Late-breaking abstract: The applicability of urinary leukotriene E4 (uLTE4) measurement as a non-invasive method for diagnosis of aspirin exacerbated respiratory disease (AERD)

Overproduction of cysteinyl leukotrienes (CysLT) is associated with AERD. uLTE4 is considered to be the most reliable analytic parameter of endogenous synthesis of CysLT. Aspirin challenge is a gold standard in diagnosing AERD. Objectives - to compare baseline uLTE4 concentrations between 3 large groups of patients (AERD, aspirin tolerant asthma (ATA), healthy controls (HC)) in order to set the potential cut-off uLTE4 level for diagnosing AERD. Patients with clinically stable AERD (n=247), ATA (n=239), HC (n=96) were enrolled. Special questionnaire was used to collect clinical data from each group. uLTE4 in morning samples was quantified by ELISA (Cayman Chemicals Co.). Chronic sinusitis, nasal polyposis, polypectomies, and overall number of hospitalizations due to asthma were more frequent in patients with AERD. AERD patients exhibited significantly higher mean levels of uLTE4 than ATA patients and HC (2190, 616, 580 pg/mg creat. respectively); AERD vs. ATA, p 780 pg/mg creat.). The OR for diagnosing AERD vs. ATA in the 4th quartile was 5.3 (95%CI; 3.32-8.49). The ROC curve analysis identified the threshold for AERD vs. ATA at the level of uLTE4>800 pg/mg creat. (sens. 49%, spec. 81%, AUC = 0.699). Our data suggests that uLTE4 threshold of ca. 800 pg/mg creat. is associated with an increased likelihood of diagnosing AERD. Measurement of uLTE4 could be helpful in identifying patients with AERD, who cannot undergo aspirin challenge.