Values of fractional exhaled nitric oxide for cough-variant asthma in children with chronic cough

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.

Mechanic study based on untargeted metabolomics of Pi-pa-run-fei-tang on pepper combined with ammonia induced chronic cough model mice

ETHNOPHARMACOLOGICAL RELEVANCE

Pi-pa-run-fei-tang (PPRFT), a traditional Chinese medicine formula with long-standing history, demonstrated beneficial effect on chronic cough. However, the mechanism underlying efficacy unclear. In current research, we explored the impact and molecular mechanism of chronic cough mouse stimulating with capsaicin combined with ammonia.

AIM OF THE STUDY

To investigate the metabolic modulating effects, and potential mechanisms underlying the therapeutic effect of PPRFT in chronic cough.

MATERIALS AND METHODS

Chronic cough mouse models were created by stimulating mice by capsaicin combined with ammonia. Number of coughs and cough latency within 2 min were recorded. With lung tissue and serum samples collected for histopathology, metabolomics, RT-qPCR, immunohistochemistry, and WB analysis. Lymphocytes were isolated and flow cytometric assays were conducted to evaluate the differentiation between Th17 and Treg cell among CD4+ cells.

RESULTS

Results indicated that PPRFT obviously reduced the number of coughs, prolonged cough latency, reduced inflammatory cell infiltration and lung tissues damage, and decreased the serum level of IL-6, IL-1β, TNF-α, and IL-17 while increasing IL-10 levels. Notably, PPRFT suppressed Th17 cell divergence and promoted Treg cell divergence. Furthermore, serum metabolomic assays showed that 46 metabolites differed significantly between group, with 35 pathways involved. Moreover, mRNA levels of IL-6, NF-κB, IL-17, RORγT, JAK2, STAT3, PI3K and AKT in lung tissues remarkably reduced and mRNA levels of IL-10 and FOXP3 were elevated after PPRFT pretreatment. Additionally, PPRFT treatments decreased the protein levels of IL-6, NF-κB, IL-17, RORγT, p-JAK2, p-STAT3, p-PI3K, and p-AKT and increased the protein levels of IL-10 and FOXP3, but no significantly effects to the levels on JAK2, STAT3, PI3K, and AKT in the lungs.

CONCLUSION

Conclusively, our result suggested the effect with PPRFT on chronic cough may be mediated through IL-6/JAK2/STAT3 and PI3K/AKT/NF-κB pathway, which regulate the differentiation between Th17 and Treg cell. This beneficial effect of PPRFT in capsaicin and ammonia-stimulated chronic cough mice indicates its potential application in treating chronic cough.

Validity of fractional exhaled nitric oxide and small airway lung function measured by IOS in the diagnosis of cough variant asthma in preschool children with chronic cough

BACKGROUND

To investigate the role of combined impulse oscillometry (IOS) and fractional exhaled nitric oxide (FeNO) in the diagnosis of cough variant asthma (CVA) in preschool children.

METHODS

A total of 197 preschool-aged children with chronic cough were selected from the paediatric outpatient clinic. Allergy histories were collected for all children along with IOS and FeNO. Paediatric respiratory specialists divided the children into a CVA group (n = 90) and a noncough variant asthma (nCVA) group (n = 107) according to the diagnostic criteria for CVA After diagnostic treatment, the correlation between the FeNO and IOS values and the diagnosis in the two groups was analysed, and the area under the curve (AUC) of each index was calculated.

RESULTS

(1) X5 was significantly different between the CVA group and the nCVA group (- 4.22 vs. - 3.64, p < 0.001), as was the FeNO value (29.07 vs. 16.64, p < 0.001). (2) Receiver operating characteristic (ROC) analysis showed that the AUCs of FeNO alone and X5 alone were 0.779 and 0.657, respectively, while the AUC of FeNO (cut-off value of 18 ppb) plus X5 (cut-off value of -4.15 cmH2O/(l/s)) reached 0.809.

CONCLUSIONS

Children with CVA may have small airway dysfunction at an early stage. For preschool children with chronic cough, the combination of FeNO and X5 can better identify those with CVA.

TRIAL REGISTRATION NUMBER

This trial was registered with and approved by the Chinese Clinical Trial Registry, with registration number ChiCTRcRRC-17011738, and was reviewed and approved by the Ethics Committee of Southwest Hospital.

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].

Perspectives on chronic cough in Korea

Chronic cough is a common condition, and generally affects about 3% of Korean adults with a significant influence on quality of life (QoL). Despite continued clinical and academic efforts, there are unmet needs for chronic cough prevention and management in Korea. Epidemiologically, there are two major challenges: an aging population and air pollution. Korea is one of the most rapidly aging countries, and the relative proportion of elderly to younger people is expected to double within the next two decades. Air pollution is a major concern, but there is very limited evidence on the effects of air pollutant on cough in Korean patients. Clinically, upper and lower airway diseases, such as rhinitis/rhinosinusitis and cough variant asthma/eosinophilic bronchitis, are reported to account for about 75% of chronic cough in Korean adults, which formed the basis in formulating clinical practice guidelines. However, further studies are warranted to resolve clinical uncertainty, particularly for the evaluation and treatment of upper airway conditions in chronic cough. The prevalence of gastroesophageal reflux disease (GERD) is increasing, thus its relevance to cough among Koreans may warrant re-evaluation. Infection-associated chronic cough, such as tuberculosis, is another continuing concern. The proportion of chronic refractory or unexplained cough is assumed to be 10–20% among patients visiting referral clinics for chronic cough. This review presents our perspectives on current epidemiological and clinical issues of chronic cough in Korea, and addresses major knowledge gaps and future research priorities.