Sham CPAP vs. Straight CPAP for Chronic Cough

Study Overview
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Brief Summary
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Chronic cough is an important clinical problem in primary care and sub-specialty practice. Besides the distress experienced by patients with chronic cough, significant healthcare resources are expended to understand the role of gastroesophageal reflux, asthma and post-nasal drip in understanding their contribution to cough. Obstructive sleep apnea (OSA) is common in patients with chronic cough. More importantly, treatment of OSA with continuous positive airway pressure (CPAP) has led to improvement in cough for chronic cough patients. Mechanisms by which OSA therapy with CPAP can improve cough includes beneficial effects on reflux and airway inflammation. The aim of this study is to definitively establish that CPAP therapy for treatment of OSA in chronic cough patients improves cough. While these patients with chronic cough are not routinely screened and treated for OSA, this study aims to evaluate these chronic cough patients with screening questionnaires for OSA and if necessary with polysomnography and randomize them to either CPAP or sham CPAP for 6 weeks.

Official Title
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Prospective Study of Efficacy of Sham CPAP vs. Straight CPAP on Cough Intensity in Patients With Chronic Cough

Conditions
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Chronic Cough, OSA

Intervention / Treatment
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* Device: Straight CPAP
* Device: Sham CPAP


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Cough of more than 2 month duration Not active smoker with history of stoppage of smoking for more than 6 months Evaluation and treatment by other providers for suspected gastroesophageal reflux disease (GERD), upper airway cough syndrome (UACS), or cough-variant asthma (CVA) for at least 1 month Normal chest radiography or computed tomography (CT) scans (patients with up to 2 lung nodules less than 3 mm will be allowed if there is no history of malignancy elsewhere) Normal spirometry with predicted diffusing capacity of the lung for carbon dioxide (DLCO) more than 50% predicted. Pulmonary Function Test criteria: no evidence of airflow limitation (FEV1/FVC > 0.7) or significant chest restriction (FVC > 70% predicted) with predicted DLCO more than 50% predicted Exclusion Criteria: Pregnancy Recent pneumonia (less than 6 months) Congestive heart failure, acute or chronic renal disease, jaundice or chronic liver disease, pulmonary embolism, stroke or neurodegenerative disease, malignancy Use of supplemental oxygen or positive airway pressure therapy (if patients have been diagnosed with obstructive sleep apnea in the past but were non-compliant with positive airway pressure therapy, they will not be excluded) Use of opiates for cough suppression (opiate use for pain suppression can be included) Alcoholism, drug dependence (including chewing tobacco) or illicit drug use Esophageal cancer or laryngeal surgery Craniofacial abnormalities that preclude CPAP placement

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Straight CPAP<br>Patients randomized to straight CPAP will receive 10 cm of air pressure, or as determined by the results of polysomnography, for 6 weeks. Following the 6-week visit, patients will be placed on straight CPAP with equipment approved by insurance for an additional 6 weeks. | Device: Straight CPAP<br> <br> |
| Sham Comparator: Sham CPAP<br>Patients randomized to sham CPAP will receive 1-2 cm of air pressure for 6 weeks. Following the 6-week visit, patients will be placed on straight CPAP with equipment approved by insurance for an additional 6 weeks. | Device: Sham CPAP<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Leicester Cough Questionnaire Score | Subjects will complete the Leicester Cough Questionnaire at the baseline and 6-week visits. The Leicester Cough Questionnaire comprises 19 items, which assess symptoms, or the impact of symptoms, over the last 2 weeks on a seven-point Likert scale. Scores in three domains (physical, psychological and social) are calculated as a mean for each domain (range 1 to 7). A total score (range 3 to 21) is also calculated by adding the domain scores together. Higher scores indicate better quality of life. The change in Leicester Cough Questionnaire score will be compared between the Straight CPAP and Sham CPAP groups | Baseline and 6 weeks | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Cough Frequency | Subjects will wear a Leicester cough monitor for 24 hours at the baseline and 6-week visits, which will record cough frequency during that period. The change in cough frequency from baseline to 6 weeks will be compared between the Straight CPAP and SHAM CPAP groups | Baseline and 6 weeks | 
| 8 Isoprostane Level in Exhaled Breath Condensate | Samples of breath condensate will be collected from study subjects at the baseline and 6-week visits. The 8 isoprostane level from baseline to 6-weeks will be compared between the Straight CPAP and Sham CPAP groups | Baseline and 6 weeks | 
| Interleukin-8 (IL-8) Level in Exhaled Breath Condensate | Samples of breath condensate will be collected from study subjects at the baseline and 6-week visits. IL-6 level from baseline to 6-weeks will be compared between the Straight CPAP and Sham CPAP groups | Baseline and 6 weeks | 
| Nitrite/Nitrate (NOX) Level in Exhaled Breath Condensate | Samples of breath condensate will be collected from study subjects at the baseline and 6-week visits. NOX level from baseline to 6-weeks will be compared between the Straight CPAP and Sham CPAP groups. | Baseline and 6 weeks | 
| Hydrogen Peroxide (H2O2) Level in Exhaled Breath Condensate | Samples of breath condensate will be collected from study subjects at the baseline and 6-week visits. H2O2 level from baseline to 6-weeks will be compared between the Straight CPAP and Sham CPAP groups | Baseline and 6 weeks | 
| Change in Leukotriene B4 (LTB4) Level in Exhaled Breath Condensate | Samples of breath condensate will be collected from study subjects at the baseline and 6-week visits. The change in LTB4 level from baseline to 6-weeks will be compared between the Straight CPAP and Sham CPAP groups | Baseline and 6 weeks | 
| Change in Gastroesophageal Reflux Disease Quality of Life (GERD-QoL) Questionnaire Score | Subjects will complete the GERD-QoL questionnaire at the baseline and 6-week visits. The GERD-QoL comprises 15 items on a five-point Likert scale; lowest possible score (0) = no symptoms, greatest possible score (75) = worst symptoms. The change in GERD-QoL score will be compared between the Straight CPAP and Sham CPAP groups | Baseline and 6 weeks | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Obstructive Sleep Apnea, CPAP