The potential role of direct and indirect bronchial challenge testing to identify overtreatment of community managed asthma

Should Airway Hyper-Responsiveness Be Included in the Definition of Clinical Remission With Biologic Therapy in Severe Asthma

Airway hyper-responsiveness (AHR) is a tenet of the persistent asthma phenotype along with reversible airway obstruction and type 2 (T2) inflammation. Indirect acting challenges such as mannitol are more closely related to the underlying T2 inflammatory process as compared with direct challenges. In this review article, we summarise the current literature and explore the future role of mannitol AHR in clinical remission with biologics.

Efficacy of biologic therapy on airway hyperresponsiveness in asthma

Airway hyperresponsiveness refers to an exaggerated bronchial constrictor response to a given exogenous inhaled agent and is governed by airway smooth muscle along with mucosal inflammation in asthma. In recent years, the advent of biologics and antialarmins has transformed severe asthma treatment in terms of reducing oral-corticosteroid-requiring exacerbations and improving disease control, asthma quality of life, and spirometry-measured lung function. In contrast, there have been comparatively fewer studies investigating the efficacy of biologics in airway hyperresponsiveness. In this focused review, we summarize the existing evidence base in this area regarding omalizumab, mepolizumab, benralizumab, and tezepelumab.

Use of Fractional Exhaled Nitric Oxide to Guide the Treatment of Asthma: An Official American Thoracic Society Clinical Practice Guideline

Background: The fractional exhaled nitric oxide (FE_NO) test is a point-of-care test that is used in the assessment of asthma.

Objective: To provide evidence-based clinical guidance on whether FE_NO testing is indicated to optimize asthma treatment in patients with asthma in whom treatment is being considered.

Methods: An international, multidisciplinary panel of experts was convened to form a consensus document regarding a single question relevant to the use of FE_NO. The question was selected from three potential questions based on the greatest perceived impact on clinical practice and the unmet need for evidence-based answers related to this question. The panel performed systematic reviews of published randomized controlled trials between 2004 and 2019 and followed the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) evidence-to-decision framework to develop recommendations. All panel members evaluated and approved the recommendations.

Main Results: After considering the overall low quality of the evidence, the panel made a conditional recommendation for FE_NO-based care. In patients with asthma in whom treatment is being considered, we suggest that FE_NO is beneficial and should be used in addition to usual care. This judgment is based on a balance of effects that probably favors the intervention; the moderate costs and availability of resources, which probably favors the intervention; and the perceived acceptability and feasibility of the intervention in daily practice.

Conclusions: Clinicians should consider this recommendation to measure FE_NO in patients with asthma in whom treatment is being considered based on current best available evidence.

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.

Comparison of methacholine and mannitol challenges: importance of method of methacholine inhalation

Background

Direct inhalation challenges (e.g. methacholine) are stated to be more sensitive and less specific for a diagnosis of asthma than are indirect challenges (e.g. exercise, non-isotonic aerosols, mannitol, etc.). However, data surrounding comparative sensitivity and specificity for methacholine compared to mannitol challenges are conflicting. When methacholine is inhaled by deep total lung capacity (TLC) inhalations, deep inhalation inhibition of bronchoconstriction leads to a marked loss of diagnostic sensitivity when compared to tidal breathing (TB) inhalation methods. We hypothesized that deep inhalation methacholine methods with resulting bronchoprotection may be the explanation for conflicting sensitivity/specificity data.

Methods

We reviewed 27 studies in which methacholine and mannitol challenges were performed in largely the same individuals. Methacholine was inhaled by dosimeter TLC methods in 13 studies and by tidal breathing in 14 studies. We compared the rates of positive methacholine (stratified by inhalation method) and mannitol challenges in both asthmatics and non-asthmatics.

Results

When methacholine was inhaled by TLC inhalations the prevalence of positive tests in asthmatics, 60.2% (548/910), was similar to mannitol, 58.9% (537/912). By contrast, when methacholine was inhaled by tidal breathing the prevalence of positive tests in asthmatics 83.1% (343/413) was more than double that of mannitol, 41.5% (146/351). In non-asthmatics, the two methacholine methods resulted in positive tests in 18.8% (142/756) and 16.2% (27/166) by TLC and TB inhalations respectively. This compares to an overall 8.3% (n = 76) positive rate for mannitol in 913 non-asthmatics.

Conclusion

These data support the hypothesis that the conflicting data comparing methacholine and mannitol sensitivity and specificity are due to the method of methacholine inhalation. Tidal breathing methacholine methods have a substantially greater sensitivity for a diagnosis of asthma than either TLC dosimeter methacholine challenge methods or mannitol challenge. Methacholine challenges should be performed by tidal breathing as per recent guideline recommendations. Methacholine (more sensitive) and mannitol (more specific) will thus have complementary diagnostic features.

Priorities for future research into asthma diagnostic tools: A PAN-EU consensus exercise from the European asthma research innovation partnership (EARIP)

The diagnosis of asthma is currently based on clinical history, physical examination and lung function, and to date, there are no accurate objective tests either to confirm the diagnosis or to discriminate between different types of asthma. This consensus exercise reviews the state of the art in asthma diagnosis to identify opportunities for future investment based on the likelihood of their successful development, potential for widespread adoption and their perceived impact on asthma patients. Using a two-stage e-Delphi process and a summarizing workshop, a group of European asthma experts including health professionals, researchers, people with asthma and industry representatives ranked the potential impact of research investment in each technique or tool for asthma diagnosis and monitoring. After a systematic review of the literature, 21 statements were extracted and were subject of the two-stage Delphi process. Eleven statements were scored 3 or more and were further discussed and ranked in a face-to-face workshop. The three most important diagnostic/predictive tools ranked were as follows: "New biological markers of asthma (eg genomics, proteomics and metabolomics) as a tool for diagnosis and/or monitoring," "Prediction of future asthma in preschool children with reasonable accuracy" and "Tools to measure volatile organic compounds (VOCs) in exhaled breath."

Bronchoprovocation Testing in Asthma: An Update

Bronchial hyperresponsiveness (BHR) is defined as a heightened bronchoconstrictive response to airway stimuli. It complements the cardinal features in asthma, such as variable or reversible airflow limitation and airway inflammation. Although BHR is considered a pathophysiologic hallmark of asthma, it should be acknowledged that this property of the airway is dynamic, because its severity and even presence can vary over time with disease activity, triggers or specific exposure, and with treatment. In addition, it is important to recognize that there is a component that is not reflective of a specific disease entity.

Fatal Asthma: An Audit of 30 Million Patient-Years of Health Plan Membership from 2007 to 2015

BACKGROUND

Without accurate data on deaths directly caused by asthma, prevention will be difficult.

OBJECTIVE

To determine how often asthma could be confirmed as a proximal cause of death in a large well-defined population with active health plan membership and no acute barriers to medical care.

METHODS

All deaths occurring in active Kaiser Permanente Southern California health plan members between 2007 and 2015 were identified. Asthma-coded deaths were manually audited for cause. Health care and asthma medication use in the 6 months before death were determined.

RESULTS

There were 248 (0.80 per 100,000 patient-years) unaudited asthma-coded deaths. There were only 63 (26.5%) (0.20 per 100,000 patient-years) asthma-confirmed deaths. Individuals with asthma-confirmed deaths were younger, less likely to have ever smoked, and had fewer emergency visits in the 6 months before death compared with those with asthma excluded. Individuals with asthma-confirmed deaths used preventative inhalers at very low rates. We unexpectedly found that ever inclusion in the 2016 National Committee for Quality Assurance health effectiveness data and information set (HEDIS) for persistent asthma was associated with a higher risk of all-cause early death. Individuals with asthma-confirmed deaths were also unlikely to be in the HEDIS asthma dataset in the year they died, thus not targeted for outreach.

CONCLUSIONS

Audit-confirmed fatal asthma is more likely to occur in younger, nonsmoking, individuals, using very low rates of preventive inhalers. This will be a very difficult group to prospectively identify and manage effectively. Further research into the reasons for early death after HEDIS asthma dataset inclusion is warranted.

PTTG1IP and MAML3, novel genomewide association study genes for severity of hyperresponsiveness in adult asthma

BACKGROUND

The severity of bronchial hyperresponsiveness (BHR) is a fundamental feature of asthma. The severity of BHR varies between asthmatics and is associated with lack of asthma control. The mechanisms underlying this trait are still unclear. This study aimed to identify genes associated with BHR severity, using a genomewide association study (GWAS) on the slope of BHR in adult asthmatics.

METHODS

We performed a GWAS on BHR severity in adult asthmatics from the Dutch Asthma GWAS cohort (n = 650), adjusting for smoking and inhaled corticosteroid use, and verified results in three other cohorts. Furthermore, we performed eQTL and co-expression analyses in lung tissue.

RESULTS

In the discovery cohort, one genomewide significant hit located in phosphodiesterase 4D, cAMP-specif (PDE4D) and 26 SNPs with P-values < 1*10^-5 were found. None of our findings replicated in adult and childhood replication cohorts jointly. In adult cohorts separately, rs1344110 in pituitary tumour-transforming 1 interacting protein (PTTG1IP) and rs345983 in Mastermind-like 3 (MAML3) replicated nominally; minor alleles of rs345983 and rs1344110 were associated with less severe BHR and higher lung tissue gene expression. PTTG1IP showed significant co-expression with pituitary tumour-transforming 1, the binding factor of PTTG1lP, and with vimentin and E-cadherin1. MAML3 co-expressed significantly with Mastermind-like 2 (MAML2), both involved in Notch signalling.

CONCLUSIONS

PTTG1IP and MAML3 are associated with BHR severity in adult asthma. The relevance of these genes is supported by the eQTL analyses and co-expression of PTTG1lP with vimentin and E-cadherin1, and MAML3 with MAML2.

Developments in the field of allergy in 2014 through the eyes of Clinical and Experimental Allergy

The pathogenesis of asthma continues to be a major topic of interest to our authors with reviews and original papers on the role of viruses, mechanisms of inflammation, biomarkers, and phenotypes of asthma being major topics. A number of papers described new treatments for asthma focusing on blocking the Th2 response reflecting the fact that two decades of work in this area is finally bearing fruit. The pathogenesis of chronic rhinosinusitis is a growing area of interest, but there has been less on the genetics of airways disease than in previous years possibly reflecting the degree of rigour (and therefore a smaller body of work), with which these sorts of studies are now being undertaken. There continues to be a wide range of papers dealing with mechanisms of allergic disease ranging from clinical-based studies to basic research and the use of in vivo animal models especially mice. As before, mechanisms and new approaches to immunotherapy are common themes. Several were published in the allergens section investigating modification of allergens to increase their effectiveness and reduce the risk of adverse events. Risk factors for allergic disease was a common theme in the epidemiology section and food allergy a common theme in clinical allergy with papers on the development of protocols to induce tolerance and attempts to find biomarkers to distinguish sensitization from allergic disease. This was another exciting year for the editors, and we hope the readers of the journal.

Development and validation of a predictive model of failed stepping-down of inhaled corticosteroids in adult asthmatics

BACKGROUND

Asthma guidelines suggest stepping-down of inhaled corticosteroids (ICSs) when asthma is stable.

OBJECTIVE

To determine outcomes of stepping-down and prediction of outcome after stepping-down of ICSs in controlled adult asthma.

METHODS

We performed a retrospective study on 21-81 year-old hospital-based outpatients with asthma in Japan. Protocol for stepping-down of ICSs was performed according to the GINA guideline. Failure/success of stepping-down is judged as occurring exacerbation or not for stepping-down of ICSs. Multiple logistic regression analysis was used to develop a prediction model for failed stepping-down, and then was validated by the leave-one-out cross-validation method. Our model of prediction score was calculated using receiver-operating characteristic area under the curve (AUC) analysis. The Nelson-Aalen curve demonstrated time to failure of stepping-down of ICSs.

RESULTS

A total of 126 patients with asthma attempted the stepping-down of ICSs according to the guideline. Of patients with follow-up, 97 (77.0%) of stepping-down attempts were successful. Using multivariate logistic regression analysis, comorbidity with rhinitis/rhinosinusitis and phlegm grade were independent predictors of failed stepping-down of ICSs, with odds ratios of 3.8 (95% confidence interval, 1.04-13.3; P=0.04) and 1.3 (95% confidence interval, 1.01-11.5; P=0.04), respectively. These variables were then used to build a prediction score in terms of the prediction of failed stepping-down events. When the two variables were added to form the prediction score, the discriminative power of scores calculated by the prediction model using the AUC was 0.75 (range: 0.62-0.88) for naïve prediction and 0.72 (range: 0.60-0.86) after cross-validation. In the time-to-failure models, cumulative hazard ratio of failed stepping-down have fixed 1 year after stepping-down.

CONCLUSION

Our results suggest that comorbidity with rhinitis/rhinosinusitis and phlegm grade are imperative to predict failed stepping-down of ICSs in controlled patients with adult asthma.

Mechanisms of airway hyper-responsiveness in asthma: the past, present and yet to come

Airway hyper-responsiveness (AHR) has long been considered a cardinal feature of asthma. The development of the measurement of AHR 40 years ago initiated many important contributions to our understanding of asthma and other airway diseases. However, our understanding of AHR in asthma remains complicated by the multitude of potential underlying mechanisms which in reality are likely to have different contributions amongst individual patients. Therefore, the present review will discuss the current state of understanding of the major mechanisms proposed to contribute to AHR and highlight the way in which AHR testing is beginning to highlight distinct abnormalities associated with clinically relevant patient populations. In doing so we aim to provide a foundation by which future research can begin to ascribe certain mechanisms to specific patterns of bronchoconstriction and subsequently match phenotypes of bronchoconstriction with clinical phenotypes. We believe that this approach is not only within our grasp but will lead to improved mechanistic understanding of asthma phenotypes and we hoped to better inform the development of phenotype-targeted therapy.