Abstract
BackgroundNasal nitric oxide (nNO), a noninvasive indicator for eosinophilic airway inflammation, has not been adequately studied in different types of rhinitis. The aim of this study was to compare nNO levels between allergic (AR) and non-allergic rhinitis (NAR). Patients were included based on their chronic nasal symptoms. Total nasal symptoms score (TNSS) were evaluated. nNO was measured transnasally with a flow of 5 ml/s from the nostril with an NO analyzer (NIOX MINO; Aerocrine, Sweden). Results were evaluated as parts per billion (ppb).ResultsFour hundred forty-three patients (277 F/166 M)—337 with AR (76%) and 106 with NAR (24%)—were assessed. Patients with AR had significantly higher TNSS, more severe disease, and longer duration of disease compared to NAR group. Allergic rhinitis had significantly higher nNO levels than NAR (370 ppb vs 290 ppb) (p = 0.001). Likewise, significant differences were observed in female gender, in patients with BMI ≥ 25 kg/m2 and those without sinusitis between the two groups. When nNO were further evaluated in comorbid asthma, patients with AR w/o asthma had the highest TNSS and had significantly higher nNO level (p < 0.001). NAR+A group, with the longest duration of rhinitis, was significantly older and had the lowest nNO level (p < 0.001).ConclusionsThis study showed that nNO levels were significantly higher in AR patients than NAR. Although there is no recommended standard threshold for nNO, this study confirmed the utility of nNO in differentiating AR and NAR in addition to its known fast and non-invasive advantages.
Highlights
Nasal nitric oxide, a noninvasive indicator for eosinophilic airway inflammation, has not been adequately studied in different types of rhinitis
Rhinitis can be divided into two different groups, which differ in some features, namely, concomitant allergy and non-allergic, according to allergen sensitivity defined by skin prick tests (SPTs) and/or serum-specific IgE [2]
We found that rhinitis and comorbid asthma were responsible for increased fractional exhaled Nitric oxide (NO) (FeNO) regardless of atopy [10]
Summary
Nasal nitric oxide (nNO), a noninvasive indicator for eosinophilic airway inflammation, has not been adequately studied in different types of rhinitis. Rhinitis is known as an inflammation of the nasal mucosa and estimated to affect almost 200 million people worldwide [1] This creates indirect costs by loss of work and productivity, as well as a huge burden on society by increasing the needs of medical treatment. Some authors showed increased NO levels in patients with AR, whereas other studies reported no differences [6, 7] This could be due to regulatory effect of NO on cellular functions in response to variable conditions, such as degree of exposure to allergen; presence of infectious inflammation; undertreatment with corticosteroids; confounding factors such as smoking, asthma, rhinosinusitis, and nasal polyps; and the occlusion of sinus ostia. Kulkarni et al showed localized immunoreactivity for nasal NOS in healthy human epithelial cells, olfactory mucosa, olfactory receptor neurons, and multiple nerve fibers [9]
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