The role of nasal fractional exhaled nitric oxide as an objective parameter independent of nasal airflow resistance in the diagnosis of allergic rhinitis

Severe Type 2 Inflammation Leads to High Platelet-Activating-Factor-Associated Pathology in Chronic Rhinosinusitis with Nasal Polyps-A Hierarchical Cluster Analysis Using Bulk RNA Barcoding and Sequencing

Platelet-activating factor (PAF) is a phospholipid-derived inflammatory mediator that triggers various inflammatory conditions, including eosinophil activation and recruitment. This study aimed to evaluate the expressions of PAF-metabolism-associated genes, namely genes coding the enzymes involved in PAF synthesis (LPCAT1, LPCAT2, LPCAT3, and LPCAT4), PAF degradation (PAFAH1B2, PAFAH1B3, and PAFAH2), and the gene for the PAF receptor (PTAFR) in subtypes of CRSwNP classified by clinical- or hierarchal-analysis-based classifications. Transcriptomic analysis using bulk RNA barcoding and sequencing (BRB-seq) was performed with CRSwNP, including eosinophilic CRS (ECRS) (n = 9), nonECRS (n = 8), ECRS with aspirin-exacerbated respiratory disease (Asp) (n = 3), and controls with a normal uncinate process mucosa (n = 6). PTAFR was only upregulated in ECRS and nonECRS. In the hierarchical cluster analysis with clusters 1 and 2 reflecting patients with low-to-moderate and high levels of type 2 inflammation, respectively, cluster 1 exhibited a significant downregulation of LPCAT2 and an upregulation of PTAFR expression, while cluster 2 showed an upregulation of LPCAT1, PAFAH1B2, and PTAFR and downregulation of PAFAH2 expression. Understanding this strong PAF-associated pathophysiology in the severe type 2 inflammation group could provide valuable insights into the treatment and management of CRSwNP.

Nasal Nitric Oxide as a Biomarker in the Diagnosis and Treatment of Sinonasal Inflammatory Diseases: A Review of the Literature

OBJECTIVE

To critically review the literature on nasal nitric oxide (nNO) and its current clinical and research applicability in the diagnosis and treatment of different sinonasal inflammatory diseases, including acute bacterial rhinosinusitis (ABRS), allergic rhinitis (AR), and chronic rhinosinusitis (CRS).

METHODS

A search of the PubMed database was conducted to include articles on nNO and sinonasal diseases from January 2003 to January 2020. All article titles and abstracts were reviewed to assess their relevance to nNO and ABRS, AR, or CRS. After selection of the manuscripts, full-text reviews were performed to synthesize current understandings of nNO and its applications to the various sinonasal inflammatory diseases.

RESULTS

A total of 79 relevant studies from an initial 559 articles were identified using our focused search and review criteria. nNO has been consistently shown to be decreased in ABRS and CRS, especially in cases with nasal polyps. While AR is associated with elevations in nNO, nNO levels have also been found to be lower in AR cases with higher symptom severity. The obstruction of the paranasal sinuses is speculated to be an important variable in the relationship between nNO and the sinonasal diseases. Treatment of these diseases appears to affect nNO through the reduction of inflammatory disease burden and also mitigation of sinus obstruction.

CONCLUSION

nNO has been of increasing interest to researchers and clinicians over the last decade. The most compelling data for nNO as a clinical tool involve CRS. nNO can be used as a marker of ostiomeatal complex patency. Variations in measurement techniques and technology continue to impede standardized interpretation and implementation of nNO as a biomarker for sinonasal inflammatory diseases.

International consensus statement on allergy and rhinology: Allergic rhinitis - 2023

BACKGROUND

In the 5 years that have passed since the publication of the 2018 International Consensus Statement on Allergy and Rhinology: Allergic Rhinitis (ICAR-Allergic Rhinitis 2018), the literature has expanded substantially. The ICAR-Allergic Rhinitis 2023 update presents 144 individual topics on allergic rhinitis (AR), expanded by over 40 topics from the 2018 document. Originally presented topics from 2018 have also been reviewed and updated. The executive summary highlights key evidence-based findings and recommendation from the full document.

METHODS

ICAR-Allergic Rhinitis 2023 employed established evidence-based review with recommendation (EBRR) methodology to individually evaluate each topic. Stepwise iterative peer review and consensus was performed for each topic. The final document was then collated and includes the results of this work.

RESULTS

ICAR-Allergic Rhinitis 2023 includes 10 major content areas and 144 individual topics related to AR. For a substantial proportion of topics included, an aggregate grade of evidence is presented, which is determined by collating the levels of evidence for each available study identified in the literature. For topics in which a diagnostic or therapeutic intervention is considered, a recommendation summary is presented, which considers the aggregate grade of evidence, benefit, harm, and cost.

CONCLUSION

The ICAR-Allergic Rhinitis 2023 update provides a comprehensive evaluation of AR and the currently available evidence. It is this evidence that contributes to our current knowledge base and recommendations for patient evaluation and treatment.

Significance of Exhaled Nitric Oxide and Carbon Monoxide in Auxiliary Diagnosis and Evaluation of Allergic Rhinitis

OBJECTIVE

The concentration of exhaled NO and CO is considered as a candidate marker of respiratory inflammatory disease. This report discusses the exhaled NO and CO in the auxiliary diagnosis and evaluation of allergic rhinitis (AR).

METHODS

60 AR patients from October 2017 to March 2019, compared with 30 healthy controls. The severity of AR disease was distinguished by symptom score. Both groups were tested for exhaled nitric oxide through the nose or mouth and exhale carbon monoxide through the mouth. AR patients received glucocorticoid nasal spray for 1 month and were tested again for nNO, eNO, eCO, and symptom score.

RESULTS

Before treatment, all the nNO, eNO, and eCO of the AR group were higher than the control group. There were differences in the severe and moderate subgroup: severe > moderate > mild. eCO was not significantly different between the mild and control groups. The nNO, eNO, and eCO levels were positively correlated with symptom score. After treatment, nNO decreased significantly in the three subgroups; eNO and eCO in the severe AR group decreased significantly. Drawing the ROC curve, the area under curve (AUC) of nNO is 0.978. The AUC of eNO and eCO was 0.786 and 0.577, respectively.

CONCLUSION

The nNO, eNO, and eCO in the AR group are higher than healthy people, which positively correlated with the severity of AR symptoms. The detection of nNO, eNO, and eCO can monitor the changes of AR. The detection of nNO level as an indicator of AR auxiliary diagnosis has high accuracy.

In healthy subjects nasal nitric oxide does not correlate with olfactory sensitivity, trigeminal sensitivity, and nasal airflow

OBJECTIVE

The aim of the study was to determine the relationship between nasal nitric oxide (nNO) and olfactory sensitivity, trigeminal sensitivity and nasal airflow in healthy subjects.

STUDY DESIGN

This is a correlational study.

SETTING

This study was carried out in a tertiary referral centre.

PARTICIPANTS

Forty healthy participants were recruited.

MAIN OUTCOME MEASURES

nNO was measured using a chemiluminescence analyser (Niox Vero^® , Circassia AB, Uppsala, Sweden), olfactory sensitivity was determined using phenyl ethyl alcohol odour thresholds using the 'Sniffin' Sticks', trigeminal sensitivity was assessed with carbon dioxide delivered by an automated device, and nasal airflow was measured using the peak nasal inspiratory flow (PNIF).

RESULTS

The median nNO was 518 ppb (IQR =333) in the right nostril, and it was 567 ppb (IQR = 314) in the left nostril. The median odour threshold was 7.1 (IQR = 4.4), the median CO₂ threshold was 919 ms (IQR = 1297) and the mean PNIF was 108 L/min (SEM = 4.9). nNO did not correlate significantly with odour threshold, CO₂ threshold or PNIF (Spearman's |ρ|  <0.15, p > .18).

CONCLUSION

In healthy subjects, nNO does not appear to be associated with olfactory sensitivity, trigeminal sensitivity and PNIF.

Nasal Nitric Oxide in the Upper Airway Inflammatory Diseases

Exhaled nitric oxide (eNO) from the lower respiratory tract is used commonly in diagnosis and treatment monitoring of asthma patients. However, nasal nitric oxide (nNO) has not been widely used in patients with upper airway inflammatory diseases due to its lack of standardized measurement methods. Nasal nitric oxide is produced mainly by the paranasal sinus mucosa and partially by the nasal mucosa and increases with inflammation. Nasal nitric oxide not only locally supports the defensive mechanism of the upper respiratory tract, but also remotely controls pulmonary function by acting as an aerocrine. Nasal NO can be affected by various physiologic and pathologic factors of the upper respiratory tract. This article will review the origin of nNO, its function, various measurement methods, and difference in presentation among upper respiratory tract inflammatory diseases such as allergic rhinitis, upper respiratory tract infection, nasal polyp, rhinosinusitis, primary ciliary dyskinesia, cystic fibrosis, Young’s syndrome, diffuse panbronchiolitis, empty nose syndrome, and obstructive sleep apnea. Future studies should identify the mechanism of action of nNO in various upper respiratory tract inflammatory diseases and obtain highly reproducible normal values of nNO based on a standardized measurement method with a deeper understanding of factors affecting nNO. Then, nNO will be useful for more rapid and simpler diagnosis of various upper respiratory tract diseases and for monitoring their treatment.

The Functional Diversity of Nitric Oxide Synthase Isoforms in Human Nose and Paranasal Sinuses: Contrasting Pathophysiological Aspects in Nasal Allergy and Chronic Rhinosinusitis

The human paranasal sinuses are the major source of intrinsic nitric oxide (NO) production in the human airway. NO plays several roles in the maintenance of physiological homeostasis and the regulation of airway inflammation through the expression of three NO synthase (NOS) isoforms. Measuring NO levels can contribute to the diagnosis and assessment of allergic rhinitis (AR) and chronic rhinosinusitis (CRS). In symptomatic AR patients, pro-inflammatory cytokines upregulate the expression of inducible NOS (iNOS) in the inferior turbinate. Excessive amounts of NO cause oxidative damage to cellular components, leading to the deposition of cytotoxic substances. CRS phenotype and endotype classifications have provided insights into modern treatment strategies. Analyses of the production of sinus NO and its metabolites revealed pathobiological diversity that can be exploited for useful biomarkers. Measuring nasal NO based on different NOS activities is a potent tool for specific interventions targeting molecular pathways underlying CRS endotype-specific inflammation. We provide a comprehensive review of the functional diversity of NOS isoforms in the human sinonasal system in relation to these two major nasal disorders' pathologies. The regulatory mechanisms of NOS expression associated with the substrate bioavailability indicate the involvement of both type 1 and type 2 immune responses.

[Correlation between exhaled nitric oxide and carbon monoxide and allergic rhinitis]

Objective:In this study, the level of nasal nitric oxide（nNO）, exhaled nitric oxide（eNO）, and exhaled carbon monoxide（eCO） in patients with allergic rhinitis（AR） were tested, to explore the correlation between nNO, eNO, eCO and AR. Method:A total of 60 AR patientswere enrolled as the allergy group and then divided into mild, medium and severe subgroups according to symptom scores. 30 healthy volunteers were recruited as control group. The levels of nNO, eNO and eCO were detected in AR group, AR subgroups and control group. Result:The levels of nNO, eNO and eCO in AR group were higher than those in control group（P<0.05）. nNO, eNO and eCO levels were positively correlated with symptom scores（P<0.05）.Pairwise comparison was used between mild, moderate and severe subgroups. The difference of both nNO and eNO levels between mild, moderate and severe AR subgroups was statistically significant, severe>and moderate>were mild（P<0.05）, but there was no significant difference in eNO levels between the mild AR subgroup and the control group（P>0.05）. Level of eCO in severe AR subgroup was higher than those in moderate and mild AR subgroups（P<0.05）, but there was no significant difference between mild, moderate AR subgroups and control group（P>0.05）. nNO, eNO and eCO levels were used as indicators to evaluate the severity of AR, and the receiver operating characteristic（ROC） curves were plotted. The area under curve（AUC） was 0.978, 0.786 and 0.577, respectively. Taking eCO level as the indicator for disease assessment of severe AR, the AUC was 0.728. It showed that nNO had a high accuracy in evaluating the severity of AR, eNO had a certain accuracy in evaluating the severity of AR, and eCO had a certain accuracy in the assessment of severe AR. Conclusion:The detection of nNO, eNO and eCO levels can be used as an objective assessment method of the severity of AR.

The effect of medical treatment on nasal exhaled nitric oxide (NO) in patients with persistent allergic rhinitis: A randomized control study

PURPOSE

This study aimed to evaluate the role of nasal nitric oxide (NO) in the management of patients with persistent allergic rhinitis (PER).

METHODS

It was a randomized and comparative study. The study subjects were classified as controls (healthy subjects) or patients with PER based on defined criteria. All clinical, functional and biological data were collected for analyzing. Nasal fractional exhaled nitric oxide (FENO) was measured by electroluminescence device. Patients with PER were randomized for treatment with antihistamine (ATH) combined with leukotriene receptor antagonists (LRA) or only with intranasal steroids (INS).

RESULTS

During two years, 501 subjects were included: 234 control subjects and 267 patients with PER. The levels of nasal NO, total IgE, blood eosinophil counts, and apnea-hypopnea index (AHI) in patients with PER were higher than controls (P < 0.001; P < 0.05; P < 0.05; P < 0.01; respectively). There were statistically significant correlations between nasal NO, nasal peak flows, total IgE, and blood eosinophil counts in patients with PER (R = -0.687 and P = 0.0012; R = -0.643 and P = 0.0018; R = 0.432 and P = 0.0024; R = 0.445 and P = 0.002; respectively). After 6 months of treatment, patients treated with INS had greater improvement of clinical symptoms and reduction of nasal NO values than patients treated with ATH + LRA (985 ± 253 vs. 732 ± 298 ppb; P < 0.05).

CONCLUSION

Nasal NO measurement is a useful tool for the follow-up of patients with PER. It also helps clinicians to estimate the level of response to treatment in patients with PER.

Nasal nitric oxide in upper airways in children with asthma and allergic rhinitis

PURPOSE

The aim of this study is to compare levels of nasal nitric oxide (nNO) in pediatric patients with respiratory diseases.

MATERIALS AND METHODS

nNO was measured by an electrochemical analyzer in 179 patients aged 7-15 with asthma, allergic rhinitis or with asthma and allergic rhinitis and in healthy children recruited from a local allergology clinic. Correlations between nNO levels and patient clinical parameters were assessed.

RESULTS

nNO was significantly higher in patients with allergic rhinitis (2316.3 ± 442.33 ppb, p < 0.001) as well as with asthma and allergic rhinitis (2399.9 ± 446.73 ppb, p < 0.001) compared to asthmatic and healthy children (1066.4 ± 416.75; 836.2 ± 333.47 ppb, respectively). A receiver operating characteristic curve analysis revealed that a cut-off value of 1545 ppb nNO and 1459 ppb nNO has sensitivity of 100% and specificity of 100% in distinguishing allergic rhinitis and combined asthma and allergic rhinitis from healthy subjects. A positive correlation between nNO and age and height was determined only in groups of healthy controls. We found no association between nNO level and clinical parameters including percent of eosinophils and total IgE.

CONCLUSION

Levels of nNO are currently measured by different analyzers and with different methods, so assessment of nNO is in need of standardization improvement to become a more reliable tool. However, because it is cheap, painless and fast, it may be helpful in combination with recognition of clinical symptoms and typical diagnostic methods, especially in estimation of inflammation.

Diagnostic value of FeNO and MMEF for predicting cough variant asthma in chronic cough patients with or without allergic rhinitis

OBJECTIVE

To evaluate the diagnostic value of fractional exhaled nitric oxide (FeNO) and maximum mid-expiratory flow (MMEF) for differentiating cough variant asthma (CVA) from chronic cough in patients with or without allergic rhinitis.

METHODS

In total, 328 patients with chronic cough who underwent spirometry and FeNO testing were consecutively included in the retrospective analysis. Patients were divided into the CVA (n = 125) or NCVA (n = 203) groups according to the diagnostic criteria of CVA. Receiver operating characteristic (ROC) curves were established to assess the diagnostic efficiency and optimal cutoff points of FeNO and MMEF for the prediction of CVA.

RESULTS

The optimal cutoff values of FeNO and MMEF to discriminate CVA from chronic cough were 24.5 ppb (AUC, 0.765; sensitivity, 69.60%; specificity 72.91%; PPV, 61.27%; NPV, 79.57%) and 66.2% (AUC, 0.771; sensitivity, 67.20%; specificity 78.33%; PPV, 65.63%; NPV, 79.50%). The optimal cutoff values of combining FeNO with MMEF to discriminate CVA from chronic cough were >22 ppb for FeNO and <62.6% for MMEF (AUC, 0.877). In patients with and without allergic rhinitis, the optimal cutoff point of FeNO to discriminate CVA from chronic cough was 24.5 ppb (AUC, 0.820) and 33.5 ppb (AUC, 0.707), respectively.

CONCLUSIONS

FeNO and MMEF might have greater value as negative parameters for differentiating CVA from chronic cough. Combining FeNO and MMEF provided a significantly better prediction than either alone. The diagnostic accuracy of FeNO for predicting CVA in chronic cough patients with allergic rhinitis was higher than in chronic cough patients without allergic rhinitis.

The Clinical Significance of Nasal Nitric Oxide Concentrations in Preschool Children with Nasal Inflammatory Disease

BACKGROUND

Allergic rhinitis is an allergic inflammation of the nasal airways, and chronic rhinosinusitis is an inflammation of the paranasal sinuses. It can be induced by infection, allergy, or autoimmune problems. Diagnosis of these two diseases is made primarily based on clinical symptoms, allergen test, and imaging. The allergen test is invasive and expensive. The imaging test is harmful to children. Measurement of nasal nitric oxide (NNO) was noninvasive, without radiation, and inexpensive. This study was to evaluate the clinical significance of NNO in preschool children with nasal inflammatory diseases.

METHODS

A total of 55 cases of allergic rhinitis, including 35 mild cases and 20 moderate to severe cases, and 33 cases of chronic rhinosinusitis, including 18 mild cases and 15 moderate to severe cases were selected as the experimental group. Fifty healthy preschool children were chosen as the control group. The levels of NNO in all children were measured. The differences in the levels of NNO among allergic rhinitis, chronic rhinosinusitis, and the control group were compared. The levels of NNO in the control group were also analyzed.

RESULTS

The levels of NNO were significantly higher in preschool children with allergic rhinitis than in the control group, and the differences were significant. However, the levels of NNO in preschool children with chronic rhinosinusitis were lower than in the control group. In the control group, the levels of NNO were not significantly different between genders, and no significant correlation between NNO levels and the children's height was found.

CONCLUSION

As a noninvasive method for detecting nasal inflammatory diseases, measuring the levels of NNO had a high clinical significance in preschool children.

Clinical Utility Of The Exhaled Nitric Oxide (NO) Measurement With Portable Devices In The Management Of Allergic Airway Inflammation And Asthma

Nitric oxide (NO) is a potential bioactive gas produced continuously and constantly in the airways of healthy subjects. In allergic airway inflammation, the level of exhaled NO is usually increased and mediated by inducible nitric oxide synthase (iNOS) enzyme presenting in the epithelium and different inflammatory cells. The measurement of NO concentration in the airway is possible with portable devices which use an electroluminescence technique. In subjects with upper airway with allergic inflammation such as in allergic rhinitis, the measurement of nasal NO (nNO) may help to diagnose and manage the disease. In the lower airway, increased fractional exhaled NO (FENO) reflects directly the inflammatory process that occurs in the airways that are typically seen in asthma. It has been shown that there is a strong correlation between FENO levels and increased activity of airway inflammation mediated by immuno-allergic cells and mediators. Thus, FENO has higher specificity and sensitivity than other methods in diagnosing the severity of inflammation in asthmatic patients. Moreover, the correlation between increased FENO levels and a high risk of bronchial hyperresponsiveness has also been demonstrated. FENO is also a relevant biomarker to evaluate asthma status due to the change of its values occurring earlier than clinical manifestations and spirometry parameters. In addition, the measurement of FENO with portable devices helps to support the diagnosis of asthma, to follow-up the control of asthma and to personalize asthmatic patients for target treatment with biologic therapy. Therefore, measuring FENO with portable devices in the diagnosis and treatment of allergic airway inflammation, especially in asthma, is one of the most essential applications of NO biomarkers in exhaled breath.

Reduced nasal nitric oxide levels in patients with eosinophilic chronic rhinosinusitis

BACKGROUND

In Eosinophilic chronic rhinosinusitis (ECRS), it is difficult to estimate the refractoriness and recurrence risk for each patient. Fraction of exhaled nitric oxide (FeNO) is known as a biomarker of eosinophilic inflammation in lower airway. It has been reported that nasal NO has some crucial functions in the upper and lower airways. However, in upper airway, paranasal sinuses, the usefulness of NO measurement remains controversial. The purpose of this study is to identify the usefulness of nasal NO measurement in ECRS and the involvement of nasal NO in the pathogenesis of ECRS.

METHODS

We compared the nasal NO levels of ECRS, non-ECRS, and normal control groups. Correlation between nasal NO levels and clinical findings were observed. Then, we compared nasal NO levels before and after endoscopic sinus surgery (ESS). We also examine whether nasal NO levels might discriminate ECRS by the receiver operating characteristic (ROC) curve analysis.

RESULTS

Nasal NO levels were significantly decreased in ECRS compared to the other two groups. Moreover, nasal NO levels in ECRS significantly and negatively correlated with eosinophil levels and CT score. However, they did not correlate with the nasal polyp score. Nasal NO levels were not upregulated soon after opening the sinus ostium by ESS. The ROC curves for nasal NO levels were used to discriminate all CRS patients and ECRS patients from normal controls.

CONCLUSIONS

Nasal NO may be useful as a marker of ECRS severity and low nasal NO levels in ECRS may contribute to its pathogenesis.

Nasal Nitric Oxide Is Correlated With Nasal Patency and Nasal Symptoms

PURPOSE

Nitric oxide (NO) is an important endogenous mediator in both upper and lower respiratory systems. The purpose of the present study was to extract nasal NO (nNO) normal range of Chinese adults and the internal influencing factors. The differences in nNO levels between rhinitis and asymptomatic atopic subjects, and the diagnostic value of nNO in allergic rhinitis (AR) were further investigated.

METHODS

One thousand adults were recruited from the general public. Participants were divided into different subgroups according to the questionnaires and skin prick tests. In all of these subjects, nNO, fractional exhaled NO (FeNO) and nasal airflow resistance were measured. The normal ranges of nNO and FeNO, the differences between subgroups, and the correlations between NO (nNO and FeNO) and other internal factors were analyzed.

RESULTS

Both nNO and FeNO levels were significantly higher in AR patients than in healthy and asymptomatic atopic subjects. The nNO levels were significantly lower in asymptomatic atopic subjects than in normal adults. FeNO levels were significantly higher in non-AR patients than in the healthy and asymptomatic atopic adults. The cutoff value of nNO for the diagnosis of AR was 117.5 ppb (sensitivity, 50.9%; specificity, 63.9%). The nNO levels were correlated with FeNO levels, total nasal resistance measured at 75Pa, nasal volume within 0-7 cm from the anterior nares (V_0-7cm) and nasal symptom visual analogue scale (VAS) scores, while the FeNO levels were correlated with age, height, weight, body surface area, nasal volume of V_0-7cm and the nasal symptom VAS score.

CONCLUSIONS

The nNO level can be significantly different between healthy and AR patients and may be significantly correlated with nasal symptoms and nasal patency of rhinitis patients. However, the clinical value of nNO is still in the exploration stage.

Study of nasal exhaled nitric oxide levels in diagnosis of allergic rhinitis in subjects with and without asthma

Background

The measure of fractional exhaled nitric oxide (FENO) in the airways is a useful tool to guide the diagnosis and titration of inhaled corticosteroids in patients with asthma. However, its role in diagnosis of allergic rhinitis (AR), especially in subjects with asthma, is not well established.

Objective

To study the cutoff of nasal FENO in the diagnosis of subjects with AR and AR-asthma compared to age-matched subjects without AR or asthma and its correlations with the clinical and functional characteristics.

Methods

The study was cross sectional and descriptive. Subjects were grouped into control subjects, AR, and AR-asthma, based on the inclusion criteria. Exhaled NO (nasal FENO, bronchial FENO, and alveolar concentration of NO) was measured by multiple flow electro-luminescence device.

Results

Six hundred twenty-eight subjects were included: 217 control subjects (children: n=98, 10±4 years; adults: n=119, 50±16 years), 168 subjects with AR (children: n=54, 10±3 years; adults: n=114, 49±15 years), and 243 subjects with AR-asthma (children: n=115, 10±3 years; adults: n=128, 51±14 years). Nasal peak inspiratory flow and peak expiratory flow were lower in subjects with AR and AR-asthma than in control subjects (P<0.01 and P<0.01; and P<0.05 and P<0.01, respectively). Nasal FENO levels were significantly higher in subjects with AR and AR-asthma than in control subjects (1614±629 and 1686±614 ppb vs 582±161 ppb; P<0.001 and P<0.001, respectively). In subjects with AR non-asthma, the cutoffs of nasal FENO for those diagnosed with AR were 775 ppb in children, 799 ppb in adults, and 799 in the general population (sensitivity: 92.68%, 92.63%, and 92.65%, respectively; specificity: 91.67%, 95.00%, and 96.87%, respectively). In subjects with AR-asthma, the cutoffs of nasal FENO were higher, especially in asthma children (1458 ppb; sensitivity: 72.97% and specificity: 95.83%).

Conclusion

Nasal FENO measurement is a useful technique for the diagnosis of AR in subjects with and without asthma.