Leukotriene D4 Bronchial Provocation Test (LTD4-BPT) as an Indicator for the Use of Leukotriene Receptor Antagonist (LTRA)
Leukotriene D4 Bronchial Provocation Test (LTD4-BPT) as an Indicator for the Use of Leukotriene Receptor Antagonist (LTRA)
Background: Therapeutic outcomes of leukotriene receptor antagonist (LTRA) vary in
 asthmatics，and there's not an ideal and simple way for prediction at present.

 Objective：To investigate whether leukotriene D4 bronchial provocation test (LTD4-BPT) could
 be an indicator of actual therapeutic outcome of LTRA.

 Methods：A single centre, open-labeled trial was performed in 32 asthmatics with positive
 LTD4-BPT result for a month. All subjects were categorized according to airway responsiveness
 to leukotriene D4（PD20FEV1-LTD4）. Subjects received montelukast therapy (10mg, once per
 night), and reassessment was performed (3~5) days after withholding LTRA. The primary
 end-point was the difference in monthly PEFR. Secondary endpoints included the difference in
 FENO, PD20FEV1-LTD4, PD20FEV1-MCh, pre-test FEV1, ACT score, AQLQ symptom score, week 4
 PEFmax and PEFmin as compared with week 1, gradual decrease in the use of salbutamol and the
 days without using salbutamol.
Our primary goal was to determine whether LTD4-BPT could be a clear indicator for assessing
 efficacy of LTRA. Logistic regression model was adopted for statistical analysis. In this
 model, pre-treatment PD20FEV1-LTD4 represented anticipated efficacy. The median of
 PD20FEV1-LTD4 was used for classification of asthmatics, with a lower figure representing a
 better anticipated outcome. Various variables, including the difference in pre- and post-
 treatment FENO, PEFmax, PEFmin, PEFR, PD20FEV1 and asthma scores, were introduced in the
 model representing the actual efficacy of LTRA. We aimed to test whether there would be
 certain parameters that assist prediction of anticipated outcome.
Inclusion Criteria:

 -  subjects aged between 18 and 65，without acute upper respiratory tract infection for
 the past 2 weeks

 -  had a normal chest radiographic result

 -  had a baseline spirometry with the forced expiratory volume in one second (FEV1) of
 not less than 60% predicted

 -  had withheld leukotriene receptor antagonists (LTRA) for over 5 days

 -  oral glucocorticosteroid or anti-histamine for 3 days

 -  oral xanthenes or long-acting bronchodilators for 2 days

 -  inhaled corticosteroid or long-acting bronchodilator for a day as well as short-acting
 bronchodilator for 4 hours prior to the measurement

 Exclusion Criteria:

 -  subjects had a fall of no less than 15% in FEV1 after repetitive forced respiration or
 a fall of no less than 20% in FEV1 after the inhalation of ethanol diluent control

 -  had a past confirmed history of respiratory disease other than bronchial asthma (COPD,
 bronchiectasis, pulmonary thromboembolism, etc.) or other severe systemic
 disease（myocardial infarction, malignant tumor, etc.）

 -  had a poor cooperation to the test or limited understandings, were immunocompromised,
 or had participated other clinical trials for the past 3 months.