The Effect of a Proton-pump Inhibitor in Unexplained Chronic Cough Patients

Gastro-oesophageal reflux treatment for prolonged non-specific cough in children and adults

BACKGROUND

Gastroesophageal reflux disease (GORD) is said to be the causative factor in up to 41% of adults with chronic cough. Treatment for GORD includes conservative measures (diet manipulation), pharmaceutical therapy (motility or prokinetic agents, H(2)-antagonist and proton pump inhibitors (PPI)) and fundoplication.

OBJECTIVES

To evaluate the efficacy of GORD treatment on chronic cough in children and adults with GORD and prolonged cough that is not related to an underlying respiratory disease, i.e. non-specific chronic cough.

SEARCH STRATEGY

We searched the Cochrane Airways Group Specialised Register, the Cochrane Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, review articles and reference lists of relevant articles. The date of last search was 8 April 2010.

SELECTION CRITERIA

All randomised controlled trials (RCTs) on GORD treatment for cough in children and adults without primary lung disease.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. We contacted study authors for further information.

MAIN RESULTS

We included 19 studies (six paediatric, 13 adults). None of the paediatric studies could be combined for meta-analysis. A single RCT in infants found that PPI (compared to placebo) was not efficacious for cough outcomes (favouring placebo OR 1.61; 95% CI 0.57 to 4.55) but those on PPI had significantly increased adverse events (OR 5.56; 95% CI 1.18 to 26.25) (number needed to treat for harm in four weeks was 11 (95% CI 3 to 232)). In adults, analysis of H(2) antagonist, motility agents and conservative treatment for GORD was not possible (lack of data) and there were no controlled studies of fundoplication. We analysed nine adult studies comparing PPI (two to three months) to placebo for various outcomes in the meta-analysis. Using intention-to-treat, pooled data from studies resulted in no significant difference between treatment and placebo in total resolution of cough (OR 0.46; 95% CI 0.19 to 1.15). Pooled data revealed no overall significant improvement in cough outcomes (end of trial or change in cough scores). We only found significant differences in sensitivity analyses. We found a significant improvement in change of cough scores at end of intervention (two to three months) in those receiving PPI (standardised mean difference -0.41; 95% CI -0.75 to -0.07) using generic inverse variance analysis on cross-over trials. Two studies reported improvement in cough after five days to two weeks of treatment.

AUTHORS' CONCLUSIONS

PPI is not efficacious for cough associated with GORD symptoms in very young children (including infants) and should not be used for cough outcomes. There is insufficient data in older children to draw any valid conclusions. In adults, there is insufficient evidence to conclude definitely that GORD treatment with PPI is universally beneficial for cough associated with GORD. Clinicians should be cognisant of the period (natural resolution with time) and placebo effect in studies that utilise cough as an outcome measure. Future paediatric and adult studies should be double-blind, randomised controlled and parallel-design, using treatments for at least two months, with validated subjective and objective cough outcomes and include ascertainment of time to respond as well as assessment of acid and/or non-acid reflux.

Gastro-oesophageal reflux treatment for prolonged non-specific cough in children and adults

BACKGROUND

Cough is a very common symptom presenting to medical practitioners. Gastroesophageal reflux disease (GORD) is said to be the causative factor in up to 41% of adults with chronic cough. However cough and GORD are common ailments and their co-existence by chance is high. Also cough can induce reflux episodes. Treatment for GORD includes conservative measures (diet manipulation), pharmaceutical therapy (motility or prokinetic agents, H(2) antagonist and proton pump inhibitors (PPI)) and fundoplication.

OBJECTIVES

To evaluate the efficacy of GORD treatment on chronic cough in children and adults with GORD and prolonged cough that is not related to an underlying respiratory disease i.e. non-specific chronic cough.

SEARCH STRATEGY

The Cochrane Register of Controlled Trials (CENTRAL), the Cochrane Airways Group Specialised Register Collaboration and Cochrane Airways Group, MEDLINE and EMBASE databases, review articles and reference lists of relevant articles were searched. The date of last search was 7th April 2006.

SELECTION CRITERIA

All randomised controlled trials on GORD treatment for cough in children and adults without primary lung disease.

DATA COLLECTION AND ANALYSIS

Results of searches were reviewed against pre-determined criteria for inclusion. Two independent reviewers selected, extracted and assessed data for inclusion. Authors were contacted for further information. Data was analysed as "intention to treat" as well as "treatment received". Paediatric and adults data were considered separately. Sensitivity analyses were performed.

MAIN RESULTS

Thirteen studies (3 paediatric, 10 adults) were included. Data from six were available for analysis. None of the paediatric studies could be included in meta-analysis. In adults, analysis on use of H(2) antagonist, motility agents and conservative treatment for GORD were not possible (from lack of data) and there were no controlled studies on fundoplication as an intervention. Six adult studies comparing PPI (2-3 months) to placebo were analysed for various outcomes in the meta-analysis. Enrolment of subjects for two studies were primarily from medical clinics and another 4 studies were otolaryngology clinic patients or patients with laryngitis. Using "intention to treat", pooled data from 4 studies resulted in no significant difference between treatment and placebo in total resolution of cough, Odds Ratio 0.46 (95% CI 0.19 to 1.15). Pooled data revealed no overall significant improvement in cough outcomes (end of trial or change in cough scores). Significant differences were only found in sensitivity analyses. A significant improvement in change of cough scores was found in end of intervention (2-3 months) in those receiving PPI with a standardised mean difference of -0.41 (95%CI -0.75, -0.07) using GIV analysis on cross over trials. Two studies reported improvement in cough after 5 days to 2 weeks of treatment.

AUTHORS' CONCLUSIONS

There is insufficient evidence to definitely conclude that GORD treatment with PPI is universally beneficial for cough associated with GORD in adults. The beneficial effect was only seen in sub-analysis and its effect was small. The optimal duration of such a trial of therapy to evaluate response could not be ascertained in the meta-analysis although two RCTs reported significant change by 2 weeks of therapy. Clinicians should be cognisant of a period (natural resolution with time) and placebo effect in studies that utilise cough as an outcome measure. Data in children are inconclusive. Future paediatric and adult studies are needed whereby studies should be double blind, randomised controlled, parallel design, using treatments for at least two months, with validated subjective and objective cough outcomes and include ascertainment of time to respond as well as assessment of acid and/or non acid reflux whilst on therapy.