Effectiveness of Interventions Targeting Treatable Traits for the Management of Obstructive Airway Diseases: A Systematic Review and Meta-Analysis

Contemporary Concise Review 2023: Asthma

Asthma research and management needs to meet the priorities of the end user-patients, carers and clinicians. A better understanding of the natural history of asthma and the progression of disease has highlighted the importance of early identification of patients with asthma and the potential role of early intervention. Management of mild asthma requires a consistent approach with the same detail and consideration used when managing severe disease. Evidence around treatable traits approaches continues to evolve, supporting the role of a personalized medicine in asthma. Oral corticosteroid (OCS) stewardship continues to be an urgent issue in asthma management. Strategies to taper OCS doses and the implementation of biologic therapies for their steroid sparing benefits will be important steps to address this problem. The concept of remission in asthma provides an ambitious target and treatment outcome.

The treatable traits of asthma in pregnancy: a clinical audit

Rationale

Poor asthma control in pregnancy is associated with adverse perinatal outcomes. Treatable traits improve patient outcomes but the pattern and prevalence of treatable traits in pregnant women with asthma is unknown. Whether treatable traits in pregnant women with asthma can be identified via a virtual care consult is also unknown. The objective of the present study was to assess the prevalence of treatable traits in pregnant women with asthma using a virtual model of care.

Methods

Pregnant women with asthma (n=196) underwent an assessment by an asthma nurse educator and a respiratory physician via telehealth. In this clinical audit, 16 treatable traits were assessed including two traits in the pulmonary domain, five traits in the behavioural/risk factors domain and nine traits in the extrapulmonary domain.

Results

Pregnant women with asthma had a mean±sd of 7.5±2.0 treatable traits per person including 1.0±0.7 treatable traits per person in the pulmonary domain, 3.5±1.56 in the extrapulmonary domain and 2±0.9 in the risk factor/behavioural domain. Treatable traits in the behavioural/risk factor domain were most prevalent and these included limited asthma knowledge (96%), inadequate inhaler technique (84%) and no written asthma action plan (80%). On average 3.8±1.24 interventions per person were delivered for a mean±sd of 7.5±2.0 treatable traits per person.

Conclusion

Virtual antenatal asthma care is a feasible approach for assessing treatable traits in pregnant women with mild asthma. Pregnant women with asthma exhibit multiple management issues. Virtual models of care might increase asthma in pregnancy service uptake and acceptability.

Treatable Traits in Asthma: The Importance of Extrapulmonary Traits-GERD, CRSwNP, Atopic Dermatitis, and Depression/Anxiety

Treatable traits is a personalized medicine approach to the management of airway disease. Assessing traits within the 3 domains of pulmonary, extrapulmonary, and behavioral/lifestyle/risk factor traits, and applying targeted treatments to effectively manage these traits, enables a holistic and personalized approach to care. Asthma is a heterogeneous and complex airway disease that is frequently complicated by several extrapulmonary traits that impact asthma outcomes and predict future outcomes. We propose that the identification of extrapulmonary and behavioral risk factor traits and the implementation of targeted therapy will lead to improved management of people with asthma. Furthermore, many extrapulmonary traits present as "connected comorbidities"; that is, they coexist with asthma, have an impact on asthma, and effective treatment improves both asthma and the comorbidity or the comorbidities may share a similar mechanism. In this review, we explore this concept and look at atopic dermatitis, chronic rhinosinusitis with nasal polyps, gastroesophageal reflux disease, anxiety, and depression as treatable traits of asthma and how these can be managed using this approach.

Treatable traits models of care

Treatable traits is a personalized approach to the management of respiratory disease. The approach involves a multidimensional assessment to understand the traits present in individual patients. Traits are phenotypic and endotypic characteristics that can be identified, are clinically relevant and can be successfully treated by therapy to improve clinical outcomes. Identification of traits is followed by individualized and targeted treatment to those traits. First proposed for the management of asthma and chronic obstructive pulmonary disease (COPD) the approach is recommended in many other areas of respiratory and now immunology medicine. Models of care for treatable traits have been proposed in different diseases and health care setting. In asthma and COPD traits are identified in three domains including pulmonary, extrapulmonary and behavioural/lifestyle/risk-factors. In bronchiectasis and interstitial lung disease, a fourth domain of aetiological traits has been proposed. As the core of treatable traits is personalized and individualized medicine; there are several key aspects to treatable traits models of care that should be considered in the delivery of care. These include person centredness, consideration of patients' values, needs and preferences, health literacy and engagement. We review the models of care that have been proposed and provide guidance on the engagement of patients in this approach to care.

The treatable traits approach to adults with obstructive airways disease in primary and secondary care

The treatable traits approach is based on the recognition that the different clinical phenotypes of asthma and chronic obstructive airways disease (COPD) are a heterogeneous group of conditions with different underlying mechanisms and clinical manifestations, and that the identification and treatment of the specific clinical features or traits facilitates a personalised approach to management. Fundamentally, it recognises two important concepts. Firstly, that treatment for obstructive lung disease can achieve better outcomes if guided by specific clinical characteristics. Secondly, that in patients with a diagnosis of asthma, and/or COPD, poor respiratory health may also be due to numerous overlapping disorders that can present with symptoms that may be indistinguishable from asthma and/or COPD, comorbidities that might require treatment in their own right, and lifestyle or environmental factors that, if addressed, might lead to better control rather than simply increasing airways directed treatment. While these concepts are well accepted, how best to implement this personalised medicine approach in primary and secondary care within existing resource constraints remains uncertain. In this review, we consider the evidence base for this management approach and propose that the priority now is to assess different prototype templates for the identification and management of treatable traits in both asthma and COPD, in primary, secondary and tertiary care, to provide the evidence that will guide their use in clinical practice in different health care systems.

Treatable traits for long COVID

Long COVID, or post-acute COVID-19 sequelae, is experienced by an estimated one in eight adults following acute COVID-19. Long COVID is a new and complex chronic health condition that typically includes multiple symptoms that cross organ systems and fluctuate over time; a one-size-fits-all approach is, therefore, not likely to be appropriate nor relevant for long COVID treatment. 'Treatable Traits' is a personalized medicine approach, purpose-built to address the complexity and heterogeneity of complex chronic conditions. This comprehensive review aimed to understand how a treatable traits approach could be applied to long COVID, by first identifying the most prevalent long COVID treatable traits and then the available evidence for strategies to target these traits. An umbrella review of 22 systematic reviews identified 34 symptoms and complications common with long COVID, grouped into eight long COVID treatable trait clusters: neurological, chest, psychological, pain, fatigue, sleep impairment, functional impairment and other. A systematic review of randomized control trials identified 18 studies that explored different intervention approaches for long COVID prevention (k = 4) or management (k = 14). While a single study reported metformin as effective for long COVID prevention, the findings need to be replicated and consensus is required around how to define long COVID as a clinical trial endpoint. For long COVID management, current evidence supports exercise training or respiratory muscle training for long COVID treatable traits in the chest and functional limitation clusters. While there are studies exploring interventions targeting other long COVID treatable traits, further high-quality RCTs are needed, particularly targeting treatable traits in the clusters of fatigue, psychological, pain and sleep impairment.

Can Treatable Traits Be the Approach to Addressing the Complexity and Heterogeneity of COPD?

The complexity of COPD implies the need to identify groups of patients with similar clinical characteristics and prognosis or treatment requirements. This is why much attention has been paid to identifying the different clinical phenotypes by investigating the clinical expression of the disease, and endotypes by studying the biological networks that enable and limit reactions. However, this approach is complicated because one endotype gives rise to one or more clinical characteristics, and clinical phenotypes can be derived from several endotypes. To simplify the approach, a new taxonomic classification of COPD based on the different causes (or etiotypes) has been proposed, but these etiotypes have not yet been validated. A simpler method is the so-called tractable traits approach, which is free from any designation of the disorder to be treated and does not present the criticality of using etiotypes. A large randomised controlled trial on using the treatable traits approach in COPD is still lacking. Nevertheless, this approach is already applied by following the GOLD strategy. However, its application is complicated because several potentially treatable traits have been identified within the pulmonary domain, the extrapulmonary domain, and the behavioural/risk factor domain. In addition, the hierarchy of the dominant treatable traits has not yet been established, and they change over time both spontaneously and because of treatment. This means that the patients being treated according to the tractable traits approach must be constantly followed over time so that the therapy is focused on their temporal needs.

Revisiting asthma pharmacotherapy: where do we stand and where do we want to go?

Several current guidelines/strategies outline a treatment approach to asthma, which primarily consider the goals of improving lung function and quality of life and reducing symptoms and exacerbations. They suggest a strategy of stepping up or down treatment, depending on the patient's overall current asthma symptom control and future risk of exacerbation. While this stepwise approach is undeniably practical for daily practice, it does not always address the underlying mechanisms of this heterogeneous disease. In the last decade, there have been attempts to improve the treatment of severe asthma, such as the addition of a long-acting antimuscarinic agent to the traditional inhaled corticosteroid/long-acting β2-agonist treatment and the introduction of therapies targeting key cytokines. However, despite such strategies several unmet needs in this population remain, motivating research to identify novel targets and develop improved therapeutic and/or preventative asthma treatments. Pending the availability of such therapies, it is essential to re-evaluate the current conventional "one-size-fits-all" approach to a more precise asthma management. Although challenging, identifying "treatable traits" that contribute to respiratory symptoms in individual patients with asthma may allow a more pragmatic approach to establish more personalised therapeutic goals.

Treatable traits: a comprehensive precision medicine approach in interstitial lung disease

Interstitial lung disease (ILD) is a diverse group of inflammatory and fibrotic lung conditions causing significant morbidity and mortality. A multitude of factors beyond the lungs influence symptoms, health-related quality of life, disease progression and survival in patients with ILD. Despite an increasing emphasis on multidisciplinary management in ILD, the absence of a framework for assessment and delivery of comprehensive patient care poses challenges in clinical practice. The treatable traits approach is a precision medicine care model that operates on the premise of individualised multidimensional assessment for distinct traits that can be targeted by specific interventions. The potential utility of this approach has been described in airway diseases, but has not been adequately considered in ILD. Given the similar disease heterogeneity and complexity between ILD and airway diseases, we explore the concept and potential application of the treatable traits approach in ILD. A framework of aetiological, pulmonary, extrapulmonary and behavioural and lifestyle treatable traits relevant to clinical care and outcomes for patients with ILD is proposed. We further describe key research directions to evaluate the application of the treatable traits approach towards advancing patient care and health outcomes in ILD.

Impact of Treatable Traits on Asthma Control and Quality of Life

BACKGROUND

Many adult patients with asthma have uncontrolled disease and impaired quality of life, despite current asthma-specific drug therapies.

OBJECTIVE

This study aimed to investigate the prevalence of 9 traits in patients with asthma, their associations with disease control and quality of life, and referral rates to nonmedical health care professionals.

METHODS

Retrospectively, data from patients with asthma were collected in 2 Dutch hospitals (Amphia Breda and RadboudUMC Nijmegen). Adult patients without exacerbation <3 months who were referred for a first-ever elective, outpatient, hospital-based diagnostic pathway were deemed eligible. Nine traits were assessed: dyspnea, fatigue, depression, overweight, exercise intolerance, physical inactivity, smoking, hyperventilation, and frequent exacerbations. To assess the likelihood of having poor disease control or decreased quality of life, the odds ratio (OR) was calculated per trait. Referral rates were assessed by checking patients' files.

RESULTS

A total of 444 adults with asthma were studied (57% women, age: 48 ± 16 years, forced expiratory volume in 1 second: 88% ± 17% predicted). Most patients (53%) were found to have uncontrolled asthma (Asthma Control Questionnaire ≥1.5 points) and decreased quality of life (Asthma Quality of Life Questionnaire <6 points). Generally, patients had 3.0 ± 1.8 traits. Severe fatigue was most prevalent (60%) and significantly increased the likelihood of having uncontrolled asthma (OR: 3.0, 95% confidence interval [CI]: 1.9-4.7) and decreased quality of life (OR: 4.6, 95% CI: 2.7-7.9). Referrals to nonmedical health care professionals were low; most referrals were to a respiratory-specialized nurse (33%).

CONCLUSION

Adult patients with asthma with a first-ever referral to a pulmonologist frequently exhibit traits justifying the deployment of nonpharmacological interventions, especially in those with uncontrolled asthma. However, referrals to appropriate interventions appeared infrequent.

Treatable Traits in Airway Disease: From Theory to Practice

Chronic airway diseases such as asthma and chronic obstructive pulmonary disease are prevalent and complex conditions that often coexist in the same patient. To address this complexity in clinical practice, and to move forward toward personalized and precision medicine of airway diseases, a strategy based on the identification and treatment of so-called "treatable traits" (TTs) has been proposed. A TT is a recognizable phenotypic or endotypic characteristic that can be assessed and successfully targeted by therapy to improve a clinical outcome in a patient with airway disease. Importantly, TTs can coexist in the same patient, so they are not mutually exclusive. The TT strategy proposes to investigate in each individual patient with chronic airway disease the number and type of TTs present and to treat each of them according to guideline recommendations. This strategy is agnostic (ie, independent) to the traditional diagnostic labels (asthma, chronic obstructive pulmonary disease), so it can be applied to any patient with airway disease. Currently, there is firm evidence supporting the adequacy and validity of the TT strategy. Here, we review the current state of the art of this topic, first by presenting its theoretical background and then by discussing how to best implement it in clinical practice.

Comparison of health-related quality of life measures in asthma-COPD overlap

OBJECTIVE

The Asthma Quality of Life Questionnaire (AQLQ) and COPD assessment test (CAT) are used to assess the health status of asthma and chronic obstructive pulmonary disease (COPD), respectively. However, whether these questionnaires are appropriate in patients with asthma-COPD overlap (ACO) has not been reported. This study aimed to evaluate the performance of the AQLQ and CAT in subjects with ACO.

METHODS

Subjects were enrolled from two previously described observational studies in Beijing, China. ACO was defined by a consensus definition from a roundtable discussion. All subjects completed the AQLQ, CAT, St George's Respiratory Questionnaire (SGRQ), pulmonary function tests, and the Asthma Control Questionnaire (ACQ)-5. Cross-sectional construct validity was evaluated by correlating the AQLQ and CAT with SGRQ score and other measures of asthma and COPD severity.

RESULTS

147 subjects with ACO were recruited. There were floor effects on non-respiratory components of the CAT, and ceiling effects on emotion domains of the AQLQ. Both questionnaires were significantly correlated with ACQ-5 score but were not correlated with FEV1% predicted or FVC% predicted. The AQLQ and CAT were strongly correlated with SGRQ score (r = -0.657 and r = 0.623, respectively). Multivariable linear regression analysis showed that the AQLQ (standardized β-coefficient = -0.449, p < .001) had a stronger association with SGRQ score compared with CAT (standardized β-coefficient = 0.211, p = .023).

DISCUSSION

The AQLQ and CAT were both valid for assessing the health-related quality of life in subjects with ACO, but the AQLQ performed better than CAT.

Evolving Concept of Severe Asthma: Transition From Diagnosis to Treatable Traits

In recent decades, the concept of severe asthma has evolved from an umbrella term encompassing patients with high-intensity treatment needs to a clinical syndrome with heterogeneous, albeit distinct, pathophysiological processes. Biased and unbiased cluster approaches have been used to identify several clinical phenotypes. In parallel, cellular and molecular approaches allow for the development of biological therapies, especially targeting type 2 (T2) cytokine pathways. Although T2-biologics have significantly improved clinical outcomes for patients with severe asthma in real-world practice, questions on the proper use of biologics remain open. Furthermore, a subset of severe asthma patients remains poorly controlled. The unmet needs require a new approach. The “treatable traits” concept has been suggested to address a diversity of pathophysiological factors in severe asthma and overcome the limitations of existing treatment strategies. With a tailored therapy that targets the treatable traits in individual patients, better personalized medical care and outcomes should be achieved.