Understanding Asthma Type, Risk, Prevalence, and Disparities
Understanding asthma risk factors may help improve treatment options and highlight disparities in asthma prevalence.
Asthma, triggered by many factors, is one of the most common chronic respiratory illnesses in the United States. Understanding the multiple subtypes of asthma and evaluating patient risk factors may provide insight into asthma prevalence and disparities.
The National Heart, Lung, and Blood Institute (NHLBI), a subset of the NIH, defines asthma as a chronic respiratory disease that causes inflammation in the airways, making it difficult to breathe. Although the disease is commonly diagnosed in childhood, the condition can be prevalent at any age.
Additionally, those with allergies or exposure to respiratory irritants are more likely to have asthma. Beyond varying patient risks, asthma severity can also range from very mild and rare symptoms to severe, acute, and potentially fatal episodes.
The most common asthma symptoms include chest tightness, coughing, shortness of breath, and wheezing. While these symptoms may be the same for other conditions, asthmatic patients experience these symptoms frequently, worsen with viral infections, are triggered by exercise, allergens, and colds, or worsen in the morning and evening.
Asthma attacks are episodes of severe asthma exacerbation, difficulty breathing, or wheezing caused by blockages in the airways. According to the Cleveland Clinic, asthma attacks can be caused by bronchospasms, inflammation, and excess mucus production. Each narrows the airways, restricting air movement in and out of the lungs.
Types of Asthma
According to the American lung association, asthma is just an overarching disease with multiple subtypes, including the following:
- Allergic asthma
- Aspirin-induced asthma
- Cough-variant asthma
- Exercise-induced asthma
- Nighttime asthma
- Steroid-resistant asthma
- Occupational asthma
Many of these types of asthma are linked to a particular root cause or condition that results in respiratory inflammation. Understanding asthma’s type and underlying cause can help inform treatment approaches and chronic disease management.
Asthma Risk Factors
Like many chronic diseases, the cause of asthma can vary, making it difficult to determine the exact source. However, research has suggested multiple factors can contribute to elevated asthma risk.
Biological
Asthma risk is significantly increased for patients who have a biological parent with asthma or a genetic predisposition to the condition. The ALS notes that a family history of asthma increases the risk of asthma by 3–6 times.
Additional insights from the Global Allergy and Airways Patient Platform revealed that having a biological parent with asthma is linked to a 25% asthma risk, doubling to 50% when both parents have the condition.
However, the condition is not entirely genetic. Although many studies have revealed a genetic link to asthma, identical twin studies have shown that it is not based on genetics alone, with only a 75% probability that both twins would have asthma.
Allergies
Another risk factor for asthma is allergy history. While having allergies does not necessarily mean someone will be an asthma patient, healthcare providers have documented a link between the two conditions. The patients may have an overactive immune response to common substances. Allergic asthma may be triggered by common daily substances such as pollen, pet dander, dust mites, and mold.
“For people with allergic asthma, an outdoor or indoor allergen may trigger symptoms. For a person with non-allergic asthma, there may be other triggers. These triggers include smoke, pollutants, exercise, viruses, and many other things. Interestingly, a person with allergic asthma may experience intensified symptoms from these triggers,” reveals the Allergy and Asthma Network.
Respiratory Illness
Viral respiratory infections and other lung diseases may also trigger asthma. Notably, infection with SARS-CoV-2, the virus that causes COVID-19, has been linked to asthma and other pulmonary diseases.
Beyond the effects of the pandemic on asthma rates, an article published in the Lancet analyzing the link between respiratory syncytial virus infection (RSV) and childhood asthma determined that avoiding RSV infection during infancy reduced the risk of pediatric asthma.
Occupational
Occupational exposure to common irritants may also impair lung function and cause patients to have an increased risk of asthma. According to the American Lung Association (ALA), roughly 11 million workers in the US are exposed to substances, like wood dust, chemical fumes, molds, or smoke, that can cause asthma symptoms.
Environmental Factors
Beyond that, air pollution plays a critical role in asthma development. Adolescents and adults living in urban communities with smog are at a significantly higher risk for asthma.
A study published in the Lancet Planetary Health revealed that increased air pollution with particulate matter and oxidizing agents is linked to increased asthma rates. “Increased air quality index values, driven predominantly by increased PM2.5 and O₃ concentrations, were significantly associated with asthma exacerbations and decreases in pulmonary function that occurred in the absence of a provoking viral infection," the article noted.
One study published in the International Journal of Environmental Research and Public Health notes that 12.7% of pediatric asthma cases are associated with gas stove use.
"Gas stove usage should be considered in multi-faceted asthma prevention approaches. Given that this exposure is preventable, our study demonstrates that known mitigation strategies will lessen childhood asthma burden from gas stoves, particularly in states with elevated PAFs. Further research is needed to quantify the burden experienced at the state and county levels, as well as the impacts of implementing mitigation strategies through intervention studies," noted researchers in the study.
This data has prompted multiple government officials, including Richard Trumka Jr, United States Consumer Product Safety Commission (CPSC) commissioner, to consider adding warnings to gas stoves or eliminating them.
Other Factors
Lifestyle factors such as smoking may also trigger asthma symptoms. Finally, obesity or excess weight is linked to increased asthma prevalence. The ALA notes that having a BMI higher than 30 increases the risk of asthma by 4%.
Asthma Prevalence
Data from the Centers for Disease Control and Prevention (CDC) suggests that over 7% of people in the United States have asthma. Meanwhile, the WHO estimates that, in 2019, over 260 million people were impacted by life-threatening asthma globally.
According to the ALA, over 3,000 people died of asthma in 2016. Despite those deaths, data suggests that the asthma death rate declined by 41% between 1999 and 2016, likely due to the increased availability of asthma medications.
Regardless of asthma treatment availability, a 2022 study published in JAMA Pediatrics notes disparities in asthma risk and prevalence across racial demographics. Black children are nearly 50% more likely to have asthma than White children. Beyond that, researchers determined that Hispanic children are disproportionately at risk for asthma, with a 29% greater incidence rate than White children.
Investigators in the publication note, “Despite decades of research, the structural, social, behavioral, and biological determinants that drive these inequitable outcomes remain ill-defined, due in part to the highly correlated nature of race and ethnicity, poverty, adverse physical environments, unequal access to healthcare, and a multitude of structural, systemic, and institutional determinants that are deeply ingrained in US policies and culture,” stated researchers in the publication.
Asthma Treatment Options
Although there is no cure for asthma, an asthma action plan can effectively manage the condition. Two main types of inhalers are used for asthma management: bronchodilators and steroids.
There are multiple different options for respiratory medications to manage asthma. One of the most common treatments for asthma is a bronchodilator, such as albuterol, which comes in various forms. There are adrenergic and anticholinergic bronchodilators and short- and long-acting versions of these medications.
Short-acting ß₂ adrenergic agonists (SABAs) treat bronchospasms and shortness of breath experienced by many patients with asthma and chronic obstructive pulmonary disease (COPD).
Despite being one of the main treatments to manage asthma, liquid albuterol has been in short supply across the United States. In March 2023, the American Society of Hospital Pharmacists reported shortages of nine albuterol inhalation solutions linked to a domestic manufacturer's bankruptcy.
Another standard treatment option for asthma is inhaled corticosteroids, which minimize the inflammatory response in the airways by inhibiting eosinophils, T-lymphocytes, mast cells, and dendritic cells.
There are also some less common alternatives for managing asthma, including mast cell stabilizers and auto-IgE antibodies. Other medication options include leukotriene receptor antagonists, antihistamines, epinephrine, respiratory stimulants, and pulmonary surfactant therapy.
