[The diagnostic role of the methacholine inhalation challenge in adult patients with chronic persistent cough].
Chronic persistent cough (CPC) is a common medical problem. We determined the value of the methacholine inhalation challenge (MIC) in the evaluation of CPC. We also sought other clinical factors that affect MIC. Patients were selected for the study if 1) CPC was the only presenting symptom, 2) a current roentgenogram did not contribute to the diagnosis, and 3) spirometry revealed a normal FEV1. We measured the minimum dose of methacholine (bronchial sensitivity, Dmin) by the "Asthograph" method. We determined the correlation between log Dmin and demographic and clinical variables, i.e. age, %FVC, %FEV1, FEV1%, %V50, %V25, eosinophil count in peripheral blood, and serum IgE level. The causes of CPC in 51 patients (20 men and 31 women, mean age 41 years) were cough-variant asthma in 29 patients, postinfectious persistent cough in 13 patients, atopic cough in 6 patients, and others in 3 patients. Log Dmin significantly but weakly correlated with %V25 (4 = 0.31, p = 0.02). The sensitivity and specificity of Dmin (< 10 units) in diagnosing cough-variant asthma was 93% and 87%, respectively. Demographic or clinical variables other than Dmin were not useful for the diagnosis of cough-variant asthma. We conclude that MIC is useful for the differential diagnosis of CPC while the usefulness is limited in some cases.
Fujimori
K
K
Department of Internal Medicine, Prefectural Shibata Hospital.
Suzuki
E
E
Arakawa
M
M
Gejyo
F
F
D000328:Adult; D001249:Asthma / Q000175:diagnosis*; D016535:Bronchial Hyperreactivity; D001985:Bronchial Provocation Tests; D016085:Bronchoconstrictor Agents; D002908:Chronic Disease; D003371:Cough / Q000175:diagnosis*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007239:Infections / Q000150:complications; D008297:Male; D016210:Methacholine Chloride
D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride