The value of small airway function parameters and fractional exhaled nitric oxide for predicting positive methacholine challenge test in asthmatics of different ages with FEV1 ≥ 80% predicted

Fractional Exhaled Nitric Oxide Testing for the Diagnosis and Management of Asthma: a Health Technology Assessment

Background

Asthma is a common respiratory disease characterized by airflow obstruction caused by inflammation and narrowing of the airways. Nitric oxide is a gas that is present at low levels in the lungs, but that is elevated in the presence of airway inflammation. Fractional exhaled nitric oxide (FeNO) testing may help in the diagnosis and management of asthma by measuring the amount of nitric oxide in the breath. We conducted a health technology assessment of FeNO testing for the diagnosis and management of asthma in children and adults, which included an evaluation of the accuracy, effectiveness, cost-effectiveness, the budget impact of publicly funding FeNO testing, and patient preferences and values.

Methods

We performed a systematic literature search of the clinical evidence. We assessed the risk of bias of each included study using the Quality Assessment of Diagnostic Accuracy Studies tool, version 2 (QUADAS-2) and of each systematic review using the Risk of Bias Assessment Tool for Systematic Reviews (ROBIS). We evaluated the quality of the body of evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria. We performed a systematic economic literature search and conducted cost-utility analyses with a 20-year time horizon from a public payer perspective. We also analyzed the budget impact of publicly funding FeNO testing in children and adults in Ontario. To contextualize the potential value of FeNO testing, we spoke with people with asthma and their care partners.

Results

We included 48 primary studies assessing the diagnostic accuracy of FeNO testing and 2 reviews evaluating the effectiveness of FeNO testing for asthma management in the clinical evidence review. The use of FeNO testing for the diagnosis of asthma reported variable (~30% to 90%) sensitivities (GRADE: Very low) and consistently high (~70% to 100%) specificities (GRADE: Low) in children and adults. FeNO testing for asthma management likely reduced exacerbations in children (GRADE: Moderate) and adults (GRADE: Moderate), lowered oral corticosteroid use in children (GRADE: Moderate), and slightly improved lung function in a mixed population (GRADE: Moderate), but little to no improvement was seen in other outcomes. We found that, for asthma diagnosis, FeNO testing in addition to standard testing is cost-effective in children, with an incremental cost-effectiveness ratio (ICER) of $6,192 per quality-adjusted life-year (QALY) gained. FeNO testing is not cost-effective for asthma diagnosis in adults except when a higher FeNO cut-off is applied. For asthma management, the ICER of FeNO testing compared with standard care alone is $103,893 per QALY gained in children and $200,135 per QALY gained in adults. Publicly funding FeNO testing as an adjunct to standard testing for asthma diagnosis over the next 5 years would cost about $0.10 million to $0.22 million for children and $1.19 million to $1.61 million for adults over the next 5 years, and for asthma management would cost about $22.37 million for children and $195.99 million for adults over the next 5 years. Participants were unaware if they had experience with FeNO testing because of its similarity to other types of asthma testing, but they reported valuing the potential of FeNO testing to provide more information about their condition as well as aid in the diagnosis and management. Barriers to access include lack of awareness and the limited availability of FeNO testing across the province.

Conclusions

We found that FeNO testing had good diagnostic specificity (i.e., low false positive rate), supporting its use as an adjunct to standard testing to help rule-in an asthma diagnosis in both children and adults. FeNO testing to monitor and manage asthma likely resulted in a reduction in the number of people who experienced exacerbations and used oral corticosteroids, but may make little to no difference in improving other health outcomes. FeNO testing is likely cost-effective as an additional test to support the diagnosis of asthma in children, as well as in adults when a higher FeNO cut-off is applied, but is likely not cost-effective as an additional test to monitor and manage asthma in both children and adults. We estimate that publicly funding FeNO testing as an adjunct to standard testing for asthma diagnosis in Ontario would result in additional costs of $0.10 million to $0.22 million for children and $1.19 million to $1.61 million for adults over the next 5 years. For monitoring and managing asthma, FeNO testing would result in additional costs of $22.37 million for children and $195.99 million for adults over the next 5 years. People we spoke with were unaware if they had experience with FeNO testing because of its similarity to other types of asthma testing, but they reported valuing the potential of FeNO testing to provide more information about their condition as well as aid in the diagnosis and management of asthma.

The role of hematological parameters in asymptomatic and non-severe cases of Omicron variant infection

BACKGROUND

Omicron variants are currently the predominant circulating lineage worldwide and most cases are mild or asymptomatic. The Omicron variant is characterized by high transmissibility and immune evasion. Early identification of Omicron cases in clinical settings is crucial for controlling its spread. Previous studies have indicated that changes in hematological parameters can be used to predict the severity of coronavirus disease 2019 (COVID-19). However, the role of hematological parameters in non-severe and asymptomatic cases remains unknown. This study aimed to investigate the role of hematological parameters in non-severe and asymptomatic Omicron variant infections.

METHODS

Hematological parameters and results were analyzed and compared in symptomatic (n = 356) and asymptomatic (n = 171) groups respectively, and between these two groups with positive COVID-19 tests. The utility of hematological parameters for predicting positive COVID-19 tests was analyzed using receiver operating characteristic curves.

RESULTS

Individuals with non-severe cases exhibited decreased levels of platelets, lymphocytes, eosinophils, basophils, lymphocytes (%), eosinophils (%), and basophils (%), while exhibiting elevated counts of monocytes, neutrophils (%), monocytes (%), neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio (PLR), and C-reactive protein (CRP) when compared to suspected cases or asymptomatic carriers. In asymptomatic patients, positive carriers had lower leukocyte, neutrophil, and lymphocyte counts but higher monocyte, monocyte (%), PLR, and CRP levels than negative carriers. Basophil counts combined with lymphocytes or the PLR demonstrated a more significant predictive value in screening non-severe cases earlier compared to other parameters. The combined assessment of the monocyte (%) and the PLR had the highest area under the curve for diagnosing asymptomatic carriers.

CONCLUSIONS

Circulating basophils, alone or in combination with other hematological parameters, may be used as efficient biomarkers for early screening of non-severe Omicron cases.

Sex differences of small airway function and fractional exhaled nitric oxide in patients with mild asthma

BACKGROUND

Sex differences of small airway function (SAF) and fractional exhaled nitric oxide (FeNO) in patients with mild asthma remain unclear.

OBJECTIVE

To evaluate sex differences of SAF and FeNO in patients with mild asthma confirmed by positive methacholine challenge test (MCT) result.

METHODS

This cross-sectional, double-centered, observational study enrolled 1609 adult patients with forced expiratory volume in 1 second greater than or equal to 80% and suspected asthma symptoms. Data of spirometry, FeNO, impulse oscillometry measurements, and peripheral blood test result were compared between males and females. The receiver-operating characteristic curves of SAF parameters and FeNO in predicting positive MCT result were also calculated.

RESULTS

In patients with mild asthma matched by age, males had better SAF but higher FeNO levels than females (60 [29.27%] vs 187 [46.75%] for small airway dysfunction, 78.6% vs 72.0% for forced expiratory flow [FEF]_50%, 67.5% vs 60.1% for FEF_75%, 73.7% vs 67.4% for FEF_25%-75%, and 42.0 ppb vs 29.0 ppb for FeNO, respectively, all P ≤ .001). The FeNO levels in male current smokers were considerably lower than those of nonsmokers. SAF and FeNO values declined more rapidly with age among female than male patients with asthma. The optimal cutoff values of FEF_25%-75%, FEF_50%, and FeNO for predicting a positive MCT result were 81.5%, 86.4%, and 41.0 ppb in males vs 73.7%, 76.9%, and 35.0 ppb in females.

CONCLUSION

In patients with mild asthma, the female patients have worse SAF, lower FeNO levels, and a more prominent decline trend of those parameters with age than males. Sex-specific cutoff values should be considered when SAF parameters (FEF_25%-75%, FEF_50%), alone or combined with FeNO, are used to predict positive MCT result in asthma diagnosis.

Prediction of bronchodilation test in adults with chronic cough suspected of cough variant asthma

Background

Many patients with cough variant asthma (CVA) are underdiagnosed and undertreated due to the atypical symptoms, low diagnostic sensitivity of bronchodilator response (BDR), and limited application of bronchial challenge test.

Objective

To investigate whether airway reversibility in BDR can predict CVA diagnosis in patients with chronic cough and negative BDR.

Methods

This open-label, prospective cohort study included patients with chronic cough, nearly normal chest CT scan, and negative BDR results. Inhaled corticosteroids and long-acting β₂ agonists were given for 4 weeks. The confirmed diagnosis of CVA was defined as improved symptoms and an increase of forced expiratory volume in 1 s (FEV₁) by >12% and >200 mL after 4 weeks of treatment.

Results

Of 155 patients recruited, 140 completed the study. Patients in the CVA positive diagnosis group had greater absolute (Δ) and percent (Δ%) improvements in FEV₁ and forced expiratory flows (FEFs), and higher fractional exhaled nitric oxide (FENO) than in the CVA negative diagnosis group. The area under the receiver operating characteristic curves (AUCs) of ΔFEV₁%, FEF_25-75%pred (percentage of predicted forced expiratory flow at 25% to 75%) and FENO for CVA positive diagnosis was 0.825, 0.714, and 0.637, with cutoff values of 5.90%, 61.99% and 41.50 ppb, respectively. A joint model of ΔFEV₁% combined with FEF_25-75%pred or FENO increased the AUC to 0.848 and 0.847, respectively.

Conclusion

ΔFEV₁% in BDR can predict a CVA diagnosis and response to anti-asthma treatment in patients with chronic cough and negative BDR.

Clinical trial registration

[http://www.chictr.org.cn/index.aspx], identifier [ChiCTR2000029065].

Small Airways: The “Silent Zone” of 2021 GINA Report?

Asthma is a chronic disease, affecting approximately 350 million people worldwide. Inflammation and remodeling in asthma involve the large airways, and it is now widely accepted that the small airways (those with an internal diameter <2 mm) are involved in the pathogenesis of asthma and are the major determinant of airflow obstruction in this disease. From a clinical perspective, small airways dysfunction (SAD) is associated with more severe bronchial hyperresponsiveness, worse asthma control and more exacerbations. Unlike the GOLD guidelines which, in their definition, identify COPD as a disease of the small airways, the Global Initiative for Asthma (GINA) guidelines do not refer to the prevalence and role of SAD in asthmatic patients. This decision seems surprising, given the growing body of compelling evidence accumulating pointing out the high prevalence of SAD in asthmatic patients and the importance of SAD in poor asthma control. Furthermore, and remarkably, SAD appears to possess the characteristics of a treatable pulmonary trait, making it certainly appealing for asthma control optimization and exacerbation rate reduction. In this mini-review article, we address the most recent evidence on the role of SAD on asthma control and critically review the possible inclusion of SAD among treatable pulmonary traits in international guidelines on asthma.

Correlation between Reduced FEF25-75% and a Positive Methacholine Challenge Test in Adults with Nonobstructive Baseline Spirometry

Objective

To clarify whether in adults with a nonobstructive spirometry a reduced FEF25-75% is associated with a positive methacholine challenge test (MCT).

Methods

Data was collected for all the patients who had a MCT done between April 2014 and January 2020 but had nonobstructive baseline spirometry. Logistic regression was utilized to estimate the log odds of a positive methacholine test as a function of FEF25-75% and also for age, gender, BMI, FEV1, and FEV1/FVC.

Results

Out of 496 patients, 187 (38%) had a positive MCT. Baseline characteristics in two groups were similar except that patients with positive MCT were younger (32 ± 11.57 vs. 38 ± 13.25 years, respectively, p < 0.001). Mean FEF25-75% was lower in MCT positive (3.12 ± 0.99 L/s) vs. MCT negative (3.39 ± 0.97 L/s) patients, p = 0.003. Logistic regression results suggest that MCT outcome is inversely related to FEF25-75%, age, and gender. Specifically, as FEF25-75% percentage of predicted value increases, the log odds of a positive MCT decrease (odds ratio (OR) = 0.90, 95% confidence intervals (CI) = 0.84-0.96, p = 0.002). Also, as age increases, the log odds of a positive MCT decrease (OR = 0.95, 95%CI = 0.94-0.97, p < 0.001).

Conclusions

Reduced FEF25-75% in adults with nonobstructive spirometry can predict a positive response to MCT in younger patients. However, this relationship becomes weaker with increasing age.

Small Airway Dysfunction Measured by Impulse Oscillometry and Fractional Exhaled Nitric Oxide Is Associated With Asthma Control in Children

BACKGROUND

Impulse oscillometry (IOS) and fractional exhaled nitric oxide (FeNO) are sensitive and non-invasive methods to measure airway resistance and inflammation, although there are limited population-based studies using IOS and FeNO to predict asthma control.

OBJECTIVE

This study aimed to investigate the utility of IOS and FeNO for assessing childhood asthma control in terms of small airway dysfunction and airway inflammation.

METHODS

This prospective observational cohort study enrolled 5,018 school children (aged 6-12 years), including 560 asthmatic children and 140 normal participants. FeNO, spirometry, IOS, bronchial dilation test, total IgE, and childhood asthma control test (C-ACT) were measured. FeNO, IOS, spirometry, and C-ACT results were correlated with childhood asthma with and without control.

RESULTS

Uncontrolled asthmatic children had abnormal FeNO, IOS, and spirometric values compared with control subjects (P < 0.05). IOS parameters with R5, R5-R20, X5, Ax, △R5, and FeNO can predict lower C-ACT scales by the areas under receiver operating characteristic curves (AUCs) (0.616, 0.625, 0.609, 0.622, 0.625, and 0.714). A combination of FeNO (>20 ppb) with IOS measure significantly increased the specificity for predicting uncontrolled asthma patients compared with FeNO alone (P < 0.01). A multiple regression model showed that small airway parameter (R5-R20) was the strongest risk factor [OR (95% CI): 87.26 (7.67-993.31)] for uncontrolled asthma patients. Poor control with lower C-ACT scales correlated with high FeNO (r = -0.394), R5 (r = -0.106), and R5-R20 (r = -0.129) in asthmatic children (P < 0.05).

CONCLUSION

A combined use of FeNO and IOS measurements strongly predicts childhood asthma with or without control.

Transcriptome analysis in patients with asthma after inhaled combination therapy with long-acting β2-agonists and corticosteroids

Introduction: Asthma is one of the major public health problems that imposes a great burden on societal, financial, and healthcare around the world. Asthma poorly affects the health-related quality of life and daily activities of patients. Treatment of asthma, including inhaled corticosteroids (ICS) and long-acting beta-agonists (LABAs), mainly aims to improve the lung function and reduce symptoms and exacerbations. Current treatment regimens are symptom-based strategies, and the status of airway inflammation after treatment is yet unknown. We conducted this study to understand the comprehensive inflammation or airway remodeling status of patients after ICS-LABA treatment through RNA transcriptome analysis. Materials and methods: Eight newly diagnosed asthmatic patients and two healthy subjects were recruited in this study. Asthmatic patients underwent blood tests, lung function test, and RNA transcriptome analysis before and after ICS-LABA treatment. Results: In comparison with healthy subjects, pretreatment asthmatic patients had higher expression of protein tyrosine kinase and related signaling pathways. After ICS-LABA treatment, the expression of nuclear receptor transcription coactivator, N-acetyltransferase, protein tyrosine kinase, nuclear receptor, and RNA polymerase II-activating transcription factor were downregulated. However, the post-treatment asthmatic patients still had higher expression of cysteine-type endopeptidase, endodeoxyribonuclease, apolipoprotein, and unfolded protein was still upregulated than healthy subjects. Conclusions: The combination of ICS/LABAs decreased airway inflammatory and remodeling pathways. However, allergen stimulation-related pathways were still upregulated in patients after ICS/LABA treatment. The combination of medication and allergen removal is a complete strategy for asthma.

The Value of Fractional Exhaled Nitric Oxide and Impulse Oscillometric and Spirometric Parameters for Predicting Bronchial Hyperresponsiveness in Adults with Chronic Cough

Purpose

To evaluate the contribution of fractional exhaled nitric oxide (FeNO) and impulse oscillometry (IOS) and spirometric parameters in predicting bronchial hyperresponsiveness (BHR) in adults with chronic cough.

Patients and Methods

In total, 112 patients with chronic cough were enrolled in this prospective diagnostic study. Receiver operating characteristic (ROC) curves were generated to assess the diagnostic efficiency and optimal cut-off values of FeNO and IOS and spirometric parameters in predicting BHR. Optimal combinations of FeNO and IOS and spirometric parameters for BHR prediction were investigated using univariate and multivariate logistic regression models. Bootstrapping was employed for internal validation. Model discrimination and calibration were assessed using indices and calibration plots.

Results

Rhinitis and values of FeNO, IOS parameters (resonant frequency (Fres), reactance at 5 Hz (X5), and integrated area of low-frequency X (AX)) and spirometric parameters (FEV1, PEF, MEF₇₅, MEF₅₀, MEF₂₅, MMEF) were significantly different between patients with BHR and those without BHR (P < 0.05). After adjusting for rhinitis, logistic analyses showed that FeNO combined with Fres, FeNO combined with MMEF, or the combination of FeNO, Fres and MMEF had high predictive value in diagnosing BHR; the areas under the ROC curves (AUCs) of the corresponding three models were 0.914, 0.919 and 0.927, respectively. In addition, the three models displayed good discrimination, with high C-index values and good calibration.

Conclusion

FeNO combined with Fres or MMEF or a combination of these three parameters may be conveniently used as indicators in BHR prediction.