Sham CPAP vs. Straight CPAP for Chronic Cough

Not Applicable

Completed

Conditions: Chronic Cough
OSA

Registration Number: NCT03172130

Lead Sponsor: Krishna M. Sundar

Brief Summary: 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.

Detailed Description: Not available

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 22

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

Study & Design

Study Type: INTERVENTIONAL

Study Design: PARALLEL

Primary Outcome Measures

Name	Time	Method
Change in Leicester Cough Questionnaire Score	Baseline and 6 weeks	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

Secondary Outcome Measures

Name	Time	Method
Interleukin-8 (IL-8) Level in Exhaled Breath Condensate	Baseline and 6 weeks	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
Change in Cough Frequency	Baseline and 6 weeks	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
8 Isoprostane Level in Exhaled Breath Condensate	Baseline and 6 weeks	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
Hydrogen Peroxide (H2O2) Level in Exhaled Breath Condensate	Baseline and 6 weeks	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
Change in Gastroesophageal Reflux Disease Quality of Life (GERD-QoL) Questionnaire Score	Baseline and 6 weeks	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
Change in Leukotriene B4 (LTB4) Level in Exhaled Breath Condensate	Baseline and 6 weeks	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
Nitrite/Nitrate (NOX) Level in Exhaled Breath Condensate	Baseline and 6 weeks	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.