Exacerbation-Prone Asthma: A Biological Phenotype or a Social Construct

Climate change and its impact on asthma

ABSTRACT

Earth's climate is changing at an unprecedented pace, primarily due to anthropogenic causes including greenhouse gas emissions. Evidence shows a strong link between climate change and its effects on asthma. Healthcare professionals must be educated to advocate for and lead effective strategies to reduce the health risks of climate change.

Socioeconomic status, diet, and recurrent severe asthma exacerbations in Puerto Rican youth

Background

Why Puerto Rican youths have higher rates of severe asthma exacerbations (SAEs) than their non-Hispanic White peers is unclear.

Objective

We aimed to identify risk factors associated with recurrent SAEs in Puerto Rican youths with asthma.

Methods

We performed cross-sectional and longitudinal analyses of recurrent SAEs in 209 Puerto Rican youths with asthma who participated in 2 cross-sectional studies approximately 5.2 years apart: the Puerto Rico Genetics of Asthma and Lifestyle study (visit 1, participants aged 6-14 years) and the Epigenetic Variation and Childhood Asthma in Puerto Ricans study (visit 2, participants aged 9-20 years). Recurrent SAEs were defined as at least 2 SAEs in the previous year.

Results

Of the youths in our study, there were 80 (38.3%) and 47 (22.4%) with recurrent SAEs at visit 1 and visit 2, respectively, and 31 participants (14.8%) had persistent recurrent SAEs (ie, recurrent SAEs at both visits). In multivariable analyses, low household income was significantly associated with 2.4 to 12.3 times increased odds of recurrent SAEs in all analyses, with stronger longitudinal associations. Low parental education level, nonprivate or employer-based health insurance, overweight or obesity, residential proximity to a major road, and low or moderate level of outdoor activity were each significantly associated with recurrent SAEs in at least 1 analysis. Further, persistence of low parental numeracy level, low household income, and an unhealthy diet were each associated with persistent recurrent SAEs.

Conclusion

In this study of Puerto Rican youths with asthma, persistence of low parental numeracy level, a low household income, and an unhealthy diet were associated with persistent recurrent SAEs. Our findings support policies promoting equity and healthy lifestyles for Puerto Rican children and their families.

The Child Opportunity Index 2.0 and exacerbation-prone asthma in a cohort of urban children

RATIONALE

Social determinants of health underlie disparities in asthma. However, the effects of individual determinants likely interact, so a summary metric may better capture their impact. The Child Opportunity Index 2.0 (COI) is one such tool, yet its association with exacerbation-prone (EP) asthma is unknown.

OBJECTIVE

To investigate the association between the COI and EP asthma and clinical measures of asthma severity in children.

METHODS

We analyzed data from two prospective observational pediatric asthma cohorts (n = 193). Children were classified as EP (≥1 exacerbation in the past 12 months) or exacerbation-null (no exacerbations in the past 5 years). Spirometry, exhaled nitric oxide, IgE, and Composite Asthma Severity Index (CASI) were obtained. The association between COI and EP status was assessed with logistic regression. We fit linear and logistic regression models to test the association between COI and each clinical measure.

RESULTS

A 20-point COI decrease conferred 40% higher odds of EP asthma (OR 1.4; 95%CI 1.1-1.76). The effect was similar when adjusted for age and sex (OR 1.38, 95%CI 1.1-1.75) but was attenuated with additional adjustment for race and ethnicity (OR 1.19, 95%CI 0.92-1.54). A similar effect was seen for the Social/Economic and Education COI domains but not the Health/Environment Domain. A 20-point COI decrease was associated with an increase in CASI of 0.34. COI was not associated with other clinical measures.

CONCLUSIONS

Lower COI was associated with greater odds of EP asthma. This highlights the potential use of the COI to understand neighborhood-level risk and identify community targets to reduce asthma disparities.

The Asthma Impairment and Risk Questionnaire enhances the assessment of asthma control

BACKGROUND

Asthma control is often overestimated in routine practice, and despite advances in the understanding of immunopathology and the availability of new precision therapies, the burden of disease remains unacceptably high.

OBJECTIVE

To compare the performance of the Asthma Impairment and Risk Questionnaire (AIRQ) with patient and physician assessments and the Asthma Control Test (ACT) in identifying asthma control.

METHODS

Baseline data from a longitudinal study of the AIRQ were analyzed. Patients with asthma in the United States aged 12 years and older followed in 24 specialty practices and 1 specialty-affiliated primary care clinic were enrolled between May and November 2019. At entry, participants completed AIRQ and ACT, and participants and physicians completed 5-point Likert scale assessments of control.

RESULTS

A total of 1112 participants were enrolled (mean [SD] age = 43.9 [19.3] years, 70% of the female sex, 78% White). Overall, 62% of participants rated themselves as well- or completely controlled, and 54% were rated comparably by physicians. The ACT classified 49% of participants as well-controlled, with 35% similarly categorized by AIRQ. Previous-year exacerbations were experienced by 32% of participants who self-rated as well- or completely controlled, 30% who were rated as well- or completely controlled by physicians, and 29% assessed as well-controlled by ACT, but only 15% of those classified as well-controlled by AIRQ.

CONCLUSION

The burden of asthma is substantial in patients cared for by asthma specialists, and asthma control is overestimated by patients, physicians, and the symptom-based ACT. The AIRQ assesses risk in addition to symptom control and may serve to improve asthma control determination by assessing previous exacerbations.

Incidence rates of childhood asthma with recurrent exacerbations in the US Environmental influences on Child Health Outcomes (ECHO) program

BACKGROUND

Descriptive epidemiological data on incidence rates (IRs) of asthma with recurrent exacerbations (ARE) are sparse.

OBJECTIVES

This study hypothesized that IRs for ARE would vary by time, geography, age, and race and ethnicity, irrespective of parental asthma history.

METHODS

The investigators leveraged data from 17,246 children born after 1990 enrolled in 59 US with 1 Puerto Rican cohort in the Environmental Influences on Child Health Outcomes (ECHO) consortium to estimate IRs for ARE.

RESULTS

The overall crude IR for ARE was 6.07 per 1000 person-years (95% CI: 5.63-6.51) and was highest for children aged 2-4 years, for Hispanic Black and non-Hispanic Black children, and for those with a parental history of asthma. ARE IRs were higher for 2- to 4-year-olds in each race and ethnicity category and for both sexes. Multivariable analysis confirmed higher adjusted ARE IRs (aIRRs) for children born 2000-2009 compared with those born 1990-1999 and 2010-2017, 2-4 versus 10-19 years old (aIRR = 15.36; 95% CI: 12.09-19.52), and for males versus females (aIRR = 1.34; 95% CI 1.16-1.55). Black children (non-Hispanic and Hispanic) had higher rates than non-Hispanic White children (aIRR = 2.51; 95% CI 2.10-2.99; and aIRR = 2.04; 95% CI: 1.22-3.39, respectively). Children born in the Midwest, Northeast and South had higher rates than those born in the West (P < .01 for each comparison). Children with a parental history of asthma had rates nearly 3 times higher than those without such history (aIRR = 2.90; 95% CI: 2.43-3.46).

CONCLUSIONS

Factors associated with time, geography, age, race and ethnicity, sex, and parental history appear to influence the inception of ARE among children and adolescents.

Factors to Consider in Prescribing Asthma Biologic Therapies to Children

The increasing availability of biologics, both by expanding age indications and by development of new therapies, provides additional options to treat children and adolescents with severe asthma. However, the evidence for these biologics in these populations is limited compared with that for adult studies. As such, before initiation of therapy, possible alternative therapies that can also provide asthma control, confirmation of the diagnosis of asthma, management of comorbidities, and assessment of adherence should be explored. The choice of a biologic should be a shared decision-making process between providers and families, balancing biologic efficacy, goals of care, administration, and ability to treat multiple conditions. Response to treatment should be periodically evaluated not only to ensure an ineffective treatment is not continued but also to consider when to potentially discontinue therapy should it be beneficial. The utilization of biologics in children and adolescents with severe asthma also leads to unanswered questions on their role in disease remission and long-term outcomes.

Workup of difficult-to-treat asthma: implications from treatable traits

Traditional stepwise approach usually adjusts the treatment regimen based on changes in asthma symptoms and severity to achieve good asthma control. However, due to the generalized heterogeneity and complexity of asthma, its therapeutic efficacy in difficult-to-treat asthma is limited. Recently, a precision medicine approach based on the identification and intervention of treatable traits of chronic airway disease has been proposed and appears to be of greater benefit to asthmatics. We reported a 71-year-old male with uncontrolled asthma and multiple exacerbations over the past year. He complained of persistent dyspnea despite high-dose of inhaled corticosteroids plus other controllers. Does this patient have some potential treatable traits contributing to difficult-to-treat asthma? Through a multidimensional assessment of three domains including pulmonary, extrapulmonary, and behavioral/risk factors, 15 treatable traits were identified in the patient, mainly including airflow limitation, eosinophilic airway inflammation, small airway dysfunction, exacerbation prone, dilated cardiomyopathy, diabetes mellitus, inhaler device polypharmacy, smoking, and the absence of an asthma action plan. After targeted treatment for these treatable traits, the patient experienced significant improvement in dyspnea and he could maintain good asthma control with low-dose inhaled corticosteroids and long-acting β₂-agonist. This study shows that, in response to the limitation of a stepwise approach to therapy, treatable traits is a new strategy where patients are individually assessed for a specified set of treatable problems, and an individualized treatment program is developed and implemented based on this multidimensional assessment, especially for difficult-to-treat asthma.

Exacerbation-prone pediatric asthma is associated with arginine, lysine, and methionine pathway alterations

BACKGROUND

The asthma of some children remains poorly controlled, with recurrent exacerbations despite treatment with inhaled corticosteroids. Aside from prior exacerbations, there are currently no reliable predictors of exacerbation-prone asthma in these children and only a limited understanding of the potential underlying mechanisms.

OBJECTIVE

We sought to quantify small molecules in the plasma of children with exacerbation-prone asthma through mass spectrometry-based metabolomics. We hypothesized that the plasma metabolome of these children would differ from that of children with non-exacerbation-prone asthma.

METHODS

Plasma metabolites were extracted from 4 pediatric asthma cohorts (215 total subjects, with 41 having exacerbation-prone asthma) and detected with a mass spectrometer. High-confidence annotations were retained for univariate analysis and were confirmed by a sensitivity analysis in subjects receiving high-dose inhaled corticosteroids. Metabolites that varied by cohort were excluded. MetaboAnalyst software was used to identify pathways of interest. Concentrations were calculated by reference standardization.

RESULTS

We identified 32 unique, cohort-independent metabolites that differed in children with exacerbation-prone asthma compared to children with non-exacerbation-prone asthma. Comparison of metabolite concentrations to literature-reported values for healthy children revealed that most metabolites were decreased in both asthma groups, but more so in exacerbation-prone asthma. Pathway analysis identified arginine, lysine, and methionine pathways as most impacted.

CONCLUSIONS

Several plasma metabolites are perturbed in children with exacerbation-prone asthma and are largely related to arginine, lysine, and methionine pathways. While validation is needed, plasma metabolites may be potential biomarkers for exacerbation-prone asthma in children.

Functional immunophenotyping of children with critical status asthmaticus identifies differential gene expression responses in neutrophils exposed to a poly(I:C) stimulus

The host immune response to a viral immune stimulus has not been examined in children during a life-threatening asthma attack. We determined whether we could identify clusters of children with critical asthma by functional immunophenotyping using an intracellular viral analog stimulus. We performed a single-center, prospective, observational cohort study of 43 children ages 6-17 years admitted to a pediatric intensive care unit for an asthma attack between July 2019 to February 2021. Neutrophils were isolated from children, stimulated overnight with LyoVec poly(I:C), and mRNA was analyzed using a targeted Nanostring immunology array. Network analysis of the differentially expressed transcripts for the paired LyoVec poly(I:C) samples was performed. We identified two clusters by functional immunophenotyping that differed by the Asthma Control Test score. Cluster 1 (n = 23) had a higher proportion of children with uncontrolled asthma in the four weeks prior to PICU admission compared with cluster 2 (n = 20). Pathways up-regulated in cluster 1 versus cluster 2 included chemokine receptor/chemokines, interleukin-10 (IL-10), IL-4, and IL-13 signaling. Larger validation studies and clinical phenotyping of children with critical asthma are needed to determine the predictive utility of these clusters in a larger clinical setting.

Socioeconomic status associates with worse asthma morbidity among Black and Latinx adults

BACKGROUND

Asthma disproportionately affects African American/Black (AA/B) and Hispanic/Latinx (H/L) patients and individuals with low socioeconomic status (SES), but the relationship between SES and asthma morbidity within these racial/ethnic groups is inadequately understood.

OBJECTIVE

To determine the relationship between SES and asthma morbidity among AA/B and H/L adults with moderate to severe asthma using multidomain SES frameworks and mediation analyses.

METHODS

We analyzed enrollment data from the PeRson EmPowered Asthma RElief randomized trial, evaluating inhaled corticosteroid supplementation to rescue therapy. We tested for direct and indirect relationships between SES and asthma morbidity using structural equation models. For SES, we used a latent variable defined by poverty, education, and unemployment. For asthma morbidity, we used self-reported asthma exacerbations in the year before enrollment (corticosteroid bursts, emergency room/urgent care visits, or hospitalizations), and Asthma Control Test scores. We tested for mediation via health literacy, perceived stress, and self-reported discrimination. All models adjusted for age, sex, body mass index, ethnicity, and comorbidities.

RESULTS

Among 990 AA/B and H/L adults, low SES (latent variable) was directly associated with hospitalizations (β = 0.24) and worse Asthma Control Test scores (β = 0.20). Stress partially mediated the relationship between SES and increased emergency room/urgent care visits and worse asthma control (β = 0.03 and = 0.05, respectively). Individual SES domains were directly associated with asthma morbidity. Stress mediated indirect associations between low educational attainment and unemployment with worse asthma control (β = 0.05 and = 0.06, respectively).

CONCLUSIONS

Lower SES is directly, and indirectly through stress, associated with asthma morbidity among AA/B and H/L adults. Identification of stressors and relevant management strategies may lessen asthma-related morbidity among these populations.

Long-term Natural History of Severe Asthma Exacerbations and Their Impact on the Disease Course

Rationale

The long-term natural history of asthma in terms of successive severe exacerbations and the influence of each exacerbation on the course of the disease is not well studied.

Objectives

To investigate the long-term natural history of asthma among patients who are hospitalized for asthma for the first time in terms of the risk of future severe exacerbations and heterogeneity in this risk across patients.

Methods

Using the administrative health databases of British Columbia, Canada (January 1, 1997 to March 31, 2016), we created an incident cohort of patients with at least one asthma exacerbation that required inpatient care. We estimated the 5-year cumulative incidence of severe exacerbations after successive numbers of previous events. We used a joint frailty model to investigate the extent of between-individual variability in exacerbation risk and the associations of each exacerbation with the rate of subsequent events. Analyses were conducted separately for pediatric (<14 years old) and adult (⩾14 years old) patients.

Results

Analyses were based on 3,039 pediatric (mean age at baseline, 6.4; 35% female) and 5,442 (mean age at baseline, 50.8; 68% female) adult patients. The 5-year rates of severe exacerbations after the first three events were 0.16, 0.29, and 0.35 for the pediatric group, and 0.14, 0.33, and 0.49 for the adult group. Both groups exhibited substantial variability in patient-specific risks of exacerbation: the mid-95% interval of 5-year risk of experiencing a severe exacerbation ranged from 11% to 24% in pediatric patients and from 8% to 40% in adult patients. After controlling for potential confounders, the first follow-up exacerbation was associated with an increase of 79% (95% confidence interval [CI], 11–189%) in the rate of subsequent events in the pediatric group, whereas this increase was 188% (95% CI, 35–515%) for the adult group. The effects of subsequent exacerbations were not statistically significant.

Conclusions

After the first severe exacerbation, the risk of subsequent events is substantially different among patients. The number of previous severe exacerbations carries nuanced prognostic information about future risk. Our results suggest that severe exacerbations in the early course of asthma detrimentally affect the course of the disease and risk of subsequent exacerbations.

Nonrespiratory Comorbidities in Asthma

Asthma is a chronic heterogeneous airway disease. Common comorbid conditions are often disproportionately present in severe asthma. Optimal care of patients with asthma requires the recognition and treatment of these comorbid conditions. This review outlines the pathophysiological mechanisms between nonrespiratory comorbid conditions and asthma and their effect on asthma outcomes. They include: type 2 diabetes mellitus, hypertension, atherosclerotic cardiovascular disease, adrenal and thyroid gland diseases, pregnancy, osteoporosis, adverse effects from medications, and mental health disorders. Studies indicate how poor glycemic control of type 2 diabetes mellitus is associated with not only greater health care utilization but poorer asthma outcomes. Also, a large health care claims database indicates that a substantial proportion of pregnant women have uncontrolled asthma and are prescribed suboptimal controller therapy. Additional data about these nonrespiratory comorbidities and medications known to benefit both nonrespiratory comorbidities and asthma are necessary.