Diagnostic accuracy of FeNO in asthma and predictive value for inhaled corticosteroid responsiveness: A prospective, multicentre study

Biologics in Asthma: Role of Biomarkers

Our modern understanding of asthma mainly concerns identification of inflammatory endotype to guide management. The distinction mostly concerns identification of type-2 inflammation, for which different biomarkers have been well characterized. Blood eosinophils corroborate activity in the interleukin (IL)-5 axis while fraction of exhaled nitric oxide is indicative of the IL-4/IL-13 axis, giving us an indication of activity in these distinct but complementary pathways. These biomarkers predict disease activity, with increased risk of exacerbations when elevated, and a further, multiplicative increase when both are elevated. Serum immunoglobulin E is also implicated in this pathway, and can represent allergen-related stimulation.

Noninvasive Disease Assessment in Eosinophilic Esophagitis With Fractionated Exhaled Nitric Oxide, Blood, and Fecal Biomarkers

BACKGROUND

Eosinophilic Esophagitis (EoE) is a chronic inflammatory condition of the esophagus triggered by food and aeroallergens. There is a need for noninvasive biomarkers that reliably detect EoE in patients with cardinal symptoms and predict treatment response to reduce endoscopic evaluations.

STUDY

Nonasthmatic patients 18 years or above with suspected or diagnosed EoE, gastroesophageal reflux disease (GERD), and control individuals with indication for endoscopy were enrolled prospectively between November 2020 and May 2022. Participants underwent body plethysmography with fractionated exhaled nitric oxide (FeNO) level measurement. Besides, serum and fecal biomarkers were measured by ELISA. A follow-up examination was scheduled after treatment initiation in patients with active EoE.

RESULTS

The median FeNO level in active EoE (20 ppb) was higher compared with GERD (15 ppb, P=0.038) and control individuals (14 ppb, P=0.046). Median FeNO did not significantly differ in EoE patients who underwent follow-up assessment after treatment response (20 ppb vs. 18 ppb, P=0.771). Serum EDN, ECP, and the absolute eosinophil blood count (AEC) were elevated in active EoE compared with control individuals but not compared with GERD except for AEC. Serum EDN, ECP and AEC decreased in EoE in remission at follow-up assessment. None of the fecal biomarkers was elevated in active EoE or during treatment.

CONCLUSIONS

Assessment of FeNO may have diagnostic value in differentiating patients with active EoE from non-EoE patients but is not a suitable marker for monitoring disease activity. Serum EDN, ECP, TARC, and AEC levels are emerging as potential candidates for monitoring disease activity in EoE.

Associations between nocturnal bedtime and asthma among adults in the United States

BACKGROUND

Sleep disorders have a significant impact on asthma. The aim of this study was to explore the association between nocturnal bedtime and asthma among adults in the United States.

METHODS

This study was a cross-sectional analysis involving 11,475 participants from the National Health and Nutrition Examination Survey (NHANES) during the period of 2015-2018. Nocturnal bedtime was categorized into three distinct groups: 2100 h or earlier, between 2100 h and 2300 h, and 2300 h or later. The association between night bedtime and asthma was detected using multivariable logistic regression analyses. Additionally, subgroup analyses were conducted to assess the impact of subgroups.

RESULTS

After adjustment for confounders, a positive association was revealed between later bedtime (after 2300 h) and the prevalence of asthma (OR = 1.20, 95%CI: 1.01-1.43). In the subgroup analysis, the following factors were associated with increased risk: 18-39 years (OR = 1.23, 95%CI: 1.02-1.48); female sex (OR = 1.30, 95%CI: 1.01-1.68); Hispanic patients (OR = 1.66, 95%CI: 1.17-2.37); heavy drinkers (OR = 1.52, 95%CI: 1.17-1.96); Body Mass Index (BMI) (< 25 kg/m2) (OR = 1.45, 95%CI: 1.13-1.87); vigorous physical activity (OR = 1.32, 95%CI: 1.05-1.65);Significant interactions were found between nocturnal bedtime and asthma based on age, sex, eosinophils (EOS) percent and depression (P Interaction < 0.05).

CONCLUSION

Our results confirmed a moderately increased risk of asthma attributed to later bedtime, especially in 18-39 years, women and patients of Hispanic ethnicity. Future studies should investigate the underlying mechanisms of this association and explore the clinical implications for asthma management.

Body Weight and Allergic Asthma: A Narrative Review

Obesity is a known risk factor for asthma development, progression, and exacerbation. Nevertheless, the underlying pathophysiological mechanisms explaining how obesity contributes to the development and progression of asthma have yet to be established. Here, we review human studies examining the associations between asthma and obesity, focusing on the literature from the past 10 years. Overall, current evidence suggests that while both asthma and obesity are complex diseases with significant heterogeneity, they both share various features of chronic inflammation. Furthermore, the interactions between asthma and obesity likely involve allergen-specific T helper type 2 (type 2) immune responses, as well as diverse non-type 2 inflammatory pathways. However, despite considerable progress, studies to date have not definitively elucidated the mechanisms that account for the observed association. A large-scale population-based study combined with translational immunological research, including targeted asthma therapies and pharmacological weight loss therapies, may be required to properly dissect the details of obesity-related asthma pathophysiology.

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.

Endotyping Chronic Respiratory Diseases: T2 Inflammation in the United Airways Model

Over the past 15 years, the paradigm of viewing the upper and lower airways as a unified system has progressively shifted the approach to chronic respiratory diseases (CRDs). As the global prevalence of CRDs continues to increase, it becomes evident that acknowledging the presence of airway pathology as an integrated entity could profoundly impact healthcare resource allocation and guide the implementation of pharmacological and rehabilitation strategies. In the era of precision medicine, endotyping has emerged as another novel approach to CRDs, whereby pathologies are categorized into distinct subtypes based on specific molecular mechanisms. This has contributed to the growing acknowledgment of a group of conditions that, in both the upper and lower airways, share a common type 2 (T2) inflammatory signature. These diverse pathologies, ranging from allergic rhinitis to severe asthma, frequently coexist and share diagnostic and prognostic biomarkers, as well as therapeutic strategies targeting common molecular pathways. Thus, T2 inflammation may serve as a unifying endotypic trait for the upper and lower airways, reinforcing the practical significance of the united airways model. This review aims to summarize the literature on the role of T2 inflammation in major CRDs, emphasizing the value of common biomarkers and integrated treatment strategies targeting shared molecular mechanisms.

Effect of Buteyko breathing technique on clinical and functional parameters in adult patients with asthma: a randomized, controlled study

BACKGROUND

The established therapy of asthma might be supported by additional non-pharmaceutical measures, such as the Buteyko breathing technique (BBT); however, the available data are mixed. To clarify the effects of BBT in patients with asthma, we investigated whether it led to clinical improvements with correlation to functional parameters.

METHODS

Using a randomized, controlled design, we studied two groups (n = 30 each) of patients with asthma under either BBT or usual therapy (UT) w/o BBT over a period of 3 months. The primary outcome comprised the voluntary control pause (CP) after 3 months, secondary outcomes an additional breathhold parameter, forced expiratory volume in 1 s (FEV1), capnovolumetry, exhaled nitric oxide (FeNO), Asthma Control Questionnaire (ACQ) and Nijmegen Questionnaire (NQ), and the use of medication (β2-agonists; inhaled corticosteroids, ICS).

RESULTS

CP showed significant time-by-group interaction [F(1,58.09) = 28.70, p < 0.001] as well as main effects for study group [F(1,58.27) = 5.91, p = 0.018] and time [F(1,58.36) = 17.67, p < 0.001]. ACQ and NQ scores were significantly (p < 0.05 each) improved with BBT. This was associated with reductions in the use of β2-agonists and ICS (p < 0.05 each) by about 20% each. None of these effects occurred in the UT group. While FEV1 and the slopes of the capnovolumetric expiratory phases 2 and 3 did not significantly change, the capnovolumetric threshold volume at tidal breathing increased (p < 0.05) with BBT by about 10 mL or 10%, compared to baseline, suggesting a larger volume of the central airways. No significant changes were seen for FeNO.

CONCLUSIONS

BBT was clinically effective, as indicated by the fact that the improvement in symptom scores and the small increase in bronchial volume occurred despite the significant reduction of respiratory pharmacotherapy. As the self-controlled Buteyko breathing therapy was well-accepted by the participants, it could be considered as supporting tool in asthma therapy being worth of wider attention in clinical practice. Trial registration Retrospectively registered on 10 March 2017 at ClinicalTrials.gov (NCT03098849).

The Saudi initiative for asthma - 2024 update: Guidelines for the diagnosis and management of asthma in adults and children

The Saudi Initiative for Asthma 2024 (SINA-2024) is the sixth version of asthma guidelines for the diagnosis and management of asthma for adults and children that was developed by the SINA group, a subsidiary of the Saudi Thoracic Society. The main objective of the SINA is to have guidelines that are up-to-date, simple to understand, and easy to use by healthcare workers dealing with asthma patients. To facilitate achieving the goals of asthma management, the SINA Panel approach is mainly based on the assessment of symptom control and risk for both adults and children. The approach to asthma management is aligned for age groups: adults, adolescents, children aged 5-12 years, and children aged <5 years. SINA guidelines have focused more on personalized approaches reflecting a better understanding of disease heterogeneity with the integration of recommendations related to biologic agents, evidence-based updates on treatment, and the role of immunotherapy in management. The medication appendix has also been updated with the addition of recent evidence, new indications for existing medication, and new medications. The guidelines are constructed based on the available evidence, local literature, and the current situation at national and regional levels. There is also an emphasis on patient-doctor partnership in the management that also includes a self-management plan.

Development of a diagnostic score using FeNO and symptoms to predict asthma

BACKGROUND

Fractional exhaled nitric oxide (FeNO) is known as effective for ruling-in asthma. The diagnostic value might be increased in combination with clinical signs and symptoms (CSS). The aim was to develop a new model for ruling-in and ruling-out asthma.

METHODS

Diagnostic multi-centre study in three practices of pneumologists in Germany. Whole-body plethysmography was combined with bronchodilation tests or bronchial provocation as diagnostic reference standard. Follow-up was performed after 3 months. An expert committee evaluated test results, symptoms, and course of disease for the final diagnosis. Relevant CSS known from guidelines were used to enable combinatorial development of decision rules. Outcomes of multiple logistic regression modeling were translated into a diagnostic score and internally validated by ten-fold cross validation.

RESULTS

308 patients with complete follow-up were included. 186 (60.4%) were female, average age was 44.7 years and 161 (52.5%) had asthma. The average area under the receiver operating curve (AUC) of the diagnostic score was 0.755 (interquartile range 0.721-0.814). Allergic rhinitis, wheezing, dyspnea on exertion, coughing attacks at night, and awakening by shortness of breath were leading symptoms for ruling-in asthma. Frequent coughing and frequent respiratory infections were leading symptoms for ruling-out. The combination of FeNO and CSS allowed ruling-in asthma with a probability of up to 99%, and ruling-out with a post-test probability down to 9%.

CONCLUSION

The diagnostic scoring model increased the diagnostic value of FeNO in combination with CSS. The new decision rule allowed to rule-in asthma with high certainty, and also to rule-out with acceptable certainty.

Exhaled Biomarkers for Point-of-Care Diagnosis: Recent Advances and New Challenges in Breathomics

Cancers, chronic diseases and respiratory infections are major causes of mortality and present diagnostic and therapeutic challenges for health care. There is an unmet medical need for non-invasive, easy-to-use biomarkers for the early diagnosis, phenotyping, predicting and monitoring of the therapeutic responses of these disorders. Exhaled breath sampling is an attractive choice that has gained attention in recent years. Exhaled nitric oxide measurement used as a predictive biomarker of the response to anti-eosinophil therapy in severe asthma has paved the way for other exhaled breath biomarkers. Advances in laser and nanosensor technologies and spectrometry together with widespread use of algorithms and artificial intelligence have facilitated research on volatile organic compounds and artificial olfaction systems to develop new exhaled biomarkers. We aim to provide an overview of the recent advances in and challenges of exhaled biomarker measurements with an emphasis on the applicability of their measurement as a non-invasive, point-of-care diagnostic and monitoring tool.

The Accuracy of a Screening Tool in Epidemiological Studies-An Example of Exhaled Nitric Oxide in Paediatric Asthma

Diagnostic tests are widely used in medicine, especially in the clinical setting. The doctor's decision regarding the treatment process is mostly based on the result of the diagnostic test. The value of the test is expressed by its accuracy. It is easier to verify the accuracy of a diagnostic test in a clinical setting in comparison to an epidemiological setting. Moreover, a very good test may not work in epidemiological settings in the same effective way as in a clinical setting, especially because the accuracy is affected by the prevalence of the disease. The aim of the study is to assess the accuracy of FeNO measurement in different respiratory disorders or symptoms, including their prevalence, in a childhood population. The secondary aim is to suggest the optimal FeNO cut-off for epidemiological screening for respiratory diseases and symptoms.

METHODS

The cross-sectional study included 447 children (50.8% boys and 49.2% girls) aged 6-9 years. An adapted version of the ISAAC questionnaire was used for the assessment of the respiratory status. FeNO was measured with an electrochemical device (Niox Mino) according to ERS/ATS recommendations. For interpretation, the FeNO cut-off values of 20 parts per billion (ppb), 25 ppb and 35 ppb were applied taking the real-life prevalence of the disease or symptoms into consideration and also for simulated prevalences of 20%, 30%, 40%, 50% for the interpretation of the accuracy of the test. The accuracy was calculated according to the following formula: Accuracy = (Prevalence) (Sensitivity) + (1- Prevalence) (Specificity). The area under the curve was calculated based on logistic regression.

RESULTS

For all respiratory outcomes, FeNO accuracy decreased with increasing prevalence, and in general the area under the curve (AUC) was low. The highest FeNO accuracy was found for any asthma diagnosis (with possible coexisting diseases/symptoms), i.e., 78.6%, 92.8% and 88.5% for FeNO cut-offs >19 ppb, >24 ppb and >34 ppb, respectively. The AUC was 0.628. For the same FeNO cut-offs, the accuracy of an asthma diagnosis without any coexisting diseases and symptoms was 81.2%, 87.5%, 92.9%, respectively, with an AUC of 0.757.

CONCLUSION

FeNO accuracy decreases with increasing prevalence of the respiratory disease and symptoms. The best accuracy for the FeNO cut-off in the screening of asthma for epidemiological purposes is 35 ppb. For isolated asthma, the best accuracy for FeNO was 92.9%.