The prevalence of nasal polyps and the corresponding urinary LTE4 levels in severe compared to mild and moderate asthma.

BACKGROUND: Several comorbid conditions may contribute to worsening asthma symptoms, including nasal polyps (NPs). Cysteinyl leukotrienes (Cys-LTs) play a crucial role in asthma pathophysiology, and specific receptors for CysLTs are reported as upregulated in nasal polyp tissues. The aim of the present study was to assess the prevalence of nasal polyps in severe vs. mild and moderate asthma, and to compare the corresponding levels of urinary Leukotriene E4 (LTE4). MATERIALS AND METHODS: A cohort of 386 asthma patients were studied: n=166 with mild, n=146 with moderate and n=74 severe asthma. All patients performed a nasal endoscopy and urine were collected in the morning for the quantitative LTE4 immunoenzimatic assay (Cayman Chemical, MI, USA). Intolerance to ASA was also assessed by means of a nasal provocation test with L-ASA. RESULTS: The prevalence of NPs was the following: 8 cases (4.8%) in mild; 14 (9.6%) in moderate, and 33 (44.6%) in severe asthma. Mean urinary LTE4 levels were increasing according to the disease severity. ASA-intolerance was assessed in 1 patient in mild asthma (0.6%), 14 in moderate asthma (9.6%) and 28 in severe asthma (37.8%). CONCLUSIONS: Nasal polyps represent a comorbid which is highly frequent in severe asthma. Both their prevalence and the corresponding mean LTE4 levels in urine proved in strict, direct relationship with asthma severity. In severe asthma, nasal polyps represent a condition which is associated with the highest excretion of urinary LTE4 and ASA intolerance.