WAO - ARIA consensus on chronic cough: Executive summary

Acute cough is a highly prevalent symptom in clinical practice. Chronic cough is a complex disease with significant impact on quality of life. The mechanistic pathways of chronic cough in cough-comorbid clinical phenotypes are elusive. Mounting evidence suggests presence of a hypersensitive cough reflex and implication of transient receptor potential channels and P2X receptors in cough neuronal pathways. Previously, the World Allergy Organization (WAO)/Allergic Rhinitis and its Impact on Asthma (ARIA) Joint Committee on Chronic Cough published updated experimental and clinical data on chronic cough, in addition to a multidisciplinary care pathway approach to its management. The goal of this manuscript is to provide clinicians with a succinct summary of chronic cough pathophysiology, clinical phenotypes, and management strategies in both primary and cough specialty care. This executive summary is a primer for clinicians on chronic cough. Increasing awareness on the topic among primary care physicians will improve the outcome of management of patients with chronic cough.

A Study on the Association between Cough Sensitivity and Acute Exacerbations in Patients with Chronic Obstructive Pulmonary Disease

OBJECTIVE

To investigate the relationship between cough sensitivity and acute exacerbation in stable chronic obstructive pulmonary disease (COPD) patients.

METHODS

Stable COPD patients who visited our department from July 2022 to June 2023 were included. They were subjected to cough sensitivity test, spirometry, induced sputum cytology examination, questionnaire assessment such as cough symptom score, etc. They were followed up for 12 months, and were divided into the acute exacerbation (AE) group and the stable group according to whether acute exacerbation occurred during the follow-up period. We compared the differences in cough sensitivity, pulmonary function, and questionnaires between the two groups, analyzed the relationship between cough sensitivity and acute exacerbation, and screened the risk factors for AECOPD.

RESULTS

A total of 145 patients with stable COPD were included. AE group (n = 94) had lower FEV1/FVC (50.08 ± 11.11 versus 54.28 ± 11.58, p = 0.03) and cough sensitivity lgC5 [-0.01(0.90) versus 0.59(0.90), p < 0.01] than those in the stable group (n = 51) patients, the daytime cough symptom score [2(2) versus 1(2), p = 0.02] and VAS score [50(40) versus 30(50), p < 0.01] were higher than stable group. Multivariate logistic regression analysis showed lgC5 (OR = 0.34, 95% CI = 0.16-0.71, p < 0.01) was an independent risk factor for AECOPD. When lgC5 was used to predict acute exacerbation in stable COPD patients, the AUC was 0.69, the sensitivity was 59.57%, and the specificity was 72.55%.

CONCLUSION

Although causality is not necessarily demonstrated, baseline cough sensitivity lgC5 in stable COPD patients is an independent risk factor for AECOPD, and it has some predictive value for future acute exacerbations.

Diagnostic value of the pepsin concentration in saliva and induced sputum for gastroesophageal reflux-induced chronic cough: a prospective clinical study

Background

Finding a simple, effective and rapid diagnostic method to improve the diagnosis of gastroesophageal reflux-induced chronic cough (GERC) is indicated. Our objective was to determine the diagnostic value of the pepsin concentration in saliva and induced sputum for GERC.

Methods

171 patients with chronic cough were enrolled. The diagnosis and treatment followed the chronic cough diagnosis and treatment protocol. Saliva and induced sputum were collected, and the pepsin concentration was determined using Peptest. A Gastroesophageal Reflux Diagnostic Questionnaire (GerdQ) was completed. The diagnostic value of the pepsin concentration in saliva and induced sputum for GERC was analysed and compared.

Results

The salivary pepsin concentration predicted GERC with an area under the receiver operating characteristic curve (AUC) of 0.845. The optimal cut-off value was 76.10 ng·mL-1, the sensitivity was 83.58% and the specificity was 82.69%. The pepsin concentration in the induced sputum supernatant for GERC had an AUC of 0.523. When GerdQ was used for GERC diagnosis, the AUC was 0.670 and the diagnostic value of salivary pepsin was better compared to GerdQ (DeLong test, p=0.0008). Salivary pepsin had a comparable diagnostic value to GerdQ (AUC 0.779 versus 0.826; p=0.4199) in acidic GERC. Salivary pepsin had superior diagnostic value compared to GerdQ (AUC 0.830 versus 0.533; p<0.0001) in non-acidic GERC.

Conclusions

A salivary pepsin concentration >76.10 ng·mL-1 is of good diagnostic value for GERC, especially in non-acidic GERC. The pepsin concentration in induced sputum has a low diagnostic value.

Coughing our guts up: how do we diagnose reflux cough?

Should Peptest be routinely used in a cough clinic? The answer is yes, but only as part of more intricate workup in which discovering the nature of the reflux is as important as identifying its presence. https://bit.ly/3QkbChb.

Positive effect of deep diaphragmatic breathing training on gastroesophageal reflux-induced chronic cough: a clinical randomized controlled study

BACKGROUND AND OBJECTIVE

To explore the efficacy of deep diaphragmatic breathing training (DEP) in patients with gastroesophageal reflux-induced chronic cough (GERC).

METHODS

A randomized controlled study was conducted involving 60 GERC patients who were divided into the intervention group and the control group (each with 30 patients). Both groups received routine medication treatment for GERC, while the intervention group received DEP training additionally. Both groups were evaluated by cough symptom scores, Hull airway reflux questionnaire (HARQ), gastroesophageal reflux diagnostic questionnaire (GerdQ), generalized anxiety disorder scale-7 (GAD-7), patient health questionnaire-9 (PHQ-9), Pittsburgh sleep quality index (PSQI), the Leicester cough questionnaire (LCQ), as well as capsaicin cough sensitivity testing, B-ultrasound and surface electromyography (sEMG) of the diaphragmatic muscles before and after treatment. The cough resolution rate and changes of the above indictors was compared between the two groups after eight weeks of treatment.

RESULTS

After eight weeks of treatment, cough symptoms improved in both groups, but the cough resolution rate in the intervention group of 94% was significantly higher than that in the control group of 77% (χ2 = 6.402, P = 0.041). The intervention group showed significant improvements to the control group in GerdQ (6.13(0.35) VS 6.57(0.77)), GAD-7 (0(0;1) VS 1(0;3)), PSQI (2(1;3) VS 4(3;6)), LCQ (17.19(1.56) VS 15.88(1.92)) and PHQ-9 (0(0;0) VS 0(0;3)) after treatment. Compared to control group, sEMG activity of the diaphragmatic muscle was significantly increased in the intervention group after treatment, measured during DEP (79.00(2.49) VS 74.65 (1.93)) and quiet breathing (72.73 (1.96) VS 67.15 (2.48)).

CONCLUSION

DEP training can improve cough symptoms as an adjunctive treatment in GERC patients.

TRIAL REGISTRATION

The protocol was registered in February 2, 2022 via the Chinese Clinical Trials Register ( http://www.chictr.org.cn/ ) [ChiCTR2200056246].

Potassium-Competitive Acid Blocker Versus Proton Pump Inhibitor: A Pilot Study on Comparable Efficacy in the Treatment of Gastroesophageal Reflux-Related Cough

Acid inhibitors have been considered in treating gastroesophageal reflux-related cough (GERC). Compared to proton pump inhibitors (PPIs), potassium-competitive acid blockers (P-CABs) have more potent and durable effects on anti-acid secretion. However, whether vonoprazan and esomeprazole have different therapeutic effects on GERC remains unknown. Patients diagnosed with GERC were enrolled in our study and randomly treated with vonoprazan (20 mg, once daily, P-CAB) or esomeprazole (20 mg, twice daily, PPI) for two months. A prokinetic agent was also administered. Patients were followed up once a month. Cough severity visual analogue scale (VAS) was measured as the primary outcome, while cough symptom score (CSS) and scores for cough-related quality-of-life or reflux-related symptoms were the secondary endpoints. A total of 50 patients completed the study, with 25 patients in each group. P-CAB and PPI groups showed similar decreases in cough severity VAS and CSS scores after the 2-month treatment (all P < 0.001). For quality-of-life, the Leicester Cough Questionnaire (LCQ) score increased significantly from baseline in both groups, but the P-CAB group had greater improvement and a higher LCQ score in month 2 (all P ≤ 0.05). For reflux-related symptoms, the Hull Airway Reflux Questionnaire (HARQ) score declined substantially over time in the P-CAB group, while the reflux symptom index (RSI) score decreased in both groups. The P-CAB group tended to have a lower HARQ (P = 0.051) and RSI (P = 0.069) scores in month 2. In conclusion, vonoprazan may be comparable to esomeprazole in cough symptom relief in GERC during the 2-month treatment period, but possibly provides better gains on classic reflux symptoms and quality-of-life. The long-term efficacy of P-CABs on GERC may be worth further exploration. Trial Registration: Chinese Clinical Trial Registry Identifier: ChiCTR2200067089.

A comparison between a gastroesophageal reflux disease questionnaire-based algorithm and multichannel intraluminal impedance-pH monitoring for the treatment of gastroesophageal reflux-induced chronic cough

BACKGROUND

Empiric therapy with multichannel intraluminal impedance-pH monitoring (MII-pH) has been used for the initial treatment of gastroesophageal reflux-induced chronic cough (GERC). However, an algorithm based on the gastroesophageal reflux disease questionnaire (GerdQ) has the potential to achieve a simple, structured, and effective treatment approach for patients with GERC.

OBJECTIVES

This study compared the efficacy of anti-reflux therapy based on GerdQ (new structured pathway, NSP) with medical treatment after MII-pH examination (ordinary clinical pathway, OCP) in the management of GERC.

DESIGN

For the NSP, we adapted the GerdQ score to establish the basis for a treatment algorithm. For the OCP, treatment was determined using the MII-pH examination results.

METHODS

The non-inferiority (NI) hypothesis was used to evaluate NSP versus OCP.

RESULTS

Overall, the NSP and OCP-based therapeutic algorithms have similar efficacy for GERC [NI analysis: 95% confidence interval (CI), -4.97 to 17.73, p = 0.009; superiority analysis: p = 0.420]. Moreover, the cough symptom scores and cough threshold improved faster in the NSP group than in the OCP group at week 8 (p < 0.05). In the subgroup analyses using the GerdQ and GerdQ impact scale (GIS) scores, patients with low-likelihood GERC (GerdQ < 8) were more likely to benefit from OCP (NI analysis: 95% CI, -19.73 to 18.02, p = 0.213). On the other hand, in patients with high-likelihood and low-reflux impact GERC patients (GerdQ > 8 and GIS < 4), the NSP arm was not inferior to the standard treatment of OCP (NI analysis: 95% CI, -8.85 to 28.21%, p = 0.04; superiority analysis: p = 0.339), indicating that GerdQ- and GIS-guided diagnosis and management of patients with GERC could be an alternative to MII-pH management, especially in settings with reduced medical resources.

CONCLUSIONS

The use of the GerdQ algorithm should be considered when handling patients with GERC in the primary care setting.

TRIAL REGISTRATION

This research was registered in the Chinese Clinical Trials Registry (ChiCTR-ODT-12001899).

Mean Nocturnal Baseline Impedance (MNBI) Provides Evidence for Standardized Management Algorithms of Nonacid Gastroesophageal Reflux-Induced Chronic Cough

BACKGROUND

The clinical management of nonacid gastroesophageal reflux-induced chronic cough (GERC) is challenging, and patient response to standard antireflux therapy (omeprazole 20 mg twice daily plus mosapride 10 mg thrice daily) is suboptimal. This study aimed to identify predictors of standard antireflux therapy efficacy and provide evidence for standardized management algorithms of nonacid GERC.

METHODS

A total of 115 nonacid GERC patients who underwent multichannel intraluminal impedance-pH monitoring (MII-pH) were enrolled between March 2017 and March 2021. Retrospective analysis of general information and MII-pH indications were used to establish a regression analysis model for multiple factors affecting standard antireflux therapy efficacy.

RESULTS

90 patients met the inclusion criteria, and the overall response rate to standard antireflux therapy was 55.5% (50/90). The mean nocturnal baseline impedance (MNBI) (1817.75 ± 259.26 vs. 2369.93 ± 326.35, P = 0.030) and proximal MNBI (1833.39 ± 92.16 vs. 2742.57 ± 204.64, P ≤ 0.001) of responders were lower than those of nonresponders. Weakly acid reflux (56.00 (31.70, 86.00) vs. 14.00 (14.00, 44.20), P = 0.022), nonacid reflux (61.35 (15.90.86.50) vs. 21.60 (0.00, 52.50), P = 0.008), and proximal extent (19.00 (5.04, 24.00) vs. 5.50 (2.56, 11.13), P = 0.011) were markedly higher in responders than nonresponders. Proximal MNBI (OR = 0.997, P = 0.042, and optimal cutoff = 2140 Ω) and weakly acid reflux (OR = 1.051, P = 0.029, and optimal cutoff = 45) were independent predictors of standard antireflux therapy efficacy. The combination predictive value did not show better results than either individual predictor.

CONCLUSIONS

Proximal MNBI < 2140 Ω may be used to screen patients with nonacid GERC suitable for standard antireflux therapy and in standardized management algorithms for nonacid GERC. In the absence of MNBI, weakly acid reflux > 45 can be used as an auxiliary indicator.

Diagnostic value of reflux episodes in gastroesophageal reflux-induced chronic cough: a novel predictive indicator

Background

Multichannel intraluminal impedance and pH-monitoring (MII-pH) is an essential testing modality for gastroesophageal reflux-induced chronic cough (GERC), while the existing diagnostic criteria still have some inherent defects. This study aimed to explore the diagnostic value of a direct and objective index, reflux episodes, and related parameters in MII-pH in different types of GERC.

Methods

Patients with chronic cough suspected of gastroesophageal reflux disease who successfully received MII-pH were enrolled. The differences in MII-pH parameters were analyzed among patients with different etiologies and the predictive diagnostic value of reflux episodes and related parameters were analyzed in patients with GERC, acid GERC, and non-acid GERC, and compared with existing diagnostic criteria.

Results

A total of 190 patients with suspected GERC who underwent MII-pH were enrolled; 131 of these patients were finally diagnosed with GERC. When the reflux episodes were used to diagnose GERC, the area under the curve (AUC) was 0.684; when the acid reflux episodes and the ratio of acid reflux episodes were used to diagnose acid GERC, the AUCs were 0.769 and 0.854; when the non-acid reflux episodes and the ratio of non-acid reflux episodes were used to diagnose non-acid GERC, the AUCs were 0.735 and 0.705, respectively. When the non-acid reflux episodes > 58 and the proportion of non-acid reflux episodes > 68.18% were used alone or in combination to diagnose non-acid GERC, their diagnostic value was significantly better than SAP or SI (all ps < 0.05).

Conclusion

The number of reflux episodes has a good diagnostic value for GERC, especially in the diagnosis of non-acid GERC.

WAO-ARIA consensus on chronic cough - Part III: Management strategies in primary and cough-specialty care. Updates in COVID-19

Background

Chronic cough management necessitates a clear integrated care pathway approach. Primary care physicians initially encounter the majority of chronic cough patients, yet their role in proper management can prove challenging due to limited access to advanced diagnostic testing. A multidisciplinary approach involving otolaryngologists and chest physicians, allergists, and gastroenterologists, among others, is central to the optimal diagnosis and treatment of conditions which underly or worsen cough. These include infectious and inflammatory, upper and lower airway pathologies, or gastro-esophageal reflux. Despite the wide armamentarium of ancillary testing conducted in cough multidisciplinary care, such management can improve cough but seldom resolves it completely. This can be due partly to the limited data on the role of tests (eg, spirometry, exhaled nitric oxide), as well as classical pharmacotherapy conducted in multidisciplinary specialties for chronic cough. Other important factors include presence of multiple concomitant cough trigger mechanisms and the central neuronal complexity of chronic cough. Subsequent management conducted by cough specialists aims at control of cough refractory to prior interventions and includes cough-specific behavioral counseling and pharmacotherapy with neuromodulators, among others. Preliminary data on the role of neuromodulators in a proof-of-concept manner are encouraging but lack strong evidence on efficacy and safety.

Objectives

The World Allergy Organization (WAO)/Allergic Rhinitis and its Impact on Asthma (ARIA) Joint Committee on Chronic Cough reviewed the recent literature on management of chronic cough in primary, multidisciplinary, and cough-specialty care. Knowledge gaps in diagnostic testing, classical and neuromodulator pharmacotherapy, in addition to behavioral therapy of chronic cough were also analyzed.

Outcomes

This third part of the WAO/ARIA consensus on chronic cough suggests a management algorithm of chronic cough in an integrated care pathway approach. Insights into the inherent limitations of multidisciplinary cough diagnostic testing, efficacy and safety of currently available antitussive pharmacotherapy, or the recently recognized behavioral therapy, can significantly improve the standards of care in patients with chronic cough.

Can acid exposure time replace the DeMeester score in the diagnosis of gastroesophageal reflux-induced cough?

Background:

The objective of this study was to compare the predictive accuracy of the acid exposure time (AET) with the DeMeester score (DMS) for gastroesophageal reflux–induced cough (GERC).

Methods:

A total of 277 patients who underwent multichannel intraluminal impedance pH monitoring (MII-pH) were enrolled, and their clinical information and laboratory results were retrospectively analyzed. The diagnostic value of AET for GERC was compared with that of the DMS, symptom association probability (SAP), and symptom index (SI).

Results:

A total of 236 patients met the inclusion criteria, 150 patients (63.65%) were definitely diagnosed with GERC, including 111(74%) acid GERC and 39 (26%) nonacid GERC. The optimal cutoff value of AET for diagnosing GERC was AET > 4.8%, and its diagnostic value was equal to that of DMS > 14.7 (AUC = 0.827 versus 0.818, p = 0.519) and was superior to that of SAP (AUC = 0.827 versus 0.689, p = 0.000) and SI (AUC = 0.827 versus 0.688, p = 0.000). When using both DMS > 14.7 and AET > 4.8% or either of the two for the diagnosis of GERC, the diagnosis rate was not improved over using DMS > 14.7 alone. The diagnostic value of AET and DMS for acid GERC were both high and equivalent (AUC = 0.925 versus 0.922, p = 0.95). The optimal cutoff value of AET for diagnosing acid GERC was AET > 6.2%.

Conclusion:

AET and DMS are both equal in discriminating GERC. A GERC diagnosis should be considered when AET > 4.8%, whereas an acid GERC diagnosis should be considered when AET > 6.2%.

Cough hypersensitivity in patients with metabolic syndrome: a clinical finding and its possible mechanisms

Purpose

To investigate the changes of cough sensitivity in patients with metabolic syndrome and its possible mechanisms.

Method

A total of 29 metabolic syndrome (MetS) patients with OSAHS (group-1), 22 MetS patients without OSAHS (group-2), and 25 healthy controls (group-3) were included. All participants underwent a routine physical examination and completed the gastroesophageal reflux disease questionnaire (GerdQ), and the inflammatory mediator profile were determined. The cough threshold for capsaicin, induced sputum cell count and cell classification, and inflammatory mediators in induced sputum supernatants were compared. The correlation between capsaicin cough sensitivity and various indicators in the MetS population was analyzed.

Results

The minimum concentration of inhaled capsaicin needed to induce ≥ 5 coughs (C5) was significantly different among three groups (H = 14.393, P = 0.001) and lower for group-1 and group-2 than it for group-3 (P = 0.002, P = 0.005). The percentage of neutrophils in induced sputum and the concentrations of calcitonin gene-related peptide (CGRP), substance P (SP), and interleukin 8 (IL-8) in the sputum supernatant of group-1 and group-2 were significantly higher than those of group-3. Besides, the pepsin concentrations were significantly different among the 3 groups (F = 129.362, P < 0.001), which significantly was highest in group-1 (P < 0.001) and lowest in group-3 (P < 0.001). Triglycerides, AHI, pepsin concentration and BMI were risk factors of increased capsaicin cough sensitivity.

Conclusion

Increased capsaicin cough sensitivity in MetS patients is closely related to sleep apnea and gastroesophageal reflux. For patients in MetS patients without OSAHS, gastroesophageal reflux is an important factor for increased capsaicin cough sensitivity. Airway inflammation, especially airway neurogenic inflammation, may also play a role in the pathogenesis of increased capsaicin cough sensitivity.

Trial registration The protocol was registered in the Chinese Clinical Trials Register (http://www.chictr.org.cn/) (ChiCTR1800014768). Written informed consent was obtained from all participants before enrollment.

Pressure and length of the lower esophageal sphincter as predictive indicators of therapeutic efficacy of baclofen for refractory gastroesophageal reflux-induced chronic cough

BACKGROUND

Therapeutic efficacy of baclofen is suboptimal in the treatment of refractory gastroesophageal reflux-induced chronic cough (GERC). The purpose of the study is to identify its therapeutic predictors in a prospective clinical study.

METHODS

138 patients with suspected refractory GERC were treated with baclofen. Before the therapy, all the patients underwent esophageal manometry and multichannel intraluminal impedance-pH monitoring to establish the diagnosis. After the efficacy of baclofen was evaluated, a stepwise logistic regression analysis was performed to identify the therapeutic predictors of baclofen and to establish a regression prediction model.

RESULTS

The overall response rate of baclofen treatment was 52.2% (72/138). The lower esophageal sphincter pressure (LESP) (odds ratio (OR) = 0.592, P = 0.000) and lower esophageal sphincter length (LESL) (OR = 0.144, P = 0.008) were independent predictors of baclofen efficacy. The optimal cut-off point to predict baclofen efficacy for LESP was 11.00 mmHg, with a sensitivity of 83.7% and specificity of 79.1% while that for LESL was 2.35 cm, with a sensitivity of 81.6% and specificity of 72.1%. The highest predictive specificity (90.7%) was achieved when both LESP and LESL were jointly used.

CONCLUSIONS

LESP and LESL may be used to screen the patients with refractory GERC suitable for baclofen therapy and help improve the therapeutic precision.

CLINICAL TRIAL REGISTRATION

ChiCTR- ONC-13003123.

Diagnostic accuracy of multichannel intraluminal impedance-pH monitoring for gastroesophageal reflux-induced chronic cough

OBJECTIVES

To elucidate the accuracy and advantages of Multichannel intraluminal impedance-pH monitoring (MII-pH) in diagnosing gastroesophageal reflux-induced chronic cough (GERC).

METHODS

The patients with suspected GERC were recruited and underwent MII-pH, GERC was confirmed by subsequent anti-reflux treatment despite the findings of MII-pH. Its diagnostic accuracy in identifying GERC were evaluated by receiver operating characteristic (ROC) analysis and compared with that of 24-h esophageal pH monitoring.

RESULTS

Among 158 patients completing both MII-pH and anti-reflux therapy, GERC was diagnosed in 136 patients, including acid GERC in 96 patients (70.6%), non-acid GERC in 30 patients (22.0%), neither one of both GERC in 10 patients (7.4%). For the identification of GERC, MII-pH presented with the sensitivity of 92.6%, specificity of 63.6%, positive predictive value of 94.0%, negative predictive value of 58.3% and area under ROC curve of 0.863, which was totally superior to 24-h esophageal pH monitoring. As the essential criteria of MII-pH, esophageal acid exposure time and symptom associated probability had a limited diagnostic value when used alone, but improved greatly the diagnostic yield when used in combination, even with a suboptimal efficacy.

CONCLUSION

MII-pH is a more sensitive test for identifying GERC, but with a suboptimal diagnostic efficacy.

Gastroesophageal reflux and asthma: when, how, and why

PURPOSE OF REVIEW

Gastro-esophageal reflux is a possible cause of uncontrolled symptoms of asthma and should be actively investigated and treated before severe asthma is diagnosed and biological therapy started.

RECENT FINDINGS

Recent investigations on esophageal function and tissue biomarkers in patients with asthma and associated GERD have established a relevant role for esophageal motility and neuronal sensory abnormalities in linking the two diseases. Characterization of the underpinning inflammatory substrate has showed mixed results as both neutrophilic and eosinophilic type 2 inflammatory changes have been described.

SUMMARY

New findings regarding inflammatory mechanisms in GERD-associated asthma as well as new diagnostic tools to investigate functional esophageal abnormalities and characterize asthma endotype have identified potential treatable traits that may improve the clinical management and outcome of asthmatic patients with GERD.

Sensitivity and specificity of combination of Hull airway reflux questionnaire and gastroesophageal reflux disease questionnaire in identifying patients with gastroesophageal reflux-induced chronic cough

Background

There is a need to find a simple, non-invasive and effective diagnostic tool for diagnosing gastroesophageal reflux-induced chronic cough (GERC) in clinic. This study aimed to evaluate the predictive diagnostic value of Hull airway reflux questionnaire (HARQ) and its combination with gastroesophageal reflux disease questionnaire (GerdQ) for GERC.

Methods

Chronic cough patients were enrolled and the diagnosis of GERC was established according to the chronic cough diagnosis and treatment process. The diagnostic value of HARQ and GerdQ alone or the combination of HARQ and GerdQ was analyzed.

Results

A total of 402 patients with chronic cough were eventually enrolled, including 166 GERC patients. When the HARQ score was used to predict the diagnosis of GERC, the area under the ROC curve was 0.796. The sensitivity and specificity were 77.19% and 77.06%, respectively. When the GerdQ was used to predict the diagnosis of GERC, the area under the ROC curve was 0.763. The sensitivity and specificity were 70.18% and 76.15%, respectively. When HARQ combined with GerdQ were used to predict the diagnosis of GERC, the area under the ROC curve was 0.848. The sensitivity and specificity were 77.19% and 79.82%, respectively.

Conclusions

HARQ used to evaluate the cough hypersensitivity has a certain predictive diagnostic value for GERC. The diagnosis of GERC should be considered when the HARQ score is ≥24. The predictive diagnostic value of the combination of HARQ and GerdQ is significantly higher, which makes the diagnosis of GERC simpler, quicker and more effective.

Clinical outcomes of gastroesophageal reflux disease-related chronic cough following antireflux fundoplication

BACKGROUND

Despite the effectiveness of antireflux fundoplication for typical gastroesophageal reflux disease, outcomes regarding surgical therapy for patients with gastroesophageal reflux disease-related chronic cough are currently unclear. The purpose of this study was to evaluate whether antireflux surgery for patients with chronic cough is effective, and to assess the correlation between indexes, such as symptom index and symptom association probability, and response to surgery.

METHODS

We performed a retrospective review of a prospectively collected database from a 3-site institution from 2013 to 2017. Of 1149 patients who underwent antireflux surgery, 41 presented with chronic cough as a main symptom related to gastroesophageal reflux disease. Preoperatively, patients underwent a symptom assessment, esophagogastroduodenoscopy, esophageal 24-h pH monitoring, and manometry. Patients were followed up at 6 weeks and 12 months post-surgery.

RESULTS

Thirty-three (80.5%) patients underwent Nissen fundoplication, while 8 (19.5%) underwent Toupet fundoplication. Isolated chronic cough was present in 8 (19.5%) patients, and median (range) DeMeester score was 28.9 (0.3-96.7). After 12-month follow-up, chronic cough was absent in 28 (68.3%) patients (P = .02). Typical reflux symptoms responded well to surgery, but response was not optimal. Postoperative dysphagia and atypical reflux symptoms were slightly worse on long-term follow-up; however, differences were not significant (P ≥ .2). When examining how the different symptom indexes correlated with complete, partial, or no response in patients with gastroesophageal reflux disease-related cough, there was no notable agreement on predicted response to surgery.

CONCLUSIONS

Antireflux surgery, although less predictable, is effective for the treatment of gastroesophageal reflux disease-related chronic cough.

Assessing different diagnostic tests for gastroesophageal reflux disease: a systematic review and network meta-analysis

BACKGROUND

The aim of the current systematic review and network meta-analysis (NMA) was to assess the diagnostic characteristics of the gastroesophageal reflux disease questionnaire (GERDQ), proton-pump inhibitor (PPI) test, baseline impedance, mucosal impedance, dilated intercellular spaces (DIS), salivary pepsin, esophageal pH/pH impedance monitoring and endoscopy for gastroesophageal reflux disease (GERD).

METHODS

We searched PubMed and the Cochrane Controlled Trial Register database (from inception to 10 April 2018) for studies assessing the diagnostic characteristics of the GERDQ, PPI test, baseline impedance, mucosal impedance, DIS, or salivary pepsin and esophageal pH/pH impedance monitoring/endoscopy in patients with GERD. Direct pairwise comparison and a NMA using Bayesian methods under random effects were performed. We also assessed the ranking probability.

RESULTS

A total of 40 studies were identified. The NMA found no significant difference among the baseline impedance, mucosal impedance, and esophageal pH/pH impedance monitoring and endoscopy in terms of both sensitivity and specificity. It was also demonstrated that the salivary pepsin detected by the Peptest device had comparable specificity to esophageal pH/pH impedance monitoring and endoscopy. Results of ranking probability indicated that esophageal pH/pH impedance monitoring and endoscopy had highest sensitivity and specificity, followed by mucosal impedance and baseline impedance, whereas GERDQ had the lowest sensitivity and PPI test had the lowest specificity.

CONCLUSIONS

In a systematic review and NMA of studies of patients with GERD, we found that baseline impedance and mucosal impedance have relatively high diagnostic performance, similar to esophageal pH/pH impedance monitoring and endoscopy.

Reflux characteristics in patients with gastroesophageal reflux-related chronic cough complicated by laryngopharyngeal reflux

Background

This study aimed to investigate the reflux characteristics in patients with gastroesophageal reflux-related chronic cough (GERC) complicated by laryngopharyngeal reflux (LPR).

Methods

Patients with chronic cough were recruited. Reflux symptom index (RSI) scoring, cough symptom scoring, assessment of capsaicin cough sensitivity, and multichannel intraluminal impedance and pH monitoring (MII-pH) were performed.

Results

RSI score in GERC patients was significantly higher than that in patients with atopic cough (AC), cough variant asthma, eosinophilic bronchitis (EB), and upper airway cough syndrome (UACS) (P<0.05). The RSI score in non-acid GERC patients was significantly higher than that in acid GERC patients (P=0.003). The cut-off value of the RSI score was defined as 19 during diagnosis of non-acid GERC. In the RSI ≥19 group, there was more proximal reflux and more significant gas and non-acid reflux, and the efficacy of a combined use of baclofen or gabapentin was better than that of the RSI <19 group (P<0.05). The efficacy of proton pump inhibitor (PPI) at a routine dosage together with prokinetic agents in the RSI <19 group was better than that in the RSI ≥19 group (P=0.009).

Conclusions

LPR overlaps with GERC in part. GERC patients with higher RSI scores may present more proximal reflux, non-acid reflux, and gas reflux, and get better efficacy with neuromodulators (gabapentin or baclofen) used as an add-on therapy.

Types and applications of cough-related questionnaires

Cough is a normal protective reflex that can effectively remove foreign bodies and secretions from the airway. However, excessive cough adversely affects a patient's physiological, psychological and social functions. Thus, it is important to effectively evaluate the severity of cough to determine its diagnosis and treatment. Cough severity can be assessed with subjective or objective tools. Herein, we summarize the subjective evaluation of cough severity with questionnaires.

Changing etiological frequency of chronic cough in a tertiary hospital in Shanghai, China

Background

The frequency distributions of the etiologies of chronic cough have changed over time. This study aimed to investigate the changing etiological frequency of chronic cough in a tertiary hospital in Shanghai, China, and to explore the clinical significance.

Methods

Medical records of 1,311 patients with chronic cough who visit our hospital between January 2009 and December 2016 were retrospectively reviewed. The etiologies of chronic cough were identified according to a standardized step-by-step diagnostic protocol and the changes in the etiological frequency of chronic cough over the years were using the Chi-squared (χ²) test.

Results

Cough variant asthma (CVA) (449/1,311, 34.2%), gastroesophageal reflux-related chronic cough (GERC) (374/1,311, 28.5%), upper airway cough syndrome/postnasal drip syndrome (UACS/PNDs) (241/1,311, 18.4%), atopic cough (AC) (188/1,311, 14.3%), and non-asthmatic eosinophilic bronchitis (NAEB) (147/1,311, 11.2%) were the common causes of chronic cough in descending order. The post-infectious cough (PIC) (39/1,311, 3.0%) and angiotensin-converting enzyme inhibitor (ACEI)-induced cough (25/1,311, 1.9%) were less common. During the 8-year period, the proportion of CVA (χ²=72.86, P<0.0001) and UACS/PNDs (χ²=68.80, P<0.0001) decreased, while those of NAEB (χ²=51.38, P<0.0001), GERC (χ²=55.95, P<0.0001) and AC (χ²=39.09, P<0.0001) increased.

Conclusions

The etiological frequency of chronic cough varies over time, and it may encourage the adjustment of the current diagnostic and therapeutic strategies for chronic cough.

The diagnostic value of GerdQ in subjects with atypical symptoms of gastro-esophageal reflux disease

BACKGROUND

Symptoms are essential in the clinical diagnosis of gastro-esophageal reflux disease (GERD). Questionnaires such as GerdQ have been developed as diagnostic aids. GerdQ has been thoroughly validated in well-characterized GERD patients, but has not yet been fully evaluated in a population that includes subjects with atypical symptoms.

AIM

To evaluate GerdQ in a population with typical and/or atypical symptoms of GERD, defined by 24-h pH monitoring. The secondary aim was to investigate the outcome of GerdQ depending on the response to proton pump inhibitor (PPI) treatment.

METHODS

The study included 646 subjects referred for 24-h pH monitoring due to a clinical suspicion of GERD. All subjects completed GerdQ before performing a 24-h pH monitoring.

RESULTS

In total, 377 (58%) subjects were diagnosed with GERD based on symptoms and 24-h pH monitoring (GERD_pH). Of these, 46% had atypical main symptoms. Overall, GerdQ (at cut-off 8) predicted GERD_pH with a sensitivity and specificity of 62% and 74%, respectively. A high specificity but poor sensitivity for diagnosis of GERD_pH was found for atypical main symptoms such as cough, dysphagia and globus. GerdQ had a relatively high sensitivity and specificity in predicting PPI response and a PPV of 99% at cut-off 8.

CONCLUSIONS

GerdQ has a diagnostic value in an unselected population presenting with typical and/or atypical symptoms of GERD, but a low sensitivity for diagnosis of GERD_pH was found in subjects with predominant symptoms such as cough, dysphagia and globus.

Randomised clinical trial: gabapentin vs baclofen in the treatment of suspected refractory gastro-oesophageal reflux-induced chronic cough

BACKGROUND

Neuromodulators are considered potential therapeutic options for refractory gastro-oesophageal reflux-induced chronic cough.

AIM

To compare the efficacy of gabapentin and baclofen in patients with suspected refractory gastro-oesophageal reflux-induced chronic cough.

METHODS

Two hundred and thirty-four patients with suspected refractory gastro-oesophageal reflux-induced chronic cough, who failed an 8-week course of omeprazole and domperidone, were recruited into the open-labelled study and randomly assigned to receive either gabapentin (maximum daily dose of 900 mg) or baclofen (maximum daily dose of 60 mg) for 8 weeks as add-on therapy to the previous treatment. The primary end point was the successful rate of cough resolution; and the secondary end-points included cough sensitivity to capsaicin and gastro-oesophageal reflux disease questionnaire score and reported side effects.

RESULTS

One hundred and eleven patients in the gabapentin group and 106 in the baclofen group completed the study. The overall success rate for cough resolution was comparable (57.3% vs 53.0%, χ²  = 0.357, P = 0.550) between the two groups. In parallel, cough sensitivity to capsaicin and gastro-oesophageal reflux disease questionnaire score decreased after treatment with either gabapentin or baclofen. However, gabapentin was associated with less frequent somnolence (20.5% vs 35.0%, χ²  = 6.156, P = 0.013) and dizziness (11.1% vs 23.9%, χ²  = 6.654, P = 0.010) than baclofen.

CONCLUSIONS

Gabapentin and baclofen have similar therapeutic efficacy for suspected refractory gastro-oesophageal reflux-induced chronic cough. However, gabapentin may be preferable because of fewer side effects. Trial Register: http://www.chictr.org/; No.: ChiCTR-ONC-13003066.

Surgical Treatment of Extraesophageal Manifestations of Gastroesophageal Reflux Disease

OBJECTIVE

To review the current literature on the role of antireflux surgery (ARS) for the treatment of extraesophageal manifestations of GERD. The extraesophageal manifestations of gastroesophageal reflux disease (GERD) include chronic cough, laryngopharyngeal reflux, and asthma. They are responsible for significant morbidity in affected patients and a high economic burden on healthcare resources. We recently published a larger review on the symptoms, diagnosis, medical, and surgical treatment of the extraesophageal manifestations of GERD. Through our investigation, we found that the role of ARS for respiratory symptoms was unclear. Hence, we resorted through the data of our previous meta-analysis to compile a comprehensive and focused review on the role of ARS for respiratory symptoms.

METHODS

Using the archive of our previous meta-analysis, we selected studies extracted from the MEDLINE, Cochran, PubMed, Google Scholar, and Embase databases pertaining to the surgical treatment of extraesophageal manifestations of reflux (cough laryngopharyngeal reflux, and asthma). We applied a similar reporting methodology as was used in our previous manuscript and then hand searched the bibliographies of included studies yielding a total of 27 articles for review. We graded the level of evidence and classified recommendations by size of treatment effect per the American Heart Association Task Force on Practice Guidelines.

RESULTS

Observational data indicated that syndromes of chronic cough, laryngopharyngeal reflux and asthma might improve after antireflux surgery only in highly selected patients-likely those with non-acid reflux-while those patients with objective markers of asthma severity do not. Because of the varied methods of diagnosis and surgical technique, non-comparative observational data may be unreliable. Additionally, our search found no randomized controlled trials (RCTs) comparing antireflux surgery to medical therapy in the treatment of cough or laryngopharyngeal reflux. One RCT compared medical treatment to antireflux surgery in patients with asthma, but medical treatment included high-dose H₂ blockers instead of PPIs.

CONCLUSIONS

Extraesophageal manifestations of GERD are common, costly, and difficult to treat. ARS might be effective in highly selected patients, especially in those whose extraesophageal manifestations are caused by non-acid reflux. The available data to date are generally of poor quality or outdated. Well-designed randomized controlled trials or large-scale observational cohort studies are urgently needed.

Association of cough hypersensitivity with tracheal TRPV1 activation and neurogenic inflammation in a novel guinea pig model of citric acid-induced chronic cough

Objective

This study was performed to establish a novel model of citric acid-induced chronic cough in guinea pigs and to investigate the pathogenesis of cough hypersensitivity.

Methods

Healthy conscious guinea pigs inhaled citric acid (0.4 M) for 3 minutes twice daily for 25 days. Cough reactivity was evaluated, substance P (SP) and calcitonin gene-related peptide (CGRP) in bronchoalveolar lavage fluid were detected, and transient receptor potential cation channel subfamily V member 1 (TRPV1) protein expression in the trachea and bronchus was determined. Tracheal and bronchial tissues were examined for TRPV1.

Results

Inhalation of 0.4 M citric acid increased coughing in a time-dependent manner: coughing peaked at 15 days and reached the lowest level at 25 days. This was accompanied by similar changes in SP, CGRP, and TRPV1 protein expression. TRPV1 was mainly observed in the mucosal and submucosal layer of the trachea and bronchi. The areas of TRPV1 positivity in the trachea and bronchi of citric acid-treated animals were significantly larger than in the control group.

Conclusions

Repeated inhalation of citric acid can be employed to establish a chronic cough model in guinea pigs. Cough hypersensitivity in this model is related to tracheal TRPV1 activation and neurogenic inflammation.

Efficacy of sequential three-step empirical therapy for chronic cough

Background:

Empirical three-step therapy has been proved in just one hospital. This study aimed to demonstrate applicability of the sequential empirical three-step therapy for chronic cough in different clinical settings.

Methods:

Sequential empirical three-step therapy was given to patients with chronic cough in one tertiary and three secondary care respiratory clinics. Recruiters were initially treated with methoxyphenamine compound as the first-step therapy, followed by corticosteroids as the second-step therapy and the combination of a proton-pump inhibitor and a prokinetic agent as the third-step therapy. The efficacy of the therapy was verified according to the changes in cough symptom score between pre- and post-treatment, and compared among the different clinics.

Results:

In total 155 patients in one tertiary clinic and 193 patients in secondary care clinics were recruited. The total dropout ratio is significantly higher in the secondary care clinics than that in the tertiary clinic (9.3% versus 3.2%, p = 0.023). The therapeutic success rate for cough was 38.7% at first-step therapy, 32.3% at second-step therapy and 20.0% at third-step therapy in the tertiary clinic, and comparable to corresponding 49.7%, 31.1% and 4.1% in secondary care clinics. Furthermore, the overall cough resolution rate was not significantly different (91.0% versus 85.0%, p = 0.091). However, the efficacy of the third-step therapy is much higher (20.0% versus 4.1%, p = 0.001) in the tertiary clinic than in the secondary care clinics.

Conclusions:

Sequential empirical three-step therapy is universally efficacious and useful for management of chronic cough in different clinical settings.

Cough hypersensitivity in patients with obstructive sleep apnea hypopnea syndrome

PURPOSE

The purpose of this study was to investigate cough hypersensitivity and its potential mechanisms in patients with obstructive sleep apnea hypopnea syndrome (OSAHS).

METHODS

Fifteen OSAHS patients, 12 simple snoring patients, and 15 healthy volunteers received cough sensitivity test and induced sputum cytology. Cough thresholds C2 and C5 (the minimum of capsaicin inducing ≥ 2 and ≥ 5 coughs, respectively), total cell count, cell differentials and the levels of bradykinin, histamine, prostaglandin E₂, substance P, calcitonin gene-related peptide, pepsin, and interleukin-2 in the induced sputum detected by enzyme-linked immunosorbent assay were compared. The linear correlation between lgC2 and lgC5 and apnea hypopnea index, cell differentials, and inflammatory mediators in the induced sputum was calculated in OSAHS patients.

RESULTS

OSAHS patients presented with a significant lower C2 and C5 (P < 0.01), increased lymphocyte but decreased macrophage and neutrophil proportions in the induced sputum (P < 0.01), and higher contents of substance P, calcitonin gene-related peptide and interleukin-2 (P < 0.01) but similar levels of bradykinin, pepsin, prostaglandin E₂, and histamine (P > 0.05) in the supernatant of induced sputum, when compared with simple snoring patients and healthy volunteers. However, theses variable were comparable between simple snoring patients and healthy volunteers (P > 0.05). Finally, lgC2 or lgC5 was negatively related to apnea hypopnea index, lymphocyte percentage, and the levels of substance P, calcitonin gene-related peptide or interleukin-2 in the sputum (P < 0.01). There was a positive linear correlation between lymphocyte percentage and interleukin-2 level in the induced sputum (r = 0.63, P = 0.00).

CONCLUSION

OSAHS patients have a predisposition of cough hypersensitivity associated with airway inflammation.

Study on the Therapeutic Effects of Drug and Cognitive-Behavioral Therapy on Non-Erosive Reflux Disease Patients With Emotional Disorders

OBJECTIVE

To assess the correlation between the incidence of non-erosive reflux disease (NERD) and mental and psychological factors, deepen the understanding of the pathogenesis of NERD and explore effective treatments.

METHODS

NERD patients with mood disorders who met the inclusion criteria were randomly divided into a drug treatment group, a psychotherapy group, and a psychotherapy combined with drug treatment group. Before and after treatment, the patients were retrospectively analyzed using the gastroesophageal reflux disease Questionnaire, Hamilton Depression Scale, Hamilton Anxiety Scale, and SF-36 Quality of Life Scale.

RESULTS

All three treatments were found to relieve patients' symptoms and improve their quality of life to some extent. The psychotherapy combined with drug treatment group showed the best overall curative effect. The Hamilton Depression and Anxiety Scale scores were significantly lower in the psychotherapy-alone group and psychotherapy combined with drug treatment group than in the drug treatment alone group at 4, 8, and 12 weeks (P < 0.05).

CONCLUSION

Medication, psychotherapy, and psychotherapy combined with medication can relieve clinical symptoms and improve quality of life to varying degrees in patients with NERD.

Diagnosis and Treatment of the Extraesophageal Manifestations of Gastroesophageal Reflux Disease

OBJECTIVE

To review the clinical presentation, diagnosis, and treatment options available for management of extraesophageal manifestations of gastroesophageal reflux disease (GERD) and to compare the most recent technological advances to the existing guidelines.

SUMMARY BACKGROUND DATA

Extraesophageal manifestations of GERD include cough, laryngopharyngeal reflux (LPR), and asthma. Recent advances in diagnostic modalities may have outpaced the existing diagnostic and therapeutic clinical guidelines.

METHODS

We searched the MEDLINE, Cochrane, and Embase databases for articles pertaining to the presentation, diagnosis, and treatment of extraesophageal manifestations of reflux, specifically cough due to reflux, LPR, and asthma due to reflux. Search terms applied to 3 thematic topics: diagnosis, medical treatment, and surgical treatment. We had searched the bibliographies of included studies, yielding a total of 271 articles for full review. We graded the level of evidence and classified recommendations by size of treatment effect, according to the guidelines from the American Heart Association Task Force on Practice Guidelines.

RESULTS

One hundred twenty-eight articles met criteria for analysis. Our findings show that the diagnosis of cough, LPR, or asthma due to gastroesophageal reflux is difficult, as no criterion standard test exits. Also, patients often present without heartburn or regurgitation typical of GERD. Combined multichannel intraluminal impedance, the pH (MII-pH) monitoring system, and the symptom association probability (SAP) test might distinguish extraesophageal manifestations of reflux from idiopathic chronic cough, laryngitis due to other causes, and atopic asthma. In addition, extraesophageal manifestations of reflux are most effectively diagnosed with a stepwise approach incorporating empiric treatment and antisecretory therapy, combined MII-pH monitoring, and surgical intervention in few selected cases.

CONCLUSIONS

Recent studies demonstrate the potential diagnostic role of MII-pH monitoring. Surgical intervention provides resolution of extraesophageal symptoms less reliably than typical symptoms when the patient has GERD.

A stepwise protocol for the treatment of refractory gastroesophageal reflux-induced chronic cough

BACKGROUND

Refractory gastroesophageal reflux-induced chronic cough (GERC) is difficult to manage. The purpose of the study is to evaluate the efficacy of a novel stepwise protocol for treating this condition.

METHODS

A total of 103 consecutive patients with suspected refractory reflux-induced chronic cough failing to a standard anti-reflux therapy were treated with a stepwise therapy. Treatment commences with high-dose omeprazole and, if necessary, is escalated to subsequent sequential treatment with ranitidine and finally baclofen. The primary end-point was overall cough resolution, and the secondary end-point was cough resolution after each treatment step.

RESULTS

High-dose omeprazole eliminated or improved cough in 28.1% of patients (n=29). Further stepwise of treatment with the addition of ranitide yielded a favorable response in an additional 12.6% (n=13) of patients, and subsequent escalation to baclofen provoked response in another 36.9% (n=38) of patients. Overall, this stepwise protocol was successful in 77.6% (n=80) of patients. The diurnal cough symptom score fell from 3 [1] to 1 [0] (Z=6.316, P=0.000), and the nocturnal cough symptom score decreased from 1 [1] to 0 [1] (Z=-4.511, P=0.000), with a corresponding reduction in the Gastroesophageal Reflux Diagnostic Questionnaire score from 8.6±1.7 to 6.8±0.7 (t=3.612, P=0.000). Conversely, the cough threshold C2 to capsaicin was increased from 0.49 (0.49) µmol/L to 1.95 (2.92) µmol/L (Z=-5.892, P=0.000), and the cough threshold C5 was increased from 1.95 (2.92) µmol/L to 7.8 (5.85) µmol/L (Z=-5.171, P=0.000).

CONCLUSIONS

Sequential stepwise anti-reflux therapy is a useful therapeutic strategy for refractory reflux-induced chronic cough.

The Clinical Value of Deflation Cough in Chronic Coughers With Reflux Symptoms

BACKGROUND

Patients with deflation cough (DC), the cough-like expulsive effort(s) evoked by maximal lung emptying during a slow vital capacity maneuver, also present symptoms of gastroesophageal reflux. DC can be inhibited by prior intake of antacids. We wished to assess DC prevalence and association between DC and chemical characteristics of refluxate in patients with gastroesophageal reflux symptoms.

METHODS

A total of 157 consecutive outpatients underwent DC assessment and 24-h multichannel intraluminal impedance pH (MII-pH) monitoring; 93/157 also had chronic cough. Patients performed two to four slow vital capacity maneuvers and DC was detected aurally. Subsequently, they underwent 24-h MII-pH monitoring, the outcomes of which were defined as abnormal when acid or non-acid reflux events were > 73.

RESULTS

DC occurred in 46/157 patients, 18 of whom had abnormal MII-pH outcomes; 28 of the remaining 111 patients without DC also had abnormal MII-pH findings. Thus, in the patients as a group, there was no association between DC and MII-pH outcomes. DC occurred in 40/93 of the chronic coughers; 15 of whom had acid reflux. All but 2 of the 53 patients without DC had normal MII-pH outcomes (P < .001), and the negative predictive value of DC for excluding acid reflux was 96.2%. At follow-up, 65% of coughers showed significant improvement after treatment.

CONCLUSIONS

The overall prevalence of DC was 29%, increasing to 43% in chronic coughers in whom the absence of DC virtually excludes acid reflux. Therefore, DC assessment may represent a useful screening test for excluding acid reflux in chronic coughers with reflux symptoms.

Diagnosis and treatment of patients with nonacid gastroesophageal reflux-induced chronic cough

Gastroesophageal reflux (GER) is one of the most common causes of chronic cough, and chronic cough due to GER represents a subtype of GER-related diseases. Gastroesophageal reflux-induced chronic cough (GERC) can be divided into two subgroups based on the pH of the GER. Nonacid GERC is less common than acid GERC, and its diagnosis and treatment strategy have not been standardized. However, nonacid GERC usually presents with its unique set of characteristics and features upon diagnosis and treatment in the clinic. Although the underlying molecular mechanism of nonacid GERC is not fully understood, it is considered to be associated with reflux theory, reflex theory and airway hypersensitivity. Multi-channel intraluminal impedance combined with pH monitoring is a promising new technique that can detect both acid and nonacid reflux, and our findings as well as those of others have shown its usefulness in diagnosing nonacid GERC. Development of new diagnostic techniques has led to an increased rate of nonacid GERC diagnosis. We summarize our experience in the diagnosis and treatment of nonacid GERC and provide a guide for future therapeutic approaches.

Refractory chronic cough due to gastroesophageal reflux: Definition, mechanism and management

Refractory chronic cough due to gastroesophageal reflux is a troublesome condition unresponsive to the standard medical anti-reflux therapy. Its underlying mechanisms may include incomplete acid suppression, non-acid reflux, transient lower esophageal sphincter relaxations and esophageal hypersensitivity. The diagnosis of this disorder depends on both the findings of multi-channel intraluminal impedance-pH monitoring and the subsequent intensified anti-reflux therapy. The strategies of pharmacological treatment for refractory chronic cough due to reflux include the optimization of proton pump inhibitors and add-on therapies with histamine H₂ receptor antagonists, baclofen and gabapentin. However, the further study is needed to satisfy its management.