ABSTRACT
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 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.