Sham CPAP vs. Straight CPAP for Chronic Cough

Krishna M. Sundar22 enrolled

Overview

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.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

DOUBLE

Enrollment

Conditions

Chronic Cough OSA

Eligibility

Sex: ALLMin age: 18 YearsMax age: 80 Years

Medical Language ↔ Plain English

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

Outcomes

Primary Outcomes

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