Does body mass index influence responsiveness to inhaled corticosteroids in persistent asthma?

Impact of obesity on airway remodeling in asthma: pathophysiological insights and clinical implications

The prevalence of obesity among asthma patients has surged in recent years, posing a significant risk factor for uncontrolled asthma. Beyond its impact on asthma severity and patients' quality of life, obesity is associated with reduced lung function, increased asthma exacerbations, hospitalizations, heightened airway hyperresponsiveness, and elevated asthma-related mortality. Obesity may lead to metabolic dysfunction and immune dysregulation, fostering chronic inflammation characterized by increased pro-inflammatory mediators and adipocytokines, elevated reactive oxygen species, and reduced antioxidant activity. This chronic inflammation holds the potential to induce airway remodeling in individuals with asthma and obesity. Airway remodeling encompasses structural and pathological changes, involving alterations in the airway's epithelial and subepithelial layers, hyperplasia and hypertrophy of airway smooth muscle, and changes in airway vascularity. In individuals with asthma and obesity, airway remodeling may underlie heightened airway hyperresponsiveness and increased asthma severity, ultimately contributing to the development of persistent airflow limitation, declining lung function, and a potential increase in asthma-related mortality. Despite efforts to address the impact of obesity on asthma outcomes, the intricate mechanisms linking obesity to asthma pathophysiology, particularly concerning airway remodeling, remain incompletely understood. This comprehensive review discusses current research investigating the influence of obesity on airway remodeling, to enhance our understanding of obesity's role in the context of asthma airway remodeling.

Obesity and Insulin Resistance in Asthma Pathogenesis and Clinical Outcomes

Common inflammatory ground links obesity, insulin resistance, and asthma. As recognition of their interplay, one worsening the natural course of the other, is recognised, questions remain about how to adequately address them altogether to improve clinical outcomes. The present manuscript sheds light on the problem, describing possible pathophysiological links, clinical views, and therapeutic challenges, raising questions about what remains to be done, and calling for multidisciplinary treatment of these patients to detect diseases early and adequately address them before they become full-blown and deteriorate their health and quality of life.

Bronchodilator reversibility testing in morbidly obese non-smokers: fluticasone/salmeterol efficacy versus salbutamol bronchodilator

A positive response in reversibility testing is widely used to diagnose patients with airway limitations. However, despite its simple procedure, it doesn't accurately reflect the exact airway irreversibility. This study aimed to investigate the efficacy of a bronchodilation reversibility test using salbutamol and fluticasone/salmeterol combination in obese non-smoker subjects.The study included patients without a history of obstructive lung disease or bronchodilators. A sub-classification of patients based on body mass index (BMI) was carried out into normal (< 24.9 kg/m2), overweight (25-29.9 kg/m2), and obese (BMI ≥ 30). Spirometry measurements were performed before and after salbutamol or fluticasone/salmeterol administration.The study included 415 (49.9% male) patients with a mean age of 40.92 ± 10.86 years. Obese subjects showed a high prevalence of restrictive patterns (23.4%), with non-significantly lower spirometric values compared to normal and overweight subjects (p > 0.05). The magnitude of bronchodilation, as identified by spirometry, following fluticasone/salmeterol was higher in all participants, with a significant increase in obese subjects with a p-value of 0.013, 0.002, and 0.035 for FEV1, FEV1% predicted, and FEV1/FVC, respectively.Fluticasone/salmeterol combination increases FEV1, FEV1% of predicted, and FEV1/FVC ratio than the conventional test using salbutamol inhaler, and it can be a potential candidate for assessment of airway obstruction using reversibility test, especially among the obese population.

Clinical characteristics and cytokine profiles of adult obese asthma with type2 inflammation

Obesity-related non-eosinophilic asthma has been identified as a phenotype of asthma. However, mepolizumab and omalizumab improve asthma control in severe asthma with obesity, implying that type-2 cytokines may be involved in the deterioration of control in obese asthma. Despite this, the clinical details of obese asthma with positive type-2 inflammation markers have not yet been reported. The objective of this study was to investigate the clinical characteristics of patients with obese asthma with positive type-2 inflammation markers. Adult obese asthmatic patients were enrolled and were classified into two groups: obese asthma with positive type-2 inflammation markers (T2) and obese asthma with negative type-2 inflammation markers (NT2), then data were compared. In total, 434 patients were enrolled (85% of patients were at GINA therapy step 4-5). The T2 group had a higher proportion of patients with persistent asthma since childhood and with allergic rhinitis. A higher percentage of patients used high-dose inhaled corticosteroids (ICS) and experienced acute exacerbations (annual exacerbation ratio ≥ 1) in the T2 group. Multivariate logistic regression analysis showed that the T2 group was independently associated with younger age, comorbidity of allergic rhinitis, persistent asthma since childhood, use of high-dose ICS, and acute exacerbation rate ≥ 1. Adipocytokine levels were similar between the groups. Collectively, obese asthma with positive type-2 inflammation markers is characterised by a higher percentage of persistent asthma since childhood and more severe asthma.

Association of genetic risk and lifestyle with incident adult-onset asthma in the UK Biobank cohort

Background

Both genetic and lifestyle factors contribute to the development of asthma, but whether unfavourable lifestyle is associated with similar increases in risk of developing asthma among individuals with varying genetic risk levels remains unknown.

Methods

A healthy lifestyle score was constructed using body mass index, smoking status, physical activities and dietary pattern to further categorise into ideal, intermediate and poor groups. Genetic risk of asthma was also categorised as three groups based on the tertiles of polygenic risk score established using 212 reported and verified single-nucleotide polymorphisms of European ancestry in the UK Biobank study. We examined the risk of incident asthma related with each lifestyle level in each genetic risk group by Cox regression models.

Results

Finally, 327 124 participants without baseline asthma were included, and 157 320 (48.1%) were male. During follow-up, 6238 participants (1.9%) developed asthma. Compared to ideal lifestyle in a low genetic risk group, poor lifestyle was associated with a hazard ratio of up to 3.87 (95% CI, 2.98-5.02) for developing asthma in a high genetic risk group. There was interaction between genetic risk and lifestyle, and the population-attributable fraction of lifestyle and genetic risk were 30.2% and 30.0% respectively.

Conclusion

In this large contemporary population, lifestyle and genetic factors jointly play critical roles in the development of asthma, and the effect values of lifestyle on incident adult-onset asthma were greater than that of genetic risk. Our findings highlighted the necessity of a comprehensive intervention for the prevention of asthma despite the genetic risk.

Distribution, composition, and activity of airway-associated adipose tissue in the porcine lung

Patients with comorbid asthma-obesity experience greater disease severity and are less responsive to therapy. We have previously reported adipose tissue within the airway wall that positively correlated with body mass index. Accumulation of biologically active adipose tissue may result in the local release of adipokines and disrupt large and small airway function depending on its anatomical distribution. This study therefore characterized airway-associated adipose tissue distribution, lipid composition, and adipokine activity in a porcine model. Airway segments were systematically dissected from different locations of the bronchial tree in inflation-fixed lungs. Cryosections were stained with hematoxylin and eosin (H&E) for airway morphology, oil red O to distinguish adipose tissue, and Nile blue A for lipid subtype delineation. Excised airway-associated adipose tissue was cultured for 72 h to quantify adipokine release using immunoassays. Results showed that airway-associated adipose tissue extended throughout the bronchial tree and occupied an area proportionally similar to airway smooth muscle within the wall area. Lipid composition consisted of pure neutral lipids (61.7 ± 3.5%), a mixture of neutral and acidic lipids (36.3 ± 3.4%), or pure acidic lipids (2.0 ± 0.8%). Following tissue culture, there was rapid release of IFN-γ, IL-1β, and TNF-α at 12 h. Maximum IL-4 and IL-10 release was at 24 and 48 h, and peak leptin release occurred between 48 and 72 h. These data extend previous findings and demonstrate that airway-associated adipose tissue is prevalent and biologically active within the bronchial tree, providing a local source of adipokines that may be a contributing factor in airway disease.

Impact of body mass index on omalizumab response in adults with moderate-to-severe allergic asthma

BACKGROUND

Effectiveness of asthma treatment, including biologics, may be different in patients with higher body mass index (BMI).

OBJECTIVE

To evaluate response to omalizumab (dosed by serum immunoglobulin E level and weight) by BMI category.

METHODS

Pooled data from 2 randomized, double-blind, placebo-controlled studies of adults with moderate-to-severe allergic asthma were analyzed by BMI category (<25 kg/m² [normal or underweight], n = 397; 25 to <30 kg/m² [overweight], n = 330; ≥ 30 kg/m² [obese], n = 268). Placebo-adjusted exacerbation rate reductions were evaluated by Poisson regression modeling. Changes from baseline in forced expiratory volume in 1 second, beclomethasone dipropionate (BDP) dose, Total Asthma Symptom Score, and Asthma Quality of Life Questionnaire were evaluated by analysis of covariance.

RESULTS

Greater placebo-adjusted exacerbation rate reductions (95% confidence interval) were observed with increasing BMI (normal or underweight, -37.4% [-69.0% to 26.8%]; overweight, -52.7% [-78.4% to 3.7%]; obese, -71.9% [-86.9% to -39.5%]). There were no differences in forced expiratory volume in 1 second improvement between BMI categories at week 16 (normal or underweight, 76.2 [5.3-147.1] mL; overweight, 98.1 [13.9-182.4] mL; obese, 69.1 [-18.9 to 157.2] mL). No differences in BDP dose reduction (µg) were noted between BMI categories (normal or underweight, 23.0 [15.7-30.3]; overweight, 22.5 [13.5-31.5]; obese, 16.6 [5.8-27.3]). Fewer patients in the higher BMI categories eliminated BDP use. There were trends for smaller improvements with higher BMI in Total Asthma Symptom Score (normal/underweight, -0.52 [-0.82 to -0.22]; overweight, -0.50 [-0.80 to -0.20]; obese, -0.39 [-0.77 to 0.00]) and Asthma Quality of Life Questionnaire (normal or underweight, 0.34 [0.16-0.52]; overweight, 0.34 [0.13-0.55]; obese, 0.15 [-0.08 to 0.39]).

CONCLUSION

Omalizumab provides benefit to patients with moderate-to-severe allergic asthma, regardless of BMI.

TRIAL REGISTRATION

Studies 008/009 were conducted before clinical trial registration was required, and therefore clinical trial registration numbers are not available.

Reference Gene Validation for RT-qPCR in PBMCs from Asthmatic Patients with or without Obesity

Obesity is known to impair the efficacy of glucocorticoid medications for asthma control. Glucocorticoid-induced gene expression studies may be useful to discriminate those obese asthmatic patients who present a poor response to glucocorticoids. The expression of genes of interest is normalized with respect to reference genes (RGs). Ideally, RGs have a stable expression in different samples and are not affected by experimental conditions. The objective of this work was to analyze suitable RGs to study the role of glucocorticoid-induced genes in obese asthmatic patients in further research. The gene expression of eight potential RGs (GUSB, B2M, POLR2A, PPIA, ACTB, GAPDH, HPRT1, and TBP) was assessed with reverse transcription-quantitative polymerase chain reaction in peripheral blood mononuclear cells (PBMCs) from asthmatic, obese asthmatic, and healthy individuals. Their stability was analyzed using four different algorithms-BestKeeper, ΔCt, geNorm, and NormFinder. geNorm analysis recommended the use of a minimum of three genes for normalization. Moreover, intergroup variation due to the treatment was calculated by NormFinder, which found that B2M was the gene that was least affected by different treatments. Comprehensive rankings indicated GUSB and HPRT1 as the best RGs for qPCR in PBMCs from healthy and asthmatic subjects, while B2M and PPIA were the best for obese asthmatic subjects. Finally, our results demonstrated that B2M and HPRT1 were the most stable RGs among all groups, whereas ACTB, TBP, and GAPDH were the worst shared ones.

Airway epithelial Paraoxonase-2 in obese asthma

Background

Obesity in asthmatics has been associated with higher airway oxidative stress in which dysfunctional mitochondria are a potential contributing source of excess free radicals. Paraoxonase 2 (PON2) plays an important role in reducing mitochondrial-derived oxidative stress and could, therefore, have therapeutic potential in these patients.

Objectives

We used primary human bronchial epithelial cells (HBECs) from asthmatics and healthy controls to evaluate: a) protein levels of Paraoxonase 2 and b) to test the potential protective effect of quercetin supplementation in cells under oxidative stress conditions.

Results

Compared to lean controls, obese asthmatics had significantly lower PON2 airway epithelial levels (respectively, 1.08 vs. 0.47 relative units normalized by GAPDH) (p-value < 0.006). Treating HBECs in vitro for 24 hrs. with 25μM quercetin significantly increased PON2 protein levels: 15.5 treated cells vs. 9.8 untreated cells (relative units normalized by GAPDH) (p value = 0.004). Notably, compared to untreated cells, quercetin supplementation reduces mitochondrial superoxide and hydrogen peroxide production on HBECs cells exposed to different oxidative stress triggers such as 1–2 Naphthoquinone (1–2 NQ) and hydrogen peroxide, suggesting that PON2 might play a protective role ameliorating oxidative injury on human airway epithelium.

Conclusion

Compared to lean controls, obese asthmatics have significantly reduced PON2 levels in airway epithelial cells. Treatment with quercetin in vitro increased PON2 protein levels and prevented oxidative stress from different types of stimuli. Hence, quercetin supplementation may be a potential therapeutic strategy to prevent obesity-mediated airway oxidative stress in obese asthmatics.

Positive Expiratory Pressure: A Potential Therapy to Mitigate Acute Bronchoconstriction in the Asthma of Obesity

Late-onset non-allergic (LONA) asthma in obesity is characterized by increased peripheral airway closure secondary to abnormally collapsible airways. We hypothesized that positive expiratory pressure (PEP) would mitigate the tendency to airway closure during bronchoconstriction, potentially serving as rescue therapy for LONA asthma of obesity. The PC₂₀ dose of methacholine was determined in 18 obese participants with LONA asthma. At each of 4 subsequent visits, we used oscillometry to measure input respiratory impedance (Z_rs) over 8 minutes; participants received their PC₂₀ concentration of methacholine aerosol during the first 4.5 minutes. PEP combinations of either 0 or 10 cmH₂O either during and/or after the methacholine delivery were applied, randomized between visits. Parameters characterizing respiratory system mechanics were extracted from the Z_rs spectra. In 18 LONA asthma patients (14 females, BMI: 39.6±3.4 kg/m²), 10 cmH₂O PEP during methacholine reduced elevations in the central airway resistance, peripheral airway resistance and elastance, and breathing frequency was also reduced. During the 3.5 min following methacholine delivery, PEP of 10 cmH₂O reduced A_x and peripheral elastance compared to no PEP. PEP mitigates the onset of airway narrowing brought on by methacholine challenge, and airway closure once it is established. PEP thus might serve as a non-pharmacologic therapy to manage acute airway narrowing for obese LONA asthma.

Asthma medication use in obese and healthy weight asthma: systematic review/meta-analysis

BACKGROUND

Obesity is a common comorbidity in asthma and associated with poorer asthma control, more frequent/severe exacerbations, and reduced response to asthma pharmacotherapy.

OBJECTIVE

This review aims to compare use of all classes of asthma medications in obese (body mass index (BMI) ≤30 kg·m^-2) versus healthy-weight (BMI <25 kg·m^-2) subjects with asthma.

DESIGN

Databases including CINAHL (Cumulative Index to Nursing and Allied Health Literature), Cochrane, Embase and MEDLINE were searched up to July 2019 for English-language studies that recorded medication use or dose in obese and healthy-weight adults with asthma. A critical appraisal checklist was utilised for scrutinising methodological quality of eligible studies. Meta-analysis was performed and heterogeneity was examined with the use of the Chi-squared test. This review was conducted based on a published protocol (www.crd.york.ac.uk/PROSPERO CRD42020148671).

RESULTS

Meta-analysis showed that obese subjects are more likely to use asthma medications, including short-acting β₂-agonists (OR 1.75, 95% CI 1.17-2.60; p=0.006, I²=41%) and maintenance oral corticosteroids (OR 1.86, 95% CI 1.49-2.31; p<0.001, I²=0%) compared to healthy-weight subjects. Inhaled corticosteroid (ICS) dose (µg·day^-1) was significantly higher in obese subjects (mean difference 208.14, 95% CI 107.01-309.27; p<0.001, I²=74%). Forced expiratory volume in 1 s (FEV₁) % predicted was significantly lower in obese subjects (mean difference -5.32%, 95% CI -6.75--3.89; p<0.001, I²=42%); however, no significant differences were observed in FEV₁/forced vital capacity (FVC) ratio between groups.

CONCLUSIONS

We found that obese subjects with asthma have higher use of all included asthma medication classes and higher ICS doses than healthy-weight asthma subjects, despite lower FEV₁ and a similar FEV₁/FVC %. A better understanding of the factors driving increased medication use is required to improve outcomes in this subgroup of asthmatics.

A comparative study of clinical profile and symptom control in overweight and normal weight school-age children with mild persistent asthma

OBJECTIVES

To find out the proportion of children with poor symptom control in overweight/obese and normal weight children with mild persistent asthma and to know the sociodemographic and clinical correlates of poor symptom control in them.

MATERIALS AND METHODS

Children aged 6 to 12 years with mild persistent asthma with BMI Z score for age and sex more than +1 Z score on WHO BMI Z score chart for age and sex formed the cases. Age- and sex-matched asthmatics with BMI Z score for age and sex between -2 Z and +1 Z score formed the controls. FEV1, FEV1/FVC were measured in both groups using Care Fusion Jaeger spirometer. Symptom control was assessed by ACT score. Statistical analysis was done using SPSS version 19 and Vassarstats.

RESULTS

The proportion of children with poor control was 19.1% in the overweight/obese group and 23.4% in the normal weight group. There was no significant correlation between BMI and symptom control as assessed by the ACT score. Overweight/obese children with good control showed a slightly lower FEV1/FVC ratio and higher median eosinophil count compared to children with normal weight. Gastroesophageal reflux and allergic rhinitis were more commonly seen in overweight/obese children. In the poor control group, FEV1, FEV1/FVC, and median eosinophil counts were not significantly different between overweight/obese and normal weight group but were less when compared to good control group.

CONCLUSION

The proportion of poor symptom control was not high in overweight/obese asthmatic children compared to normal weight asthmatic children. No significant risk factors for poor symptom control could be identified in our study for either of the groups.

Glucagon-like peptide 1 receptor (GLP-1R) agonist relieved asthmatic airway inflammation via suppression of NLRP3 inflammasome activation in obese asthma mice model

BACKGROUND

Obesity is a correctable factor for uncontrolled bronchial asthma. However, the effects of glucagon-like peptide-1 receptor (GLP-1R) agonist, a recently approved antiobestic drug, on airway hyperresponsiveness (AHR) and immune responses are not known.

METHODS

Mice were fed with high-fat diet (HFD, 60% fat) for 8 weeks to induce obesity. Ovalbumin (OVA) sensitization and challenges were performed for 7 weeks. The mice were injected intraperitoneally with GLP-1R agonist 5 times a week for 4 weeks after OVA sensitization. After AHR measurement, expression of Th2, Th17 cytokines, and interleukin (IL)-33 were measured in BALF and lung tissues. Moreover, IL-1β and activity level of nucleotide oligomerization domain-like receptor protein 3 (NLRP3) were analyzed to investigate the mechanism of GLP-1R agonist on asthmatic airway inflammation.

RESULTS

HFD induced significant weight gain, OVA sensitization and challenge in obese mice made eosinophilic airway inflammation, and increased AHR. Treatment with GLP-1R agonist-induced weight loss suppressed eosinophilic airway inflammation and decreased AHR. Expression of IL-4, 5, and 33 was increased in BALF of obese asthma mice followed by a decrease in response to GLP-1R agonist treatment. Moreover, lung tissue H&E stain revealed that peribronchial inflammation induced by obesity and OVA was effectively suppressed by GLP-1R agonist. Expressions of NLRP3, activated caspase-1, and IL-1β were increased in lung tissues of obese asthma mice and demonstrated a decrease in response to GLP-1R agonist treatment.

CONCLUSIONS

GLP-1R agonist effectively induced weight loss, suppressed eosinophilic bronchial airway inflammation, and AHR in obese asthma mice. These effects were mediated by suppression of NLRP3 inflammasome activity and IL-1β. GLP-1R agonist is proposed as a novel anti-asthmatic agent targeting the obese asthmatics.

Association between obesity and lung function changes by sex and age in adults with asthma

OBJECTIVE

The lung function changes presenting before and after asthma treatment in obese people remain largely unknown. This study aimed to investigate the association between obesity and lung function changes before and after treatment in adults with asthma.

METHODS

We enrolled 937 newly diagnosed asthma patients from Cohort for Reality and Evolution of Adult Asthma in Korea cohort in 2015-2017, who performed follow-up spirometry after three months of asthma treatment. The percentage changes (Δ) between the spirometry results before and after treatment were calculated. Patients were categorized into four body mass index (BMI) groups; underweight (<18.5), normal (18.5-22.9), overweight (23.0-24.9), and obese (≥25.0). Association between percent change of pulmonary function and BMI was analyzed according to sex and/or age (< 45 yrs, 45-65 yrs, ≥ 65 yrs), which were statistically corrected for age, sex, smoking status, and medication history.

RESULTS

There was no consistent correlation between BMI and each lung function parameter. However, there were significant differences between BMI and ΔFEV₁/FVC before and after 3 months of controller treatment. The obese asthmatics showed significantly lower ΔFEV₁/FVC (6.0 ± 13.5%) than the underweight (12.6 ± 21.4%, P = 0.044) or normal weight (9.1 ± 14.6%, P = 0.031). Middle-aged women had higher BMI (24.11 ± 3.60 vs. 22.39 ± 3.52) and lower ΔFEV₁/FVC (5.7 ± 11.9% vs. 8.9 ± 14.3%, P = 0.012) than young women.

CONCLUSIONS

Obesity is negatively correlated with the ΔFEV₁/FVC before and after controller treatment. Sex and age differentially contribute to lung function changes in response to asthma medications in adult asthmatics, showing a significant decrease in the ΔFEV₁/FVC in middle-aged women.

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.

Drug Dose Selection in Pediatric Obesity: Available Information for the Most Commonly Prescribed Drugs to Children

Obesity rates continue to rise in children, and little guidance exists regarding the need for adjustment away from total body weight-based doses for those prescribing drugs to this population of children. A majority of drugs prescribed to children with obesity result in either sub-therapeutic or supra-therapeutic concentrations, placing these children at risk for treatment failure and drug toxicities. In this review, we highlight available obesity-specific pharmacokinetic and dosing information for the most frequently prescribed drugs to children in the inpatient and outpatient clinical settings. We also comment on available dosing recommendations for drugs prescribed to treat common pediatric obesity-related comorbidities. This review highlights that there is no safe or proven 'rule of thumb,' for dosing drugs for children with obesity, and a striking lack of pharmacokinetic data to support the creation of dosing guidelines for children with obesity for the most commonly prescribed drugs. It is important that those prescribing for children with obesity are aware of these gaps in knowledge and of potential drug treatment failure or adverse events related to drug toxicity as a result of these knowledge gaps. Until more data are available, we recommend close monitoring of drug response and adverse events in children with obesity receiving commonly prescribed drugs.

Weighing in on asthma: Insights on BMI, magnesium, and hospitalizations from the Ohio Pediatric Asthma Repository

Objective: Little is known about weight status and its effects on clinical course during hospitalization for asthma exacerbation. We sought to evaluate associations between weight status, specifically body mass index (BMI), with inpatient clinical course and clinical history.Methods: We retrospectively analyzed data from 2012 to 2013 on children hospitalized for asthma exacerbation in a state-wide longitudinal cohort, the Ohio Pediatric Asthma Repository. We examined BMI continuously (z scores) and categorically, comparing overweight and obese (Ov/Ob) to non-overweight and non-obese (nOv/nOb) children. We used linear mixed models controlling for site effects to determine if BMI was related to length of stay, as determined by physiologic readiness for discharge (PRD), defined as time to albuterol spaced every 4 h, need for nonstandard care or clinical history.Results: Across six hospitals, 874 children were included in analyses. BMI was positively associated with PRD (p=.008) but this increase was unlikely to be clinically significant. Ov/Ob children were more likely than nOv/nOb to require nonstandard care with repeat magnesium dosing in intensive care after dosing in the emergency department (OR = 3.23, 95%CI 1.39-7.78). Hospitalization in the year prior to enrollment was positively associated with BMI percentile (73.3 vs. 66.0, p=.028). Sleep disordered breathing was also associated with higher BMI percentile (78.2 vs. 65.9; p=.0013).Conclusions: Ov/Ob children had similar PRD to nOv/nOb children and were prone to repeat magnesium dosing. Previous hospitalization for exacerbation was positively associated with increasing BMI percentile. Additional research should investigate differential magnesium use by weight status, quantifying risks and benefits.

Influence of weight status in the response to Step-2 maintenance therapies in children with asthma

Introduction

Overweight children with asthma may display impaired response to inhaled corticosteroids (ICS), possibly due to non-eosinophilic inflammation or weight-related lung compression; these mechanisms may differentially affect response to ICS and leukotriene receptor antagonists (LTRAs). We assessed whether weight status modified the response to low-dose ICS and LTRA Step-2 monotherapy.

Methods

A historical cohort study from clinical data linked to administrative databases was conducted among children aged 2–18 years with specialist-diagnosed asthma who were initiating or continuing a Step-2 monotherapy from 2000 to 2007 at the Montreal Children’s Hospital Asthma Centre. The outcome was time-to-management failure defined as any step-up in therapy, acute care visit, hospitalisation or oral corticosteroids for asthma, whichever occurred first. The independent and joint effects of weight status (body mass index [BMI] percentile) and time-varying treatment on time-to-management failure were estimated with marginal structural Cox models. The likelihood ratio test (LRT) and relative excess risk due to interaction (RERI) were computed to assess treatment effect modification by weight status on the multiplicative and additive scales.

Results

Of the 433 and 85 visits with a low-dose ICS and LTRA prescription, respectively, 388 management failures occurred over 14 529 visit-weeks of follow-up. Children using LTRA compared with low-dose ICS tended to have an overall higher risk of early management failure (HR 1.52; 95% CI 0.72 to 3.22). Irrespective of treatment, the hazard of management failure increased by 5% (HR 1.05; 95% CI 1.01 to 1.10) for every 10-unit increase in BMI percentile. An additional hazard reduction of 17% (HR 0.83; 95% CI 0.70 to 0.99) was observed for every 10-unit increase in BMI percentile among LTRA users, but not for ICS (HR 0.95; 95% CI 0.86 to 1.04). The LRT indicated a departure from exact multiplicativity (p<0.0001), and the RERIs for ICS and LTRA were −0.05 (95% CI −0.14 to 0.05) and −0.52 (95% CI −1.76 to 0.71).

Conclusions

Weight status was associated with earlier time-to-management failure in children prescribed Step-2 therapy. This hypothesis-generating study suggests that LTRA response increases in children with higher BMI percentiles, although further research is warranted to confirm findings.

Obesity and asthma: clinical and laboratory characterization of a common combination

OBJECTIVE

To evaluate the relationship between obesity and asthma.

METHODS

This was a preliminary cross-sectional analysis involving 925 subjects with mild-to-moderate or severe asthma evaluated between 2013 and 2015. Obesity was defined on the basis of body mass index (BMI) and abdominal circumference. We collected clinical, laboratory, and anthropometric parameters, as well as pulmonary function test results and data regarding comorbidities. The subjects also completed asthma control and quality of life questionnaires.

RESULTS

Obese individuals had a significantly higher number of neutrophils in peripheral blood than did nonobese individuals (p = 0.01). Among the obese individuals, 163 (61%) had positive skin-prick test results, as did 69% and 71% of the individuals classified as being overweight or normal weight, respectively. Obese individuals showed lower spirometric values than did nonobese individuals, and 32% of the obese individuals had uncontrolled asthma, a significantly higher proportion than that found in the other groups (p = 0.02).

CONCLUSIONS

Obese individuals with asthma seem to present with poorer asthma control and lower pulmonary function values than do nonobese individuals. The proportion of subjects with nonatopic asthma was higher in the obese group. Our results suggest that obese individuals with asthma show a distinct inflammatory pattern and are more likely to present with difficult-to-control asthma than are nonobese individuals.

Impact of Obesity on Asthma Morbidity During a Hospitalization

BACKGROUND

Asthma and obesity are 2 common pediatric problems. Obesity is a known risk factor for asthma, and obese children with asthma have higher disease burden. However, little is known on how obesity in urban minority children, mainly Hispanic and African American children, impacts morbidity during pediatric asthma hospitalizations.

METHODS

A retrospective chart review was conducted on children and adolescents age 2 to 18 years hospitalized at the Children's Hospital at Montefiore for an acute asthma exacerbation. We elucidated the association of overweight or obese status with severity of the exacerbation, quantified by length of stay (LOS) and need for intensive care management. Multivariate analysis was conducted to identify independent predictors of LOS.

RESULTS

A total of 975 children met the inclusion criteria, of whom 55% were normal weight and 45% were overweight or obese. Sixty percent were Hispanic, and 37% were African American. The overall average LOS was 2.57 days (range: 0.67-12.92). Overweight or obese status was associated with a higher asthma severity at baseline (P = .021). Overweight or obese children had a longer average LOS compared with normal weight children (2.75 vs 2.39 days; P < .01) with more PICU stays (P = .006), even after adjustment for higher baseline asthma severity. The severity of the exacerbation did not differ by ethnicity.

CONCLUSIONS

Obesity in children hospitalized for asthma is associated with more severe asthma exacerbations, longer LOS, and increased use of PICU level care, independent of their higher baseline disease severity and ethnicity.

Diet and Metabolism in the Evolution of Asthma and Obesity

Obesity is a major risk factor for asthma. This association appears related to altered dietary composition and metabolic factors that can directly affect airway reactivity and airway inflammation. This article discusses how specific changes in the western diet and metabolic changes associated with the obese state affect inflammation and airway reactivity and reviews evidence that interventions targeting weight, dietary components, lifestyle, and metabolism might improve outcomes in asthma.

Obesity-associated severe asthma in an adult Japanese population

BACKGROUND

Severe asthma is increasingly being recognized as an important public health issue. Obesity has been identified as a risk factor for poor asthma control and for worsening of asthma severity. However, most studies investigating obese patients with asthma have been performed in Western countries. Reports on the characteristics of obese Japanese individuals with severe asthma are lacking. Herein, we investigated the clinical characteristics of patients with obesity-associated severe asthma in a Japanese population and the association between obesity and poor asthma control.

METHODS

We conducted a retrospective observational study of adult patients with severe asthma. Patients were classified into two groups based on the definition of obesity recommended by the Japan Society for the Study of Obesity: obese (OB) group (body mass index [BMI] ≥25 kg/m²) and non-obese (NOB) group (BMI <25 kg/m²). The two groups were compared. The characteristics of obesity and the metabolic functions are known to differ between males and females; therefore, we analyzed male-only and female-only cohorts separately.

RESULTS

A total of 492 patients were enrolled. Age, smoking history in terms of number of pack-years, daily controller medications use, and spirometric data were not significantly different between the OB and NOB groups in either cohort. In the female cohort, the annual exacerbation ratio and the percentage of frequent exacerbators were significantly higher in the OB group compared to the NOB group. A multivariate logistic regression analysis showed that obesity was independently associated with frequent asthma exacerbations in the female cohort.

CONCLUSIONS

Our study revealed that obesity, defined as a BMI ≥25 kg/m², was independently associated with poor asthma control (including acute exacerbations) in adult Japanese females with severe asthma.

The asthma-obesity relationship: underlying mechanisms and treatment implications

PURPOSE OF REVIEW

Obesity is a worldwide epidemic with a prevalence that has tripled in the last two decades. Worldwide, more than 1.5 billion adults are overweight and more than 500 million obese. Obesity has been suggested to be a risk factor for the development of more difficult-to-control asthma. Although the mechanisms underlying the asthma-obesity relationship are not fully understood, several possible explanations have been put forward. These will be reviewed in this manuscript as well as the implications for the treatment of overweight and obese asthma patients.

RECENT FINDINGS

Insulin resistance is a possible factor contributing to the asthma-obesity relationship and the effect is independent of other components of the metabolic syndrome such as hypertriglyceridemia, hypertension, hyperglycemia, and systemic inflammation. Obesity has important effects on airway geometry, by especially reducing expiratory reserve volume causing obese asthmatics to breathe at low lung volumes. Furthermore, obesity affects the type of inflammation in asthma and is associated with reduced inhaled corticosteroids treatment responsiveness.

SUMMARY

Obesity induces the development of asthma with a difficult-to-control phenotype. Treatment targeting insulin resistance may be beneficial in obese asthma patients, especially when they have concomitant diabetes. Systemic corticosteroids should be avoided as much as possible as they are not very effective in obese asthma and associated with side-effects like diabetes, weight gain, and osteoporosis.

Body mass index of patients with chronic obstructive pulmonary disease is associated with pulmonary function and exacerbations: a retrospective real world research

Background

Chronic obstructive pulmonary disease (COPD) is prevalent in China. The role of body mass index (BMI) in COPD progression and prognosis is unclear. We analyzed the association between BMI and pulmonary function, inflammation levels and exacerbation in Chinese COPD patients.

Methods

Our retrospective real world research included 744 patients with COPD diagnosed by spirometry and hospitalized from January 1st, 2014 to December 31st, 2016. The indicators were gathered from hospital records database and frequency of exacerbation in the three years were followed up. All 744 patients were divided into four groups by BMI grades. We analyzed the association between BMI and pulmonary function, inflammation levels and exacerbation by Spearman bivariate correlations, Kruskal-Wallis test, Mann-Whitney U test and logistic regression.

Results

The singly proportion (median of BMI) of these patients in underweight, normal weight, overweight and obesity was 7.80% (17.54), 45.97% (22.12), 27.96% (27.00) and 18.28% (31.25) respectively. With increasing of BMI grades, the values of forced expiratory volume in 1 second (FEV₁), peak expiratory flow (PEF), forced expiratory flow (FEF25/50/75) and diffusing capacity of carbon monoxide (DLCO) were correspondingly increasing; the percentage of neutrophils and C-reactive protein (CRP) presented significant declining trend while the trend of the percentage of eosinophils was negative; the dose of systemic corticosteroid and length of stay present decreasing tendency; the frequency of exacerbation and hospitalization were decreasing. These were similar results in gender, smoking status COPD subgroups.

Conclusions

In our study, BMI was moderately correlated with pulmonary function positively and exacerbations negatively. To some extent, BMI might be a useful indicator to predict the prognosis of COPD patients and for long-term management.

Overweight, Obesity, and Lung Function in Children and Adults-A Meta-analysis

BACKGROUND

There is conflicting evidence on the effect of obesity on lung function in adults and children with and without asthma. We aimed to evaluate the relation between overweight or obesity and lung function, and whether such relationship varies by age, sex, or asthma status.

METHODS

We searched PubMed, Scopus, CINAHL, Cochrane, and EMBASE for all studies (in English) reporting on obesity status (by body mass index) and lung function, from 2005 to 2017. Main outcomes were forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), FEV1/FVC, forced expiratory flow between 25th and 75th percentile of the forced vital capacity (FEF25-75), total lung capacity (TLC), residual volume (RV), and functional residual capacity (FRC). Random-effects models were used to calculate the pooled risk estimates; each study was weighed by the inverse effect size variance. For each outcome, we compared overweight or obese ("obese") subjects with those of normal weight.

RESULTS

All measures of lung function were decreased among obese subjects. Obese adults showed a pattern (lower FEV1, FVC, TLC, and RV) different from obese children (more pronounced FEV1/FVC deficit with unchanged FEV1 or FVC). There were also seemingly different patterns by asthma status, in that subjects without asthma had more marked decreases in FEV1, TLC, RV, and FRC than subjects with asthma. Subjects who were obese (as compared with overweight) had even further decreased FEV1, FVC, TLC, RV, and FRC.

CONCLUSIONS

Obesity is detrimental to lung function, but specific patterns differ between children and adults. Physicians should be aware of adverse effects of obesity on lung function, and weight control should be considered in the management of airway disease among the obese.

Acute lung injury induced by intestinal ischemia and reperfusion is altered in obese female mice

RATIONAL

Acute lung injury (ALI) is a common complication after intestinal ischemia and reperfusion (I/R) injury that can lead to acute respiratory distress syndrome (ARDS). We have previously demonstrated that females are protected against lung damage induced by intestinal I/R through an estrogen mediated mechanism.

OBJECTIVES

To investigate the effect of obesity on ALI induced by intestinal I/R in female mice.

METHODS

C57Bl/6 female mice were fed with a standard low-fat diet (SD) or a high-fat diet (HFD) for 9 weeks. Intestinal I/R injury was induced by a 45 min occlusion of the mesenteric artery followed by 2 and 24 h of reperfusion.

RESULTS

Significant increase in lung myeloperoxidase expression (MPO) and neutrophil numbers of SD and HFD mice occurred at 2 h and 24 h of reperfusion. Furthermore, HFD mice presented a significant increase in lung eosinophil peroxidase (EPO) expression and eosinophil numbers compared to SD mice. Lung wet/dry weight ratio was significantly greater in HFD mice at 2 and 24 h of reperfusion, accompanied by a significant increase in the expression of inducible NO in the lung tissue and a significant decrease in arterial oxygen saturation at 24 h of reperfusion relative to SD mice.

CONCLUSION

Obesity predisposes female mice to increased pulmonary oedema and deterioration in gas exchange, which is accompanied by an increase in iNOS expression in the lung.

Roflumilast Ameliorates Airway Hyperresponsiveness Caused by Diet-Induced Obesity in a Murine Model

Obese patients with asthma respond poorly to conventional asthma medications, resulting in severe symptoms and poor prognosis. Roflumilast, a phosphodiesterase-4 inhibitor that lowers the levels of various substances that are implicated in obese subjects with asthma, may be effective in the treatment of those subjects. We evaluated the potential of roflumilast as a novel therapeutic agent for obese subjects with asthma. We designed three models: diet-induced obesity (DIO); DIO with ovalbumin (OVA); and OVA. We fed C57BL/6J mice a high-fat diet for 3 months with or without OVA sensitization and challenge. Roflumilast or dexamethasone was administered orally three times at 2-day intervals in the last experimental week. Airway hyperresponsiveness resulting from DIO significantly improved in the roflumilast-treated group compared with the dexamethasone-treated groups. Although DIO did not affect the cell proliferation in bronchoalveolar lavage fluid, increased fibrosis was seen in the DIO group, which significantly improved from treatment with roflumilast. DIO-induced changes in adiponectin and leptin levels were improved by roflumilast, whereas dexamethasone aggravated them. mRNA levels and proteins of TNF-α, transforming growth factor-β, IL-1β, and IFN-γ increased in the DIO group and decreased with roflumilast. The reactive oxygen species levels were also increased in the DIO group and decreased by roflumilast. In the DIO plus OVA and OVA models, roflumilast improved Th1 and Th2 cell activation to a greater extent than dexamethasone. Roflumilast is significantly more effective than dexamethasone against airway hyperresponsiveness caused by DIO in the murine model. Roflumilast may represent a promising therapeutic agent for the treatment of obese patients with asthma.

Physiological Mechanisms of Airway Hyperresponsiveness in Obese Asthma

Obesity affects the incidence and severity of asthma in at least two major phenotypes: an early-onset allergic (EOA) form that is complicated by obesity and a late-onset nonallergic (LONA) form that occurs only in the setting of obesity. Both groups exhibit airway hyperresponsiveness to methacholine challenge but exhibit differential effects of weight loss. Measurements of lung function in patients with LONA obese asthma suggest that this group of individuals may simply be those unlucky enough to have airways that are more compliant than average, and that this leads to airway hyperresponsiveness at the reduced lung volumes caused by excess adipose tissue around the chest wall. In contrast, the frequent exacerbations in those with EOA obese asthma can potentially be explained by episodic inflammatory thickening of the airway wall synergizing with obesity-induced reductions in lung volume. These testable hypotheses are based on the strong likelihood that LONA and EOA obese asthma are distinct diseases. Both, however, may benefit from targeted therapeutics that impose elevations in lung volume.

Asthma and obesity

The problem of modern medicine is to optimize the treatment of patients with comorbidity, whose number has been growing steadily in recent years. The concurrence of asthma and obesity determines the severity of disease, low-level control, and resistance to basic therapy in conjunction with more frequent use of β-agonists for relief of symptoms, and frequent hospitalizations for a disease exacerbation. Currently, there are only a few known pathogenetic components that are responsible for the negative impact of visceral obesity on the course of asthma.

Interacting effects of obesity, race, ethnicity and sex on the incidence and control of adult-onset asthma

Background

To improve care and control for patients with adult-onset asthma, a better understanding of determinants of their risk and outcomes is important. We investigated how associations between asthma, asthma control and obesity may be modified by patient demographic characteristics.

Methods

This retrospective study of adults enrolled in several health plans across the U.S. (n = 2,860,305) examined the interacting effects of obesity, age, race, and sex on adult-onset asthma and asthma control. Multivariable adjusted Cox and logistic regression models estimated hazard ratios (HR), and 95 % confidence intervals (CI) for the associations between body mass index (BMI) and study outcomes, and interactions of BMI with demographic characteristics.

Results

Compared with individuals who had a BMI <25 kg/m², the hazard of adult-onset asthma progressively increased with increasing BMI, from a 12 % increase among persons with a BMI of 25.0–29.9 kg/m² (HR 1.12, 95 % CI 1.10, 1.14) to an almost 250 % increase among persons with a BMI ≥50 kg/m² (HR 2.49, 95 % CI 2.38, 2.60). The magnitude of the association between obesity and asthma risk was greater for women (compared with men) and lower for Blacks (compared with non-Hispanic Whites). Among individuals with asthma, obesity was associated with poorly controlled and high-risk asthma.

Conclusions

The present study demonstrates that the magnitude of the associations between obesity and adult-onset asthma incidence and control are modified by race, age, and sex. Understanding the role of obesity in the development of adult-onset asthma will help to improve asthma treatment algorithms and to develop targeted interventions.

Asthma phenotypes: the intriguing selective intervention with Montelukast

Asthma is a heterogeneous disease, usually characterized by chronic airway inflammation and a variable course associated with various underlying mechanisms that can differ between individuals. Patients with asthma can therefore exhibit different phenotypes, a term used to define the observable characteristics of an organism resulting from the interaction between its genetic makeup and the environment. The heterogeneity of asthma has received a large amount of attention in the last few years in order to better tailor treatment according to the different clinical and biological phenotypes of the disease. Specific asthma phenotypes may require an approach to treatment sometimes different from that recommended by current guidelines, so a personalized approach to asthma pharmacotherapy is recommended. Growing evidence suggests that leukotrienes play an important role in the pathogenesis of bronchial asthma. The mechanisms of action of leukotriene-receptor antagonists theoretically predict a good response in some asthma “phenotypes”.In this article we have performed an analysis of the recent literature (controlled clinical trials and real-life studies) about a possible selective intervention with Montelukast in specific asthma phenotypes.

Asthma symptoms in obese adults: The challenge of achieving asthma control

The association between asthma and obesity is well-described, but not straightforward, and according to current guidelines asthma control is more difficult to achieve in obese patients. The currently available studies evaluating response to pharmacological asthma therapy in obese patients show that these patients have an altered, in general less favorable, response to both reliever and controller medication compared to normal weight patients. However, at present, the limited available evidence precludes evidence-based recommendations. The 'obesity-related asthma' phenotype has different characteristics, including association with atopy and type of airway inflammation, compared to 'classic' asthma. Furthermore, weight loss in patients with this phenotype leads to an improvement in symptoms, lung function, and airway responsiveness, as well as a reduction in medication utilization and hospital admissions. Obese patients, who present with symptoms suggesting a diagnosis of asthma, may have a distinct phenotype or a disease mimicking asthma, likely to have a potentially higher remission rate. And by that, our approach to this group of patients should combine pharmacologic and non-pharmacologic therapies, including exercise, weight loss and dietary interventions, instead of primarily focusing on disease control by stepping up asthma therapy.

Emerging corticosteroid agonists for the treatment of asthma

INTRODUCTION

Asthma is one of the most frequent chronic diseases worldwide. For decades, asthma has been treated with bronchodilators and inhaled corticosteroids (ICS). However, adverse effects of ICS and disease heterogeneity necessitate improvements in the existing treatment regimes. Recently approved ICS show improved pharmocodynamic properties. Nevertheless, emerging drugs acting on the same receptor as the ICS, glucocorticoid receptor agonists (GRAs), are under current research. These drugs exhibit selective action on the glucocorticoid receptor (GR), which may improve their adverse effect profile, compared to the currently approved ICS that act unselectively on the GR.

AREAS COVERED

The present article reviews emerging GRAs for the treatment of asthma. Furthermore, the more recently approved ICS with improved safety profiles are reviewed.

EXPERT OPINION

Compared with drugs acting on other pathological pathways, research in GRAs for asthma is sparse. However, a few promising agents acting selectively on the GR are currently under investigation and may reach approval for asthma treatment. These drugs exhibit improved pharmacodynamic properties due to selectivity in the mechanism of action, including promotion of transrepression and reduction of transactivation. However, competition from already approved ICS and other emerging treatment options may lead to cessation of development of the new GRAs.

Obesity and bronchodilator response in black and Hispanic children and adolescents with asthma

BACKGROUND

Obesity is associated with poor asthma control, increased asthma morbidity, and decreased response to inhaled corticosteroids. We hypothesized that obesity would be associated with decreased bronchodilator responsiveness in children and adolescents with asthma. In addition, we hypothesized that subjects who were obese and unresponsive to bronchodilator would have worse asthma control and would require more asthma controller medications.

METHODS

In the Study of African Americans, Asthma, Genes, and Environments (SAGE II) and the Genes-environments and Admixture in Latino Americans (GALA II) study, two identical, parallel, case-control studies of asthma, we examined the association between obesity and bronchodilator response in 2,963 black and Latino subjects enrolled from 2008 to 2013 using multivariable logistic regression. Using bronchodilator responsiveness, we compared asthma symptoms, controller medication usage, and asthma exacerbations between nonobese (< 95th% BMI) and obese (≥ 95th% BMI) subjects.

RESULTS

The odds of being bronchodilator unresponsive were 24% (OR, 1.24; 95% CI, 1.03-1.49) higher among obese children and adolescents compared with their not obese counterparts after adjustment for age, race/ethnicity, sex, recruitment site, baseline lung function (FEV1/FVC), and controller medication. Bronchodilator-unresponsive obese subjects were more likely to report wheezing (OR, 1.38; 95% CI, 1.13-1.70), being awakened at night (OR, 1.34; 95% CI, 1.09-1.65), using leukotriene receptor inhibitors (OR, 1.33; 95% CI, 1.05-1.70), and using inhaled corticosteroid with long-acting β2-agonist (OR, 1.37; 95% CI, 1.05-1.78) than were their nonobese counterpart. These associations were not seen in the bronchodilator-responsive group.

CONCLUSIONS

Obesity is associated with bronchodilator unresponsiveness among black and Latino children and adolescents with asthma. The findings on obesity and bronchodilator unresponsiveness represent a unique opportunity to identify factors affecting asthma control in blacks and Latinos.

Prospective Study on the Relationship of Obesity to Asthma Impairment and Risk

BACKGROUND

Although studies consistently show an association between obesity and increased asthma incidence, the role of obesity in asthma control is less clear.

OBJECTIVE

The objective of this study was to evaluate the association between baseline body mass index (BMI) and measures of subsequent asthma control in a large real-world cohort of adults with persistent asthma.

METHODS

In Kaiser Permanente Southern California (KPSC), a large managed care organization, we identified adults with persistent asthma in 2006, continuous health plan enrollment in 2007 and 2008, and a BMI measurement in 2006 or 2007. Each patient's last BMI measure in 2006 or 2007 was categorized into a BMI group: normal (<25 kg/m(2)), overweight (25-29.9 kg/m(2)), or obese (≥30 kg/m(2)). Asthma control outcomes in 2008 included asthma hospitalizations or emergency department visits (EDHO), oral corticosteroid dispensings linked to an asthma encounter (OCS), and dispensing of ≥7 short-acting beta-agonist canisters (SABA7). Multivariable analyses were conducted to assess the relationships of BMI categories with the risk of the asthma control outcomes after controlling for potential confounders.

RESULTS

In the 10,233 eligible adults-after adjusting for potential demographic, comorbidity, and prior utilization confounders-we found an increased relative risk (RR) of EDHO in overweight and obese (RR 1.40, 95% CI 1.10-1.78) individuals. Only obesity was associated in adjusted analyses with a significant increased relative risk of SABA7 (RR 1.27, 95% CI 1.15-1.40).

CONCLUSIONS

Elevated BMI, particularly obesity, is associated with subsequent poor asthma control, especially in the risk domain (exacerbations). These findings further support the importance of facilitating weight loss in overweight and obese adults with asthma.

The future of genomic testing in primary care: the changing face of personalized medicine

Primary care is recognized worldwide as a key component for improving health outcomes in the population. At the same time, healthcare systems are rapidly changing with increasing expectations from technological advances. Genomics is a major driver in changing how medicine is being practiced; however, the importance for primary care has been under-appreciated. Strategically implementing genomics in a way that accounts for the unique characteristics of the primary care context is essential. In this perspective, we present important areas that we believe are critical in consideration of both the future of genomic medicine and primary healthcare delivery.

Obesity in asthma: approaches to treatment

There is mounting evidence that obesity is associated with asthma, both of which are seeing a dramatic increase in prevalence. Not only is obesity a risk factor for the development of asthma but it is also associated with poor asthma control. Asthma phenotypes associated with obesity include early-onset allergic asthma and late-onset non-allergic asthma. The pathogenesis of the linkage is complex; obesity causes a variety of mechanical, metabolic, and immunological changes that can affect the airways. The treatment of asthma in obesity can be challenging, as obesity is associated with poor response to standard controller medications. A tailored approach that involves combining pharmacologic and non-pharmacologic therapies including weight loss, dietary interventions, and exercise, along with identification and treatment of obstructive sleep apnea, should therefore be considered in this population.

Obesity and asthma: physiological perspective

Obesity induces some pertinent physiological changes which are conducive to either development of asthma or cause of poorly controlled asthma state. Obesity related mechanical stress forces induced by abdominal and thoracic fat generate stiffening of the lungs and diaphragmatic movements to result in reduction of resting lung volumes such as functional residual capacity (FRC). Reduced FRC is primarily an outcome of decreased expiratory reserve volume, which pushes the tidal breathing more towards smaller high resistance airways, and consequentially results in expiratory flow limitation during normal breathing in obesity. Reduced FRC also induces plastic alteration in the small collapsible airways, which may generate smooth muscle contraction resulting in increased small airway resistance, which, however, is not picked up by spirometric lung volumes. There is also a possibility that chronically reduced FRC may generate permanent adaptation in the very small airways; therefore, the airway calibres may not change despite weight reduction. Obesity may also induce bronchodilator reversibility and diurnal lung functional variability. Obesity is also associated with airway hyperresponsiveness; however, the mechanism of this is not clear. Thus, obesity has effects on lung function that can generate respiratory distress similar to asthma and may also exaggerate the effects of preexisting asthma.