Role of nasal nitric oxide in the diagnostic evaluation of rhinitis (EPONA study)

Introduction:Rhinitis is an inflammatory disease and its diagnosisis established by clinical criteria since the complementary examina-tions have a limited role. Although the usefulness of exhaled nitricoxide (FeNO) in the diagnostic assessment of bronchial inflammationhas been widely analyzed, nasal nitric oxide (nFeNO) has attractedless interest and the few available results are ambivalent.Objectives:The objectives of the present study were to determinethe efficacy of nFeNO to: 1. Establish the diagnosis of rhinitis; and2. Discriminate allergic rhinitis (AR) from non-allergic rhinitis (NAR).Material and methods:Prospective and controlled study withhealthy subjects, which included patients with rhinitis. AR andNAR were phenotypically defined according to positive or negativeprick test results, respectively; the control group was collectedfrom people without upper or lower respiratory tract disease andthe prick test was negative. In all sample included the followingmeasurements were performed: FeNO and nFeNO (NOVario Ana-lyzer) were performed; spirometry; eosinophil counts in blood andnose (by nasal brushing); bilateral nasal endoscopy; and acousticrhinometry.Results:We included 147 cases (AR=61, NAR=53 and controls=33),with a mean age of 37 (SD 11.2) years, 66% men. The table belowshows the results of the variables analyzed by group. Patients withrhinitis compared to controls had significantly greater FeNO produc-tion, as well as a higher proportion of eosinophils in blood and nose,but not in nFeNO production. However, when the two subgroups ofrhinitis were compared, AR patients had significantly higher FeNOand nFeNO than NAR, in addition to blood and nose eosinophils.There were no differences in acoustic rhinometry values betweengroups.Conclusions:Although nFeNO does not appear to identify patientswith rhinitis, it may be useful in discriminating AR from NAR. In rou-tine clinical practice, it could help guide to identify an AR in caseswith inconclusive results of the complementary tests commonly usedin its diagnosis