Urinary cysteinyl leukotriene E4 level and therapeutic response to montelukast in children with mild obstructive sleep apnea.

BACKGROUND Antileukotriene has been used for alleviating disease severity in children with adenotonsillar hypertrophy (ATH) and mild obstructive sleep apnea (OSA). Previous study showed the relationship between urinary cysteinyl leukotriene E₄ (uLTE₄) level and therapeutic response to montelukast in asthmatic adults. However, this relationship has never been investigated in pediatric OSA. OBJECTIVES To determine the relationship between uLTE₄ level and therapeutic response to montelukast in children with ATH and mild OSA. METHODS Children aged 3-15 yrs who had ATH and mild OSA were enrolled. All had quality of life (assessed by Thai version OSA-18 QoL questionnaire) and uLTE₄ levels measured prior to start a 6-week course of montelukast treatment. Overnight polysomnography (PSG) and QoL reassessment were performed after completing the treatment. Those who demonstrated a large improvement of mean total QoL score or ≥ 50% decrease of obstructive apnea-hypopnea index (OAHI) after the treatment were defined as responders. RESULTS Twenty-six children were enrolled (mean age 7.5 ± 2.9 yrs, 38.5% male). After 6-week course of montelukast, nine (34.6%) children showed significant improvement. The mean uLTE₄ level from the responders was higher comparing to the non-responders (2,952.56 ± 966.9 vs. 978.6 ± 460.8 pg/mg creatinine; p < 0.001). uLTE₄ level of ≥ 1,457 pg/mg creatinine had 100% sensitivity and 88.2% specificity in identifying the responders. CONCLUSIONS We found the association between ULTE4 and therapeutic response to monteleukast. The uLTE₄ level of ≥ 1,457 pg/mg creatinine could predict the therapeutic response to montelukast in children who had ATH and mild OSA.