IMPORTANCE OF SPUTUM DIFFERENTIAL CELL COUNTING IN THE DIAGNOSIS OF AIRWAY DISEASES

We examined the sputum of sputum of 114 subjects by noninvasive method s (voluntary coughing or induced cough with hypertonic saline) to dete rmine whether sputum examination could be used to separate patients wi th episodic wheezing, dyspnea or cough of unknown origin into differen t diagnostic categories. An increased percentage of sputum eosinophils was seen in 92% (48/52) of asthmatics, 36% (9/25) of patients with ch ronic obstructive pulmonary disease (COPD) and 28% (7/25) of chronic c oughers, but not in any of the 12 patients with congestive heart failu re (CHF). Eight patients with combined symptoms of COPD and asthma (mi xed COPD subgroup) showed above average diurnal peak expiratory flow v ariation (10.3 +/- 2.1% vs 2.5 +/- 1.4%, p < 0.05) and an above averag e percentage of sputum eosinophils (19.8 +/- 9.1 vs 2.1 +/- 3.2, P < 0 .01) than those in the pure COPD group. After therapeutic corticostero id trial, all of the mixed COPD patients and six of the 17 pure COPD p atients were steroid responders. Seven of the 25 chronic coughers had sputum eosinophilia, but no asthmatic symptoms. The cough symptoms sub sided in five of these seven patients alter steroid treatment but not in the other 18 chronic coughers. Further study is indicated to determ ine if simple eosinophilic bronchitis is an early stage of asthma. In conclusion, sputum differential cell counting is a useful noninvasive diagnostic tool in differentiating diseases with episodic wheezing or chronic cough.