Airway inflammation in patients with symptoms suggesting asthma but with normal lung function

Abstract

The hypothesis that eosinophilic airway inflammation is present in many patients presenting with respiratory symptoms suggestive of asthma but with normal lung function was tested. Thirty-six consecutive patients presenting with these features were studied. Twenty-five asthmatics and 43 healthy volunteers served as control groups. Signs of eosinophilic inflammation in blood and induced sputum were studied. Patients with respiratory symptoms were single-blindly treated with inhaled beclomethasone dipropionate (BDP), 800 microg daily, or placebo for 3 months, and re-examined at 3 months and 1 yr. Patients with respiratory symptoms had higher numbers of blood and sputum eosinophils than healthy persons (p<0.0001), but the degree of eosinophilic inflammation was less pronounced than in asthmatics (p<0.01). Three-month's treatment with BDP significantly reduced total symptom score (p<0.001), cough score (p<0.0001), and the number of blood eosinophils (p<0.01). For cough alone, the improvement was significant compared with placebo (p<0.05). The patients were followed-up for 1 yr, and 17 (55%) still had symptoms but retained normal lung function. Four (13%) patients had developed asthma and another 10 (32%) had become free of symptoms. Using lung function measurements and induced sputum analyses, a group of patients with symptoms suggestive of asthma and signs of eosinophilic airway inflammation but without enough airflow variability to be diagnosed as asthmatics were detected. They seemed to respond favourably to inhaled beclomethasone dipropionate treatment.