Despite the clinical clues of bronchial asthma, some chronic coughers fail to be diagnosed due to negative test results. This study was aimed at evaluating the diagnostic performance of routine objective tests and identifying a cost-effective approach for asthmatics with a chronic cough.

Patients with a chronic cough of more than 3 weeks duration, and showing normal chest radiograph and spirometry were enrolled. On the first visit, objective tests, composed of serum total IgE, peripheral blood eosinophil count, spontaneous sputum eosinophil count, methacholine bronchial provocation test (MBPT) and paranasal sinus radiograph, were performed, with the simultaneous administration of oral prednisolone (0.5mg/kg) for one week. The final diagnoses were made on the basis of the test results, and the patients grouped according to their steroid responsiveness. The role of the etiologic diagnosis tests was evaluated, and the medical costs of the final management plan simulated with respect to three assumed models.

Sixty chronic coughers were finally analyzed. The final diagnoses were as follows: bronchial asthma 21.7%, eosinophilic bronchitis 6.7%, paranasal sinusitis 18.3%, presumptive allergy 8.3% and non-diagnostic case 45.0%. Ninety percent were steroid responder. With the bronchial asthma cases, the positive rate of MBPT was 38.5%, with sputum eosinophil count in 84.6%, serum total IgE in 38.5%, and a peripheral blood eosinophil count rate of 30.8%. When the test results and steroid responsiveness data were applied to the 3 models, the chest radiograph, spirometry, sputum eosinophil count and paranasal sinus radiograph test results, and simultaneous short term steroid treatment seemed to have acceptable diagnostic performances, which could be used as a further guide to cost-effective planning.

Objective tests, composed of chest radiograph, spirometry, paranasal sinus radiograph and sputum eosinophil count, with simultaneous short term steroid treatment, are suggested as cost-effective approaches for asthmatics with a chronic cough.