Usefulness Of Exhaled Nitric Oxide In Asthma Diagnosis

Abstract

RATIONALE: Inflammation is known to underlie the pathogenesis of asthma. Nevertheless, diagnosis is made by clinical history, reversible airway obstruction and bronchial hyperresponsiveness according to international guidelines. Exhaled nitric oxide is a non-invasive inflammatory marker. The aim of the study was to assess the sensitivity and specificity of FeNO in asthma diagnosis.METHODS: Sixty-four consecutive patients reporting asthma symptoms were included in the study. All of them underwent methacholine challenge test following the five-breath dosimeter protocol, after measurement of exhaled nitric oxide with a portable device.RESULTS: Twenty-three of the 64 patients were diagnosed with asthma. A positive MCh challenge was correlated with higher FeNO levels and with basal FEV1. No correlation was found between PC20 and FeNO levels. ROC curves were built for FeNO levels (AUC: 0.79). A cut-off point for FeNO level was calculated with maximal specificity and sensitivity for asthma diagnosis (39.5 ppb).CONCLUSIONS: FeNO as marker of inflammation is highly correlated with functional parameters (MCh) in asthmatic patients. A cut-off point of 39.5 ppb was calculated for asthma diagnosis in our population. The use of FeNO measurement may be a helpful tool for asthma diagnosis in patients not able of performing MCh challenges. RATIONALE: Inflammation is known to underlie the pathogenesis of asthma. Nevertheless, diagnosis is made by clinical history, reversible airway obstruction and bronchial hyperresponsiveness according to international guidelines. Exhaled nitric oxide is a non-invasive inflammatory marker. The aim of the study was to assess the sensitivity and specificity of FeNO in asthma diagnosis. METHODS: Sixty-four consecutive patients reporting asthma symptoms were included in the study. All of them underwent methacholine challenge test following the five-breath dosimeter protocol, after measurement of exhaled nitric oxide with a portable device. RESULTS: Twenty-three of the 64 patients were diagnosed with asthma. A positive MCh challenge was correlated with higher FeNO levels and with basal FEV1. No correlation was found between PC20 and FeNO levels. ROC curves were built for FeNO levels (AUC: 0.79). A cut-off point for FeNO level was calculated with maximal specificity and sensitivity for asthma diagnosis (39.5 ppb). CONCLUSIONS: FeNO as marker of inflammation is highly correlated with functional parameters (MCh) in asthmatic patients. A cut-off point of 39.5 ppb was calculated for asthma diagnosis in our population. The use of FeNO measurement may be a helpful tool for asthma diagnosis in patients not able of performing MCh challenges.