Obesity and Asthma

The relationship between obesity and asthma is complex and linked to biologic, physiologic, environmental factors.

There is an increased prevalence of asthma in children with obesity as well as a dose-dependent effect of obesity on risk of asthma. In some studies, obesity precedes asthma and in others obesity is a risk factor for later development in asthma.

The pathophysiology of obesity related asthma is complex as there is a component of both mechanical factors: excessive mass on the chest and abdomen decreasing function residual capacity, need to breathe against increased mass, as well as inflammation from adipose tissue.

Symptoms of obesity and asthma can overlap with increased dyspnea and increased severity of exacerbations in obese children. There is also greater report of GER and sleep disturbance in obese rather than non-obese.

Workup should include evaluation for OSA, GER, metabolic syndrome, and depression as these disease processes are more common in obese children and complicate treatment of asthma.

Differentiating whether exercise related dyspnea is due to muscular deconditioning, increased effort due to mass loading on chest, versus exercise induced bronchospasm may be difficult. Therefore, bronchoprovocation testing may be helpful.

The diagnosis of asthma is the same in obese or non-obese patients based on history, demonstration of variable expiratory airflow limitation, and exclusion of other diagnoses. Spirometry is usually not affected by adipose tissue until severe and may show restriction. Dysanapsis is described in obese children and can present as high FVC with reduced FEV1 & FEV1/FVC.

Pharmacologic management of asthma in obese patients is the same. Treatment for comorbidities is recommended including consideration for behavioral, nutritional, and medical interventions for weight loss.

Further reading: Dixon, AE & Nyewnhuis SM. Obesity and Asthma. In: UpToDate, Waltham, MA. (Accessed on February 25 2021)