Asthma is a common respiratory condition in the United States. It is caused by tightening and inflammation of the muscles around the airways in the lungs, making it difficult for air to move in and out of the lungs. While many people consider asthma to be a disease of childhood, many adults struggle with the condition as well. Managing asthma is doable, but it can become life-threatening in some circumstances.
Related: Asthma: A Comprehensive Overview, 2nd Edition
Asthma in the United States
Data from the Center for Disease Control shows that in 2021, 24.9 people in the United States had asthma. This represents about 7.7% of the population. Of these people, 39.4% reported having at least one asthma attack in the past 12 months.
On average, 3,517 people die of asthma each year, and the vast majority of these (3,372) are adults. This is potentially because they have suffered from uncontrolled symptoms of asthma for a longer period and are more likely to be exposed to triggers like cigarette smoke.
Risk factors
According to the World Health Organization, asthma is often underdiagnosed and under treated in low-income areas. This may be due to a variety of factors, such as exposure to secondhand smoke, pollution, and limited access to healthcare.
The following are known risk factors for developing asthma:
- Having a close relative with asthma
- Having allergic conditions such as rhinitis or eczema
- Living in an urban area, especially one with low air quality
- Low birth weight
- Prematurity
- Exposure to secondhand smoke
- Early exposure to viral respiratory infections
- Early exposure to mold, dust mites, or chemical fumes
- Obesity
- Smoking and vaping
After developing or being diagnosed with asthma, patients can suffer from asthma attacks brought on by specific triggers. These triggers may include allergens, smoke, dust, cold weather, and exercise.
Protective factors
Research shows that early life interventions are some of the best tools for preventing the development of asthma. Supplements with vitamin D, C, and fish oil during pregnancy may have a protective effect against the development of asthma in young children. In addition, parents can protect their children from viral and bacterial infection, exposure to chemicals and pollution, and avoid secondhand smoke.
After a person develops asthma, they should be diligent in avoiding triggers, following their medication schedule, and attending their regularly scheduled wellness visits.
Pathophysiology of asthma
Patients suffering from asthma may complain of the following symptoms:
- Persistent cough that worsens at night
- Wheezing during exhalation
- Difficulty breathing or shortness of breath
- Chest tightness
While these symptoms are common in patients with asthma, they may also indicate other respiratory diseases. To have a definitive diagnosis of asthma, providers can perform pulmonary function tests to determine whether there is variability in expiratory flow.
Asthma severity can be classified into three types:
- Mild: Asthma is well controlled with step 1 or 2 treatment.
- Moderate: Asthma is well controlled with step 3 treatment.
- Severe: Step 4 or 5 treatment is required to control symptoms, or symptoms are uncontrolled despite this treatment. About 5-10% of people with asthma are considered to have severe or uncontrolled asthma.
Severe asthma is a life-threatening condition. It may require hospitalization, intubation, or even treatment with ECMO.
Phenotypes of asthma
Experts separate asthma into several different phenotypes. Allergic asthma is the most common. It is the cause of asthma symptoms in 40-50% of children and adults with asthma. This type of asthma is triggered by environmental allergens such as dust, pollen, animal dander, and dust mites. These patients often have high inflammatory markers and high levels of IgE.
Some patients suffer from non-allergic asthma, which can be more difficult to manage. These patients have asthma, but do not show allergic inflammatory markers. Non-allergic asthma can include eosinophilic and neutrophilic. Experts consider neutrophilic asthma the most difficult to manage and treat. There are no biologic medicines currently approved to treat it.
Exercise-induced asthma is one of the easiest types to understand and treat, since exacerbations are easily predictable. This type of asthma makes breathing difficult during exercise and resolves with rest.
Aspirin-exacerbated respiratory disease is the least common asthma. These patients have exacerbations after taking NSAIDs.
Standards of care for managing asthma
The National Institues of Health have created a thorough guideline outlining the standards of care in managing asthma. This guideline covers recommendations for treating and managing asthma in children and adults with different phenotypes of asthma and severity of symptoms.
- For patients with persistent asthma, doctors recommend using intermittent inhaled corticosteroids. Inhaled corticosteroids help control inflammation in the airways over time.
- Using of long acting antimuscarinic agents (LAMAs) in addition to inhaled corticosteroids for managing asthma long-term. A LAMA is a strong bronchodilator, which allows the airway muscles to relax.
- Reduction of exposure to indoor allergens, pollution, and secondhand smoke.
- Using immunotherapy for people suffering from allergic asthma. Immunotherapy may reduce or even eliminate symptoms for children and adults. (such as grass, dander, or ragweed pollen).
- Fractional exhaled nitric oxide (FeNO) testing to manage asthma or confirm an asthma diagnosis. This test measures the amount of nitric oxide, a byproduct of inflammation, in the air the patient breathes out.
- Bronchial thermoplasty (BT) may treat selected adults with severe asthma. This treatment uses heat to reduce inflammation around the smooth muscle in the airways.
- Keeping a rescue inhaler available at all times in case of an asthma attack. Fast acting bronchodilators such as albuterol are the most effective for the treatment of an acute asthma attack.
