Methacholine challenge test in the diagnosis of airway hyperresponsiveness in the State of Qatar

We retrospectively analyzed the results of 263 consecu-tive Methacholine challenge tests (MCTs) (lone in our labo-ratory between July 2000 and June 2003, in symptomatic adult patients with no history of bronchial asthma or chronic lung disease, who presented with chronic non-pro-ductive cough, shortness ofbreath (subjective dyspnea), or both. All of these patients had normal results ofchestphysi-ccil examination, chest radiographs and screening spiro-metric measurements (FEVj > 80 % (predicted). We con-sidered a 20 % fall in the f orced expiratory volume in the first second (FEV{) as the primary outcome measure (MCT PC 20-FEV1), and a 35 % fall in the specif ic conductance (sGaw) (is the primary outcome in patients who cannot perform acceptable spirometry. Out of 263 patients, 79 pa-tients (30 %) were positive for bronchial hyper-responsive-ness (BHR), 20 patients (25. 3 %) of the positive patients had sever BHR, 18 patients (22. 8 %) had moderate BHR, and 41 patients (51. 9 %) hod mild BHR.