Phenotyping patients with chronic cough presenting to a specialist clinic

Introduction: Chronic cough is a common complaint, accounting for one third of all referrals to chest physicians. National and international guidelines exist for treatment and investigation, despite this, in upto 42% of patients, no cause for cough is found. Whether this represents undiagnosed pathology, inadequate treatment or 'idiopathic cough' is unclear. Gastro-oesophageal reflux is reported as a common cause of chronic cough but the exact mechanism by which this occurs is unclear. Both direct cough receptor stimulation (microaspiration and LPR), and indirect stimulation (an oesophago-tracheo-bronchial reflex) have been proposed. Methods: 100 chronic cough patients have been comprehensively investigated, incorporating routine bronchoscopy and oesophageal impedance/pH into the diagnostic algorithm. Cough has been evaluated, both before and after treatment, by subjective assessment and objective cough sound monitoring. Results: Subjective assessment of cough was found to be affected by patient anxiety and depression and related only moderately to cough frequency.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

PCR based bronchoscopic detection of common respiratory pathogens in chronic cough: a case control study

BACKGROUND: Viral respiratory tract infection is the most frequent cause of acute cough and is reported at onset in about one third of patients with chronic cough. Persistent infection is therefore one possible explanation for the cough reflex hypersensitivity and pulmonary inflammation reported in chronic cough patients. METHODS: Bronchoscopic endobronchial biopsies and bronchoalveolar lavage cell counts were obtained from ten healthy volunteers and twenty treatment resistant chronic cough patients (10 selected for lavage lymphocytosis). A screen for known respiratory pathogens was performed on biopsy tissue. Chronic cough patients also underwent cough reflex sensitivity testing using citric acid. RESULTS: There was no significant difference in incidence of infection between healthy volunteers and chronic cough patients (p = 0.115) or non-lymphocytic and lymphocytic groups (p = 0.404). BAL cell percentages were not significantly different between healthy volunteers and chronic cough patients without lymphocytosis. Lymphocytic patients however had a significantly raised percentage of lymphocytes (p < 0.01), neutrophils (p < 0.05), eosinophils (p < 0.05) and decreased macrophages (p < 0.001) verses healthy volunteers. There was no significant difference in the cough reflex sensitivity between non-lymphocytic and lymphocytic patients (p = 0.536). CONCLUSIONS: This study indicates latent infection in the lung is unlikely to play an important role in chronic cough, but a role for undetected or undetectable pathogens in either the lung or a distal site could not be ruled out. TRIALS REGISTRATION: Current Controlled Trials ISRCTN62337037 & ISRCTN4014720