chronic cough, and laryngeal disorders including paroxysmal laryngospasm. Laryngo-pharyngeal reflux disease is an extraoesophageal variant of GORD that can affect the larynx and pharynx. Despite numerous research efforts, the diagnosis of laryngopharyngeal reflux often remains elusive, unproven and controversial, and its treatment is then still empiric. Aim of this paper is to review the current literature on upper aerodigestive tract disorders in relation to pathologic gastro-oesophageal reflux, focusing in particular on the pathophysiology base and results of the surgical treatment of GORD.

Anatomy and neurophysiology of cough: CHEST Guideline and Expert Panel report

Bronchopulmonary C-fibers and a subset of mechanically sensitive, acid-sensitive myelinated sensory nerves play essential roles in regulating cough. These vagal sensory nerves terminate primarily in the larynx, trachea, carina, and large intrapulmonary bronchi. Other bronchopulmonary sensory nerves, sensory nerves innervating other viscera, as well as somatosensory nerves innervating the chest wall, diaphragm, and abdominal musculature regulate cough patterning and cough sensitivity. The responsiveness and morphology of the airway vagal sensory nerve subtypes and the extrapulmonary sensory nerves that regulate coughing are described. The brainstem and higher brain control systems that process this sensory information are complex, but our current understanding of them is considerable and increasing. The relevance of these neural systems to clinical phenomena, such as urge to cough and psychologic methods for treatment of dystussia, is high, and modern imaging methods have revealed potential neural substrates for some features of cough in the human.

Lung diffusion capacity in children with respiratory symptoms and untreated GERD

BACKGROUND

Gastroesophageal reflux disease (GERD) is associated with many respiratory disorders, among which, chronic cough, laryngitis, and asthma are among the most common. We investigated lung function, including gas diffusion capacity, in children with poor asthma control or chronic laryngitis with untreated GERD.

MATERIAL AND METHODS

A total of 71 children, aged 6-17 years, with chronic respiratory and other symptoms suggestive for GERD, were enrolled and divided into 2 groups: chronic laryngitis and asthma. Participants underwent 24-hour pH monitoring and lung function assessment, measurement of single-breath diffusing capacity of the lung for carbon monoxide (DLCO), and fraction of exhaled nitric oxide (FENO) measurement.

RESULTS

24-hour pH monitoring was positive for GERD in 92.1% of preselected children with asthma and 90.1% of children with chronic recurrent laryngitis. All flows (PEF, MEF75, MEF50, and MEF25) were significantly lower in the asthma group, while FENO and DLCO were significantly lower in the laryngitis group. A significant inverse relationship was found between DLCO and all reflux indexes in the laryngitis group. Each unit change of Johnson-DeMeester score and Boix-Ochoa score increased the odds for significantly lower DLCO in laryngitis patients by 3.9% and 5.5%, respectively.

CONCLUSIONS

In children with uncontrolled asthma and chronic laryngitis, the regurgitation of gastric contents due to GERD contributes to poor asthma control and aggravation of chronic laryngitis. Despite having normal lung function, the gas diffusion capacity should be controlled in patients with GERD and chronic laryngitis, and it might be the very first abnormality in distal airways.

Gastroesophageal reflux in bronchiectasis and the effect of anti-reflux treatment

BACKGROUND

Bronchiectasis is a progressive and fatal disease despite the available treatment regimens. Gastroesophageal reflux (GER) may play an important role in the progression of bronchiectasis. However, active anti-reflux intervention such as Stretta radiofrequency (SRF) and/or laparoscopic fundoplication (LF) have rarely been used to treat Bronchiectasis.

CASE PRESENTATION

Seven patients' clinical outcomes for treating GER-related deteriorated bronchiectasis were retrospective reviewed. All patients were treated by SRF and/or LF, and had follow-up periods ranging from one to five years. Typical GER symptoms, respiratory symptoms, medication consumption and general health status were assessed during the follow-ups. At the latest follow-up all patients were alive. The typical GER symptoms disappeared in five people and were significantly improved in the other two. Two had complete remissions of both respiratory symptoms and bronchiectasis exacerbations; four had significantly improved respiratory symptoms to mild/moderate degrees as well as reduced or zero bronchiectasis exacerbations, which allowed them to resume the physical and social functions; one's respiratory symptoms and bronchiectasis exacerbations were not much improved, yet she was in stable condition and satisfied with the results.

CONCLUSIONS

Potentially, GER plays an important role in some patients with bronchiectasis, and active anti-reflux treatments can be beneficial. Future clinical studies are suggested to clarify GER's role in bronchiectasis and to further determine whether anti-reflux interventions for GER can improve the outcomes of patients with bronchiectasis.

Response of the airways and autonomic nervous system to acid perfusion of the esophagus in patients with asthma: a laboratory study

BACKGROUND

Gastro-esophageal reflux disease (GERD) predisposes to airway disease through a vagally-mediated esophago-bronchial reflex. This study investigates this vagal response to esophageal acid perfusion.

METHODS

40 asthmatics with mild stable asthma participated. Each subject underwent spirometry and autonomic function testing (valsalva maneuver, heart rate response to deep breathing and to standing from supine position) four times: a) before intubation, b) after intubation, and then immediately after perfusion with, in random order, c) concentrated lime juice solution (pH 2-3) and d) 0.9% saline. Subjects were blinded to the solution perfused.

RESULTS

Asthmatics were of mean (SD) age 34.3 years (1.3), and 67.5% of them were females. pH monitoring demonstrated that 20 subjects had abnormal reflux and 20 did not. In each group 10 subjects had a positive GERD symptom score. Following perfusion with acid compared to saline, all subjects showed significant decreases in FEV1 and PEFR and significant increases in the mean valsalva ratio and heart rate difference on deep breathing from baseline values, but no changes in FVC or heart rate ratio on standing. There were no significant differences in any of the parameters between subjects with and without reflux.

CONCLUSIONS

Acid stimulation of the distal esophagus results in increased parasympathetic activity and concomitant broncho-constriction in asthmatics irrespective of their reflux state. This strengthens the hypothesis that GER triggers asthma-like symptoms through a vagally mediated esophago-bronchial reflex and encourages a possible role for anti-cholinergic drugs in the treatment of reflux-associated asthma.

Acid-sensing by airway afferent nerves

Inhalation of acid aerosol or aspiration of acid solution evokes a stimulatory effect on airway C-fiber and Aδ afferents, which in turn causes airway irritation and triggers an array of defense reflex responses (e.g., cough, reflex bronchoconstriction, etc.). Tissue acidosis can also occur locally in the respiratory tract as a result of ischemia or inflammation, such as in the airways of asthmatic patients during exacerbation. The action of proton on the airway sensory neurons is generated by activation of two different current species: a transient (rapidly activating and inactivating) current mediated through the acid-sensing ion channels, and a slowly activating and sustained current mediated through the transient receptor potential vanilloid type 1 (TRPV1) receptor. In view of the recent findings that the expression and/or sensitivity of TRPV1 are up-regulated in the airway sensory nerves during chronic inflammatory reaction, the proton-evoked irritant effects on these nerves may play an important part in the manifestation of various symptoms associated with airway inflammatory diseases.

Extra-esophageal manifestations of gastroesophageal reflux disease: controversies between epidemiology and clicnic

Gastroesophageal reflux disease (GERD) is widely associated with asthma, chronic cough, and laryngitis. Many studies have focused on acidic reflux; however, acid is just one of many factors that can cause pulmonary injury. The discrepancy between the high frequency of GERD in asthmatic patients and the ineffective reflux therapy outcomes in these patients suggests that GERD may cause injury through other mechanisms, such as pepsinogen, pepsin, bile salts, or other components of reflux materials, instead of the acid. Research using appropriate and innovative methodologies to investigate these potential inflammatory agents in patients with GERD is required to determine the underlying factors associated with pulmonary disorders in these patients.

Pediatric gastroesophageal reflux disease

This article reviews the mechanisms responsible for gastroesophageal reflux disease (GERD), available techniques for diagnosis, and current medical management. In addition, it extensively discusses the surgical treatment of GERD, emphasizing the use of minimally invasive techniques.

Different gastoroesophageal reflux symptoms of middle-aged to elderly asthma and chronic obstructive pulmonary disease (COPD) patients

Symptomatic differences and the impact of gastroesophageal reflux disease (GERD) have not been clarified in patients with asthma and chronic obstructive pulmonary disease (COPD). The purpose of this study is to assess the differences of GERD symptoms among asthma, COPD, and disease control patients, and determine the impact of GERD symptoms on exacerbation of asthma or COPD by using a new questionnaire for GERD. A total of 120 subjects underwent assessment with the frequency scale for the symptoms of GERD (FSSG) questionnaire, including 40 age-matched patients in each of the asthma, COPD, and disease control groups. Asthma and control patients had more regurgitation-related symptoms than COPD patients (p<0.05), while COPD patients had more dysmotility-related symptoms than asthma patients (p<0.01) or disease control patients (p<0.01). The most distinctive symptom of asthma patients with GERD was an unusual sensation in the throat, while bloated stomach was the chief symptom of COPD patients with GERD, and these symptoms were associated with disease exacerbations. The presence of GERD diagnosed by the total score of FSSG influences the exacerbation of COPD. GERD symptoms differed between asthma and COPD patients, and the presence of GERD diagnosed by the FSSG influences the exacerbation of COPD.

Gastro-oesophageal reflux in noncystic fibrosis bronchiectasis

The clinical presentation of noncystic fibrosis bronchiectasis may be complicated by concomitant conditions, including gastro-oesophageal reflux (GOR). Increased acidic GOR is principally caused by gastro-oesophageal junction incompetence and may arise from lower oesophageal sphincter hypotension, including transient relaxations, hiatus hernia, and oesophageal dysmotility. Specific pathophysiological features which are characteristic of respiratory diseases including coughing may further increase the risk of GOR in bronchiectasis. Reflux may impact on lung disease severity by two mechanisms, reflex bronchoconstriction and pulmonary microaspiration. Symptomatic and clinically silent reflux has been detected in bronchiectasis, with the prevalence of 26 to 75%. The cause and effect relationship has not been established, but preliminary reports suggest that GOR may influence the severity of bronchiectasis. Further studies examining the implications of GOR in this condition, including its effect across the disease spectrum using a combination of diagnostic tools, will clarify the clinical significance of this comorbidity.

Diagnosing GORD in Respiratory Medicine

Gastroesophageal reflux disease (GORD) is increasing in prevalence and is highly associated with several lung diseases such as asthma and COPD. Current diagnostic methods are imperfect, being insensitive, non-specific, expensive, or invasive. An accurate diagnosis of GORD can aid effective treatment and have significant clinical impact. Novel methods such as exhaled breath condensate analysis and electronic nose technology have the potential to improve the accuracy of diagnosing GORD.

Airway irritation and cough evoked by acid: from human to ion channel

Inhalation or aspiration of acid solution evokes airway defense responses such as cough and reflex bronchoconstriction, resulting from activation of vagal bronchopulmonary C-fibers and Aδ afferents. The stimulatory effect of hydrogen ion on these sensory nerves is generated by activation of two major types of ion channels expressed in these neurons: a rapidly activating and inactivating current mediated through ASICs, and a slow sustaining current via activation of TRPV1. Recent studies have shown that these acid-evoked responses are elevated during airway inflammatory reaction, revealing the potential convergence of a wide array of inflammatory signaling on these ion channels. Since pH in the airway fluid drops substantially in patients with inflammatory airway diseases, these heightened stimulatory effects of acid on airway sensory nerves may play a part in the manifestation of airway irritation and excessive cough under those pathophysiological conditions.

Relationship between gastro-oesophageal reflux and airway diseases: the airway reflux paradigm

Our understanding of the relationship between gastro-oesophageal reflux and respiratory disease has recently undergone important changes. The previous paradigm of airway reflux as synonymous with the classic gastro-oesophageal reflux disease (GORD) causing heartburn has been overturned. Numerous epidemiological studies have shown a highly significant association of the acid, liquid, and gaseous reflux of GORD with conditions such as laryngeal diseases, chronic rhinosinusitis, treatment resistant asthma, COPD and even idiopathic pulmonary fibrosis. However, it has become clear from studies on cough hypersensitivity syndrome that much reflux of importance in the airways has been missed, since it is either non- or weakly acid and gaseous in composition. The evidence for such a relationship relies on the clinical history pointing to symptom associations with known precipitants of reflux. The tools for the diagnosis of extra-oesophageal reflux, in contrast to the oesophageal reflux of GORD, lack sensitivity and reproducibility. Unfortunately, methodology for detecting such reflux is only just becoming available and much additional work is required to properly delineate its role.

A nocturnal decline of salivary pH associated with airway hyperresponsiveness in asthma

Salivary pH is associated with esophageal acid reflux and neutralization of esophageal acid. In this study, we assessed the association between nocturnal decline of salivary pH and airway hyperresponsiveness. Salivary pH was serially assessed in 9 patients with mild asthma (7 men and 2 women; mean age 33.3 years; mean %predicted FEV(1.0) 89.4%) and 10 healthy volunteers (6 men and 4 women; mean age 31.2 years) using a pH indicator tape. The buffering capacity of saliva was defined as the median effective dose (ED(50)) for acidification of saliva with 0.01 N HCl, and airway responsiveness was defined as the dose of methacholine producing a 35% fall in Grs (PD(35)-Grs). There was a significant correlation between the values obtained from the pH indicator tape and those obtained from the electrometric pH meter. Using the indicator tape for sequential monitoring, we observed a nocturnal fall (ΔpH) in salivary pH in all subjects. A significant correlation was found between airway hyperresponsiveness (PD(35)-Grs) and either ΔpH or ED(50) in mildly asthmatic patients. Vagal reflux dysfunction might contribute to nocturnal salivary pH as well as to airway hyperresponsiveness in mild asthmatics.

Innervation of tracheal parasympathetic ganglia by esophageal cholinergic neurons: evidence from anatomic and functional studies in guinea pigs

In the present study, we describe a subset of nerve fibers, characterized by their immunoreactivity for the calcium-binding protein calretinin, that are densely and selectively associated with cholinergic postganglionic neurons in the guinea pig tracheal ganglia. Retrograde neuronal tracing with cholera toxin B, combined with immunohistochemical analyses, showed that these nerve fibers do not originate from sensory neurons in the nodose, jugular, or dorsal root ganglia or from motor neurons in the nucleus ambiguus, dorsal motor nucleus of the vagus nerve, spinal cord, stellate ganglia, or superior cervical ganglia. Calretinin-immunoreactive nerve fibers disappeared from tracheal segments after 48 h in organotypic culture, indicating that the fibers were of extrinsic origin. However, calretinin-positive nerve fibers persisted in tracheal ganglia when tracheae were cocultured with the adjacent esophagus intact. Immunohistochemical analysis of the esophagus revealed a population of cholinergic neurons in the esophageal myenteric plexus that coexpressed calretinin. In functional studies, electrical stimulation of the esophagus in vitro evoked measurable contractions of the trachea. These contractions were not altered by prior organotypic culture of the trachea and esophagus to remove the extrinsic innervation to the airways but were significantly (P < 0.05) inhibited by the ganglionic blocker hexamethonium or by physical disruption of the tissue connecting the trachea and esophagus. These data suggest that a subset of esophageal neurons, characterized by the expression of calretinin and acetylcholine, provide a previously unrecognized excitatory input to tracheal cholinergic ganglia in guinea pigs.

GABAB receptor agonism as a novel therapeutic modality in the treatment of gastroesophageal reflux disease

Defined pharmacologically by its insensitivity to the GABA(A) antagonist bicuculline and sensitivity to the GABA analogue baclofen, the G protein-linked gamma-aminobutyric acid type B (GABA(B)) receptor couples to adenylyl cyclase, voltage-gated calcium channels, and inwardly-rectifying potassium channels. On the basis of a wealth of preclinical data in conjunction with early clinical observations that baclofen improves symptoms of gastroesophageal reflux disease (GERD), the GABA(B) receptor has been proposed as a therapeutic target for a number of diseases including GERD. Subsequently, there has been a significant effort to develop a peripherally-restricted GABA(B) agonist that is devoid of the central nervous system side effects that are observed with baclofen. In this article we review the in vitro and in vivo pharmacology of the peripherally-restricted GABA(B) receptor agonists and the preclinical and clinical development of lesogaberan (AZD3355, (R)-(3-amino-2-fluoropropyl) phosphinic acid), a potent and predominately peripherally-restricted GABA(B) receptor agonist with a preclinical therapeutic window superior to baclofen.

[Lung diseases and gastro-oesophageal reflux disease]

Gastro -oesophageal Reflux Disease is a consequence of pathological reflux from stomach to oesophagus. Whenever the refluxed contents extended beyond the oesophagus itself, is called Extraoesophageal Reflux Disease. The author proposes a review about pulmonary disorders and gastroesophageal reflux. Previously, it is evaluated in an abridged way, the concepts of each diseases and after that, in a systematic form, it is discussed the prevalence of gastro -oesophageal reflux in lung diseases, all the mechanisms studies and the impact of gastro -oesophageal treatment on lung disorders. The author concludes that is undeniable the link between Gastro -oesophageal reflux and lung diseases and further reaserch is mandatory in order to corroborate this association.

Recent findings on the pathogenesis of bronchial asthma. Part II. The role of hormonal predisposition, environmental influences and conditioning leading to bronchial asthma

In this second part of the review on the pathogenesis of asthma the hormonal factors and adverse external events are shortly reviewed which skew the balance of Th1 vs. Th2 CD4+ lymphocytes towards the latter ones and this way increase the probability of atopic diseases. Among other the role of transplacental priming, insulin, insulin-like and other growth factors, lack of the usual microbial infections in the early childhood (the so-called hygiene hypothesis), gender, diminished testosterone production, gastroesophageal reflux, adverse effects during pregnancy are discussed. A separate chapter deals with the role of central nervous system in the etiology and finally the most common allergizing and airway tissue damaging agents are listed in tabulated form.

Pulmonary manifestations of gastroesophageal reflux disease

Gastroesophageal reflux disease (GERD) may cause, trigger or exacerbate many pulmonary diseases. The physiological link between GERD and pulmonary disease has been extensively studied in chronic cough and asthma. A primary care physician often encounters patients with extra esophageal manifestations of GERD in the absence of heartburn. Patients may present with symptoms involving the pulmonary system; noncardiac chest pain; and ear, nose and throat disorders. Local irritation in the esophagus can cause symptoms that vary from indigestion, like chest discomfort and abdominal pain, to coughing and wheezing. If the gastric acid reaches the back of the throat, it may cause a bitter taste in the mouth and/or aspiration of the gastric acid into the lungs. The acid can cause throat irritation, postnasal drip and hoarseness, as well as recurrent cough, chest congestion and lung inflammation leading to asthma and/or bronchitis/ pneumonia. This clinical review examines the potential pathophysiological mechanisms of pulmonary manifestations of GERD. It also reviews relevant clinical information concerning GERD-related chronic cough and asthma. Finally, a potential management strategy for GERD in pulmonary patients is discussed.

Efficacy of esomeprazole for treatment of poorly controlled asthma

BACKGROUND

Gastroesophageal reflux is common among patients with asthma but often causes mild or no symptoms. It is not known whether treatment of gastroesophageal reflux with proton-pump inhibitors in patients who have poorly controlled asthma without symptoms of gastroesophageal reflux can substantially improve asthma control.

METHODS

In a parallel-group, double-blind trial, we randomly assigned 412 participants with inadequately controlled asthma, despite treatment with inhaled corticosteroids, and with minimal or no symptoms of gastroesophageal reflux to receive either 40 mg of esomeprazole twice a day or matching placebo. Participants were followed for 24 weeks with the use of daily asthma diaries, spirometry performed once every 4 weeks, and questionnaires that asked about asthma symptoms. We used ambulatory pH monitoring to ascertain the presence or absence of gastroesophageal reflux in the participants. The primary outcome was the rate of episodes of poor asthma control, as assessed on the basis of entries in asthma diaries.

RESULTS

Episodes of poor asthma control occurred with similar frequency in the placebo and esomeprazole groups (2.3 and 2.5 events per person-year, respectively; P=0.66). There was no treatment effect with respect to individual components of the episodes of poor asthma control or with respect to secondary outcomes, including pulmonary function, airway reactivity, asthma control, symptom scores, nocturnal awakening, or quality of life. The presence of gastroesophageal reflux, which was documented by pH monitoring in 40% of participants with minimal or no symptoms, did not identify a subgroup of patients that benefited from treatment with proton-pump inhibitors. There were fewer serious adverse events among patients receiving esomeprazole than among those receiving placebo (11 vs. 17).

CONCLUSIONS

Despite a high prevalence of asymptomatic gastroesophageal reflux among patients with poorly controlled asthma, treatment with proton-pump inhibitors does not improve asthma control. Asymptomatic gastroesophageal reflux is not a likely cause of poorly controlled asthma. (ClinicalTrials.gov number, NCT00069823.)

The characteristics of different diagnostic tests in adult mild asthmatic patients: comparison with patients with asthma-like symptoms by gastro-oesophageal reflux

BACKGROUND

Diagnosing asthma cannot be always easy. It is important to consider the validity of the diagnostic tests, and/or how much more commonly they are positive in patients with asthma compared to healthy subjects and, particularly, to patients with asthma-like symptoms.

OBJECTIVE

To evaluate the validity of diagnostic tests for asthma, in terms of sensitivity, specificity, positive and negative predictive values, in patients with bronchial asthma compared to patients affected by gastro-oesophageal reflux disease (GERD) with asthma-like symptoms, and healthy control subjects without asthma and gastro-oesophageal reflux (GER).

DESIGN

Single-center, cross-sectional, observational study.

PATIENTS

We studied 60 patients with mild asthma, 30 patients with GERD and asthma-like symptoms and 25 healthy control subjects.

MEASUREMENTS

We measured provocative concentration of methacholine causing a 20% fall in the forced expiratory volume in 1s (MCh PC(20)/FEV(1)), the amplitude percent mean of peak expiratory flow (A%M of PEF), derived from twice-daily readings for >2 weeks, the FEV(1)/forced vital capacity (FEV(1)/FVC) ratio, the eosinophil count in blood and in induced sputum and the serum eosinophil cationic protein (ECP) levels.

RESULTS

FEV(1)/FVC ratio, A%M of PEF, blood eosinophils counts and serum ECP levels were less sensitive and specific when the reference population was composed of patients with asthma-like symptoms by GER. While, MCh PC(20)/FEV(1) and induced sputum eosinophils count were the most sensitive (both 90%) and specific (89% and 92%, respectively) tests.

CONCLUSION

Our findings demonstrate that MCh PC(20)/FEV(1) and the induced sputum eosinophil count are the most useful objective tests in patients with mild asthma. All patients with asthma presented both an MCh PC(20)/FEV(1) <1500 microg and eosinophils count in the induced sputum >1%.

Omeprazole reduces the response to capsaicin but not to methacholine in asthmatic patients with proximal reflux

OBJECTIVE

To study the relationships between airway responsiveness to methacholine and capsaicin, proximal or distal reflux and the effects of short-term acid inhibition.

MATERIAL AND METHODS

Twenty-nine asthmatics, not taking steroids regularly, underwent respiratory symptom measurements, 24-h dual-probe pH monitoring, and challenges with methacholine and capsaicin. Challenges and symptom measurements were repeated after 12 days' omeprazole treatment (20 mg b.i.d.). The results (median and range) were expressed as PD20 methacholine (mg) and PD5 capsaicin (dose causing five coughs, nmol).

RESULTS

Seventeen patients presented pathological reflux in the distal esophagus, and 17 in the proximal esophagus. At baseline no correlation was found between PD20 or PD5 and reflux. Treatment with omeprazole did not change bronchial responsiveness to methacholine (basal: 0.16 mg, 0.02-1.27; omeprazole: 0.15 mg, 0.02-1.60); omeprazole decreased the tussive response to capsaicin (basal: 0.08 nmol, 0.08-2.46; omeprazole: 0.61 nmol, 0.08-9.84, p<0.001) only in patients with pathological reflux. The decrease was positively correlated with proximal acid exposure (r2=0.70, p<0.001). Omeprazole reduced asthma symptoms in patients with proximal reflux, cough in those with proximal or distal reflux.

CONCLUSIONS

In asthmatics, inhibition of gastric acid secretion does not influence bronchial hyperresponsiveness but decreases tussive sensitivity and this effect is related to proximal reflux.

Multichannel intraluminal impedance to detect relationship between gastroesophageal reflux and apnoea of prematurity

BACKGROUND

The association between gastroesophageal reflux and apnoea of prematurity is still controversial. Available data are biased by the heterogeneity of the infants enrolled as regard to some confounding factors and by the use of the traditional pH monitoring that is unable to detect non acid reflux events which might be prevalent in infants receiving frequent milk feeding. Multichannel intraluminal impedance has been recently introduced as a pH-independent method to investigate the bolus transport in hollow organs.

OBJECTIVE

To assess if combined multichannel intraluminal impedance-pH study could be useful to detect an association between gastroesophageal reflux and apnoea of prematurity.

METHODS

We prospectively evaluated a group of premature infants with apnoea of prematurity in absence of any confounding factors (ventilatory support, treatment with caffeine, permanent nasogastric tube, post-natal age older than 30 days) by simultaneous recording of 24-h multichannel intraluminal impedance-pH and cardiorespiratory monitoring. A temporal relationship between an apnoea and a reflux event was considered if both commenced within 20s of each other.

RESULTS

Six premature infants [three male; median gestational age 31 weeks (range 27-36); birth weight 1335g (range 1200-2350); age at study 17 days (range 7-28)] were studied. A total of 405 reflux events [306 (76%) weakly acid and 99 acid reflux] and 142 apnoeas were detected. The frequency of apnoeas occurring during the reflux events period was significantly greater than the one calculated for reflux-free period [0.42/min (0.00-1.28) versus 0.016/min (0.003-0.028); p<0.05]. The sub-analysis based on chemical composition and duration of refluxate showed that the frequency of apnoeas associated with weakly acid reflux events was significantly greater than the one calculated for reflux-free period [0.416/min (0.00-1.30) versus 0.016/min (0.003-0.028), respectively; p<0.05] and that the frequency of apnoeas occurring during reflux events longer than 30s was significantly higher than those occurring during shorter reflux events (22% versus 11%; p<0.004).

CONCLUSION

Our data show that weakly acidic reflux events are more prevalent than acid reflux events in premature infants, confirming the need for the use of multichannel intraluminal impedance-pH monitoring for diagnosis of gastroesophageal reflux in those patients. Gastroesophageal reflux and apnoea of prematurity are both common occurrences and, in our experience, may be temporally related especially as regard to weakly acid refluxate and reflux events longer than 30s.

Role of TRPV receptors in respiratory diseases

Transient receptor potential vanilloid type channels (TRPVs) are expressed in several cell types in human and animal lungs. Increasing evidence has demonstrated important roles of these cation channels, particularly TRPV1 and TRPV4, in the regulation of airway function. These TRPVs can be activated by a number of endogenous substances (hydrogen ion, certain lipoxygenase products, etc.) and changes in physiological conditions (e.g., temperature, osmolarity, etc.). Activation of these channels can evoke Ca(2+) influx and excitation of the neuron. TRPV1 channels are generally expressed in non-myelinated afferents innervating the airways and lungs, which also contain sensory neuropeptides such as tachykinins. Upon stimulation, these sensory nerves elicit centrally-mediated reflex responses as well as local release of tachykinins, and result in cough, airway irritation, reflex bronchoconstriction and neurogenic inflammation in the airways. Recent studies clearly demonstrated that the excitability of TRPV1 channels is up-regulated by certain autacoids (e.g., prostaglandin E(2), bradykinin) released during airway inflammatory reaction. Under these conditions, the TRPV1 can be activated by a slight increase in airway temperature or tissue acidity. Indirect evidence also suggests that TRPV channels may play a part in the pathogenesis of certain respiratory diseases such as asthma and chronic cough. Therefore, the potential use of TRPV antagonists as a novel therapy for these diseases certainly merits further investigation.

Acid-sensitive vagal sensory pathways and cough

Acid is an important mediator in the pathogenesis of cough. Inhalation of exogenous acid triggers cough and endogenous acid may contribute to cough in respiratory diseases. Acid directly stimulates vagal bronchopulmonary sensory nerves that regulate the cough reflex. Consistent with their putative role in defence against aspiration and inhaled irritants, Adelta-fibre nociceptors in the large airways are most efficiently stimulated by rapid acidification. In contrast, acid-sensitive properties of the C-fibre nociceptors allow for continuous monitoring of pH which is likely important in inflammation. Acid is also the single most important mediator in the pathogenesis of cough due to gastro-oesophageal reflux (GOR). The cough pathways can be sensitized by the sensory inputs from the oesophagus. This sensitization is likely mediated by a subset of the vagal oesophageal sensory nerves distinguished by discriminative responsiveness to noxious stimuli (nociceptors). The receptors underlying acid sensitivity of vagal sensory nerves are incompletely understood. The role of TRPV1 has been established but the roles of acid-sensing ion channels (ASIC) and other receptors await more definitive investigation. Here, we provide a brief overview of the cough-related acid-sensitive sensory pathways and discuss the mechanisms of acid sensitivity.

A proton pump inhibitor, lansoprazole, ameliorates asthma symptoms in asthmatic patients with gastroesophageal reflux disease

Aspiration of acid to the airway causes airway inflammation, and acid stress to the airway caused by gastroesophageal reflux disease (GERD) has been known as a potential mechanism of deteriorated asthma symptoms. However, the efficacy of the acid suppressive drugs, H(2)-receptor blockers (H(2) blocker) and proton pump inhibitors, on asthma symptoms and pulmonary functions remains controversial. We therefore designed the randomized prospective study to determine the efficacy of an H(2) blocker (roxatidine, 150 mg/day) and a proton pump inhibitor (lansoprazole, 30 mg/day) on asthma symptoms of 30 asthmatic patients with GERD. These patients were divided in the two groups (15 patients for each group) and treated with either roxatidine or lansoprazole. The diagnosis of GERD was established by the method of Los Angeles classification including mucosal minimum change of Grade M and questionnaire for the diagnosis of reflux disease (QUEST) score. The efficacy of acid suppressive drugs was evaluated by peak expiratory flow (PEF), asthma control questionnaire (ACQ) that evaluates the improvement of asthma symptoms, and forced expiratory volume in 1 second (FEV(1.0)). Lansoprazole, but not roxatidine, significantly improved PEF and ACQ scores (p < 0.05) with the improved QUEST scores. However, these acid suppressive drugs did not change the pulmonary function of FEV(1.0) in asthmatic patients. In conclusion, treatment with a proton pump inhibitor, lansoprazole, appears to be useful in improvement of asthma symptoms in asthmatic patients with GERD.

Anatomy and Neurophysiology of the Cough Reflex

OBJECTIVES

To describe the anatomy and neurophysiology of the cough reflex.

METHODS

A review of the literature was carried out using PubMed and the ISI Web of Knowledge from 1951 to 2004. Most of the referenced studies were carried out in animals

CONCLUSIONS

Studies carried out in animals provide suggestive but inconclusive evidence that C-fibers and rapidly adapting receptors (RARs) arising from the vagus nerves mediate coughing. Recent studies also have suggested that a vagal afferent nerve subtype that is not readily classified as a RAR or a C-fiber may play an important role in regulating cough. Afferent nerves innervating other viscera, as well as somatosensory nerves innervating the chest wall, diaphragm, and abdominal musculature also likely play a less essential but important accessory role in regulating cough. The responsiveness and morphology of the airway vagal afferent nerve subtypes and the extrapulmonary afferent nerves that regulate coughing are described.

An overview of the sensory receptors regulating cough

The cough reflex represents a primary defensive mechanism for airway protection in a variety of mammalian species. However, excessive and inappropriate coughing can emerge as a primary presenting symptom of many airway diseases. Cough disorders are characterized by a reduction in the threshold for reflex initiation and, as a consequence, the occurrence of cough in response to stimuli that are normally innocuous in nature. The current therapeutic strategies for the treatment of cough disorders are only moderately effective. This undoubtedly relates in part to limitations in our understanding of the neural components comprising the cough reflex pathway. The aim of this review is to provide an overview of current concepts relating to the sensory innervation to the mammalian airways, focusing particularly on the sensory receptors that regulate cough. In addition, the review will highlight particular areas and issues relating to cough neurobiology that are creating controversy in the field.

Pulmonary disease in rescue workers at the World Trade Center site

PURPOSE OF REVIEW

The catastrophic collapse of the World Trade Center (WTC) towers on September 11, 2001 created a large-scale disaster site in a densely populated urban environment. Over the ensuing months, tens of thousands of rescue, recovery and cleanup workers, volunteers, and residents of the adjacent community were exposed to a complex mixture of airborne pollutants. This review focuses on currently described respiratory syndromes, symptoms, and physiologic derangements in WTC rescue, recovery, and cleanup workers, discusses potential long-term effects on respiratory health, and draws parallels to community findings.

RECENT FINDINGS

Detailed qualitative and quantitative analyses of airborne pollutants with their changing composition during initial rescue/recovery and subsequent cleanup have been published. Major concerns include persistent aerodigestive tract inflammatory syndromes, such as reactive airways dysfunction syndrome (RADS), reactive upper airways dysfunction syndrome (RUDS), gastroesophageal reflux disease (GERD), and inflammatory pulmonary parenchymal syndromes, as well as respiratory tract and nonrespiratory malignancies. Aerodigestive tract inflammatory syndromes have now been documented in WTC exposed occupational groups, and syndrome incidence has been linked to WTC airborne pollutant exposure intensity. Community based investigations have yielded similar findings.

SUMMARY

While it is too early to ascertain long-term effects of WTC dust exposure, current studies already demonstrate a definite link between exposure to WTC-derived airborne pollutants and respiratory disease, both in the occupational and the community setting. A better understanding of causes and effects of this exposure will help in developing appropriate preventative tools for rescue workers in future disasters.

Gastroesophageal Reflux Disease and Asthma

STUDY OBJECTIVES

Gastroesophageal reflux disease (GERD) and asthma are common causes for consultation in primary care, but the relationship between the two remains unclear. The aim of our study was to investigate the temporal relationship between first diagnoses of GERD and asthma in general practice.

METHODS

We used the UK General Practice Research Database to identify a cohort of patients with a first diagnosis of GERD (n = 5,653) and another cohort of patients with a first diagnosis of asthma (n = 9,712) during 1996, which we compared with age-matched and sex-matched control cohorts drawn from the general population without either diagnosis. We investigated the incidence of a GERD diagnosis among the asthma patients and control subjects, and the incidence of an asthma diagnosis among the GERD patients and control subjects during a mean follow-up period of 3 years. We calculated the relative risk (RR) of these diagnoses using Cox regression analysis and examined the risk associated with medication use using nested case-control analysis.

RESULTS

The incidence rates of GERD and asthma among the control cohorts were 4.4 and 3.8 per 1,000 person-years, respectively. During the follow-up period, the RR of an incident asthma diagnosis in patients with a new diagnosis of GERD was 1.2 (95% confidence interval [CI], 0.9 to 1.6), while the RR of an incident GERD diagnosis among patients with a new diagnosis of asthma was 1.5 (95% CI, 1.2 to 1.8) after adjustment for age, sex, smoking, prior comorbidity, and number of health-care contacts. This increased risk was mainly seen during the first year of follow-up. The prior use of prescription medications for asthma and GERD had no significant effects on the risk of GERD and asthma diagnosis, respectively.

CONCLUSIONS

Patients with asthma are at a significantly increased risk of developing GERD, mainly during the first year following diagnosis. A nonsignificant increase in the risk of developing asthma was evident among GERD patients. The relationship between GERD and asthma warrants further investigation.

Asthma and gastroesophageal reflux disease in children: exploring the relationship

Asthma is a well-recognized disease and one of the most common illnesses in childhood. More recently, gastroesophageal reflux disease has increasingly been appreciated as a common daily occurrence in children and adolescents. These two diagnoses often present in tandem, with their coexistence being more frequent than would be expected for a chance occurrence. The mainstay of asthma management is the regulation and control of chronic airway hyperreactivity and inflammation. Children who do not respond to standard asthma regimens should be evaluated for other sources of their pulmonary symptoms, most notably gastroesophageal reflux. Baseline assessment of pulmonary function tests followed by an empiric trial of proton pump inhibitor therapy, using double the standard doses commonly used in acid-related disorders and administered for 3 months, is a cost-effective, noninvasive diagnostic strategy. Children who fail to exhibit pulmonary symptom improvement should be evaluated for both medication compliance and proper administration. Twenty-four-hour esophageal pH monitoring with concurrent dairy recordings of their symptoms is recommended to ascertain adequacy of acid suppression and confirm the diagnosis in those who continue to have symptoms. Children with acid-related causes of their pulmonary symptoms often require long-term treatment. Studies have confirmed the efficacy, safety, and tolerability of proton pump inhibitors in the treatment of children and adolescents. Surgery should be reserved for those with severe disease and those who are unable to comply with pharmacologic treatment.