Symptoms, lung function, and perception of asthma control: an exploration into the heterogeneity of the asthma control construct

Post-COVID breathlessness: a mathematical model of respiratory processing in the brain

Breathlessness is among the most common post-COVID symptoms. In a considerable number of patients, severe breathlessness cannot be explained by peripheral organ impairment. Recent concepts have described how such persistent breathlessness could arise from dysfunctional processing of respiratory information in the brain. In this paper, we present a first quantitative and testable mathematical model of how processing of respiratory-related signals could lead to breathlessness perception. The model is based on recent theories that the brain holds an adaptive and dynamic internal representation of a respiratory state that is based on previous experiences and comprises gas exchange between environment, lung and tissue cells. Perceived breathlessness reflects the brain's estimate of this respiratory state signaling a potentially hazardous disequilibrium in gas exchange. The internal respiratory state evolves from the respiratory state of the last breath, is updated by a sensory measurement of CO2 concentration, and is dependent on the current activity context. To evaluate our model and thus test the assumed mechanism, we used data from an ongoing rebreathing experiment investigating breathlessness in patients with post-COVID without peripheral organ dysfunction (N = 5) and healthy control participants without complaints after COVID-19 (N = 5). Although the observed breathlessness patterns varied extensively between individual participants in the rebreathing experiment, our model shows good performance in replicating these individual, heterogeneous time courses. The model assumes the same underlying processes in the central nervous system in all individuals, i.e., also between patients and healthy control participants, and we hypothesize that differences in breathlessness are explained by different weighting and thus influence of these processes on the final percept. Our model could thus be applied in future studies to provide insight into where in the processing cascade of respiratory signals a deficit is located that leads to (post-COVID) breathlessness. A potential clinical application could be, e.g., the monitoring of effects of pulmonary rehabilitation on respiratory processing in the brain to improve the therapeutic strategies.

Depressive Symptoms and Overperception of Airflow Obstruction in Older Adults With Asthma

OBJECTIVE

Older adults are at increased risk for depression and poor asthma outcomes. We examined whether depressive symptoms are associated with overperception of airflow obstruction and a pattern of worse asthma control, but not pulmonary function.

METHODS

We recruited a cohort of adults with asthma 60 years and older in East Harlem and the Bronx, New York. Baseline measures included the Geriatric Depression Scale, Asthma Control Questionnaire, and Mini Asthma Quality of Life Questionnaire. Spirometry was conducted at baseline to assess pulmonary function. Perception of airflow obstruction was assessed for 6 weeks following baseline by participants entering estimates of peak expiratory flow (PEF) into a programmable peak flow meter followed by PEF blows. Participants were blinded to actual PEF values. The percentage of time that participants were in the overperception zone was calculated as an average.

RESULTS

Among the 334 participants (51% Hispanic, 25% Black), depressive symptoms were associated with overperception of airflow obstruction (β = 0.14, p = .029), worse self-reported asthma control (β = 0.17, p = .003), and lower asthma-related quality of life (β = -0.33, p < .001), but not with lung function (β = -0.01, p = .82). Overperception was also associated with worse self-reported asthma control (β = 0.14, p = .021), but not lung function (β = -0.05, p = .41).

CONCLUSIONS

Depressive symptoms were associated with greater perceived impairment from asthma, but not pulmonary function. Overperception of asthma symptoms may play a key role in the relationship between depression and asthma outcomes in older adults.

A Systematic Review of Asthma Phenotypes Derived by Data-Driven Methods

Classification of asthma phenotypes has a potentially relevant impact on the clinical management of the disease. Methods for statistical classification without a priori assumptions (data-driven approaches) may contribute to developing a better comprehension of trait heterogeneity in disease phenotyping. This study aimed to summarize and characterize asthma phenotypes derived by data-driven methods. We performed a systematic review using three scientific databases, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. We included studies reporting adult asthma phenotypes derived by data-driven methods using easily accessible variables in clinical practice. Two independent reviewers assessed studies. The methodological quality of included primary studies was assessed using the ROBINS-I tool. We retrieved 7446 results and included 68 studies of which 65% (n = 44) used data from specialized centers and 53% (n = 36) evaluated the consistency of phenotypes. The most frequent data-driven method was hierarchical cluster analysis (n = 19). Three major asthma-related domains of easily measurable clinical variables used for phenotyping were identified: personal (n = 49), functional (n = 48) and clinical (n = 47). The identified asthma phenotypes varied according to the sample’s characteristics, variables included in the model, and data availability. Overall, the most frequent phenotypes were related to atopy, gender, and severe disease. This review shows a large variability of asthma phenotypes derived from data-driven methods. Further research should include more population-based samples and assess longitudinal consistency of data-driven phenotypes.

Subcortical gray matter volumes in asthma: associations with asthma duration, control, and anxiety

Asthma as a chronic inflammatory disease can be expected to affect central nervous system structures but little is known about subcortical structures in asthma and their potential association with illness-specific outcomes and anxiety. A total of 40 young adults (20 with asthma and 20 gender- and age-matched controls) underwent high-resolution T1-weighted MRI scan, viewed short distressing film clips, and filled in questionnaires about anxious and depressed mood, as well as asthma history, control, and catastrophizing thoughts about asthma, for those with asthma. The structural scans were processed in FSL's FIRST program to delineate subcortical structures of interest: amygdala, hippocampus, putamen, pallidum, caudate nucleus, nucleus accumbens, and thalamus. Findings showed no general reduction in subcortical gray matter volumes in asthma compared to controls. Asthma duration, asthma control, and catastrophizing of asthma and asthma attacks were negatively associated with volumes of putamen and pallidum, and to a weaker extent thalamus and amygdala, while controlling for gender, age, and corticosteroid inhaler use. In addition, stronger anxiety in response to distressing films was associated with lower volume of the pallidum, whereas general anxious and depressed mood was unrelated to subcortical structures. Thus, although there are no subcortical structural differences between young adults with asthma and healthy controls, longer asthma history, suboptimal management, and illness-related anxiety are reflected in lower gray matter volumes of subcortical structures, further emphasizing the importance of maintaining optimal asthma control.

The influence of self-assessment of asthma control on the Asthma Control Test outcome

OBJECTIVE

The Asthma Control Test (ACT) consists of five items, one of which is self-assessment of asthma control. The goal of this study was to compare the responses to the first four ACT items with the response to the fifth item and determine whether this response affects the final ACT score.

METHODS

Adult asthmatics (n = 417) were recruited from a specialty asthma center in Poland. Clinical data were collected by questionnaire. Spirometry and skin prick tests were performed for clinical evaluation. Asthma control was assessed through the ACT. The cutoff point for uncontrolled asthma was <20 points.

RESULTS

Asthma was uncontrolled in 42.5% of patients. Based upon scores of the first four ACT items, three clusters of patients were identified. Cluster 1 comprised very well-controlled asthmatics [mean (sd) ACT total score 24.7 (0.7)]. Cluster 2 included both controlled and uncontrolled asthmatics [ACT total score 20.1 (2.5)]. Cluster 3 comprised poorly controlled asthmatics [ACT total score 12.1 (2.9)]. Misjudgment of asthma control in the fifth ACT item had no impact on the ACT total score in clusters 1 and 3. In cluster 2, the response to this item caused misclassification in 10.2% of patients.

CONCLUSIONS

In patients with either very well or very poorly controlled asthma, the response to the fifth ACT item did not alter the assignment into the appropriate asthma control group. Only in a small group of patients with a total ACT score of approximately 20 points did the asthma group classification result in either controlled or uncontrolled.

Trajectories of childhood immune development and respiratory health relevant to asthma and allergy

Events in early life contribute to subsequent risk of asthma; however, the causes and trajectories of childhood wheeze are heterogeneous and do not always result in asthma. Similarly, not all atopic individuals develop wheeze, and vice versa. The reasons for these differences are unclear. Using unsupervised model-based cluster analysis, we identified latent clusters within a prospective birth cohort with deep immunological and respiratory phenotyping. We characterised each cluster in terms of immunological profile and disease risk, and replicated our results in external cohorts from the UK and USA. We discovered three distinct trajectories, one of which is a high-risk ‘atopic’ cluster with increased propensity for allergic diseases throughout childhood. Atopy contributes varyingly to later wheeze depending on cluster membership. Our findings demonstrate the utility of unsupervised analysis in elucidating heterogeneity in asthma pathogenesis and provide a foundation for improving management and prevention of childhood asthma.

Asthma causes wheezy and troubled breathing, and can be life-threatening. Scientists and doctors understand that asthma begins in early childhood. Chest infections, exposure to bacteria, viruses, and allergies may cause or trigger asthma. One person with asthma may not have the same origins as another. But it is not yet clear how various triggers may interact to trigger or exacerbate asthma.

To disentangle how these factors contribute to asthma, experts have tried to group people with asthma into subgroups. Unfortunately, the groups often vary from expert to expert. Now, some scientists are using computers to sort patients with asthma. The scientists let the computers decide the best criteria for sorting patients. This way the machines may identify patterns that are not obvious to humans.

Using this computer-based approach, Tang et al. sorted Australian children with asthma into 3 groups based on their early life allergies and respiratory health. One group has high-risk asthma with frequent chest infections and strong allergic responses. The other two groups are low-risk, but they respond differently to allergy and infection. Common tests used by doctors to diagnose patients with allergy or asthma may not work the same with all three groups. The bacteria found in the nose influence the risk of asthma, even in patients who are well, and the way this occurs varies by group. Similar groups were also found among children with asthma in the United States and the United Kingdom.

Learning more about subgroups of patients with asthma may help other scientists and doctors design better ways to diagnose, treat, or prevent asthma. Working together with scientists around the world to determine how to best describe subgroups of people according to asthma type and risk is a critical step in the process. Tang et al. hope other scientist will test whether these three groups are also found in people from other parts of the world.

Proteomic analysis of serum and sputum analytes distinguishes controlled and poorly controlled asthmatics

BACKGROUND

A major goal of asthma therapy is to achieve disease control, with maintenance of lung function, reduced need for rescue medication, and prevention of exacerbation. Despite current standard of care, up to 70% of patients with asthma remain poorly controlled. Analysis of serum and sputum biomarkers could offer insights into parameters associated with poor asthma control.

OBJECTIVE

To identify signatures as determinants of asthma disease control, we performed proteomics using Olink proximity extension analysis.

METHODS

Up to 3 longitudinal serum samples were collected from 23 controlled and 25 poorly controlled asthmatics. Nine of the controlled and 8 of the poorly controlled subjects also provided 2 longitudinal sputum samples. The study included an additional cohort of 9 subjects whose serum was collected within 48 hours of asthma exacerbation. Two separate pre-defined Proseek Multiplex panels (INF and CVDIII) were run to quantify 181 separate protein analytes in serum and sputum.

RESULTS

Panels consisting of 9 markers in serum (CCL19, CCL25, CDCP1, CCL11, FGF21, FGF23, Flt3L, IL-10Rβ, IL-6) and 16 markers in sputum (tPA, KLK6, RETN, ADA, MMP9, Chit1, GRN, PGLYRP1, MPO, HGF, PRTN3, DNER, PI3, Chi3L1, AZU1, and OPG) distinguished controlled and poorly controlled asthmatics. The sputum analytes were consistent with a pattern of neutrophil activation associated with poor asthma control. The serum analyte profile of the exacerbation cohort resembled that of the controlled group rather than that of the poorly controlled asthmatics, possibly reflecting a therapeutic response to systemic corticosteroids.

CONCLUSIONS AND CLINICAL RELEVANCE

Proteomic profiles in serum and sputum distinguished controlled and poorly controlled asthmatics, and were maintained over time. Findings support a link between sputum neutrophil markers and loss of asthma control.

Evidence for mood-dependent attentional processing in asthma: attentional bias towards health-threat in depressive mood and attentional avoidance in neutral mood

Attentional biases have been observed in populations with psychological disorders, but have been under-investigated in populations with physical illnesses. This study investigated potential attentional biases in asthma as a function of mood. Asthma (N = 45), and healthy (N = 39) participants were randomly allocated to a depressed or a neutral mood state induction. They completed a visual probe task that measured participants’ reaction times to health-threat and neutral pictures and words. Compared to the healthy controls, the asthma group showed attentional bias towards health-threat pictures in depressed mood, and avoidance of health-threat pictures in neutral mood. Attentional biases were found in a group with a physical illness as a function of induced mood. It is suggested that attentional processes in people with physical illness may be important in relation to symptom perception and illness management.

The Rhinitis Control Scoring System: Development and validation

BACKGROUND

Allergic rhinitis is a common health problem that requires regular monitoring of symptoms to provide adequate treatment. There is a need to develop rhinitis control assessment tools that are meaningful and easy to interpret by both the patient and the practitioner.

OBJECTIVE

To develop a simple, easy-to-interpret instrument, the Rhinitis Control Scoring System (RCSS), for the assessment of rhinitis control, as a companion tool to the Asthma Control Scoring System previously validated.

METHODS

After a literature review and based on the Allergic Rhinitis and its Impact on Asthma guidelines, allergic rhinitis control parameters were identified. The draft items were subjected to cognitive debriefing regarding instructions, wordings, and response options. The second version of the draft was then pretested and modified according to the results. The final draft of the RCSS, based on the intensity and frequency of symptoms, was then pilot tested with 50 subjects who had allergic rhinitis for validation of some psychometric properties. Each subject completed the RCSS in addition to other rhinitis instruments. They also had nasal peak inspiratory flow measurements.

RESULTS

The RCSS showed good internal consistency (Cronbach α = 0.84). There was strong criterion validity between the RCSS scores and the other instruments. The discriminant validity demonstrated as mean RCSS scores differed significantly across groups of patients with different Total Nasal Symptom Score severity (F = 58.8, p < 0.0001).

CONCLUSIONS

This pilot study showed that the RCSS is a simple tool to assess and quantify rhinitis control by using a percentage score. This questionnaire allows the quantification of rhinitis control and, therefore, may help guide therapeutic interventions. Combined with the Asthma Control Scoring System, it can provide a global assessment of rhinitis and asthma control. Clinical Trial number NCT00967967.

What lies beyond Asthma Control Test: Suggestions for clinical practice

BACKGROUND

Asthma Control Test (ACT ™) validity relies on Global Initiative for Asthma (GINA) definition of control. It includes neither reversibility nor inflammation assessment despite their importance as hallmark of asthma, partially unrelated to symptoms. Furthermore though rhinitis may affect the patient's perception of asthma control, its impact on ACT accuracy has not been systematically evaluated.

OBJECTIVE

To explore ACT validity according to a definition of control including: forced expiratory volume in 1 s (FEV1) ≥ 80%, negative reversibility test, exhaled nitric oxide at a flow rate of 50 ml/s (FeNO) < 50 ppb.

RESULTS

177 asthmatics referring to our Unit have been studied. ACT with cut-off score ≥20 showed a good positive predictive value (83.5%) but low sensitivity (47.8%), specificity (66.7%), and negative predictive value (26.5%). ROC curves analysis indicates that ACT in patients with mild intermittent rhinitis is more reliable (AUC: 0.714; p < 0.05) than in patients with nasal polyposis/chronic rhino-sinusitis (AUC: 0.176; p > 0.05). Considering asthma classification, the probability that ACT detects patients with uncontrolled asthma is significantly higher in moderate persistent asthma subgroup than in mild persistent asthma one (OR 5.464; IC 95%: 2.5-11,9; p < 0.05).

CONCLUSIONS

As ACT mainly relies on patient's reported outcomes, it may not completely reflect the airways inflammation and airways obstruction. The presence and severity of rhinitis may affect ACT outcome. The awareness of the variables that could influence ACT evaluation is much more important in the primary care setting where ACT may often represent the only tool for asthma assessment.

Asthma control: how it can be best assessed?

PURPOSE OF REVIEW

A control-based asthma assessment is recommended by guidelines, but questions remain about how to assess the level of asthma control, and how current control status relates to future risks and biomarkers of disease pathogenesis. This review summarizes recent published data relating to asthma control and describes the challenges created by currently available instruments.

RECENT FINDINGS

The current literature continues to show the widespread use of various assessment instruments for asthma control, in particular those with composite scores. However, poor correlations exist between the different assessment tools, and these instruments lack diagnostic accuracy to differentiate uncontrolled asthma. Whereas the concept of asthma control has been extended to add an assessment of future risks to the clinical control, clinical asthma control as measured by current available assessment tools does not necessary relate to the intrinsic disease activity which is typically characterized by inflammation in asthma.

SUMMARY

The application of asthma control assessment represents an improvement in asthma management. The measurement of underlying disease activity potentially by biomarkers to assess disease control will lead to an improved assessment of the overall control of asthma, and further studies addressing this are needed.

Factors associated with severe uncontrolled asthma and the perception of control by physicians and patients

INTRODUCTION

Despite current treatments, more than half of patients with asthma are not controlled. The objective was to evaluate the correlation between control perceived by patients and physicians, compared with control evaluated according to criteria of the Spanish Guidelines for Asthma Management (GEMA), and to investigate the factors associated with that control.

METHODS

Multicenter, cross-sectional, observational study including 343 patients with severe persistent asthma according to GEMA criteria seen in the Department of Pulmonology and Allergology. The correlation between asthma control perceived by the patient, the physician and according to clinical judgment based on the GEMA criteria was calculated, and a multivariate analysis was used to determine variables related to the perception of asthma control.

RESULTS

According to GEMA criteria, only 10.2% of patients were well controlled, 27.7% had partial control and 62.1% were poorly controlled. Both the physicians and the patients overestimated control: 75.8% and 59.3% of patients had controlled asthma according to the patient and the physician, respectively, and were not controlled according to GEMA (P<.0001). Patients with uncontrolled asthma according GEMA had higher body mass index (P=.006) and physical inactivity (P=.016). Factors associated with a perceived lack of control by both physicians and patients were: nocturnal awakenings (≥ 1 day/week), frequent use of rescue medication (≥ 5 days/week) and significant limitation in activities. Discrepant factors between physicians and patients were dyspnea and emergency room visits (patients only), FEV1 ≤ 80% and a poorer understanding of the disease by the patient (physicians only).

CONCLUSIONS

Only 10% of patients with severe asthma evaluated in this study are controlled according to GEMA criteria. Patients and physicians overestimate control and the overestimation by patients is greater. Physical inactivity and obesity are associated with a lack of control according to GEMA.

Early achievement and maintenance of stable asthma control using initially higher-dose inhaled corticosteroids as part of combination therapy: an open-label pilot study

Background

Uncontrolled asthma is characterized by considerable variability. Well controlled asthma is associated with less unplanned use of health care resources and fewer acute exacerbations. In this study, we attempted to increase inhaled corticosteroid (ICS) doses initially in suboptimally controlled asthmatics, hypothesizing that early achievement of asthma control using this strategy would be associated positively with a higher level of stability.

Methods

This was a randomized, open-label, prospective study including patients with uncontrolled asthma who were randomized to receive higher-dose (HD) ICS in combination with a long-acting beta-agonist (LABA) for one month and then shifted to doses suggested in the practice guidelines (GD) or to receive GD therapy alone. Lung function, ie, forced expiratory volume in one second (FEV₁), peak expiratory flow, Asthma Control Test scores, and frequency of acute exacerbations, was followed up for one year.

Results

Seventy-six patients were treated with the HD strategy and 80 with the GD strategy. The increase in FEV₁ from baseline was greater in the HD group than in the GD group, especially during the first month of treatment (304 ± 49 mL versus 148 ± 39 mL, respectively, P = 0.01). Numbers of patients with completely or well controlled asthma were higher in the HD group than in the GD group (92.1% versus 81.1%, respectively, P = 0.03). Further, there was a significant difference between the groups with regard to frequency of acute exacerbations (9.2% in the HD group versus 21.3% in the GD group, P = 0.02); this effect was more pronounced for patients in the HD group with partially controlled or uncontrolled asthma.

Conclusion

Patients receiving HD therapy achieved asthma control more rapidly and maintained greater stability than those receiving GD therapy. This represents a novel strategy for gaining disease control in patients with uncontrolled asthma.