ARE ASTHMA-LIKE SYMPTOMS DUE TO BRONCHIAL OR EXTRATHORACIC AIRWAY DYSFUNCTION

Patients with asthma-like symptoms may not have asthma but obstruction of the extrathoracic airway (EA). To evaluate if dysfunction of the E A causes asthma-like symptoms, we assessed bronchial and EA responsive ness to inhaled histamine in 441 patients who presented with at least one of three key symptoms-cough, wheeze, dyspnoea-but had neither docu mented asthma nor bronchial obstruction.The histamine concentrations c ausing a 20% fall in forced expiratory volume in 1 s (PC(20)FEV(1)) an d a 25% fall in maximal mid-inspiratory flow (PC(25)MIF(50)) were used as respective thresholds of bronchial and EA responsiveness. Values 8 mg/mL or less indicated bronchial (B-HR) or EA hyper-responsiveness ( EA-HR). The influence of concurrent upper respiratory tract diseases, such as post-nasal drip (PND), pharnygitis, laryngitis and sinusitis, was also assessed. We found four response patterns to the histamine ch allenge: EA-HR in 26.5% of the patients, B-HR in 11.1%, combined EA-HR and B-HR in 40.6%, and no-HR in 21.8%. Cough was reported by 79% of t he patients, wheeze by 53%, and dyspnoea by 40%. Patients with cough a s the sole presenting symptom (34.2%), as compared with those with whe eze and/or dyspnoea (20%), had significantly greater probability of ha ving EA-HR (OR 5.35, 95% CI 3.25-8.82) and lower probability of having B-HR (OR 0.45, Cl 0.28-0.70); patients with cough plus wheeze and/or dyspnoea (45.8%) had significantly greater probability of having both EA-HR and B-HR than either those with cough alone (OR 2.48, Cl 1.49-4. 13), or those with wheeze and/or dyspnoea but not cough (OR 1.74, Cl 1 .36-2.22), EA-HR alone or combined with B-HR was strongly associated w ith EA diseases, particularly pharyngitis and PND. Cough was significa ntly associated with PND, either when it was the sole symptom (OR 2.16 , Cl 1.14-4.09) or when it was combined with wheeze and/or dyspnoea (O R 3.53, Cl 1.97-6.33). Our results suggest that extrathoracic airway d ysfunction may account for asthma-like symptoms, particularly chronic cough. This abnormality seems to be sustained by chronic diseases of t he upper respiratory tract.