We studied sputum eosinophil count of patients with chronic cough. Differential count of sputum cells(simple direct smear with Wright stain) were successfully examined in 44(73%) among 60 patients with chronic cough. The patients were divided according to PC2O value; 20(45%) patients had increased airway hyper responsiveness(AHR) (PC2O < 24mg/ml), remained 24 Patients did not have any evidence of airway AHR. Age, sex, duration and severity of symptoms, serum total IgE and positive skin test reaction were not different between two groups. In patients with increased AHR, increased sputum eosinophil ratio(10%) was found in 11 patients (55%) and increased peripheral blood eosinophil ratio(>5%) was found in 66% of patients with increased AHR. In patients without increased AHR, increased sputum eosinophil ratio was found in three patients(12%) and increased peripheral blood eosinophil ratio was found in 24%. This discrepancy between two groups was statisticalla significant(p<0.01). In regarding to sputum eosinophilia, increased sputum eosinophil ratio was in 14(32%) of 44 patients with chronic cough. Eleven patients(78%) of them had increased AHR. Only nine(30%) among 30 patients without sputum eosinophilia had increased AHR. These discrepancies between two groups were statistically significant(p<0.01). To predict AHR, sputum eosinophilia has 55% of sensitivity and 88% of specificity. Significant positive correlation between peripheral blood eosinophil ratio and sputum eosinophil ratio was found in patients with cough-variant asthma (r=0.76, p<0.01), We suggest that simple direct smear for sputum eosinophil count could be an useful test to diagnose the patients with chronic cough.
Asthma ; Cough* ; Eosinophilia ; Eosinophils* ; Humans ; Immunoglobulin E ; Sensitivity and Specificity ; Skin Tests ; Sputum*