Role of Methacholine PC20 in FEF(25-75%) for the Diagnosis of Bronchial Asthma / 결핵및호흡기질환

ABSTRACT

BACKGROUND: The methacholine bronchial provocation test is a useful tool for evaluating asthma in patients with normal or near normal baseline lung function. However, the sensitivity of this test is 82~92% at most. The purpose of this study is to evaluate the clinical usefulness of FEF(25-75%) in identification of airway hyperresponsiveness in patients with suspected asthmatic symptoms. METHODS: One hundred twenty-five patients who experienced cough and wheezing within one week prior to their visiting the clinic were enrolled. RESULTS: Sixty-four subjects showed no significant reduction of FEV1 or FEF(25-75%) on the methacholine bronchial provocation test (Group I). In 24 patients, FEF(25-75%) fell more than 20% from baseline without a 20% fall of FEV1 during methacholine challenge (Group II). All patients who had more than 20% fall of FEV1 (n=37) also showed more than 20% of reduction in FEF(25-75%) (Group III). Baseline FEV1/FVC (%) and FEF(25-75%) (L) were higher in group II than group III (81.51+/-1.56% vs. 75.02+/-1.60%, p<0.001, 3.25+/-0.21 L vs. 2.45+/-0.21 L, p=0.013, respectively). Group II had greater reductions of both FEV1 and FEF(25-75%) than group I at 25 mg/mL of methacholine (p<0.001). The provocative concentration of methacholine causing a 20% fall in FEF(25-75%) in group II was about three-fold higher than that in group III. CONCLUSION: A 20% fall of FEF(25-75%) by methacholine provocation can be more sensitive indicator for detecting a milder form of airway hyperresponsiveness than FEV1 criteria.