Obesity and asthma

New Perspectives on Difficult Asthma; Sex and Age of Asthma-Onset Based Phenotypes

BACKGROUND

Asthma is a diverse condition that differs with age and sex. However, it remains unclear how sex, age of asthma onset, and/or their interaction influence clinical expression of more problematic adult "difficult" asthma.

OBJECTIVES

To better understand the clinical features of difficult asthma within a real-world clinical setting using novel phenotypic classification, stratifying subjects by sex and age of asthma onset.

METHODS

Participants in a longitudinal difficult asthma clinical cohort study (Wessex AsThma CoHort of difficult asthma; WATCH), United Kingdom (n = 501), were stratified into 4 difficult asthma phenotypes based on sex and age of asthma onset (early <18 years or adult ≥18 years) and characterized in relation to clinical and pathophysiological features.

RESULTS

The cohort had more female participants (65%) but had similar proportions of participants with early- or adult-onset disease. Early-onset female disease was commonest (35%), highly atopic, with good spirometry and strong associations with some physical comorbidities but highest psychophysiologic comorbidities. Adult-onset females also had considerable psychophysiologic comorbidities and highest obesity, and were least atopic. Amongst male subjects, proportionately more had adult-onset disease. Early-onset male disease was rarest (14%) but associated with worst lung function, high smoking, atopy, and fungal sensitization. Despite shortest disease duration, adult-onset males had highest use of maintenance oral corticosteroid, poor lung function, and highest fractional exhaled nitrogen oxide in spite of highest smoking prevalence.

CONCLUSIONS

This study shows that sex, age of asthma onset, and their interactions influence different clinical manifestations of difficult asthma and identifies a greater risk for lung function loss and oral corticosteroid dependence associated with smoking in adult-onset male subjects.

Weight Loss for Children and Adults with Obesity and Asthma. A Systematic Review of Randomized Controlled Trials

Background: Asthma and obesity are major public health problems, affecting hundreds of millions of people worldwide. Obesity is associated with increased asthma risk and severity, and lower asthma-related quality of life. Objective: In this systematic review, we aimed to evaluate whether weight loss in subjects with obesity and asthma leads to improvement in asthma-related outcomes. Data Sources and Extraction: We searched PubMed and Google Scholar for all studies in English published January 2000-December 2018. Studies were included if they were randomized, controlled clinical trials (RCTs) for overweight/obese children or adults with asthma, with sufficient data to assess outcomes and study quality. Non-randomized and non-controlled studies were excluded, as well as those in subjects without overweight/obesity, or with non-asthmatic controls. Synthesis: We identified four RCTs involving children (total n = 246) and six involving adults (n = 502). All interventions were designed for weight loss and varied from dietary restrictions to multifactorial interventions with exercise training and cognitive behavioral therapy; the duration of intervention ranged from 8 weeks to 18 months. All RCTs reported successful improvements in weight or body mass index (-0.14 standard deviation scores to -15.9% BMI reduction in children, 1.8%-14.5% weight loss in adults). RCTs generally reported improvements in asthma-related quality of life and, to some degree, asthma control. RCTs involving adults also reported improvements in lung function (FEV₁, FVC, TLC), while RCTs in children showed less consistent results. Conclusions: These findings suggest that weight loss in subjects with obesity and asthma may improve asthma outcomes. However, there was wide variability in populations studied, baseline and post-intervention assessments, follow-up length, outcome definition and reporting, and statistical approaches, which hindered the ability to compare studies, perform a pooled analysis, or assess generalizability. Primary Source of Funding: U.S. National Institutes of Health (NIH).

IL-33, diet-induced obesity, and pulmonary responses to ozone

Background

Obesity augments pulmonary responses to ozone. We have reported that IL-33 contributes to these effects of obesity in db/db mice. The purpose of this study was to determine whether IL-33 also contributes to obesity-related changes in the response to ozone in mice with diet-induced obesity.

Methods

Male wildtype C57BL/6 mice and mice deficient in ST2, the IL-33 receptor, were placed on chow or high fat diets for 12 weeks from weaning. Because the microbiome has been implicated in obesity-related changes in the pulmonary response to ozone, mice were either housed with other mice of the same genotype (same housed) or with mice of the opposite genotype (cohoused). Cohousing transfers the gut microbiome from one mouse to its cagemates.

Results

Diet-induced increases in body mass were not affected by ST2 deficiency or cohousing. In same housed mice, ST2 deficiency reduced ozone-induced airway hyperresponsiveness and neutrophil recruitment in chow-fed but not HFD-fed mice even though ST2 deficiency reduced bronchoalveolar lavage IL-5 in both diet groups. In chow-fed mice, cohousing abolished ST2-related reductions in ozone-induced airway hyperresponsiveness and neutrophil recruitment, but in HFD-fed mice, no effect of cohousing on these responses to ozone was observed. In chow-fed mice, ST2 deficiency and cohousing caused changes in the gut microbiome. High fat diet-feeding caused marked changes in the gut microbiome and overrode both ST2-related and cohousing-related differences in the gut microbiome observed in chow-fed mice.

Conclusion

Our data indicate a role for IL-33 in pulmonary responses to ozone in chow-fed but not high fat diet-fed mice and are consistent with the hypothesis that these diet-related differences in the role of IL-33 are the result of changes in the gut microbiome.

Needs for Systems Approaches to Better Treat Individuals With Severe Asthma: Predicting Phenotypes and Responses to Treatments

Asthma is a frequent heterogeneous multifactorial chronic disease whose severe forms remain largely uncontrolled despite the availability of many drugs and educational therapy. Several phenotypes and endotypes of severe asthma have been described over the last two decades. Typical type-2-immunity-driven asthma remains the most frequent phenotype, and several targeted therapies have been developed and are now available. On the contrary, non-type-2 immunity-driven severe asthma is less understood and still requires efficient innovative therapies. A personalized approach would allow improving asthma control with the help of robust biomarkers able to predict phenotypes/endotypes, exacerbations, response to targeted treatments and, in the future, possible curative options. Some data from large multicenter cohorts have emerged in recent years, especially in transcriptomics. These data have to be integrated and reproduced longitudinally to provide a systems approach for asthma care. In this focused review, the needs for such an approach and the available data will be reviewed as well as the next steps for achieving personalized medicine in asthma.

Obesity may enhance the adverse effects of NO2 exposure in urban schools on asthma symptoms in children

BACKGROUND

Sparse data address the effects of nitrogen dioxide (NO₂) exposure in inner-city schools on obese students with asthma.

OBJECTIVE

We sought to evaluate relationships between classroom NO₂ exposure and asthma symptoms and morbidity by body mass index (BMI) category.

METHODS

The School Inner-City Asthma Study enrolled students aged 4 to 13 years with asthma from 37 inner-city schools. Students had baseline determination of BMI percentile. Asthma symptoms, morbidity, pulmonary inflammation, and lung function were monitored throughout the subsequent academic year. Classroom NO₂ data, linked to enrolled students, were collected twice per year. We determined the relationship between classroom NO₂ levels and asthma outcomes by BMI stratification.

RESULTS

A total of 271 predominantly black (35%) or Hispanic students (35%) were included in analyses. Fifty percent were normal weight (5-84th BMI percentile), 15% overweight (≥85-94th BMI percentile), and 35% obese (≥95th BMI percentile). For each 10-parts per billion increase in NO₂, obese students had a significant increase in the odds of having an asthma symptom day (odds ratio [OR], 1.86; 95% CI, 1.15-3.02) and in days caregiver changed plans (OR, 4.24; 95% CI, 2.33-7.70), which was significantly different than normal weight students who exhibited no relationship between NO₂ exposure and symptom days (OR, 0.90; 95% CI, 0.57-1.42; pairwise interaction P = .03) and change in caregiver plans (OR, 1.37; 95% CI, 0.67-2.82; pairwise interaction P = .02). Relationships between NO₂ levels and lung function and fractional exhaled nitric oxide did not differ by BMI category. If we applied a conservative Holm-Bonferroni correction for 16 comparisons (obese vs normal weight and overweight vs normal weight for 8 outcomes), these findings would not meet statistical significance (all P > .003).

CONCLUSIONS

Obese BMI status appears to increase susceptibility to classroom NO₂ exposure effects on asthma symptoms in inner-city children. Environmental interventions targeting indoor school NO₂ levels may improve asthma health for obese children. Although our findings would not remain statistically significant after adjustment for multiple comparisons, the large effect sizes warrant future study of the interaction of obesity and pollution in pediatric asthma.

Lifetime overweight and adult asthma: 1978/1979 Ribeirão Preto Birth Cohort, São Paulo, Brazil

Studies focusing on obesity and asthma frequently consider the weight at a given time; thus, modeling pathways through lifetime overweight may contribute to elucidate temporal aspects in this relationship. This study modeled the pathways in the association of lifetime overweight with asthma in adult life, using data from the 1978/1979 Birth Cohort, Ribeirão Preto, São Paulo, Brazil (n = 2,063) at birth (baseline), school age (9/11 years) and adult age (23/25 years). A theoretical model was proposed to explore the effects of lifetime overweight on asthma in adult life analyzed by structural equation modeling. Parental obesity (SC - standardized coefficenttotal = 0.211, p < 0.001; SCdirect = 0.115, p = 0.007) and overweight at school age (SCtotal = 0.565, p < 0.0001; SCdirect = 0.565, p < 0.0001) were associated with overweight in adult life. Parental obesity (SCdirect = 0.105, p = 0.047) and nutritional status at birth (SCtotal = -0.124, p = 0.009; SCdirect = -0.131, p = 0.007) were associated with asthma in adult life. A higher "current adult socieconomic situation" was inversely associated to overweight (SCdirect = -0.171, p = 0.020) and to asthma in adult life (SCtotal = -0.179, p = 0.041; SCdirect = -0.182, p = 0.039). Parental obesity showed a transgenerational effect in weight, triggering to childhood and adulthood overweight. Parallel to underweight at birth, parental obesity was also a risk to asthma in adult life. While, the socioeconomic status in adult life protected from both, overweight and asthma.

Google trend analysis of climatic zone based Indian severe seasonal sensitive population

Background

Our earlier Google Trend (GT) Analytics study reported that the worldwide human population severely subject to four seasonal (sensitive) comorbid lifestyle diseases (SCLD) such as asthma, obesity, hypertension and fibrosis. The human population subject to seasonal variability in these four diseases activity referred as “severe seasonal sensitive population”. In India, the estimated burden of these four seasonal diseases is more than 350 million as on the year 2018. It is a growing crisis for India with a projected disease burden of 500 million in the year 2025. This study was aimed to decipher the genuine SCLD seasonal trends in the entire Indian population using GT and validate these trends in Indian climatic zones.

Methods

GT is used to study the temporal trends in web search using weekly Relative Search Volume (RSV) for the period 2004 to 2017. The relative search volume (RSV) of the four-severe seasonal comorbid diseases namely Asthma, Hypertension, Obesity and Fibrosis were collected with and without obesity as the reference. The RSV were collected using the GT selection options as (i) Whole India (ii) Jammu and Kashmir (Cold zone) (iii) Rajasthan (Hot and Dry zone) (iii) West Bengal (Hot and Humid zone) and (iv) Uttar Pradesh state (Composite zone). The time series analysis was carried out to find seasonal patterns, comorbidity, trends and periodicity in the entire India and four of its states (zones).

Results

Our analysis of entire India (2004–2017) revealed high significant seasonal patterns and comorbidity in all the four diseases of SCLD. The positive tau values indicated strong positive seasonal trends in the SCLD throughout the period (Table). The auto correlation analysis revealed that these diseases were subjected to 3, 4 and 6 months period seasonal variations. Similar seasonal patterns and trends were also observed in all the four Indian temperature zones. Overall study indicated that SCLD seasonal search patterns and trends are highly conserved in India even in drastic Indian climatic zones.

Conclusions

The clinical outcome arise out of these observations could be of immense significance in handling the major chronic life style diseases asthma, hypertension, obesity and fibrosis. The possible strong comorbid relationship among asthma, hypertension, obesity and fibrosis may be useful to segregate Indian seasonal sensitive population. In disease activity-based chronotherapy, the search interest of segment of the population with access to Internet may be used as an indicator for public health sectors in the early detection of SCLD from a specific country or a region. As this disease population could be highly subject to the adverse effect of seasons in addition to life style and other environmental factors. Our study necessitates that these Indian populations need special attention from the Indian health care sectors.

Overweight Proxies Are Associated with Atopic Asthma: A Matched Case-Control Study

BACKGROUND

Many studies have documented a link between overweight and asthma in children with contradictory results regarding the best way to measure overweight. Moreover, often, the dynamic development of atopy, overweight, and asthma is controlled for age dependency insufficiently.

OBJECTIVE

This study assesses and compares the associations of overweight measured as waist circumference, waist to height ratio (WHtR), neck circumference, and body mass index with the occurrence of asthma - best possibly controlling for age-dependencies of these parameters.

METHODS

From a sample of 2,511 children aged 6-17 years, we matched 157 children with asthma with 2 controls (n = 471) according to age and atopy status and performed conditional logistic regression analyses. We further investigated the role of known influencing factors of asthma occurrence.

RESULTS

In children with atopy, all overweight proxies were consistently positively associated with asthma. Statistical significance was reached for WHtR-SD score (OR 1.26, 95% CI 1.03-1.54, p = 0.025) and persisted when further covariates, such as birth weight or social status, were added to the model. Groups of atopic versus nonatopic participants do not differ in levels of interleukin-6 or high-sensitivity C-reactive protein.

CONCLUSION

In our cohort, overweight seems to carry a risk for asthma only if accompanied with atopy. We call for more strict age matching in pediatric cohort studies and longitudinal studies for a better understanding for causal links of overweight, atopy, and asthma.

Physical Activity: A Missing Link in Asthma Care

Asthma is the commonest respiratory disease and one of unceasingly increasing prevalence and burden. As such, asthma has attracted a major share or scientific interest and clinical attention. With the various clinical and pathophysiological aspects of asthma having been extensively investigated, the important association between asthma and physical activity remains underappreciated and insufficiently explored. Asthma impacts adversely on physical activity. Likewise, poor physical activity may lead to worse asthma outcomes. This concise clinical review presents the current recommendations for physical activity, discusses the available evidence on physical activity in asthma, and examines the causes of low physical activity in adult asthmatic patients. It also reviews the effect of daily physical activity and exercise training on the pathology and clinical outcomes of asthma. Finally, it summarizes the evidence on interventions targeting physical activity in asthma.

Dendritic Cell-Restricted Progenitors Contribute to Obesity-Associated Airway Inflammation via Adam17-p38 MAPK-Dependent Pathway

Proliferation of dendritic cell (DC)—restricted progenitor cells in bone marrow compartment is tightly regulated at steady state and responds to multiple tissue-specific triggers during disturbed homeostasis such as obesity. DCs in the lung stem from a rapidly dividing DC-restricted progenitor cells and are effective at generating adaptive immune responses in allergic airway inflammation. Precisely, how DC-restricted progenitor expansion and differentiation are influenced by airway inflammation to maintain constant supply of myeloid DCs is poorly understood. Here we show that a high fat diet (HFD) induces oxidative stress and accelerates the expansion of DC- restricted progenitor cells in bone marrow and correlates with persistent induction of p38 mitogen activated protein kinase (MAPK), which is blocked with a selective p38α/β MAPK inhibitor. Mice fed a HFD and sensitized to inhaled allergen house dust mite (HDM) led to alterations of DC- restricted progenitor cells that were characterized by increased expansion and seeding of lung DCs in airway inflammation. Mechanistically, we establish that the expansion induced by HFD dysregulates the expression of a disintegrin and metallopeptidase domain 17 (Adam17) and is required for p38 MAPK activation in DC-restricted progenitors. These results demonstrates that obesity produces persistent changes in DC precursors and that elevation of Adam17 expression is tightly coupled to p38 MAPK and is a key driver of proliferation. Altogether, these data provide phenotypic and mechanistic insight into dendritic cell supply chain in obesity-associated airway inflammation.

Childhood BMI and the occurrence of respiratory disease-related hospital admissions or death in adulthood: the Busselton Health Study

PURPOSE

Few studies have investigated the association of childhood obesity with respiratory disease-related outcomes in adulthood and findings are inconsistent. The aim of this study was to examine the associations of body mass index (BMI) in childhood with the occurrence of respiratory events in adulthood.

METHODS

We analyzed a cohort of 4537 school-aged children who attended the Busselton Health Study. Height and weight were measured and generated BMI z-scores were categorized into four groups. Participants were followed for respiratory disease-related hospital admissions or death using the Western Australia Data Linkage System. The associations between childhood BMI and respiratory events in adulthood were investigated using Cox regression models. A subgroup of 2196 that reattended a survey in young adulthood was also analyzed.

RESULTS

During the 122,781 person-years of follow-up, 810 participants experienced a respiratory event. Childhood BMI group was not associated with risk of respiratory event in adulthood (hazard ratio for BMI z ≥ 1 vs. < -1 = 0.90; 95% CI, 0.70-1.17; P = .295) and this persisted after adjustment for selected confounders in the subgroup (hazard ratio 0.80; 95% CI, 0.43-1.48; P = .476).

CONCLUSIONS

Childhood BMI is not associated with risk of respiratory events in adulthood.

Lung functional development and asthma trajectories

Early life environmental risk factors are associated with chronic respiratory morbidity in child- and adulthood. A possible mechanism for this sustained effect is their influence on early life lung functional growth and development, a susceptible phase of rapid lung growth with increased plasticity. We summarize evidence of hereditary and environmental ante-, peri-, and early postnatal factors on lung functional development, such as air pollution, tobacco exposure, nutrition, intrauterine growth retardation, prematurity, early life infections, microbiome, and allergies and their effect on lung functional trajectories. While some of the factors (e.g., prematurity) directly impair lung growth, the influence of many environmental factors is mediated through inflammatory processes (e.g., recurrent infections or oxidative stress). The timing and nature of these influences and their impact result in degrees of impaired maximal lung functional capacity in early adulthood; and they potentially impact future long-term respiratory morbidity such as chronic asthma or chronic obstructive airway disease (COPD). We discuss possibilities to prevent or modify such early abnormal lung functional growth trajectories and the need for future studies and prevention programs.

Sex Steroid Hormones and Asthma in a Nationwide Study of U.S. Adults

Rationale: Women have a higher burden of asthma than men. Although sex hormones may explain sex differences in asthma, their role is unclear.Objectives: To examine sex hormone levels and asthma in adults.Methods: Cross-sectional study of serum levels of free testosterone and estradiol and current asthma in 7,615 adults (3,953 men and 3,662 women) aged 18-79 years who participated in the 2013-2014 and 2015-2016 U.S. National Health and Nutrition Examination Survey. Logistic regression was used for the multivariable analysis of sex hormones and current asthma, which was conducted separately in women and men.Measurements and Main Results: Free testosterone levels in the fourth quartile were associated with lower odds of current asthma in women (odds ratio [OR] for the fourth quartile [Q4] vs. Q1, 0.56; 95% confidence interval [CI], 0.39-0.80). Given an interaction between obesity and sex hormones on current asthma, we stratified the analysis by obesity. In this analysis, elevated free testosterone (OR for Q4 vs. Q1, 0.59; 95% CI, 0.37-0.91) and estradiol (OR for Q4 vs. Q1, 0.43; 95% CI, 0.23-0.78) levels were associated with reduced odds of current asthma in obese women, and an elevated serum estradiol was associated with lower odds of current asthma in nonobese men (OR for Q4 vs. Q1, 0.44; 95% CI, 0.21-0.90).Conclusions: Our findings suggest that sex hormones play a role in known sex differences in asthma in adults. Moreover, our results suggest that obesity modifies the effects of sex hormones on asthma in adults.

The ORMDL3 Asthma Gene Regulates ICAM1 and Has Multiple Effects on Cellular Inflammation

RATIONALE

Polymorphisms on chromosome 17q21 confer the major genetic susceptibility to childhood-onset asthma. Risk alleles positively correlate with ORMDL3 (orosomucoid-like 3) expression. The locus influences disease severity and the frequency of human rhinovirus (HRV)-initiated exacerbations. ORMDL3 is known to regulate sphingolipid synthesis by binding serine palmitoyltransferase, but its role in inflammation is incompletely understood.

OBJECTIVES

To investigate the role of ORMDL3 in cellular inflammation.

METHODS

We modeled a time series of IL1B-induced inflammation in A549 cells, using cytokine production as outputs and testing effects of ORMDL3 siRNA knockdown, ORMDL3 overexpression, and the serine palmitoyltransferase inhibitor myriocin. We replicated selected findings in normal human bronchial epithelial cells. Cytokine and metabolite levels were analyzed by analysis of variance. Transcript abundances were analyzed by group means parameterization, controlling the false discovery rate below 0.05.

MEASUREMENTS AND MAIN RESULTS

Silencing ORMDL3 led to steroid-independent reduction of IL6 and IL8 release and reduced endoplasmic reticulum stress after IL1B stimulation. Overexpression and myriocin conversely augmented cytokine release. Knockdown reduced expression of genes regulating host-pathogen interactions, stress responses, and ubiquitination: in particular, ORMDL3 knockdown strongly reduced expression of the HRV receptor ICAM1. Silencing led to changes in levels of transcripts and metabolites integral to glycolysis. Increased levels of ceramides and the immune mediator sphingosine-1-phosphate were also observed.

CONCLUSIONS

The results show ORMDL3 has pleiotropic effects during cellular inflammation, consistent with its substantial genetic influence on childhood asthma. Actions on ICAM1 provide a mechanism for the locus to confer susceptibility to HRV-induced asthma.

Bidirectional Association Between Asthma and Obesity During Childhood and Adolescence: A Systematic Review and Meta-Analysis

Objective: Co-occurrence of pediatric asthma and obesity has been widely reported, yet the causal directions between these two disorders are still not well-understood. The objective of this meta-analysis is to explore whether there is a possibility of a bidirectional association for these two disorders in children and adolescents. Methods: PubMed, Embase, Web of Science, and CENTRAL databases were searched up to August 2020. Cohort studies reporting the associations of obesity with risk of physician-diagnosed asthma or physician-diagnosed asthma with risk of obesity in children and adolescents were eligible for the review. Results: A total of 3,091 records were identified from the four databases, with final inclusion of nine. Six studies reported the association between obesity and risk of asthma; three studies reported the association between asthma and risk of childhood obesity. As evaluated by the Newcastle-Ottawa quality assessment scale, all studies were assessed as high-quality studies. There was a statistically significant association between obesity and increased risk of physician-diagnosed asthma in children and adolescents. The pooled RR was 1.39 (95% CI: 1.28, 1.50; p < 0.001), with significant heterogeneity across studies (I ² = 81.7%; p _{heterogeneity} < 0.001). The pooled RR in boys was 1.53 (95% CI: 1.17, 1.99; p = 0.002), but such a significant association was not observed in girls (RR = 1.17, 95% CI: 0.79, 1.72; p = 0.434). For the association of asthma with risk of childhood obesity, the pooled RR was 1.47 (95%CI: 1.25, 1.72; p < 0.001) without statistical heterogeneity (I ² = 0%, p _{heterogeneity} = 0.652). Conclusion: There is a bidirectional association between obesity and asthma during childhood and adolescence, suggesting that childhood obesity drives an increase in the onset of asthma; meanwhile, childhood asthma may also increase risk of obesity for children and adolescents.

Correlation between eosinophil count, its genetic background and body mass index: The Nagahama Study

BACKGROUND

Obesity affects the pathogenesis of various chronic diseases, including asthma. Research on correlations between obesity/BMI and eosinophilic inflammation in asthma has yielded contradictory results, which could be partly ascribed to the absence of epidemiological data on the correlations. We aimed to elucidate the correlations between blood eosinophil count, its genetic backgrounds, and BMI in the general population.

METHODS

This community-based Nagahama study in Japan enrolled 9789 inhabitants. We conducted self-reporting questionnaires, lung function tests, and blood tests in the baseline and 5-year follow-up studies. A genome-wide association study (GWAS) was performed in 4650 subjects at the baseline and in 4206 of these at the follow-up to determine single-nucleotide polymorphisms for elevated blood eosinophil counts. We assessed the correlations between BMI and eosinophil counts using a multifaceted approach, including the cluster analysis.

RESULTS

Eosinophil counts positively correlated with BMI, observed upon the interchange of an explanatory variable, except for subjects with the highest quartile of eosinophils (≥200/μL), in whom BMI negatively correlated with eosinophil counts. GWAS and human leukocyte antigen (HLA) imputation identified rs4713354 variant (MDC1 on chromosome 6p21) for elevated eosinophil counts, independent of BMI and IgE. Rs4713354 was accumulated in a cluster characterized by elevated eosinophil counts (mean, 498 ± 178/μL) but normal BMI.

CONCLUSIONS

Epidemiologically, there may be a positive association between blood eosinophil counts and BMI in general, but there was a negative correlation in the population with high eosinophil counts. Factors other than BMI, particularly genetic backgrounds, may contribute to elevated eosinophil counts in such populations.

Special Considerations in Preschool Age

The diagnosis of asthma can be particularly difficult in young children, in whom wheezing is not always synonym with asthma. It is also difficult to predict which preschool children with wheeze will go on to be true asthmatics. In this chapter, we will characterize preschool wheezing and asthma and discuss early risk factors for the development of severe asthma. We will also review risk factors for severe acute wheezing in young children. Finally, we will describe the natural history and prognosis of wheezing and some of the attempts at early identification of children who will develop severe asthma.

Metabolic Syndrome and Incident Asthma in Chinese Adults: An Open Cohort Study

BACKGROUND

Although metabolic syndrome is awell-known risk factor for many non-communicable diseases, its contribution to asthma remains controversial.

OBJECTIVE

The aim of this study was to explore the associations of metabolic syndrome and its components with incident asthma in Chinese adults.

METHODS

We conducted an open cohort study of participants who were asthma-free at baseline (n=42,304) in the Shandong multi-center health check-up longitudinal study from 2004 to 2015. Participants aged ≥20 years and had regular physical examination (once ayear) more than three times during follow-up.

RESULTS

Ninety subjects (38 women and 52 men) developed incident asthma over 12 years of follow-up. Our study suggested that metabolic syndrome itself was not significantly associated with incident asthma in either women or men (P>0.050). Interestingly, we found that overweight and/or obesity was arisk factor for incident asthma among women but not men in the Cox proportional hazards model after adjusting covariates (adjusted incidence rate ratio (IRR)= 2.940, 95% confidence interval (CI): 1.467-5.894, P=0.002). The result was consistent with the Poisson regression model (hazard ratio (HR)= 2.241, 95% CI: 1.135-4.988, P=0.026). After stratifying according to overweight and/or obesity, we found that female subjects with overweight and obesity were associated with the occurrence of incident asthma (P<0.050). However, we did not find this result among men.

CONCLUSION

Metabolic syndrome was not significantly associated with incident asthma in both women and men; however, overweight and/or obesity was shown to be asignificant risk factor for incident asthma but only in women, not in men.

Higher Omega-3 Index Is Associated with Better Asthma Control and Lower Medication Dose: A Cross-Sectional Study

Asthma is a chronic inflammatory airway disease, associated with systemic inflammation. Omega-3 polyunsaturated fatty acids (n-3 PUFA) have established anti-inflammatory effects, thus having potential as an adjunct therapy in asthma. This study aimed to compare erythrocyte n-3 PUFA in adults with (n = 255) and without (n = 137) asthma and determine the relationship between erythrocyte n-3 PUFA and clinical asthma outcomes. Subjects had blood collected, lung function measured and Juniper Asthma Control Questionnaire (ACQ) score calculated. Fatty acids were measured in erythrocyte membranes by gas chromatography, and the omega-3 index (O3I) was calculated (% eicosapentaenoic acid + % docosahexaenoic acid). O3I was similar in subjects with and without asthma (p = 0.089). A higher O3I was observed in subjects with controlled or partially controlled asthma (ACQ < 1.5) compared to subjects with uncontrolled asthma (ACQ ≥ 1.5) (6.0% (5.4–7.2) versus 5.6% (4.6–6.4) p = 0.033). Subjects with a high O3I (≥8%) had a lower maintenance dose of inhaled corticosteroids (ICS) compared to those with a low O3I (<8%) (1000 μg (400–1000) versus 1000 μg (500–2000) p = 0.019). This study demonstrates that a higher O3I is associated with better asthma control and with lower ICS dose, suggesting that a higher erythrocyte n-3 PUFA level may have a role in asthma management.

Contemporary management techniques of asthma in obese patients

Introduction: Obesity-associated asthma represents a heterogeneous group of clinical phenotypes, including an adult-onset phenotype. These patients often have difficult to control symptoms and often are less likely to respond to conventional asthma therapies.Areas covered: This review covers the effects of lifestyle interventions, including diet and weight loss, effect asthma outcomes and how obesity-associated asthma responds to conventional approaches to asthma management.Expert opinion: Management of obesity-associated asthma should include lifestyle modifications aimed at weight reduction, management of other co-morbidities, and limiting systemic steroids. As many of these patients have non-Th2 asthma, long-acting muscarinic antagonists and macrolides may be potentially helpful. Medications to treat metabolic syndrome.

[Asthma and obesity in adults]

Asthma is a chronic inflammatory airway disorder characterized by a multitude of phenotypes. Epidemiological studies show an increase in asthma prevalence in obese patients regardless of age. The association of asthma and obesity is now considered as a phenotype with its own clinical, biological and functional characteristics. Regarding the pathophysiology of asthma and obesity, numerous factors such as nutrition, genetic predisposition, microbiome, ventilatory mechanics and the role of adipose tissue have been identified to explain the heterogeneous characteristics of patients with asthma and obesity. In adult patients with asthma and obesity, respiratory symptoms are particularly prominent and atopy and eosinophilic inflammation is uncommon compared to normal weight asthma patients. Obese asthma patients experience more hospitalizations and use more rescue medications than normal weight asthmatics. Management of asthma in obese patients is complex because these patients have less response to the usual anti-asthmatic treatments. Weight loss through caloric restriction combined with exercise is the main intervention to obtain improvement of asthma outcomes. Bariatric surgery is an invasive procedure with interesting results.

[Obesity and asthma: Mechanisms and therapeutic options]

Asthma and obesity are both common conditions, which lead to a substantial public health burden. The obese-asthma phenotype is characterized by poor asthma control, impaired lung function and decreased efficacy of inhaled treatment. However, this phenotype is highly heterogeneous and involves numerous mechanisms, including systemic inflammation and adipokines. A role for microbiota modifications and genetics has been suggested. Obese-asthma patient management currently consists in weight loss and usual anti-asthmatic treatment. New therapeutic options are being evaluated.

Decreased methylation profiles in the TNFA gene promoters in type 1 macrophages and in the IL17A and RORC gene promoters in Th17 lymphocytes have a causal association with non-atopic asthma caused by obesity: A hypothesis

Obesity is a serious public health problem worldwide and has been associated in epidemiological studies with a unique type of non-atopic asthma, although the causal association of asthma and obesity has certain criteria, such as the strength of association, consistency, specificity, temporality, biological gradient, coherence, analogy and experimentation; nevertheless, the biological plausibility of this association remains uncertain. Various mechanisms have been postulated, such as immunological, hormonal, mechanical, environmental, genetic and epigenetic mechanisms. Our hypothesis favours immunological mechanisms because some cytokines, such as tumour necrosis factor alpha (TNF-α) and interleukin (IL)-17A, are responsible for orchestrating low-grade systemic inflammation associated with obesity; however, these cytokines are regulated by epigenetic mechanisms, such as gene promoter methylation.

The Influence of Dietary Fatty Acids on Immune Responses

Diet-derived fatty acids (FAs) are essential sources of energy and fundamental structural components of cells. They also play important roles in the modulation of immune responses in health and disease. Saturated and unsaturated FAs influence the effector and regulatory functions of innate and adaptive immune cells by changing membrane composition and fluidity and by acting through specific receptors. Impaired balance of saturated/unsaturated FAs, as well as n-6/n-3 polyunsaturated FAs has significant consequences on immune system homeostasis, contributing to the development of many allergic, autoimmune, and metabolic diseases. In this paper, we discuss up-to-date knowledge and the clinical relevance of the influence of dietary FAs on the biology, homeostasis, and functions of epithelial cells, macrophages, dendritic cells, neutrophils, innate lymphoid cells, T cells and B cells. Additionally, we review the effects of dietary FAs on the pathogenesis of many diseases, including asthma, allergic rhinitis, food allergy, atopic dermatitis, rheumatoid arthritis, multiple sclerosis as well as type 1 and 2 diabetes.

Inhibiting the Notch signaling pathway suppresses Th17-associated airway hyperresponsiveness in obese asthmatic mice

Notch signaling is crucial for the regulation of asthma and obesity. The interleukin (IL)-17-expressing CD4⁺ T cell (Th17 cell) response and airway hyperresponsiveness (AHR) are critical features of both asthma and obesity. We previously demonstrated that inhibiting the Notch signaling pathway alleviates the Th17 response in a mouse model of asthma. However, obese asthmatic individuals show increased Th17 responses and AHR, with the underlying mechanism not currently understood. We aimed to assess the function of Notch signaling in obese mice with asthma and to determine the impact of a γ-secretase inhibitor (GSI), which inhibits the Notch signaling pathway, on the regulation of the Th17 response and AHR. C57BL/6 mice were administered ovalbumin (OVA) to induce asthma, while a high-fat diet (HFD) was used to induce mouse diet-induced obesity (DIO). GSI was then administered intranasally for 7 days in DIO-OVA-induced mice. The results showed increased Notch1 and hes family bHLH transcription factor 1 (Hes1) mRNA levels and Notch receptor intracellular domain (NICD) protein levels in obese asthmatic mice. Furthermore, these mice showed an increased proportion of Th17 cells, serum IL-17A, IL-6, and IL-1β levels, mucin 5AC (MUC5AC) mRNA level, retinoic acid-related orphan receptor-γt (RORγt) mRNA and protein levels, and increased AHR severity. Interestingly, GSI treatment resulted in reduced Notch1 and Hes1 mRNA and NICD protein levels in DIO-OVA-induced mice, with a decreased Th17 cell proportion and IL-17A quantity and alleviated AHR. These data strongly indicate that the Notch pathway is critical in obese asthmatic mice. In addition, inhibiting the Notch pathway ameliorates AHR and the Th17 response in obese mice with asthma.

Excessive Body Weight and Immunological Response in Children with Allergic Diseases

The prevalence of allergy and obesity is sharply on the rise in children. However, the nature of a mutual relation of the two conditions remains unclear. The aim of the study was to assess the impact of excessive body weight on the immune response in children with allergies. There were 56 children with allergies, aged 4-15 years, included into the study (41 with asthma and 15 with atopic dermatitis). Based on the body mass index, children were divided into two groups: normal weight (body mass index (BMI) <85th percentile) and excessive weight (BMI ≥ 85th percentile). The immunological parameters were evaluated by flow cytometry. We found that children with excessive body weight had a significantly lower percentage of CD4⁺ lymphocytes and a higher percentage of natural killer T cells (NKT) and CD16/56⁺ lymphocytes than those with normal weight. In the group with allergy, a significant positive association was noticed between BMI and the percentage of human leukocyte antigen (HLA)-DR-specific CD3. Further analysis was done after dividing the allergy group into the children with normal and excessive weight. There were an adverse association between BMI and the percentage of CD8⁺ lymphocytes in those with normal weight and a positive one between BMI and the percentage of CD4⁺ in those with excessive weight. We conclude that excessive body weight plays a major role in mediating the immunological response in children with allergy.

What did we learn from multiple omics studies in asthma?

More than a decade has passed since the finalization of the Human Genome Project. Omics technologies made a huge leap from trendy and very expensive to routinely executed and relatively cheap assays. Simultaneously, we understood that omics is not a panacea for every problem in the area of human health and personalized medicine. Whilst in some areas of research omics showed immediate results, in other fields, including asthma, it only allowed us to identify the incredibly complicated molecular processes. Along with their possibilities, omics technologies also bring many issues connected to sample collection, analyses and interpretation. It is often impossible to separate the intrinsic imperfection of omics from asthma heterogeneity. Still, many insights and directions from applied omics were acquired-presumable phenotypic clusters of patients, plausible biomarkers and potential pathways involved. Omics technologies develop rapidly, bringing improvements also to asthma research. These improvements, together with our growing understanding of asthma subphenotypes and underlying cellular processes, will likely play a role in asthma management strategies.

Metabolic syndrome and lung function in Korean children and adolescents: A cross-sectional study

This study aimed to investigate whether obesity and metabolic syndrome (MetS) are associated with pulmonary function in Korean children and adolescents. Data from the 2009–2011 Korea National Health and Nutrition Examination Survey which is cross-sectional, nationwide, and representative survey were used. Adjusted regression analysis was performed to evaluate the association of obesity and MetS with lung function in children and adolescents. A total of 763 children and adolescents aged 10–18 years were evaluated. We found no significant difference in FEV₁% predicted, FVC% predicted, and FEV₁/FVC ratio among the obesity groups. Subjects with MetS showed a significantly lower FEV₁ predicted (91.54 ± 0.74% vs 94.64 ± 0.73%, P = 0.004), lower FVC% predicted (91.86 ± 0.63% vs 95.20 ± 0.63%, P < 0.001), and lower FEV₁/FVC ratio (76.76 ± 0.43% vs 80.13 ± 0.43%, P < 0.001) than those without MetS. Elevated waist circumference (WC), systolic blood pressure, fasting glucose, and lower high-density lipoprotein cholesterol (HDL-C) were independently associated with lower FEV₁/FVC ratio (all P < 0.05, respectively). Among MetS components, increased WC was the most important factor influencing lower FEV₁/FVC ratio. In conclusion, lung function in MetS patients was significantly lower, and the MetS component was independently associated.

Pravastatin alleviates allergic airway inflammation in obesity-related asthma mouse model

Background: Obesity is one of the factors associated with severe, uncontrolled asthma. The effect of pravastatin on asthmatic airway inflammation in obesity has not been evaluated. Methods: C57BL/6 mice were fed a high-fat diet (HFD) to induce obesity with or without ovalbumin (OVA) sensitization and challenge. Pravastatin was administered intraperitoneally during the OVA treatment. Airway inflammation and airway hyper-responsiveness (AHR) were analyzed and lung tissues were examined. The changes in mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K)/Akt signaling pathways were measured in the lung tissues. Results: HFD with OVA sensitization and challenge exacerbated eosinophilic and neutrophilic airway inflammation and increased AHR compared to lean asthma mice. The levels of cytokines examined in bronchoalveolar lavage fluid (BALF) revealed that the expressions of IL-4, 5, and 17 were elevated in the obese asthmatic group and decreased after pravastatin treatment, indicating that both the Th2 and Th17 pathways were stimulated by HFD-induced obesity and OVA challenge and suppressed by pravastatin treatment. Moreover, the serum leptin and adiponectin ratio was elevated only in obese asthmatic mice and decreased with pravastatin administration. Pravastatin successfully alleviated the airway inflammation of lung tissues and AHR in both obese and lean asthmatic mice, however, treatment with pravastatin had no effects on BALF cell counts and cytokines in lean asthma mice. In lung tissues, the phosphorylation of p38 MAPK was significantly decreased in lean as well as obese asthmatic mice. Conclusions: Pravastatin treatment in obese asthmatic mice suppressed allergic airway infiltration and AHR by inhibition of Th2 and Th17-associated signaling pathways, decreasing the leptin expression and downstream p38 MAPK signaling pathways. The effect on lean asthmatic mice was different, independent of airway cell counts and cytokines.

The impact of weight loss beyond lung function: benefit with respect to asthma outcomes

OBJECTIVE

We evaluated the effect of weight loss (WL) on lung function (LF) in obese individuals who underwent bariatric surgery, and on asthma control, quality of life, LF, and controller medication in a sub-group of obese asthma (OA) patients.

MATERIALS AND METHODS

Obese individuals who underwent bariatric surgery between July 2015 and July 2017 were included in this prospective longitudinal study. They were classified as OA or obese non-asthmatics (O-NA). LF was assessed preoperatively and 6-9 months postoperatively. In OA patients, asthma control, quality of life, and treatment step were evaluated. P < 0.05 was considered significant.

RESULTS

Twenty-six patients (OA: n = 8; O-NA: n = 18), 84.6% with class III obesity were enrolled. Preoperatively, OA patients showed worse values of LF parameters, with upper and lower airway CARAT scores of 6.1 ± 3.1 and 13.4 ± 4.1, respectively, and 75% were in step 4 of treatment. After WL, improvements in dynamic volumes, lung capacities, and total resistance were observed in both groups. Despite greater increases in OA patients, no significant differences were observed between groups. In OA patients, improvements in CARAT score of upper (3.9 ± 1.9, p = 0.017) and lower (4.2 ± 4.4, p = 0.027) airways, and in Asthma Life Quality scores (8.1 ± 5.6, p = 0.017) were observed along with a decrease (-1.8 ± 1.0, p = 0.017) in treatment step.

CONCLUSIONS

All LF parameters improved after WL. Although the improvement was greater in OA patients, the difference between groups was not significant. Significant improvement from baseline in uncontrolled symptoms of OA patients and quality of life was observed after WL, along with a significant decrease in treatment step.

Clinical Applications of System Regulation Medicine

Increasing incidence and poor outcome of chronic non-communicable diseases in western population would require a paradigm shift in the treatments. Guidelines-based medical approaches continue to be the standard rule in clinical practice, although only less than 15% of them are based on high-quality research. For each person who benefits from the 10 best-selling drugs in the USA, a number between 4 and 25 has no one beneficial effect.

The reductionist linear medicine method does not offer solutions in the non-manifest preclinical stage of the disease when it would still be possible to reverse the pathological progression and the axiom “a drug, a target, a symptom” are still inconclusive. Needs additional tools to address these challenges.

System Medicine considers the disease as a dysregulation of the biological networks that changes throughout the evolution of the pathological process and with the comorbidities development. The strength of the networks indicates their ability to withstand dysregulations during the perturbation phases, returning to the state of stability. The treatment of dysregulated networks before the symptomatological manifestation emerges offers the possibility of treating and preventing pathologies in the preclinical phase and potentially reversing the pathological process, stopping it or preventing comorbidities. Furthermore, treating shared networks instead of individual phenotypic symptoms can reduce drug use, offering a solution to the problem of ineffective drug use.

The Effects of Obesity in Asthma

PURPOSE OF REVIEW

Rising costs and increasing morbidity makes the identification and treatment of high-risk asthma phenotypes important. In this review, we outline the complex relationship between obesity and asthma.

RECENT FINDINGS

Studies have confirmed a bi-directional relationship between obesity and asthma. Pathophysiological factors implicated include genetic risk, the effect of diet and microbiome, and obesity-related cytokines. There have been robust, albeit derived, efforts to phenotype this group with distinct clinical presentations based on age of onset of asthma. Unfortunately, the poor performance of biomarkers and traditional lung function testing has impeded diagnosis, phenotyping, and management of the obese asthma patient. There is also a lack of targeted interventions with weight loss showing some benefits. Obesity increases the prevalence of asthma and is associated with worse outcomes. There are unique research and clinical challenges while managing this group of patients.

Advances in asthma, asthma-COPD overlap, and related biologics in 2018

Over the past year, numerous important advances in our understanding of multiple aspects of asthma, ranging from disease pathogenesis to epidemiology to therapeutics, have been reported. This review is a compilation of highlights from articles published largely in the Journal of Allergy and Clinical Immunology and supplemented by articles published elsewhere that have substantially advanced the fields of asthma, chronic obstructive pulmonary disease (COPD), and asthma-COPD overlap and biologic therapies for these disorders. The intention of this article is not to provide a comprehensive review but rather to focus on several areas that have developed quickly and/or received extensive attention from our readers.

Acute Severe Asthma in Adolescent and Adult Patients: Current Perspectives on Assessment and Management

Asthma is a chronic airway inflammatory disease that is associated with variable expiratory flow, variable respiratory symptoms, and exacerbations which sometimes require hospitalization or may be fatal. It is not only patients with severe and poorly controlled asthma that are at risk for an acute severe exacerbation, but this has also been observed in patients with otherwise mild or moderate asthma. This review discusses current aspects on the pathogenesis and pathophysiology of acute severe asthma exacerbations and provides the current perspectives on the management of acute severe asthma attacks in the emergency department and the intensive care unit.

Oral corticosteroid use, obesity, and ethnicity in children with asthma

Objective: Comorbid asthma and obesity leads to poorer asthma outcomes, partially due to decreased response to controller medication. Increased oral steroid prescription, a marker of uncontrolled asthma, may follow. Little is known about this phenomenon among Latino children. Our objective was to determine whether obesity is associated with increased oral steroid prescription for children with asthma, and to assess potential disparities in these associations between Latino and non-Hispanic white children.Methods: We examined electronic health record data from the ADVANCE national network of community health centers. The sample included 16,763 children aged 5-17 years with an asthma diagnosis and ≥1 ambulatory visit in ADVANCE clinics across 22 states between 2012 and 2017. Poisson regression analysis was used to examine the rate of oral steroid prescription overall and by ethnicity controlling for potential confounders.Results: Among Latino children, those who were always overweight/obese at study visits had a 15% higher rate of receiving an oral steroid prescription than those who were never overweight/obese [rate ratio (RR) = 1.15, 95% CI 1.05-1.26]. A similar effect size was observed for non-Hispanic white children, though the relationship was not statistically significant (RR = 1.10, 95% CI: 0.92-1.33). The interactions between body mass index and ethnicity were not significant (sometimes overweight/obese p = 0.95, always overweight/obese p = 0.58), suggesting a lack of disparities in the association between obesity and oral steroid prescription by ethnicity.Conclusions: Children with obesity received more oral steroid prescriptions than those at a healthy weight, which may be indicative of worse asthma control. We did not observe significant ethnic disparities.

Asthma, obesity and targeted interventions: an update

PURPOSE OF REVIEW

Obese asthma is now widely recognized as a phenotype of difficult asthma that is common and less responsive to traditional asthma treatments, so identifying specific treatments is increasingly important.

RECENT FINDINGS

Obesity can lead to asthma through a complex relationship of causes including mechanical, inflammatory, metabolic and genetic factors. Exercise programmes including pulmonary rehabilitation, weight loss via dietary restriction, exercise and bariatric surgery, or combinations of all of these can improve quality of life, symptoms, and exercise capacity, with reductions in medication use and exacerbations, and represent tailored treatment for this phenotype of severe difficult to treat asthmatic patients.

SUMMARY

Exercise programmes and pulmonary rehabilitation, weight loss programmes targeting 5-10% weight loss and bariatric surgery are effective treatments for the obese asthma phenotype.

Understanding Asthma Phenotypes, Endotypes, and Mechanisms of Disease

The model of asthma as a single entity has now been replaced by a much more complex biological network of distinct and interrelating inflammatory pathways. The term asthma is now considered an umbrella diagnosis for several diseases with distinct mechanistic pathways (endotypes) and variable clinical presentations (phenotypes). The precise definition of these endotypes is central to asthma management due to inherent therapeutic and prognostic implications. This review presents the molecular mechanisms behind the heterogeneity of airway inflammation in asthmatic patients. Asthma endotypes may be broadly regarded as type 2 (T2) high or T2-low. Several biologic agents have been approved for T2-high asthma, with numerous other therapeutics that are incipient and similarly targeted at specific molecular mechanisms. Collectively, these advances have shifted existing paradigms in the approach to asthma to tailor novel therapies.

Evidence for lifestyle interventions in asthma

Asthma is a chronic inflammatory airways disease, estimated to affect 300 million people worldwide. Asthma management plans focus on optimisation of asthma pharmacotherapy. Lifestyle interventions also hold great promise for asthma sufferers as they are accessible, low cost and have minimal side-effects, thus making adherence more likely. This review explores lifestyle interventions that have been tested in asthma, including improving nutrition, increasing physical activity and introduction of relaxation therapies such as yoga and massage therapy. Available evidence suggests a protective effect of increasing fruit, vegetable and wholegrain intake and increasing physical activity levels in asthma. Weight loss is recommended for obese asthmatic patients, as just 5–10% weight loss has been found to improve quality of life and asthma control in most obese asthmatic patients. Other lifestyle interventions such as meditation, yoga and massage therapy show promise, with positive effects on asthma seen in some studies. However, the study protocols are highly variable and the results are inconsistent. Additional research is needed to further develop and refine recommendations regarding lifestyle modifications that can be implemented to improve asthma.

Lifestyleinterventions may be key to living well with asthma, as increasing fruit, vegetable and wholegrain intake and exercise levels are shown to improve asthma. Future recommendations may include yoga, meditation and massage.http://bit.ly/2wbJp2J

Bariatric surgery: a potential cure for asthma?

Asthma incidence and severity are increased in obese populations. Systematic reviews have shown benefit from weight-loss interventions on asthma outcomes, but the role of bariatric surgery is still unclear. In this review, cohorts of obese asthmatic patients undergoing bariatric surgery were examined regarding different asthma outcomes. The available data on patients who were followed up showed improvements in asthma control, exacerbation risk, asthma-related hospitalisation, medication use and airway hyperresponsiveness, with some patients not requiring further treatment for asthma. Follow-up duration was variable, being mostly of 1 year, with some studies reporting long-term outcomes after 5 years. The studies reviewed had many limitations, including small numbers of patients, lack of control arm in some studies and lack of standardisation of asthma diagnosis, classification and outcome measures, in addition to possible reporting bias. Data on small numbers of patients also show the possibility of benefit exclusively in nonallergic asthma. Larger, more stringent clinical trials are needed before recommending bariatric surgery for treatment of asthma.

Association Between Prediabetes/Diabetes and Asthma Exacerbations in a Claims-Based Obese Asthma Cohort

BACKGROUND

Metabolic dysfunction may contribute to worsened asthma in obesity. The relationship between prediabetes and diabetes, metabolic conditions more common in obesity, and asthma outcomes is not well characterized.

OBJECTIVE

We sought to determine the association between prediabetes/diabetes and asthma exacerbations in an obese asthma cohort.

METHODS

A retrospective cohort of US obese adults with asthma, aged 18-64, was created from a claims-based health services database spanning 2010 to 2015. Individuals with a hemoglobin A1c (HbA1c) measurement were identified, categorized as within normal (<5.6%), prediabetes (5.7% to 6.4%), and diabetes (≥6.5%) ranges. Exacerbations, defined as asthma-related hospitalization, emergency department visit, or corticosteroid prescription ±14 days of an asthma-related outpatient visit, were ascertained. Associations were fit with zero-inflated negative binomial models, adjusted for age, sex, region, smoking, medication use, and comorbidities.

RESULTS

A total of 5722 individuals were identified. Higher HgbA1c was associated with higher asthma exacerbation rates. In the fully adjusted model, compared with individuals with normal HbA1c, those in the prediabetes range had a 27% higher rate (95% confidence interval [CI], 5% to 52%), and those in the diabetes range had a 33% higher rate (95% CI, 2% to 73%).

CONCLUSIONS

Prediabetes and diabetes were associated with higher rates of asthma exacerbation among obese adults with asthma. Results support evidence that insulin resistance and metabolic syndrome, metabolic features common in prediabetes/diabetes, can influence asthma morbidity.