Asthma as a cause for, rather than a result of, gastroesophageal reflux

Pharmacological and surgical interventions for the treatment of gastro-oesophageal reflux in adults and children with asthma

BACKGROUND

Asthma and gastro-oesophageal reflux disease (GORD) are common medical conditions that frequently co-exist. GORD has been postulated as a trigger for asthma; however, evidence remains conflicting. Proposed mechanisms by which GORD causes asthma include direct airway irritation from micro-aspiration and vagally mediated oesophagobronchial reflux. Furthermore, asthma might precipitate GORD. Thus a temporal association between the two does not establish that GORD triggers asthma.

OBJECTIVES

To evaluate the effectiveness of GORD treatment in adults and children with asthma, in terms of its benefits for asthma.

SEARCH METHODS

The Cochrane Airways Group Specialised Register, CENTRAL, MEDLINE, Embase, reference lists of articles, and online clinical trial databases were searched. The most recent search was conducted on 23 June 2020.

SELECTION CRITERIA

We included randomised controlled trials comparing treatment of GORD in adults and children with a diagnosis of both asthma and GORD versus no treatment or placebo.

DATA COLLECTION AND ANALYSIS

A combination of two independent review authors extracted study data and assessed trial quality. The primary outcome of interest for this review was acute asthma exacerbation as reported by trialists.

MAIN RESULTS

The systematic search yielded a total of 3354 citations; 23 studies (n = 2872 participants) were suitable for inclusion. Included studies reported data from participants in 25 different countries across Europe, North and South America, Asia, Australia, and the Middle East. Participants included in this review had moderate to severe asthma and a diagnosis of GORD and were predominantly adults presenting to a clinic for treatment. Only two studies assessed effects of intervention on children, and two assessed the impact of surgical intervention. The remainder were concerned with medical intervention using a variety of dosing protocols. There was an uncertain reduction in the number of participants experiencing one or more moderate/severe asthma exacerbations with medical treatment for GORD (odds ratio 0.53, 95% confidence interval (CI) 0.17 to 1.63; 1168 participants, 2 studies; low-certainty evidence). None of the included studies reported data related to the other primary outcomes for this review: hospital admissions, emergency department visits, and unscheduled doctor visits. Medical treatment for GORD probably improved forced expiratory volume in one second (FEV₁) by a small amount (mean difference (MD) 0.10 L, 95% CI 0.05 to 0.15; 1333 participants, 7 studies; moderate-certainty evidence) as well as use of rescue medications (MD -0.71 puffs per day, 95% CI -1.20 to -0.22; 239 participants, 2 studies; moderate-certainty evidence). However, the benefit of GORD treatment for morning peak expiratory flow rate was uncertain (MD 6.02 L/min, 95% CI 0.56 to 11.47; 1262 participants, 5 studies). It is important to note that these mean improvements did not reach clinical importance. The benefit of GORD treatment for outcomes synthesised narratively including benefits of treatment for asthma symptoms, quality of life, and treatment preference was likewise uncertain. Data related to adverse events with intervention were generally underreported by the included studies, and those that were available indicated similar rates regardless of allocation to treatment or placebo.

AUTHORS' CONCLUSIONS

Effects of GORD treatment on the primary outcomes of number of people experiencing one or more exacerbations and hospital utilisation remain uncertain. Medical treatment for GORD in people with asthma may provide small benefit for a number of secondary outcomes related to asthma management. This review determined with moderate certainty that with treatment, lung function measures improved slightly, and use of rescue medications for asthma control was reduced. Further, evidence is insufficient to assess results in children, or to compare surgery versus medical therapy.

Hypopharyngeal and distal esophageal pH monitoring in children with gastroesophageal reflux and respiratory symptoms

PURPOSE

Fundoplication is frequently required for gastroesophageal reflux (GER)-related respiratory disease. Correlation between esophageal pH data and respiratory symptoms is poor but may be improved by monitoring hypopharyngeal pH. Reflux to the hypopharynx is underestimated by salivary bicarbonate. The aim of this study was to determine if hypopharyngeal pH monitoring using pH 4 and pH 5 as reflux thresholds could predict children with reflux-related respiratory disease.

METHODS

One hundred five children aged 4 months to 12 years underwent esophageal and hypopharyngeal pH monitoring. Hypopharyngeal pH data were analyzed using pH 4 and pH 5 as reflux thresholds. pH data from 4 groups were compared: group A, control group, no GER, no respiratory symptoms (n = 20); group B, respiratory symptoms, no GER (n = 16); group C, GER, no respiratory symptoms (n = 26); and group D, both GER and respiratory symptoms (n = 37).

RESULTS

Comparing groups C and D, there was no significant difference in hypopharyngeal pH data. Using pH 5 as the reflux threshold, children in group B refluxed to the hypopharynx significantly more frequently than controls. This was most evident in children with wheeze.

CONCLUSION

Hypopharyngeal pH monitoring does not differentiate children with GER and respiratory symptoms from those with GER alone and is therefore of doubtful value in diagnosing recurrent aspiration.

Gastroesophageal reflux, asthma, and mechanisms of interaction

Gastroesophageal reflux (GER) is a potential trigger of asthma. The esophagus and lung interact through a variety of mechanisms. Esophageal acid-induced bronchoconstriction can be provoked by a vagally mediated reflex, whereby acid in the distal esophagus produces airway responses; by neural enhancement of bronchial reactivity, whereby esophageal acid augments airway hyperresponsiveness; or by microaspiration, in which small amounts of esophageal acid in the upper airway cause significant airway responses. Interestingly, even in the microaspiration model, the vagus nerve plays a significant role. Neurogenic inflammation in the lung may occur with either vagally mediated mechanisms or with microaspiration. The prevalence of reflux symptoms, esophagitis, and abnormal esophageal acid contact time is higher in patients with asthma than in control populations. Potential mechanisms, whereby asthma may predispose to the development of GER, include autonomic dysregulation, an increased pressure gradient differential between the thorax and the abdomen, a high prevalence of hiatal hernia, alterations in crural diaphragm function, and bronchodilator medication use. Further research will help define how the esophagus and lung interact.

Medical treatment for reflux oesophagitis does not consistently improve asthma control: a systematic review

BACKGROUND

A systematic literature review was conducted to assess the effect of treating reflux oesophagitis on asthma outcomes.

METHODS

Randomised controlled trials of reflux oesophagitis treatment in adults or children that reported asthma health outcomes were included and assessed in accordance with the standard Cochrane systematic review process. Patients were typically adults with asthma and concurrent symptomatic gastro-oesophageal reflux who received interventions that included pharmacological therapy, conservative management, and surgery. The following outcome measures were assessed: lung function, peak expiratory flow, asthma symptoms, asthma medications, and nocturnal asthma.

RESULTS

From 22 potentially relevant published and unpublished randomised controlled trials, 12 were included. Treatment duration ranged from 1 week to 6 months. Eight trials reported that treatment improved at least one asthma outcome, but these outcomes differed between trials. Overall, treatment of reflux oesophagitis did not consistently improve forced expiratory volume in one second (FEV(1)), peak expiratory flow rate, asthma symptoms, nocturnal asthma symptoms, or use of asthma medications in asthmatic subjects. Significant improvement in wheeze was reported in two studies.

CONCLUSIONS

The published literature does not consistently support treatment of reflux oesophagitis as a means of controlling asthma. Further large randomised controlled trials in subjects with a demonstrated temporal relationship between gastro-oesophageal reflux and asthma are needed. These trials should be conducted over at least 6 months to allow adequate time to observe a treatment effect.

Gastro-oesophageal reflux treatment for asthma in adults and children

BACKGROUND

Asthma and gastro-oesophageal reflux are both common medical conditions and often co-exist. Studies have shown conflicting results concerning the effects of lower oesophageal acidification as a trigger of asthma. Furthermore, asthma might precipitate gastro-oesophageal reflux. Thus a temporal association between the two does not establish that gastro-oesophageal reflux triggers asthma. Randomised trials of a number of treatments for gastro-oesophageal reflux in asthma have been conducted, with conflicting results.

OBJECTIVES

The objective of this review was to evaluate the effectiveness of treatments for gastro-oesophageal reflux in terms of their benefit on asthma.

SEARCH STRATEGY

The Cochrane Airways Group trials register, review articles and reference lists of articles were searched.

SELECTION CRITERIA

Randomised controlled trials of treatment for oesophageal reflux in adults and children with a diagnosis of both asthma and gastro-oesophageal reflux.

DATA COLLECTION AND ANALYSIS

Trial quality and data extraction were carried out by two independent reviewers. Authors were contacted for confirmation or more data.

MAIN RESULTS

Nine trials met the inclusion criteria. Interventions included proton pump inhibitors (n=3), histamine antagonists (n=5), surgery (n=1) and conservative management (n=1). Treatment duration ranged from 1 week to 6 months. A temporal association between asthma and gastro-oesophageal reflux was investigated in 4 trials and found to be present in a proportion of participants in these trials. Anti-reflux treatment did not consistently improve lung function, asthma symptoms, nocturnal asthma or the use of asthma medications.

REVIEWER'S CONCLUSIONS

In asthmatic subjects with gastro-oesophageal reflux, (but who were not recruited specifically on the basis of reflux-associated respiratory symptoms), there was no overall improvement in asthma following treatment for gastro-oesophageal reflux. Subgroups of patients may gain benefit, but it appears difficult to predict responders.

Gastroesophageal reflux and asthma: are they related?

The relationship between asthma and gastroesophageal reflux (GER) is controversial. This paper reviews the evidence for an association between them, the effect of asthma on GER, and the effects of GER and antireflux therapy on asthma. The association between the two conditions seems firm but studies of the effects of GER on asthma and asthma on GER are contradictory. Critical review suggests that GER affects asthma symptoms but not pulmonary function. Antireflux therapy improves asthma symptoms and reduces medication requirements but does not improve pulmonary function. The paradox of GER causing asthma symptoms but not changing pulmonary function may be explained by its increasing minute ventilation rather than triggering bronchospasm.

Gastro-oesophageal reflux disease and asthma

Gastro-oesophageal reflux disease (GOR) and asthma are both common medical conditions that often co-exist. Studies using oesophageal manometry and 24 h ambulatory pH monitoring have shown that up to 80% of asthmatics have abnormal GOR. A number of mechanisms whereby GOR may trigger asthma have been proposed, and it is believed that acid reflux may stimulate vagal receptors in the lower oesophagus causing reflex bronchoconstriction. However, GOR may be worsened by asthma causing abnormal diaphragm mechanics and by its treatment. Formal evaluation of GOR should be considered a part of asthma assessment, particularly if asthmatic symptoms are precipitated by factors known to trigger GOR such as reclining, alcohol ingestion, and the use of theophylline. Twenty-four hour ambulatory intra-oesophageal pH monitoring remains the gold standard for the diagnosis of GOR. Medical therapy with anti-reflux medications, such as acid suppressive agents and prokinetic agents may improve both GOR and asthma control. In those who fail medical therapy, anti-reflux surgery may be warranted in some.

Risk factors for benign oesophageal disease in a random population sample

The association of sex, age, relative weight, smoking and drinking habits, chronic obstructive pulmonary disease (COPD) and economic and marital status, with benign oesophageal disease (BOD) was investigated by means of a point-prevalence study of BOD in a Danish population. A total of 346 individuals, representing subjects who gave positive responses to the discriminating questions pertaining to BOD and risk factors in a previously described questionnaire, as well as control subjects, were invited to participate in a clinical examination. Invasive investigation was accepted by 175 subjects, 114 of whom were diagnosed as having BOD. A statistically significant relationship between BOD and COPD was demonstrated by univariate analysis, and later confirmed by multivariate analysis (P less than 0.01). Odds ratios suggested a non-significant association between BOD and smoking at least 20 g tobacco a day and consuming greater than or equal to 50 alcoholic drinks per week. Obesity, sex, age, marital and economic status were not risk factors for BOD.

Gastroesophageal reflux and asthma

Gastroesophageal reflux provokes asthma in many patients. Conversely, asthma predisposes to gastroesophageal reflux. In many patients, reflux therapy will ameliorate asthma. Recognition of this relationship is facilitated by physician awareness, clinical history, selected laboratory tests, and ultimately, a careful monitoring of the response to antireflux therapy. With the introduction of effective medical antireflux therapy, the opportunity to benefit these patients has increased. Surgical management of reflux-provoked asthma remains an effective and useful alternative in selected patients.

Gastroesophageal reflux and diseases of the respiratory tract: a review

Gastroesophageal reflux is an important cause of chronic respiratory disorders. In at least two common pulmonary conditions, chronic bronchitis and asthma, there may be a ying-yang association between the pulmonary disease and gastroesophageal reflux. Gastroesophageal-provoked disease needs to be evaluated in patients with chronic respiratory disease whose condition is progressing in spite of adequate medical therapy; whose history strongly supports this concept; and whose laboratory tests suggest a causal relationship. Recognition and treatment of gastroesophageal reflux, either medical or surgical, can benefit respiratory problems of many patients.