Measurement of exhaled nitric oxide concentration in asthma: a systematic review and economic evaluation of NIOX MINO, NIOX VERO and NObreath

Artificial Intelligence in Point-of-Care Biosensing: Challenges and Opportunities

The integration of artificial intelligence (AI) into point-of-care (POC) biosensing has the potential to revolutionize diagnostic methodologies by offering rapid, accurate, and accessible health assessment directly at the patient level. This review paper explores the transformative impact of AI technologies on POC biosensing, emphasizing recent computational advancements, ongoing challenges, and future prospects in the field. We provide an overview of core biosensing technologies and their use at the POC, highlighting ongoing issues and challenges that may be solved with AI. We follow with an overview of AI methodologies that can be applied to biosensing, including machine learning algorithms, neural networks, and data processing frameworks that facilitate real-time analytical decision-making. We explore the applications of AI at each stage of the biosensor development process, highlighting the diverse opportunities beyond simple data analysis procedures. We include a thorough analysis of outstanding challenges in the field of AI-assisted biosensing, focusing on the technical and ethical challenges regarding the widespread adoption of these technologies, such as data security, algorithmic bias, and regulatory compliance. Through this review, we aim to emphasize the role of AI in advancing POC biosensing and inform researchers, clinicians, and policymakers about the potential of these technologies in reshaping global healthcare landscapes.

Recommendations for asthma monitoring in children: A PeARL document endorsed by APAPARI, EAACI, INTERASMA, REG, and WAO

Monitoring is a major component of asthma management in children. Regular monitoring allows for diagnosis confirmation, treatment optimization, and natural history review. Numerous factors that may affect disease activity and patient well-being need to be monitored: response and adherence to treatment, disease control, disease progression, comorbidities, quality of life, medication side-effects, allergen and irritant exposures, diet and more. However, the prioritization of such factors and the selection of relevant assessment tools is an unmet need. Furthermore, rapidly developing technologies promise new opportunities for closer, or even "real-time," monitoring between visits. Following an approach that included needs assessment, evidence appraisal, and Delphi consensus, the PeARL Think Tank, in collaboration with major international professional and patient organizations, has developed a set of 24 recommendations on pediatric asthma monitoring, to support healthcare professionals in decision-making and care pathway design.

Fractional nitric oxide measurement in exhaled air (FeNO): perspectives in the management of respiratory diseases

Exhaled nitric oxide (NO) production, upregulated by inflammatory cytokines and mediators in central and peripheral airways, can be easily and non-invasively detected in exhaled air in asthma and other respiratory conditions as a promising tool for disease monitoring. The American Thoracic Society and European Respiratory Society released recommendations that standardize the measurement of the fractional exhaled NO (FeNO). In asthma, increased FeNO reflects eosinophilic-mediated inflammatory pathways and, as a biomarker of T2 inflammation can be used to identify asthma T2 phenotype. In this setting its measurement has shown to be an important tool especially in the diagnostic process, in the assessment and evaluation of poor adherence or predicting positive response to inhaled corticosteroids treatment, in phenotyping severe asthma patients and as a biomarker to predict the response to biologic treatments. The discovery of the role of NO in the pathogenesis of different diseases affecting the airways and the possibility to estimate the predominant site of increased NO production has provided new insight on its regulatory role in the airways, making it suitable for a potential extended use in clinical practice for different pulmonary diseases, even though its role remains less clear than in asthma. Monitoring FeNO in pulmonary obstructive lung diseases including chronic bronchitis and emphysema, interstitial lung diseases, obstructive sleep apnea and other pulmonary diseases is still under debate but has opened up a window to the role NO may play in the management of these diseases. The use of FeNO is reliable, cost effective and recommendable in both adults and children, and should be implemented in the management of patients with asthma and other respiratory conditions.

Cost-Effectiveness of Fractional Exhaled Nitric Oxide Suppression Testing as an Adherence Screening Tool Among Patients With Difficult-to-Control Asthma

BACKGROUND

Approximately 50% of adults on long-term asthma medication are nonadherent. Current methods to detect nonadherence have had limited effect. Fractional exhaled nitric oxide suppression testing (FeNOSuppT) has demonstrated clinical effectiveness as an adherence screening tool to detect poor adherence to inhaled corticosteroids in difficult-to-control asthma prior to initiation of expensive biologic therapy.

OBJECTIVE

Estimate the cost effectiveness and budget impact of FeNOSuppT as a screen prior to the initiation of biologic therapy among U.S. adults with difficult-to-control asthma and high fractional exhaled nitric oxide (≥45 ppb).

METHODS

A decision tree simulated the progression of a cohort of patients over a 1-year time horizon into 1 of 3 states ([1] discharged from or [2] remain in specialist care; or [3] progress to biologics). Two strategies, with and without FeNOSuppT, were examined and the incremental net monetary benefit estimated using a discount rate of 3% and a willingness-to-pay threshold of $100,000 per quality-adjusted life year (QALY). Sensitivity analysis and a budget impact analysis were also undertaken.

RESULTS

In the baseline scenario, FeNOSuppT prior to the initiation of biologic therapy was associated with lower costs ($4,435/patient) and fewer QALYs (0.0023 QALY/patient) compared with no FeNOSuppT over 1 year and was considered cost effective (incremental net monetary benefit = $4,207). The FeNOSuppT was consistently found to be cost effective across a range of scenarios and in deterministic and probabilistic sensitivity analyses. Assuming differential levels of FeNOSuppT uptake (20%-100%), this was associated with budget savings ranging from USD $5 million to $27 million.

CONCLUSIONS

The FeNOSuppT is likely to be cost effective as a protocol-driven, objective, biomarker-based tool for identifying nonadherence in difficult-to-control asthma. This cost effectiveness is driven by cost savings from patients not progressing to expensive biologic therapy.

Critical evaluation of asthma biomarkers in clinical practice

The advent of personalized medicine has revolutionized the whole approach to the management of asthma, representing the essential basis for future developments. The cornerstones of personalized medicine are the highest precision in diagnosis, individualized prediction of disease evolution, and patient-tailored treatment. To this aim, enormous efforts have been established to discover biomarkers able to predict patients' phenotypes according to clinical, functional, and bio-humoral traits. Biomarkers are objectively measured characteristics used as indicators of biological or pathogenic processes or clinical responses to specific therapeutic interventions. The diagnosis of type-2 asthma, prediction of response to type-2 targeted treatments, and evaluation of the risk of exacerbation and lung function impairment have been associated with biomarkers detectable either in peripheral blood or in airway samples. The surrogate nature of serum biomarkers, set up to be less invasive than sputum analysis or bronchial biopsies, has shown several limits concerning their clinical applicability. Routinely used biomarkers, like peripheral eosinophilia, total IgE, or exhaled nitric oxide, result, even when combined, to be not completely satisfactory in segregating different type-2 asthma phenotypes, particularly in the context of severe asthma where the choice among different biologics is compelling. Moreover, the type-2 low fraction of patients is not only an orphan of biological treatments but is at risk of being misdiagnosed due to the low negative predictive value of type-2 high biomarkers. Sputum inflammatory cell analysis, considered the highest specific biomarker in discriminating eosinophilic inflammation in asthma, and therefore elected as the gold standard in clinical trials and research models, demonstrated many limits in clinical applicability. Many factors may influence the measure of these biomarkers, such as corticosteroid intake, comorbidities, and environmental exposures or habits. Not least, biomarkers variability over time is a confounding factor leading to wrong clinical choices. In this narrative review, we try to explore many aspects concerning the role of routinely used biomarkers in asthma, applying a critical view over the "state of the art" and contemporarily offering an overview of the most recent evidence in this field.

Effect of General Anesthesia Maintenance with Propofol or Sevoflurane on Fractional Exhaled Nitric Oxide and Eosinophil Blood Count: A Prospective, Single Blind, Randomized, Clinical Study on Patients Undergoing Thyroidectomy

Background: Nitric oxide (NO) is considered a means of detecting airway hyperresponsiveness, since even non-asthmatic patients experiencing bronchospasm intraoperatively or postoperatively display higher levels of exhaled NO. It can also be used as a non-invasive biomarker of lung inflammation and injury. This prospective, single-blind, randomized study aimed to evaluate the impact of two different anesthesia maintenance techniques on fractional exhaled nitric oxide (FeΝO) in patients without respiratory disease undergoing total thyroidectomy under general anesthesia. Methods: Sixty patients without respiratory disease, atopy or known allergies undergoing total thyroidectomy were randomly allocated to receive either inhalational anesthesia maintenance with sevoflurane at a concentration that maintained Bispectral Index (BIS) values between 40 and 50 intraoperatively or intravenous anesthesia maintenance with propofol 1% targeting the same BIS values. FeΝO was measured immediately preoperatively (baseline), postoperatively in the Postanesthesia Care Unit and at 24 h post-extubation with a portable device. Other variables measured were eosinophil blood count preoperatively and postoperatively and respiratory parameters intraoperatively. Results: Patients in both groups presented lower than baseline values of FeΝO measurements postoperatively, which returned to baseline measurements at 24 h post-extubation. In the peripheral blood, a decrease in the percentage of eosinophils was demonstrated, which was significant only in the propofol group. Respiratory lung mechanics were better maintained in the propofol group as compared to the sevoflurane group. None of the patients suffered intraoperative bronchospasm. Conclusions: Both propofol and sevoflurane lead to the temporary inhibition of NO exhalation. They also seem to attenuate systemic hypersensitivity response by reducing the eosinophil count in the peripheral blood, with propofol displaying a more pronounced effect and ensuring a more favorable mechanical ventilation profile as compared to sevoflurane. The attenuation of NO exhalation by both agents may be one of the underlying mechanisms in the reduction in airway hyperreactivity. The clinical significance of this fluctuation remains to be studied in patients with respiratory disease.

Dispositivos de medición de FENO

The use of devices for measuring the exhaled fraction of nitric oxide has proven to be very useful, especially in the diagnosis of asthma, prediction of response to corticosteroids, risk of exacerbations or compliance with treatment, among others, and their use is recommended by important clinical practice guidelines. In recent years we have witnessed a proliferation of options on the market with different characteristics. To help in choosing a device that suits the needs of the professionals involved in the management of asthma, this review presents some of the important characteristics of the most common devices. In addition, the existing comparative and pharmacoeconomic studies are analyzed so that professionals can make the choice of device guided by the most current evidence.

HBM4EU Diisocyanates Study—Research Protocol for a Collaborative European Human Biological Monitoring Study on Occupational Exposure

Diisocyanates have long been a leading cause of occupational asthma in Europe, and recently, they have been subjected to a restriction under the REACH regulations. As part of the European Human Biomonitoring project (HBM4EU), we present a study protocol designed to assess occupational exposure to diisocyanates in five European countries. The objectives of the study are to assess exposure in a number of sectors that have not been widely reported on in the past (for example, the manufacturing of large vehicles, such as in aerospace; the construction sector, where there are potentially several sources of exposure (e.g., sprayed insulation, floor screeds); the use of MDI-based glues, and the manufacture of spray adhesives or coatings) to test the usability of different biomarkers in the assessment of exposure to diisocyanates and to provide background data for regulatory purposes. The study will collect urine samples (analysed for diisocyanate-derived diamines and acetyl–MDI–lysine), blood samples (analysed for diisocyanate-specific IgE and IgG antibodies, inflammatory markers, and diisocyanate-specific Hb adducts for MDI), and buccal cells (micronucleus analysis) and measure fractional exhaled nitric oxide. In addition, occupational hygiene measurements (air monitoring and skin wipe samples) and questionnaire data will be collected. The protocol is harmonised across the participating countries to enable pooling of data, leading to better and more robust insights and recommendations.

Electrochemical monitoring of bronchial inflammation in pediatric athletes: A prospective study

The assessment of inflammation by accessible, reproducible and especially non-invasive methods is one of the main goals for numerous medical specialties. One variable for assessment is the fraction of nitric oxide in exhaled air (FeNO), which correlates with the inflammatory syndrome of the airways. The objective of the present study was the biochemical evaluation of FeNO in children practicing sports in Oltenia, Romania. Between January and December 2018, children practicing sports (football, track and field, judo, fencing, handball, volleyball and basketball) were enrolled in the study. The FeNO values were compared with the asthma history and with the spirometric evaluation. A total of 23 children without a previous asthma diagnosis exhibited positive spirometry results. The prevalence of the disease was 3.6% in the cohort, and FeNO dosing showed higher values in the group at risk in children diagnosed with asthma, compared with that in children without this diagnosis. The children who performed outdoor sports (soccer, and track and field) had higher electrochemical levels of nitric oxide compared with those who performed indoor sports (mean, 29.70 vs. 20.56; P<0.0005), which led to the hypothesis that these children had an increased risk of developing bronchospasm. FeNO dosing can thus be a useful and easy-to-use tool in practice for assessing bronchial inflammation in children practicing various types of sports. The spirometric data of undiagnosed asthma patients from the present study may indicate that the disease is still underdiagnosed within Romania.

Using FeNO Measurement in Clinical Asthma Management

Asthma is a common and heterogeneous disease, characterised by lower airway inflammation and airflow limitation. Critical factors in asthma management include establishing an accurate diagnosis and ensuring appropriate selection and dosage of anti-inflammatory therapies. The majority of asthma patients exhibit type 2 (T2) inflammation, with increased interleukin (IL)-4, IL-5, and IL-13 signalling, often with associated eosinophilia. Identifying lower airway eosinophilia with sputum induction improves asthma outcomes, but is time consuming and costly. Increased T2-inflammation leads to upregulation of nitric oxide (NO) release into the airway, with increasing fractional exhaled NO (FeNO) reflecting greater T2-inflammation. FeNO can be easily and quickly measured in the clinic, offering a point of care surrogate measure of the degree of lower airway inflammation. FeNO testing can be used to help confirm an asthma diagnosis, to guide inhaled corticosteroid therapy, to assess adherence to treatment, and to aid selection of appropriate biologic therapy. However, FeNO levels may also be influenced by a variety of intrinsic and extrinsic factors other than asthma, including nasal polyposis and cigarette smoking, and must be interpreted in the broader clinical context rather than viewed in isolation. This review discusses the clinical application of FeNO measurement in asthma care, from diagnosis to treatment selection, and describes its place in current international expert guidelines.

A comparative study of the RuiBreath and NIOX VERO analyzers for detecting fractional exhaled nitric oxide

Background

Fractional exhaled nitric oxide (FeNO) measurement is a reliable, noninvasive marker of airway inflammation. Portable FeNO analyzers facilitate the assessment of airway inflammation in primary care. Differences between analyzers from different manufacturers are not comparable. Here, we aimed to compare the FeNO values obtained by a new portable device (RuiBreath, Guangzhou Ruipu Medical Technology Co., Ltd, Guangzhou, China) to those obtained by the widely used NIOX VERO portable analyzer (Aerocrine AB, Solna, Sweden) in patients with asthma.

Methods

This prospective validation study enrolled patients (≥14 years old) with asthma over a 2-month period (July and August 2019) at the Beijing Chao-Yang Hospital. At least one valid FeNO measurement was obtained using each analyzer for all the participants.

Results

There were 197 participants in this study. The FeNONIOX and FeNORuiBreath values significantly differed (P=0.016). After log-transformation, a difference was found only when the FeNONIOX was <25 ppb (P<0.001). The FeNONIOX and FeNORuiBreath values had a significant correlation (r=0.938, P<0.001), which was confirmed by the Altman-Bland plot. Using a receiver-operating characteristic curve analysis, when using 49 ppb as the cut-off point for the two devices in identifying patients with symptomatic asthma symptoms, the sensitivity and specificity were 0.42 and 0.88, respectively, by NIOX, and 0.40 and 0.89, respectively, by RuiBreath.

Conclusions

This is the first report of FeNO values obtained by the new portable RuiBreath FeNO analyzer. The FeNORuiBreath values are reliable and directly comparable with the FeNONIOX values.

Cost utility of fractional exhaled nitric oxide monitoring for the management of children asthma

Introduction

Fractional exhaled nitric oxide is a simple, non-invasive measurement of airway inflammation with minimal discomfort to the patient and with results available within a few minutes. This study aimed to evaluate the cost-effectiveness of asthma management using fractional exhaled nitric oxide monitoring in patients between 4 and 18 years of age.

Methods

A Markov model was used to estimate the cost-utility of asthma management using fractional exhaled nitric oxide monitoring versus asthma management without using fractional exhaled nitric oxide monitoring (standard therapy) in patients between 4 and 18 years of age. Cost data were obtained from a retrospective study on asthma from a tertiary center, in Medellin, Colombia, while probabilities of the Markov model and utilities were obtained from the systematic review of published randomized clinical trials. The analysis was carried out from a societal perspective.

Results

The model showed that fractional exhaled nitric oxide monitoring was associated with a lower total cost than standard therapy (US $1333 vs. US $1452 average cost per patient) and higher QALYs (0.93 vs. 0.92 average per patient). The probability that fractional exhaled nitric oxide monitoring provides a more cost-effective use of resources compared with standard therapy exceeds 99% for all willingness-to-pay thresholds.

Conclusion

Asthma management using fractional exhaled nitric oxide monitoring was cost-effective for treating patients between 4 and 18 years of age with mild to moderate allergic asthma. Our study suggests evidence that could be used by decision-makers to improve clinical practice guidelines, but this should be replicated in different clinical settings.

Developing a reference protocol for structured expert elicitation in health-care decision-making: a mixed-methods study

BACKGROUND

Many decisions in health care aim to maximise health, requiring judgements about interventions that may have higher health effects but potentially incur additional costs (cost-effectiveness framework). The evidence used to establish cost-effectiveness is typically uncertain and it is important that this uncertainty is characterised. In situations in which evidence is uncertain, the experience of experts is essential. The process by which the beliefs of experts can be formally collected in a quantitative manner is structured expert elicitation. There is heterogeneity in the existing methodology used in health-care decision-making. A number of guidelines are available for structured expert elicitation; however, it is not clear if any of these are appropriate for health-care decision-making.

OBJECTIVES

The overall aim was to establish a protocol for structured expert elicitation to inform health-care decision-making. The objectives are to (1) provide clarity on methods for collecting and using experts' judgements, (2) consider when alternative methodology may be required in particular contexts, (3) establish preferred approaches for elicitation on a range of parameters, (4) determine which elicitation methods allow experts to express uncertainty and (5) determine the usefulness of the reference protocol developed.

METHODS

A mixed-methods approach was used: systemic review, targeted searches, experimental work and narrative synthesis. A review of the existing guidelines for structured expert elicitation was conducted. This identified the approaches used in existing guidelines (the 'choices') and determined if dominant approaches exist. Targeted review searches were conducted for selection of experts, level of elicitation, fitting and aggregation, assessing accuracy of judgements and heuristics and biases. To sift through the available choices, a set of principles that underpin the use of structured expert elicitation in health-care decision-making was defined using evidence generated from the targeted searches, quantities to elicit experimental evidence and consideration of constraints in health-care decision-making. These principles, including fitness for purpose and reflecting individual expert uncertainty, were applied to the set of choices to establish a reference protocol. An applied evaluation of the developed reference protocol was also undertaken.

RESULTS

For many elements of structured expert elicitation, there was a lack of consistency across the existing guidelines. In almost all choices, there was a lack of empirical evidence supporting recommendations, and in some circumstances the principles are unable to provide sufficient justification for discounting particular choices. It is possible to define reference methods for health technology assessment. These include a focus on gathering experts with substantive skills, eliciting observable quantities and individual elicitation of beliefs. Additional considerations are required for decision-makers outside health technology assessment, for example at a local level, or for early technologies. Access to experts may be limited and in some circumstances group discussion may be needed to generate a distribution.

LIMITATIONS

The major limitation of the work conducted here lies not in the methods employed in the current work but in the evidence available from the wider literature relating to how appropriate particular methodological choices are.

CONCLUSIONS

The reference protocol is flexible in many choices. This may be a useful characteristic, as it is possible to apply this reference protocol across different settings. Further applied studies, which use the choices specified in this reference protocol, are required.

FUNDING

This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 37. See the NIHR Journals Library website for further project information. This work was also funded by the Medical Research Council (reference MR/N028511/1).

Classification of non-acute bronchial asthma according to allergy and eosinophil characteristics: a retrospective study

BACKGROUND

Investigating the endotypes of the different asthma phenotypes would help disease monitoring, prognosis determination, and improving asthma management standardization. This study aimed to classify asthma into four endotypes according to the allergic and eosinophilic characteristics and explore the phenotypes (clinical characteristics, pulmonary functions, and fractional expired nitric oxide (FeNO)) of each endotype.

METHODS

This retrospective study included non-acute asthma patients treated at the First Hospital of Shanxi Medical University (05/2016-01/2018). The patients were classified into the eosinophilic allergic, eosinophilic non-allergic, non-eosinophilic allergic, and non-eosinophilic non-allergic asthma endotypes. Serum sIgE, lung function, FeNO, and induced sputum cytology were tested and compared among groups.

RESULTS

Of the 171 included patients, 22 had eosinophilic allergic asthma, 17 had eosinophilic non-allergic asthma, 66 had non-eosinophilic allergic asthma, and 66 had non-eosinophilic non-allergic asthma. Lung function measurements (FEV1%, FEF25%, FEF50%, FEF75%, and FEF25-75%) showed that airway dysfunction was worse in eosinophilic non-allergic asthma than in the other three endotypes (all P < 0.001). In allergic asthma patients, eosinophilic asthma had worse airway dysfunction than non-eosinophilic asthma (all P < 0.05). Similar results were found in non-allergic asthma (all P < 0.01). The FeNO levels in eosinophilic allergic asthma were higher than in eosinophilic non-allergic and non-eosinophilic non-allergic asthma (both P = 0.001).

CONCLUSIONS

FeNO can objectively reflect eosinophilic airway inflammation in asthma. Endotypic classification of asthma patients regarding the allergic and eosinophilic characteristics is conducive to the effective management of patients with asthma.

Economic Evaluation of the Use of FeNO for the Diagnosis and Management of Asthma Patients in Primary Care in Sweden

OBJECTIVE

To determine the economic impact of the fraction of exhaled nitric oxide (FeNO) in asthma diagnosis and management in primary care in Sweden.

METHODS

An economic model has been developed to determine the economic impact of the fraction of exhaled nitric oxide (FeNO) in asthma diagnosis and management in primary care in Sweden. The model includes the use and cost of commonly used tests, the associated outcomes and diagnostic accuracy. We compared FeNO with spirometry and reversibility testing, methacholine challenge test, allergy testing, and blood eosinophil count. One-way sensitivity analyses were performed to confirm the robustness of results.

RESULTS

Adding FeNO measurement in asthma diagnosis resulted in cost savings of SEK 672 per patient by the fourth year. The use of FeNO testing in asthma management proved to be a dominant strategy when compared with each other test except methacholine challenge test. Sensitivity analyses confirmed the robustness of the results.

CONCLUSION

Introducing FeNO testing in clinical practice for the diagnosis and management of asthma in primary care in Sweden is less costly than standard methods while providing similar health benefits.

Patients' and Clinicians' Visions of a Future Internet-of-Things System to Support Asthma Self-Management: Mixed Methods Study

BACKGROUND

Supported self-management for asthma reduces acute attacks and improves control. The internet of things could connect patients to health care providers, community services, and their living environments to provide overarching support for self-management.

OBJECTIVE

We aimed to identify patients' and clinicians' preferences for a future internet-of-things system and explore their visions of its potential to support holistic self-management.

METHODS

In an exploratory sequential mixed methods study, we recruited patients from volunteer databases and charities' social media. We purposively sampled participants to interview them about their vision of the design and utility of the internet of things as a future strategy for supporting self-management. Respondents who were not invited to participate in the interviews were invited to complete a web-based questionnaire to prioritize the features suggested by the interviewees. Clinicians were recruited from professional networks. Interviews were transcribed and analyzed thematically using PRISMS self-management taxonomy.

RESULTS

We interviewed 12 patients and 12 clinicians in the United Kingdom, and 140 patients completed the web-based questionnaires. Patients expressed mostly wanting a system to log their asthma control status automatically; provide real-time advice to help them learn about their asthma, identify and avoid triggers, and adjust their treatment. Peak flow (33/140, 23.6%), environmental (pollen, humidity, air temperature) (33/140, 23.6%), and asthma symptoms (25/140, 17.9%) were the specific data types that patient most wanted. Information about asthma and text or email access to clinical advice provided a feeling of safety for patients. Clinicians wanted automated objective data about the patients' condition that they could access during consultations. The potential reduction in face-to-face consultations was appreciated by clinicians which they perceived could potentially save patients' travel time and health service resources. Lifestyle logs of fitness regimes or weight control were valued by some patients but were of less interest to clinicians.

CONCLUSIONS

An automated internet-of-things system that requires minimal input from the user and provides timely advice in line with an asthma action plan agreed by the patient with their clinician was preferred by most respondents. Links to asthma information and the ability to connect with clinicians by text or email were perceived by patients as features that would provide a sense of safety. Further studies are needed to evaluate the usability and effectiveness of internet-of-things systems in routine clinical practice.

Risk factors and fraction of exhaled nitric oxide in obstructive sleep apnea in adults

OBJECTIVE

This study aimed to evaluate the relationship between obstructive sleep apnea (OSA) and the fraction of exhaled nitric oxide (F_ENO), and to assess the effect of risk factors of airway inflammation on OSA.

METHODS

Medical records of patients in the Respiratory Sleep Center at Chao-Yang Hospital in Beijing between January 2015 and June 2017 were analyzed. All patients were diagnosed with OSA. Data of the medical history, clinical examinations, F_ENO, and upper airway computed tomographic findings were collected. Logistic regression was used to evaluate risk factors of OSA.

RESULTS

A total of 181 patients were admitted to the Respiratory Sleep Center during the study and 170 had a diagnosis of OSA and were included in the study. Single factor analysis showed that male sex, age, body mass index, smoking index, alcohol consumption, F_ENO, soft palate thickness, soft palate length, the narrowest transverse diameter of the upper airway, tonsil size, and nasal sinusitis were risk factors for sleep-disordered breathing and disease severity.

CONCLUSIONS

Male sex, age, body mass index, F_ENO, the narrowest transverse diameter of the upper airway, and normal tonsil size are associated with OSA and disease severity. The severity of OSA is associated with F_ENO levels.

Evaluation of the diagnostic accuracy of fractional exhaled nitric oxide (FeNO) in patients with suspected asthma: study protocol for a prospective diagnostic study

INTRODUCTION

The measurement of fractional exhaled nitric oxide (FeNO) is promising for diagnosing asthma and might substitute for bronchial provocation (BP) tests. To evaluate the diagnostic accuracy of FeNO within a confirmatory study, the following hypotheses will be tested: (1) A FeNO cut-off >50 ppb (parts per billion) is suitable for diagnosing asthma (sensitivity 35%, specificity 95%); (2) If the clinical symptoms 'allergic rhinitis' and 'wheezing' are present, asthma can be diagnosed at FeNO >33 ppb with a positive predictive value (PPV) >70% and (3) A FeNO >33 ppb can predict responsiveness to inhaled corticosteroid (ICS) with a PPV >70%.

METHODS AND ANALYSIS

A prospective diagnostic study will be conducted in three practices of pneumologists in Germany. 300 patients suspected of suffering from asthma will be included. As an index test, patients perform FeNO measurement with the device NIOX VERO. As reference a test, patients are examined with whole bodyplethysmography and BP, if necessary. After 3 months, patients with an asthma diagnosis will be examined again to verify the diagnosis and evaluate ICS responsiveness. Patients who did not receive an asthma diagnosis at the initial examination will be phoned after 3 months and asked about persistent respiratory symptoms to exclude false negative findings. As a primary target, sensitivity and specificity of FeNO >50 ppb will be determined. As a secondary target the PPV for asthma at FeNO >33 ppb, when the symptoms 'allergic rhinitis' and 'wheezing' are present, will be calculated. Regarding ICS responsiveness, the PPV of FeNO >33 ppb will be determined.

ETHICS AND DISSEMINATION

The study was approved by the Ethical Committee of the Technical University of Munich (Reference number 122/20 S). The major results will be published in peer-reviewed academic journals and disseminated through conferences.

TRIAL REGISTRATION NUMBER

DRKS00021125.

Addressing Reduced Laboratory-Based Pulmonary Function Testing During a Pandemic

To reduce the spread of the severe acute respiratory syndrome coronavirus 2, many pulmonary function testing (PFT) laboratories have been closed or have significantly reduced their testing capacity. Because these mitigation strategies may be necessary for the next 6 to 18 months to prevent recurrent peaks in disease prevalence, fewer objective measurements of lung function will alter the diagnosis and care of patients with chronic respiratory diseases. PFT, which includes spirometry, lung volume, and diffusion capacity measurement, is essential to the diagnosis and management of patients with asthma, COPD, and other chronic lung conditions. Both traditional and innovative alternatives to conventional testing must now be explored. These may include peak expiratory flow devices, electronic portable spirometers, portable exhaled nitric oxide measurement, airwave oscillometry devices, and novel digital health tools such as smartphone microphone spirometers and mobile health technologies along with integration of machine learning approaches. The adoption of some novel approaches may not merely replace but could improve existing management strategies and alter common diagnostic paradigms. With these options comes important technical, privacy, ethical, financial, and medicolegal barriers that must be addressed. However, the coronavirus disease 19 pandemic also presents a unique opportunity to augment conventional testing by including innovative and emerging approaches to measuring lung function remotely in patients with respiratory disease. The benefits of such an approach have the potential to enhance respiratory care and empower patient self-management well beyond the current global pandemic.

The use of a direct bronchial challenge test in primary care to diagnose asthma

Many asthmatics in primary care have mild symptoms and lack airflow obstruction. If variable expiratory airflow limitation cannot be determined by spirometry or peak expiratory flow, despite a history of respiratory symptoms, a positive bronchial challenge test (BCT) can confirm the diagnosis of asthma. However, BCT is traditionally performed in secondary care. In this observational real-life study, we retrospectively analyze 5-year data of a primary care diagnostic center carrying out BCT by histamine provocation. In total, 998 primary care patients aged ≥16 years underwent BCT, without any adverse events reported. To explore diagnostic accuracy, we examine 584 patients with a high pretest probability of asthma. Fifty-seven percent of these patients have a positive BCT result and can be accurately diagnosed with asthma. Our real-life data show BCT is safe and feasible in a suitably equipped primary care diagnostic center. Furthermore, it could potentially reduce diagnostic referrals to secondary care.

Upper and Lower Respiratory Signs and Symptoms in Workers Occupationally Exposed to Flour Dust

A group of 142 bakers was studied in order to investigate the relationship between higher/lower respiratory signs/symptoms and inflammation biomarkers and occupational exposure to flour dust. A complete upper and lower respiratory tract evaluation was performed. Seven percent of bakers complained of lower respiratory symptoms, while 22% of them complained of upper respiratory symptoms. Fifty five percent of the bakers were allergic, and 37.1% showed sensitization to occupational allergens. Abnormal spirometries were found in 15% of bakers, while fractional exhaled nitric oxide (FeNO) was above the normal reference in 24.5% of them. Moreover, 23.8% of bakers were found to be hyposmic. Population mean peak nasal inspiratory flow (PNIF) was in the normal range even if almost all the workers suffered from neutrophilic rhinitis at nasal cytology with the number of nasal neutrophils increasing with the increase of the duration of exposure to flour dust (p = 0.03). PNIF and FEV1 (forced expiratory volume in the 1st second) showed a positive correlation (p = 0.03; r = 0.19). The Tiffeneau index decreased with the increase of dust (p = 0.017). A similar result was obtained once we divided our population into smokers and non-smokers (p = 0.021). Long-term exposure to bakery dusts can lead to a status of minimal nasal inflammation and allergy.

Accurate real-time FENO expirograms using complementary optical sensors

The fraction of exhaled nitric oxide (F_ENO) is an important biomarker for the diagnosis and management of asthma and other pulmonary diseases associated with airway inflammation. In this study we report on a novel method for accurate, highly time-resolved, real time detection of F_ENO at the mouth. The experimental arrangement is based on a combination of optical sensors for the determination of the temporal profile of exhaled NO and CO₂ concentrations. Breath CO₂ and exhalation flow are measured at the mouth using diode laser absorption spectroscopy (at 2 μm) and differential pressure sensing, respectively. NO is determined in a sidestream configuration using a quantum cascade laser based, cavity-enhanced absorption cell (at 5.2 μm) which simultaneously measures sidestream CO₂. The at-mouth and sidestream CO₂ measurements are used to enable the deconvolution of the sidestream NO measurement back to the at-mouth location. All measurements have a time resolution of 0.1 s, limited by the requirement of a reasonable limit of detection for the NO measurement, which on this timescale is 4.7 ppb (2 σ). Using this methodology, NO expirograms (F_ENOgrams) were measured and compared for eight healthy volunteers. The F_ENOgrams appear to differ qualitatively between individuals and the hope is that the dynamic information encoded in these F_ENOgrams will provide valuable additional insight into the location of the inflammation in the airways and potentially predict a response to therapy. A validation of the measurements at low-time resolution is provided by checking that results from previous studies that used a two-compartment model of NO production can be reproduced using our technology.

Relationships among bronchodilator reversibility, the fraction of exhaled nitric oxide, and the parameters of the forced oscillation technique in adult asthma treated with inhaled corticosteroids and long-acting β2 agonists combination

In bronchial asthma, both airway inflammation and reversible airway narrowing require assessment and treatment. These two pathologies are treated primarily with inhaled corticosteroids (ICS) and long-acting β2 agonists (LABA), respectively. Therefore, ICS-LABA combinations are widely used to treat asthma. Airway inflammation and reversible airway narrowing are assessed primarily with fraction of exhaled nitric oxide (FENO) and bronchodilator reversibility (BDR). The forced oscillation technique (FOT) has recently attracted attention as a method for assessing obstructive respiratory disturbance. However, little is known about the relationships among these assessments. Therefore, we investigated the relationships among BDR, FENO, and FOT during ICS-LABA combination therapy. The subjects comprised 87 patients (25 men and 62 women) with asthma undergoing ICS/LABA combination therapy from July to September 2017. We applied the FENO test, FOT, and BDR testing without the patients stopping their therapy. The rates of change in FEV₁ (ΔFEV₁%) was correlated with FENO (r = 0.278). Among the FOT parameters, X5 (r = -0.263), Fres (r = 0.292), and AX (r = 0.245) were significantly correlated with ΔFEV₁%. FENO, Fres and %FEV₁ at baseline in these stable asthmatics were significantly assosiated with ΔFEV₁% independently of the effects of age, atopy and body mass index (BMI). These results suggest that FENO and the results of respiratory function testing and FOT reflect different aspects of asthma and should be combined and comprehensively evaluated.

Fractional Exhaled Nitric Oxide (FENO) in the management of asthma: a position paper of the Italian Respiratory Society (SIP/IRS) and Italian Society of Allergy, Asthma and Clinical Immunology (SIAAIC)

Asthma prevalence in Italy is on the rise and is estimated to be over 6% of the general population. The diagnosis of asthma can be challenging and elusive, especially in children and the last two decades has brought evidences that asthma is not a single disease but consists of various phenotypes. Symptoms can be underestimated by the patient or underreported to the clinician and physical signs can be scanty. Usual objective measures, like spirometry, are necessary but sometimes not significant. Despite proper treatment, asthma can be a very severe condition (even leading to death), however new drugs have recently become available which can be very effective in its control. Since asthma is currently thought to be caused by inflammation, a direct measure of the latter can be of paramount importance. For this purpose, the measurement of Fractional Exhaled Nitric Oxide (FE_NO) has been used since the early years of the current century as a non-invasive, easy-to-assess tool useful for diagnosing and managing asthma. This SIP-IRS/SIAAIC Position Paper is a narrative review which summarizes the evidence behind the usefulness of FE_NO in the diagnosis, management and phenotypization of asthma.

Evolution of Airway Inflammation in Preschoolers with Asthma-Results of a Two-Year Longitudinal Study

Fractional exhaled nitric oxide (FeNO) is a non-invasive marker for eosinophilic airway inflammation and has been used for monitoring asthma. Here, we assess the characteristics of FeNO from preschool to school age, in parallel with asthma activity. A total of 167 asthmatic children and 66 healthy, age-matched controls were included in the 2-year prospective PreDicta study evaluating wheeze/asthma persistence in preschool-aged children. Information on asthma/rhinitis activity, infections and atopy was recorded at baseline. Follow-up visits were performed at 6-month intervals, as well as upon exacerbation/cold and 4–6 weeks later in the asthmatic group. We obtained 539 FeNO measurements from asthmatics and 42 from controls. At baseline, FeNO values did not differ between the two groups (median: 3.0 ppb vs. 2.0 ppb, respectively). FeNO values at 6, 12, 18 and 24 months (4.0, CI: 0.0–8.6; 6.0, CI: 2.8–12.0; 8.0, CI: 4.0–14.0; 8.5, CI: 4.4–14.5 ppb, respectively) increased with age (correlation p ≤ 0.001) and atopy (p = 0.03). FeNO was non-significantly increased from baseline to the symptomatic visit, while it decreased after convalescence (p = 0.007). Markers of disease activity, such as wheezing episodes and days with asthma were associated with increased FeNO values during the study (p < 0.05 for all). Age, atopy and disease activity were found to be important FeNO determinants in preschool children. Longitudinal and individualized FeNO assessment may be valuable in monitoring asthmatic children with recurrent wheezing or mild asthma.

Measurement of FeNO in asthma: what the hospital doctor needs to know

Asthma is the commonest chronic lung disease. Airway inflammation is a central component of asthma but clinical symptoms of asthma and standard spirometry are insensitive in reflecting the underlying inflammatory processes. Measurement of the fractional nitric oxide concentration in exhaled breath (FeNO) is a quantitative, non-invasive and safe method of measuring airway inflammation. Advances in technology and standardization have made FeNO measurements simple, enabling their use as a biomarker alongside traditional clinical tools in the assessment and management of asthma. Specifically, it can predict responsiveness to steroids and also newer biological therapy, predict future risk of exacerbation and help highlight treatment non-adherence, making it a useful asset to personalized medicine.

Measurement of Exhaled Nitric Oxide in Cirrhotic Patients with Esophageal and Gastric Varices

Background and aims. This study aimed to detect exhaled nitric oxide (eNO) level in cirrhotic patients and explore the correlation between eNO levels and the severity of cirrhosis. Methods. Patients were enrolled to analyze the relationship of eNO with noncirrhosis, cirrhosis, and complications of decompensated cirrhosis. We explored the potential predictive values of eNO in different states of cirrhosis. Results. The eNO levels were significantly increased in cirrhotic patients compared with noncirrhotic patients (14 (10-18) vs 8 (6-13) ppb, P < 0.001). The eNO level was increased in those with ascites (15 (14-22) vs 13 (10-18) ppb, P=0.026), with portal vein thrombosis (19.5 (11.75-22) vs 13.5 (10-17) ppb, P=0.032), or with the mucosal red-color sign of esophageal and gastric varices (EGV) (16.5 (10-21.75) vs 13 (10-14.75) ppb, P=0.041). Among cirrhotic patients undergoing hepatic venous pressure gradient (HVPG) measurement, the eNO level was significantly increased in the high-HVPG group (HVPG >12 mm Hg) compared with the low-HVPG group (6 mm Hg ≤ HVPG ≤ 12 mm Hg) (15 (11.75-19.25) vs 10 (8-14) ppb, P=0.011). Conclusions. The eNO level was increased in cirrhotic patients, especially in those complicated with ascites, portal vein thrombosis, mucosal red-color sign of varices, and high HVPG.

Serum levels of IL-5, IL-6, IL-8, IL-13 and IL-17A in pre-defined groups of adult patients with moderate and severe bronchial asthma

BACKGROUND

Bronchial asthma (BA) is a complex disease characterised by persistent inflammation. Exhaled nitric oxide (FeNO) and blood eosinophil count (b-Eos) are biomarkers for type 2 endotype of BA.

OBJECTIVE

To analyse a panel of serum interleukins and total IgE in predefined by FeNO and b-Eos groups of moderate and severe BA patients.

METHODS

Serum levels of IL-5, IL-6, IL-8, IL-13 and IL-17A (ELISA) were measured in 30 healthy controls (HC) and 80 adult BA patients. BA patients were split into 4 groups. Group 1:Low FeNO/Low b-Eos (n = 23; 28.8%); Group 2:Low FeNO/High b-Eos (n = 17; 21.3%); Group 3:High FeNO/Low b-Eos (n = 15; 18.8%); Group 4:High FeNO/High b-Eos (n = 25; 31.3%).

RESULTS

All interleukins and total IgE were significantly higher in patients with BA as compared with HC. IL-5 levels were highest in Group 2 (p < 0.05). IL-6, IL-13 and IL-17A levels were elevated in Groups 2, 3 and 4 as compared with HC (p < 0.05). Higher IL-8 levels were associated with a pattern of current smokers. Highest IL-17A levels were found in type 2 high groups with frequent exacerbations, mostly uncontrolled and severe BA. We have found a distinct pattern for each group based on demographic, clinical, functional, immunological and inflammatory characteristics.

CONCLUSION

FeNO and b-Eos are useful in the identification of severe type 2 BA subgroups with frequent exacerbations. IL-5, IL-6, IL-13 and IL-17A are involved in the persistent type 2 immune response in moderate and severe BA. We have identified a pattern of refractory, severe type 2/IL-17A high BA in the real clinical practice.

Systematic review of clinical prediction models to support the diagnosis of asthma in primary care

Diagnosing asthma is challenging. Misdiagnosis can lead to untreated symptoms, incorrect treatment and avoidable deaths. The best combination of clinical features and tests to achieve a diagnosis of asthma is unclear. As asthma is usually diagnosed in non-specialist settings, a clinical prediction model to aid the assessment of the probability of asthma in primary care may improve diagnostic accuracy. We aimed to identify and describe existing prediction models to support the diagnosis of asthma in children and adults in primary care. We searched Medline, Embase, CINAHL, TRIP and US National Guidelines Clearinghouse databases from 1 January 1990 to 23 November 17. We included prediction models designed for use in primary care or equivalent settings to aid the diagnostic decision-making of clinicians assessing patients with symptoms suggesting asthma. Two reviewers independently screened titles, abstracts and full texts for eligibility, extracted data and assessed risk of bias. From 13,798 records, 53 full-text articles were reviewed. We included seven modelling studies; all were at high risk of bias. Model performance varied, and the area under the receiving operating characteristic curve ranged from 0.61 to 0.82. Patient-reported wheeze, symptom variability and history of allergy or allergic rhinitis were associated with asthma. In conclusion, clinical prediction models may support the diagnosis of asthma in primary care, but existing models are at high risk of bias and thus unreliable for informing practice. Future studies should adhere to recognised standards, conduct model validation and include a broader range of clinical data to derive a prediction model of value for clinicians.

Comparison of three different exhaled nitric oxide analyzers in chronic respiratory disorders

BACKGROUND

Fractional exhaled nitric oxide (FeNO) measurement is a simple and non-invasive method for monitoring eosinophilic airway inflammation. New portable analyzers for FeNO measurements are constantly being developed. The aim of our study was to evaluate the agreement of FeNO values measured by new portable analyzers.

MATERIALS AND METHODS

FeNO was measured in 20 healthy subjects, 20 asthmatic and 20 chronic obstructive pulmonary disease patients using the analyzers Niox-VERO, Vivatmo-PRO and HypAir-FeNO. A linear relationship was estimated with Pearson's coefficient (r), and absolute agreement by the intraclass correlation coefficient (ICC) and bias with the limits of agreement (95% of paired differences) were assessed according to the Bland-Altman method.

RESULTS

In the study population (58 ± 14 years, 20 females), mean values of FeNO with their 95% confidence interval were 24.0 (18.6-29.4) with the Niox-VERO, 19.6 (13.6-25.7) with the Vivatmo-PRO and 20.4 (15.7-25.1) with the HypAir-FeNO. FeNO measured with the Niox-VERO was higher than the Vivatmo-PRO (mean difference of paired values +4.3; limits -16.0 to 25.7 ppb) and the HypAir-FeNO (+3.6; -12.2 to 19.4 ppb); the Vivatmo-PRO and HypAir-FeNO showed large variability of paired differences (-0.7; -16.5 to 15.0 ppb). Measurements linearly correlated with an imperfect absolute agreement: Niox-VERO versus Vivatmo-PRO r = 0.90 and ICC = 0.87; Niox-VERO versus HypAir-FeNO r = 0.93 and ICC = 0.90, Vivatmo-PRO versus HypAir-FeNO r = 0.96 and ICC = 0.93. Most of the disagreement was greater in some asthmatic patients at high values of FeNO.

CONCLUSIONS

The present study indicates that absolute exhaled NO measurements may differ to a clinically relevant extent using the Niox-VERO, Vivatmo-PRO and HypAir-FeNO analyzers. The devices cannot be used interchangeably.

Use of Symptoms Scores, Spirometry, and Other Pulmonary Function Testing for Asthma Monitoring

Asthma is a global problem affecting millions of people all over the world. Monitoring of asthma both in children and in adulthood is an indispensable tool for the optimal disease management and for the maintenance of clinical stability. To date, several resources are available to assess the asthma control, first is the monitoring of symptoms, both through periodic follow-up visits and through specific quality of life measures addressed to the patient in first person or to parents. Clinical monitoring is not always sufficient to predict the risk of future exacerbations, which is why further instrumental examinations are available including lung function tests, the assessment of bronchial hyper-reactivity and bronchial inflammation. All these tools may help in quantifying the future risk for each patient and therefore they potentially may change the natural history of asthmatic disease. The monitoring of asthma in children as in adults is certainly linked by many aspects, however the asthmatic child is a future asthmatic adult and it is precisely during childhood and adolescence that we should implement all the efforts and strategies to prevent the progression of the disease and the subsequent impairment of lung function. For these reasons, asthma monitoring plays a crucial role and must be particularly close and careful. In this paper, we evaluate several tools currently available for asthma monitoring, focusing on current recommendations emerging from various guidelines and especially on the differences between the monitoring in pediatric age and adulthood.

Exposure to Household Air Pollution from Biomass Cookstoves and Levels of Fractional Exhaled Nitric Oxide (FeNO) among Honduran Women

Household air pollution is estimated to be responsible for nearly three million premature deaths annually. Measuring fractional exhaled nitric oxide (FeNO) may improve the limited understanding of the association of household air pollution and airway inflammation. We evaluated the cross-sectional association of FeNO with exposure to household air pollution (24-h average kitchen and personal fine particulate matter and black carbon; stove type) among 139 women in rural Honduras using traditional stoves or cleaner-burning Justa stoves. We additionally evaluated interaction by age. Results were generally consistent with a null association; we did not observe a consistent pattern for interaction by age. Evidence from ambient and household air pollution regarding FeNO is inconsistent, and may be attributable to differing study populations, exposures, and FeNO measurement procedures (e.g., the flow rate used to measure FeNO).

Difference between two exhaled nitric oxide analyzers, NIOX VERO® electrochemical hand-held analyzer and NOA280i® chemiluminescence stationary analyzer

BACKGROUND

Fractional exhaled nitric oxide (FE_NO) is useful for the evaluation of eosinophilic airway inflammation, including that seen in asthma. Although a new electrochemical hand-held FE_NO analyzer, the NIOX VERO^® (Aerocrine AB, Solna, Sweden), is clinically convenient to use, it has not been fully compared with the chemiluminescence stationary electrochemical analyzer NOA280i^® (Sievers Instruments, Boulder, CO, USA) in terms of the level of measured FE_NO. The aim of this study was to determine whether there is a difference between the two analyzers.

METHODS

The FE_NO levels measured with both NIOX VERO^® and NOA280i^® were evaluated in 1,369 adults at Juntendo University Hospital from May 2016 to October 2016.

RESULTS

The median FE_NO level measured with the NIOX VERO^® was significantly lower than that measured with the NOA280i^® (41 ppb, range 5-368 ppb vs. 29 ppb, range 5-251 ppb; p < 0.001). There was a strong positive correlation in the measurement of FE_NO level between the NOA280i^® and the NIOX VERO^® (r = 0.942, p < 0.001). The following conversion equation was calculated: FE_NO (NOA280i^®) = 1.362 (SE, 0.661) + 1.384 (SE, 0.021) × FE_NO (NIOX VERO^®).

CONCLUSIONS

To our best knowledge, we have provided the first report showing that the measured FE_NO level with the NIOX VERO^® was approximately 30% lower than that with the NOA280i^® and that there was a significant correlation between the measurements of these two devices. The correction equation that we provided may help assess the data obtained by these two analyzers. Abbreviations ATS American Thoracic Society BMI Body mass index ERS European Respiratory Society FE_NO Fractional exhaled nitric oxide GINA Global Initiative for Asthma NO Nitric oxide ppb Parts per billion ROC Receiver operating characteristic SD Standard deviation.

The Role of Measurement Uncertainty in Health Technology Assessments (HTAs) of In Vitro Tests

INTRODUCTION

Numerous factors contribute to uncertainty in test measurement procedures, and this uncertainty can have a significant impact on the downstream clinical utility and cost-effectiveness of testing strategies. Currently, however, there is no clear guidance concerning if or how such factors should be considered within Health Technology Assessments (HTAs) of tests.

OBJECTIVE

The aim was to provide an introduction to key concepts in measurement uncertainty for the HTA community and to explore, via systematic review, current methods utilised within HTAs.

METHODS

HTAs of in vitro tests including a model-based economic evaluation were identified via the Centre for Reviews and Dissemination (CRD) HTA database and key reimbursement authority websites. Data were extracted to explore the specific components of measurement uncertainty assessed and methods utilised. The findings were narratively synthesised.

RESULTS

Of 107 identified HTAs, 20 (19%) attempted to assess components of measurement uncertainty: 15 did so via some form of pre-model assessment (such as a literature review or laboratory survey); four also included components within the economic model; and one considered measurement uncertainty within the model only. One study quantified the impact of measurement uncertainty on cost-effectiveness and found that this parameter significantly changed the results, but did not impact the overall decision uncertainty.

CONCLUSION

A minority of HTAs identified from this review used various approaches to assess and/or incorporate the impact of measurement uncertainty, indicating that these assessments are feasible. Uncertainty remains around best practice methodology for conducting such analyses; further research is required to ensure that future HTAs are fit for purpose.

A New Approach for Sampling Ordered Parameters in Probabilistic Sensitivity Analysis

BACKGROUND

Probabilistic sensitivity analysis (PSA) in cost-effectiveness analysis involves sampling a large number of realisations of an economic model. For some parameters, we may be uncertain around the true mean values of the variables, but the ordering of the values is known. Typical sampling approaches lack either statistical or clinical validity. For example, sampling using a common number generator results in extreme dependence, and independent sampling can lead to realisations with incorrect ordering.

METHODS

We propose a new sampling approach for ordered parameters, the difference method (DM) approach, which samples the parameters of interest via a difference parameter. If the parameters of interest are bounded, it involves transforming the variables so that they are unbounded and then sampling via the difference parameter. We have provided a Microsoft Excel workbook to implement the method. The proposed approach is illustrated with an example sampling ordered parameters for utility and cost.

RESULTS

The DM approach has a number of advantages when comparing with the typical approaches used in practice. It generates PSA samples that have similar summary statistics as the given values in our examples, while maintaining the constraint that one value was greater than another. The method also implies plausible positive correlation between the two ordered variables.

CONCLUSIONS

Both clinical and statistical validity should be checked when producing PSA samples. The DM approach should be considered as a solution to potential problems in generating PSA samples for ordered parameters.

Fractional exhaled nitric oxide as a predictor of response to inhaled corticosteroids in patients with non-specific respiratory symptoms and insignificant bronchodilator reversibility: a randomised controlled trial

BACKGROUND

Chronic non-specific respiratory symptoms are difficult to manage. This trial aimed to evaluate the association between baseline fractional exhaled nitric oxide (FeNO) and the response to inhaled corticosteroids in patients with non-specific respiratory symptoms.

METHODS

In this double-blind randomised placebo-controlled trial, we enrolled undiagnosed patients, aged 18-80 years, with cough, wheeze, or dyspnoea and less than 20% bronchodilator reversibility across 26 primary care centres and hospitals in the UK and Singapore. Patients were assessed for 2 weeks before being randomly assigned (1:1) to 4 weeks of treatment with extrafine inhaled corticosteroids (QVAR 80 μg, two puffs twice per day, equivalent to 800 μg per day beclomethasone dipropionate) or placebo. Randomisation was stratified by baseline FeNO measurement: normal (≤25 parts per billion [ppb]), intermediate (>25 tp <40 ppb), and high (≥40 ppb). The primary endpoint was change in Asthma Control Questionnaire (ACQ7) mean score. We used generalised linear modelling to assess FeNO as a predictor of response, estimating an interaction effect between FeNO and treatment on change in ACQ7. We did our primary and secondary analyses in the per-protocol set, which excluded patients with non-completion of the primary endpoint, non-compliance to treatment (ascertained by patient report), and study visits made outside the predefined visit windows. This study is registered on ClinicalTrials.gov, number NCT02294279.

FINDINGS

Between Feb 4, 2015, and July 12, 2016, we randomly assigned 294 patients to extrafine inhaled corticosteroid treatment (n=148) or placebo (n=146). Following exclusions due to protocol violations, we analysed 214 patients (114 extrafine inhaled corticosteroids and 100 placebo). We observed a significant interaction between baseline FeNO and treatment group for every 10 ppb increase in baseline FeNO, with the change in ACQ7 greater in the extrafine inhaled corticosteroids group than in the placebo group (difference between groups 0·071, 95% CI 0·002 to 0·139; p=0·044). The most common adverse events were nasopharyngitis (18 [12%] patients in the treatment group vs 13 [9%] in the placebo group), infections and infestations (25 [17%] vs 21 [14%]), and respiratory, thoracic, and mediastinal disorders (13 [9%] vs 17 [12%]).

INTERPRETATION

FeNO measurement is an easy and non-invasive tool to use in clinical practice in patients with non-specific respiratory symptoms to predict response to inhaled corticosteroids. Further research is needed to examine its role in patients with evidence of other airway diseases, such as chronic obstructive pulmonary disease.

FUNDING

Sponsored by OPRI with partial funding by Circassia and study drugs provided by TEVA.

Which inhaled corticosteroid and long-acting β-agonist combination is better in patients with moderate-to-severe asthma, a dry powder inhaler or a pressurized metered-dose inhaler?

Two main types of devices are used to facilitate the administration of inhaled corticosteroid (ICS) and long-acting β-agonist (LABA) in combination, dry powder inhalers (DPIs) and pressurized metered-dose inhalers (pMDIs). There are few reports comparing the effects of the two devices, and it is unknown which should be recommended for asthma patients with given sets of characteristics. In the current study, the beneficial effects and side effects associated with DPIs and pMDIs were compared, and the question of which device should be recommended for asthma patients was investigated. A prospective, randomized, crossover, comparative study in adult outpatients with asthma was conducted using salmeterol/fluticasone propionate combination (SFC) 50 μg/250 μg, one inhalation of Adoair® 250 Diskus® twice daily or two inhalations of Adoair® 125 Aerosol twice daily, for 8 weeks. Questionnaires, exhaled nitric oxide (FeNO) tests and pulmonary function tests were administered after the use of each device for 8 weeks, and the results derived from each device were compared. Sixty-eight subjects were included in the final analysis. There were no significant differences between quality-of-life scores, FeNO, spirometry test results and forced oscillation results. With regard to patient preferences, 57.4% preferred the Adoair® Aerosol and 35.3% preferred the Adoair® Diskus®, as determined via the comparative evaluation questionnaire. Although DPI prescription accounts for the predominant market share of combined ICS/LABA in Japan, patients preferred a pMDI device to a DPI device. Compared to DPIs, pMDIs may be the preferential choice for patients with asthma.

Relationship between Fractional Exhaled Nitric Oxide Level and Efficacy of Inhaled Corticosteroid in Asthma-COPD Overlap Syndrome Patients with Different Disease Severity

This study explored the relationship between the fractional exhaled nitric oxide (FeNO) level and the efficacy of inhaled corticosteroid (ICS) in asthma-chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS) patients with different disease severity. A total of 127 ACOS patients with ACOS (case group) and 131 healthy people (control group) were enrolled in this study. Based on the severity of COPD, the ACOS patients were divided into: mild ACOS; moderate ACOS; severe ACOS; and extremely severe ACOS groups. We compared FeNO levels, pulmonary function parameters including percentage of forced expiratory volume in 1 second (FEV1) to predicted value (FEV1%pred), ratio of FEV1 to forced vital capacity (FEV1/FVC), inspiratory capacity to total lung capacity (IC/TLC) and residual volume to total lung capacity (RV/TLC), arterial blood gas parameters, including PH, arterial partial pressure of oxygen (PaO₂) and arterial partial pressure of carbon dioxide (PaCO₂), total serum immunoglobulin E (IgE), induced sputum eosinophil (EOS), plasma surfactant protein A (SP-A), plasma soluble receptor for advanced glycation end products (sRAGE), sputum myeloperoxidase (MPO), sputum neutrophil gelatinase-associated lipocalin (NGAL) and Asthma Control Test (ACT) scores, and COPD Assessment Test (CAT) scores. Compared with pre-treatment parameters, the FeNO levels, RV/TLC, PaCO₂, total serum IgE, induced sputum EOS, plasma SP-A, sputum MPO, sputum NGAL, and CAT scores were significantly decreased after 6 months of ICS treatment, while FEV1%pred, FEV1/FVC, IC/TLC, PH, PaO2, plasma sRAGE, and ACT scores were significantly increased in ACOS patients with different disease severity after 6 months of ICS treatment. This finding suggests that the FeNO level may accurately predict the efficacy of ICS in the treatment of ACOS patients.

Exhaled nitric oxide in the diagnosis of asthma in adults: a systematic review

OBJECTIVES

To identify and synthesize evidence on the diagnostic accuracy of _FE NO for asthma in adults.

MATERIALS AND METHODS

Systematic searches (nine key biomedical databases and trial registers) were carried out on November 2014. Records were included if they recruited patients with the symptoms of asthma; used a single set of inclusion criteria; measured _FE NO₅₀ in accordance with American Thoracic Society guidelines, 2005 (off-line excluded); reported/allowed calculation of true-positive, true-negative, false-positive and false-negative patients as classified against any reference standard. Study quality was assessed using QUADAS II. Meta-analysis was planned where clinical study heterogeneity allowed. Rule-in and rule-out uses of _FE NO were considered.

RESULTS

A total of 4861 records were identified originally and 1312 in an update. Twenty-seven studies were included. Heterogeneity precluded meta-analysis. Results varied even within subgroups of studies. Cut-off values for the best sum of sensitivity and specificity varied from 12 to 55 p.p.b., but did not produce high accuracy. 100% sensitivity or 100% specificity was reported by some studies indicating potential use as a rule-in or rule-out strategy.

CONCLUSIONS AND CLINICAL RELEVANCE

_FE NO₅₀ had variable diagnostic accuracy even within subgroups of studies with similar characteristics. Diagnostic accuracy, optimal cut-off values and best position for _FE NO₅₀ within a pathway remain poorly evidenced.

Utilising exhaled nitric oxide information to enhance diagnosis and therapy of respiratory disease - current evidence for clinical practice and proposals to improve the methodology

INTRODUCTION

A non-invasive tool to diagnose respiratory diseases and to follow treatment has long been looked-for. Exhaled nitric oxide (NO) is a promising marker of inflammation in asthma but nearly 25-years of research has shown that it works in only certain endotypes of asthma. The modelling of NO dynamics of the lung can give more information than a single F_ENO value. Areas covered: The estimation of the NO production in the conducting airways and in the gas exchange area has given new insight of the NO production in diseases beyond asthma. In this article, we discuss the importance of methodology for NO measurement in the exhaled breath and the indication of applying this technique to detect respiratory disorders. This narrative review is an attempt to examine and discuss the physiological basis underlying exhaled NO measurements and the clinical evidence of the usefulness of this method in asthma and various other respiratory disorders. Expert commentary: Estimation of the NO parameters would aid in our understanding of the NO dynamics of the lung and thereby give more knowledge how to interpret the measured F_ENO value in clinical practice.

Exhaled nitric oxide levels to guide treatment for adults with asthma

BACKGROUND

Asthma guidelines aim to guide health practitioners to optimise treatment for patients so as to minimise symptoms, improve or maintain good lung function, and prevent acute exacerbations or flare-ups. The principle of asthma guidelines is based on a step-up or step-down regimen of asthma medications to maximise good health outcomes using minimum medications. Asthma maintenance therapies reduce airway inflammation that is usually eosinophilic. Tailoring asthma medications in accordance with airway eosinophilic levels may improve asthma outcomes such as indices of control or reduce exacerbations or both. Fractional exhaled nitric oxide (FeNO) is a marker of eosinophilic inflammation, and as it is easy to measure, has an advantage over other measurements of eosinophilic inflammation (for example sputum eosinophils).

OBJECTIVES

To evaluate the efficacy of tailoring asthma interventions based on exhaled nitric oxide (FeNO), in comparison to not using FeNO, that is management based on clinical symptoms (with or without spirometry/peak flow) or asthma guidelines or both, for asthma-related outcomes in adults.

SEARCH METHODS

We searched the Cochrane Airways Group Specialised Register of Trials, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, and reference lists of articles. The last searches were undertaken in June 2016.

SELECTION CRITERIA

All randomised controlled trials (RCTs) comparing adjustment of asthma medications based on exhaled nitric oxide levels compared to not using FeNO, that is management based on clinical symptoms (with or without spirometry/peak flow) or asthma guidelines or both.

DATA COLLECTION AND ANALYSIS

We reviewed results of searches against predetermined criteria for inclusion. We independently selected relevant studies in duplicate. Two review authors independently assessed trial quality and extracted data. We contacted study authors for further information, receiving responses from four.

MAIN RESULTS

We included seven adult studies; these studies differed in a variety of ways including definition of asthma exacerbations, FeNO cutoff levels used (15 to 35 ppb), the way in which FeNO was used to adjust therapy, and duration of study (4 to 12 months). Of 1700 randomised participants, 1546 completed the trials. The mean ages of the participants ranged from 28 to 54 years old. The inclusion criteria for the participants in each study varied, but all had a diagnosis of asthma and required asthma medications. In the meta-analysis, there was a significant difference in the primary outcome of asthma exacerbations between the groups, favouring the FeNO group. The number of people having one or more asthma exacerbations was significantly lower in the FeNO group compared to the control group (odds ratio (OR) 0.60, 95% confidence interval (CI) 0.43 to 0.84). The number needed to treat to benefit (NNTB) over 52 weeks was 12 (95% CI 8 to 32). Those in the FeNO group were also significantly more likely to have a lower exacerbation rate than the controls (rate ratio 0.59, 95% CI 0.45 to 0.77). However, we did not find a difference between the groups for exacerbations requiring hospitalisation (OR 0.14, 95% CI 0.01 to 2.67) or rescue oral corticosteroids (OR 0.86, 95% CI 0.50 to 1.48). There was also no significant difference between groups for any of the secondary outcomes (FEV1, FeNO levels, symptoms scores, or inhaled corticosteroid doses at final visit).We considered three included studies that had inadequate blinding to have a high risk of bias. However, when these studies were excluded from the meta-analysis, the difference between the groups for the primary outcomes (exacerbations) remained statistically significant. The GRADE quality of the evidence ranged from moderate (for the outcome 'exacerbations') to very low (for the outcome 'inhaled corticosteroid dose at final visit') based on the lack of blinding and statistical heterogeneity. Six of the seven studies were industry supported, but the company had no role in the study design or data analyses.

AUTHORS' CONCLUSIONS

With new studies included since the last version of this review, which included adults and children, this updated meta-analysis in adults with asthma showed that tailoring asthma medications based on FeNO levels (compared with primarily on clinical symptoms) decreased the frequency of asthma exacerbations but did not impact on day-to-day clinical symptoms, end-of-study FeNO levels, or inhaled corticosteroid dose. Thus, the universal use of FeNO to help guide therapy in adults with asthma cannot be advocated. As the main benefit shown in the studies in this review was a reduction in asthma exacerbations, the intervention may be most useful in adults who have frequent exacerbations. Further RCTs encompassing different asthma severity, ethnic groups in less affluent settings, and taking into account different FeNO cutoffs are required.

Accuracy of FENO for diagnosing asthma: a systematic review

BACKGROUND

Measurement of FE_NO might substitute bronchial provocation for diagnosing asthma. We aimed to investigate the diagnostic accuracy of FE_NO measurement compared with established reference standard.

METHODS

Systematic review and diagnostic meta-analysis. Data sources were Medline, Embase and Scopus up to 29 November 2015. Sensitivity and specificity were estimated using a bivariate model. Additionally, summary receiver-operating characteristic curves were estimated.

RESULTS

26 studies with 4518 participants (median 113) were included. Risk of bias was considered low for six of seven items in five studies and for five items in seven studies. The overall sensitivity in the meta-analysis was 0.65 (95% CI 0.58 to 0.72), the overall specificity 0.82 (0.76 to 0.86), the diagnostic OR 9.23 (6.55 to 13.01) and the area under the curve 0.80 (0.77 to 0.85). In meta-regression analyses, higher cut-off values were associated with increasing specificity (OR 1.46 per 10 ppb increase in cut-off) while there was no association with sensitivity. Sensitivities varied significantly within the different FE_NO devices, but not specificities. Neither prevalence, age, use of bronchoprovocation in >90% of participants or as exclusive reference standard test, nor risk of bias were significantly associated with diagnostic accuracy.

CONCLUSIONS

There appears to be a fair accuracy of FE_NO for making the diagnosis of asthma. The overall specificity was higher than sensitivity, which indicates a higher diagnostic potential for ruling in than for ruling out the diagnosis of asthma.

Fractional exhaled nitric oxide-measuring devices: technology update

The measurement of exhaled nitric oxide (NO) has been employed in the diagnosis of specific types of airway inflammation, guiding treatment monitoring by predicting and assessing response to anti-inflammatory therapy and monitoring for compliance and detecting relapse. Various techniques are currently used to analyze exhaled NO concentrations under a range of conditions for both health and disease. These include chemiluminescence and electrochemical sensor devices. The cost effectiveness and ability to achieve adequate flexibility in sensitivity and selectivity of NO measurement for these methods are evaluated alongside the potential for use of laser-based technology. This review explores the technologies involved in the measurement of exhaled NO.

Techniques and issues in breath and clinical sample headspace analysis for disease diagnosis

Analysis of volatile organic compounds (VOCs) from breath or clinical samples for disease diagnosis is an attractive proposition because it is noninvasive and rapid. There are numerous studies showing its potential, yet there are barriers to its development. Sampling and sample handling is difficult, and when coupled with a variety of analytical instrumentation, the same samples can give different results. Background air and the environment a person has been exposed to can greatly affect the VOCs emitted by the body; however, this is not an easy problem to solve. This review investigates the use of VOCs in disease diagnosis, the analytical techniques employed and the problems associated with sample handling and standardization. It then suggests the barriers to future development.

Fractional exhaled nitric oxide for the management of asthma in adults: a systematic review

The aim of this review was to evaluate the clinical effectiveness of fractional exhaled nitric oxide (FeNO) measured in a clinical setting for the management of asthma in adults.13 electronic databases were searched and studies were selected against predefined inclusion criteria. Quality assessment was conducted using QUADAS-2. Class effect meta-analyses were performed.Six studies were included. Despite high levels of heterogeneity in multiple study characteristics, exploratory class effect meta-analyses were conducted. Four studies reported a wider definition of exacerbation rates (major or severe exacerbation) with a pooled rate ratio of 0.80 (95% CI 0.63-1.02). Two studies reported rates of severe exacerbations (requiring oral corticosteroid use) with a pooled rate ratio of 0.89 (95% CI 0.43-1.72). Inhaled corticosteroid use was reported by four studies, with a pooled standardised mean difference of -0.24 (95% CI -0.56-0.07). No statistically significant differences for health-related quality of life or asthma control were found.FeNO guided management showed no statistically significant benefit in terms of severe exacerbations or inhaled corticosteroid use, but showed a statistically significant reduction in exacerbations of any severity. However, further research is warranted to clearly define which management protocols (including cut-off points) offer best efficacy and which patient groups would benefit the most.