Role of weight management in asthma symptoms and control

Obesity and adult asthma: diagnostic and management challenges

PURPOSE OF REVIEW

Despite advances in our understanding of the obese asthma phenotype, heterogeneity and large gaps in knowledge have hindered significant advances in directed interventions.

RECENT FINDINGS

Obesity is associated with poorer asthma-related outcomes and increased risk of progression to severe asthma. Obese asthma is associated with variability in the expression of inflammatory markers, lung function impairments, and response to conventional and biologic therapies. In addition, traditional asthma biomarkers are not as reliable in obese patients. Several mechanistic pathways that uniquely impact asthma in obesity have been identified. Pathways involving innate lymphoid cells (ILC) type 2 (ILC-2) cells, surfactant protein-A, cell division control protein (CDC)42, interleukin (IL)-6, IL-17, and IL-33 are likely causal inflammatory pathways. Obesity also confounds lung function parameters making accurate diagnosis more challenging. As such, personalized asthma therapies directed towards obese asthma endotypes remain elusive.

SUMMARY

Obesity confounds traditional asthma biomarkers and lung function measurements, thus defining obese asthma endotypes remains challenging. Novel pathways are being identified and hold promise for future targeted therapies. However, we are in dire need of updated guidelines regarding asthma diagnosis in obese patients and the development of biomarkers that more accurately identify specific endotypes.

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.

Asthma medication usage is significantly reduced following bariatric surgery

INTRODUCTION

Asthma is an important healthcare problem affecting millions in the United States. Additionally, a large proportion of patients with asthma suffer from obesity. These patients exhibit poor asthma control and reduced therapy response, increasing utilization of healthcare resources. Pulmonary symptoms improve after bariatric surgery (BS), and we hypothesized that asthma medication usage would decrease following BS.

METHODS

A retrospective data analysis was performed in adult patients from a single institution's database. Patients with obesity using at least one asthma medication pre-operatively who underwent BS were studied for up to 3-years post-operation. Poisson generalized linear mixed models for repeated measures were used to evaluate the effects of time and procedure type on the number of asthma medication.

RESULTS

Bariatric patients with at least one prescribed asthma medication (mean 1.4 ± 0.6) were included (n = 751). The mean age at time of operation was 46.8 ± 11.6 years, mean weight was 295.9 ± 57 lbs, and mean body mass index (BMI) was 49 ± 8.2 kg/m2; 87.7% were female, 33.4% had diabetes, 44.2% used gastroesophageal reflux disease (GERD) medication, and 64.4% used hypertension medication. The most common procedure was Roux-en-Y gastric bypass (79%), followed by sleeve gastrectomy (10.7%), adjustable gastric banding (8.1%), and duodenal switch (2.3%). The mean number of prescribed asthma medications among all procedures decreased by 27% at 30 days post-operation (p < 0.0001), 37% at 6 months (p < 0.0001), 44% at 1 year (p < 0.0001), and 46% at 3 years (p < 0.0001) after adjusting for risk factors. No significant differences in medication use over time between procedure types were observed. In the adjusted analysis, the mean number of asthma medications was 12% higher in patients using at least one GERD medication (p = 0.015) and 8% higher with 10-unit increase in pre-operative BMI (p = 0.006).

CONCLUSION

BS significantly decreases asthma medication use starting 30 days post-operation with a sustained reduction for up to 3 years.

Traditional Therapies for Severe Asthma

Severe asthma is a complex and heterogeneous disease. The European Respiratory Society and American Thoracic Society guidelines define severe asthma for patients 6 years or older as "asthma which requires treatment with high-dose inhaled corticosteroids…plus a second controller or systemic corticosteroids to prevent it from becoming 'uncontrolled' or which remains 'uncontrolled' despite this therapy." This article reviews available traditional therapies, data behind their uses in severe asthma, and varying recommendations. As various asthma endotypes and phenotypes are better understood and characterized, targeted therapies should help improve disease outcomes, efficacy, and cost-effectiveness.

The role of airway hyperresponsiveness measured by methacholine challenge test in defining asthma severity in asthma-obesity syndrome

PURPOSE OF REVIEW

Asthma is a complex disease defined by chronic inflammation of the airways. In research and clinical practice measures used for diagnosis, an assessment of control and severity of asthma are varied and there exists no gold standard. To date, several studies have explored the link between obesity and asthma although the exact mechanism is not yet fully understood. A study undertaken by our research group in 2015, on the effects of weight loss on asthma severity in obese asthmatics, demonstrated that an improvement in airway hyperresponsiveness could be achieved after significant weight reduction with a weight loss program. The objective of this article is to review the current literature for the primary and secondary outcomes studied to estimate the effects of weight loss on asthma severity in adults with obesity and asthma.

RECENT FINDINGS

A review of the most recent research conducted since 2014 demonstrates that effects of weight loss on asthma severity in adults with obesity and asthma has not been the focus of majority of the studies. Apart from our study published in 2015, very few studies used airway hyperresponsiveness as the primary or secondary outcome measure. The literature reveals that significant weight loss does, however, lead to improvement in asthma severity and control in adults with obesity and asthma.

SUMMARY

The current literature suggests that improvement in lung function requires moderate to significant (5-10%) weight loss in adults with obesity and asthma. However, with a few exceptions, the majority of these studies were small and used variable and questionable asthma severity outcome measures. There is an urgent need for standardization of diagnosis of asthma, study inclusion criteria, and outcome measures to assess asthma severity in research setting. Long-term effects of weight loss interventions on asthma severity and control, in adults with obesity and asthma, also remain unanswered.