Airways inflammation, involving infiltration of bronchial wall with activated eosinophils, mast cells and T lymphocytes, is an established feature of asthma. Clinical assessment of disease severity is based upon pulmonary function tests, their variability and symptom score. The relationship between the degree of airway inflammation and disease control is probably not significant. Differential cell count in induced sputum seems to be a useful parameter reflecting the degree of airway inflammation in patients with bronchial asthma. We investigated 67 patients with bronchial asthma of different severity and have shown statistically significant correlation between percentage of sputum eosinophils and clinical and physiological parameters of disease control. Eosinophil counts in induced sputum were negatively correlated with FEV1 (p = 0.006), ration of FEV1/VC (p < 0.001) and diurnal variability of PEF (p < 0.001). According to previous studies, where percentage of eosinophils was less than 4% in healthy subject, we determined sputum eosinophilia if eosinophil percentage was more than 4%. Sensitivity of clinical markers of disease control for predicting the degree of airway inflammation ranged between 0.15-0.74, ratio of FEV1/VC having the highest sensitivity. Specificity of clinical markers ranged from 0.43 to 0.94, diurnal variability of PEF having the highest specificity. Despite of good correlation of clinical markers of asthma severity with sputum eosinophils, pulmonary function test, diurnal variability of PEF and rescue salbutamol can hardly predict the degree of airway inflammation or the efficacy of antiinflammatory treatment in a particular patient. Percentage of sputum eosinophils seems to be a useful and promising marker for measuring the degree of airway inflammation in patients with bronchial asthma, especially in more severe cases.

Keywords: Adult; Asthma /drug therapy/; Bronchi /pathology/; Eosinophils; Female; Forced Expiratory Volume; Humans; Inflammation; Leukocyte Count; Male; Peak Expiratory Flow Rate; Sensitivity and Specificity; Sputum /cytology/; Vital Capacity