The aim of this study was to investigate and identify the relationship between urinary
cysteinyl leukotriene E(4) levels and clinical response to antileukotriene treatment in patients with
asthma. Forty-eight patients with stable mild to moderate
asthma were treated with
montelukast in a four-week trail. Asthmatic symptom score, beta(2)-agonist usage, percentage of eosinophil, total serum
IgE concentration, forced expiratory volume in the first second (FEV(1)), peak expiratory flow rate (PEFR), and urinary
leukotriene E(4) (uLTE(4)) were measured before and
after treatment. Clinical response was assessed by the improvement of
asthma symptom scores, beta(2)-agonist usage, and FEV(1). Responders were defined as patients who had to fit the following three criteria: a reduction of more than 20% in mean symptom score; a reduction of more than 20% in beta(2)-agonist usage, and a mean improvement of FEV(1) of more than 10% from baseline value. Others were classified as nonresponders. Logistic analysis was used to access the various clinical factors correlated with the clinical response. There were 25 responders and 23 nonresponders. The mean uLTE(4) level from the responders was higher than that from the nonresponders (224.5 +/- 34.4 vs. 175.3 +/- 37.1 pg/mg
creatinine, p < 0.05). There was a significant correlation between the clinical response and the uLTE(4) level but not demographic features, percentage of eosinophils, serum
IgE concentration, or spirometry (p > 0.05). Subjects with a uLTE(4) level of >/= 200 pg/mg
creatinine were 3.5 times more likely to respond to
montelukast than those with less than 200 pg/mg
creatinine (95% confidence interval [CI] = 1.7-15.8). The uLTE(4) level is closely correlated with antileukotriene treatment. uLTE(4) is a good
biomarker for selecting this
drug to treat
asthma.