Persistent Asthma Classifications

Asthma is classified by the severity of symptoms in order to direct the appropriate treatment. Based on the frequency and severity of attacks, along with a review of inhaler use and pulmonary function tests, a doctor can classify the disease using criteria from "Expert Panel Report 3 (EPR-3) Guidelines for the Diagnosis and Management of Asthma." Treatment can then be staged using one or several drugs so that the disease is neither overtreated nor undertreated.

The EPR-3 guidelines were issued in 2007 by the National Asthma Education and Prevention Program Coordinating Committee (NAEPPCC). In December 2020, the NAEPPCC issued the EPR-4 guidelines in which the classification criteria remained the same, but six other aspects of asthma management for children 12 and over and adults were updated, among them the most effective use of inhaled corticosteroids, best ways to mitigate indoor asthma triggers, and best practices for immunotherapy.

The EPR-3 guidelines are the ones most commonly used in the United States for staging of asthma treatment. There are other guidelines used internationally, including those issued by the Global Initiative on Asthma (GINA). The GINA guidelines, updated annually, are created in collaboration with the World Health Organization (WHO) and the National Heart, Lung, and Blood Institute in Bethesda, Maryland.

How Asthma Classifications Are Made

According to the EPR-3 guidelines, the assessment of asthma severity is based on five specific values, some of which are objective (with clear diagnostic measures) and others which are subjective (based on the individual's experience and perceptions).

When classifying asthma severity, the following five characteristics are assessed:

1. Symptoms, specifically the number of times per day or week an asthma attack occurs
2. Nighttime awakenings, the number of times that symptoms awaken you on a daily, weekly, or monthly basis
3. Rescue inhaler use, the number of times per day or week you need to use a short-acting inhaler to treat acute asthma symptoms
4. Interference with normal activity, a subjective assessment of how your symptoms are interfering with your ability to perform everyday tasks
5. Lung function, an evaluative measure of lung capacity and lung strength using pulmonary function tests (PFTs)

Together, these values can differentiate asthma severity into one of four classifications: mild intermittent, mild persistent, moderate persistent, or severe persistent. These classifications provide the foundation from which treatment decisions are made.

Diagnostic Process

Asthma is classified based on lung function, which is measured with a non-invasive test known as spirometry that evaluates both lung capacity and lung strength.

From a classification standpoint, there are two measures in the assessment:

• Forced expiratory volume in one second (FEV1), the amount of air you can forcefully expel from the lungs in one second
• FEV1/FVC ratio, the amount of air you can forcefully exhale in one second compared to the amount of air that can be exhaled when the lungs are completely full

Any value below the predicted range (based on your age, sex, and height) may indicate an obstructive lung disease like asthma.

The other values (symptoms, nighttime awakening, rescue inhaler use, physical impairment) can be obtained during an interview with the patient.

Also factoring into the assessment is whether oral corticosteroids (steroids) have been needed to treat severe attacks. The number of times that oral steroids are needed per year—typically in an emergency setting⁠—can alone determine if the disease is intermittent or persistent.

Monitoring Treatment Response

The assessment can also be used to monitor a person's response to treatment. Once an asthma classification is made, the assessment is repeated two to six weeks later to see if the treatment is working. If asthma control is not achieved, an adjustment to the treatment plan would be needed.

Asthma Classifications

The purpose of the asthma classification system is to direct the appropriate treatment, neither undertreating the disease (leading to treatment failure and the premature progression of the disease) nor overtreating it (leading to early drug tolerance and an increased risk of side effects).

Based on the assessment, asthma can be classified as:

Mild Intermittent Asthma

Asthma is considered mild intermittent if any or all of the following are true:

• Symptoms occur two or fewer days per week.
• Nighttime symptoms occur two days or fewer per month.
• Rescue inhalers are used two or fewer times per week (or not at all).
• Symptoms do not limit normal activities.
• Lung function is greater than 80% of the predicted value based on your age, sex, and height.

Mild Persistent Asthma

Asthma is considered mild persistent if any or all of the following are true:

• Symptoms occur more than two days a week, but not every day.
• Nighttime symptoms occur three to four times a month.
• Rescue inhalers are used more than two times weekly, but not every day, and not more than once per day.
• Asthma attacks mildly impair normal daily activities (enough that people may or may not notice).
• Lung function is greater than 80% of the predicted value based on your age, sex, and height.

Moderate Persistent Asthma

Asthma is considered moderate persistent if any or all of the following are true:

• Symptoms occur daily.
• Nighttime symptoms more than once weekly, but not nightly.
• Rescue inhalers are used daily.
• Asthma symptoms moderately impair normal activities (enough that people around you notice).
• Lung function is less than 80% of the predicted values but more than 60%.

Severe Persistent Asthma

Asthma is considered severe persistent if any or all of the following are true:

• Symptoms occur several times daily.
• Nighttime symptoms are frequent, often nightly.
• Rescue inhalers are used several times daily.
• Asthma symptoms severely impair your ability to function normally.
• Lung function is less than 60% of the predicted value.

Classification in Younger Children

In children under 12, the only variation in the classification of asthma is the FEV1/FVC ratio. While the FEV1/FVC ratio can often be normal in adults with asthma, this is less true with younger children.

Asthma classification in children is defined in part by the following FEV1/FVC ratios:

• Mild intermittent: FEV1/FVC is over 85% of the predicted value.
• Mild persistent: FEV1/FVC is over 80% of the predicted value.
• Moderate persistent: FEV1/FVC is between 75% and 80% of the predicted value.
• Severe persistent: FEV1/FVC is under 75% of the predicted value.

Treatment Approaches

The ultimate aim of asthma classification is to direct the appropriate treatment. Based on the classification, treatment can be staged according to six structured steps. With each step, the treatments become more complicated and carry a greater risk of side effects.

There is not always a clear line between when a step should or should not be started. While mild intermittent asthma is almost always treated with rescue inhalers alone, persistent asthma often requires a judgment call to pick the right combination of drugs to control asthma symptoms.

When asthma control is achieved, a specialist is better suited to decide if or when treatments can be simplified or dosages decreased.

The drugs recommended for use in treating intermittent or persistent asthma include:

• Short-acting beta-agonists (SABA) such as albuterol, also known as rescue inhalers
• Inhaled corticosteroids (ICS), typically used daily or as needed to reduce airway inflammation
• Long-acting beta-agonists (LABA) such as Singulair (montelukast), used daily to reduce airway hyperresponsiveness
• Long-acting muscarinic antagonists (LAMA), a potential alternative to adding a LABA to ICS therapy for people who cannot tolerate or aren't helped by LABAs
• Leukotriene receptor agonists (LTRA) like Zyflo CR (zileuton), taken orally to reduce airway inflammation
• Cromolyn sodium or nedocromil, known as mast cell stabilizers, useful for treating allergy-induced asthma symptoms
• Theophylline, an older drug sometimes used in combination therapy
• Xolair (omalizumab), a monoclonal antibody used to control severe allergic asthma
• Oral corticosteroids (OCS), typically reserved for emergencies or for people with severe persistent asthma

The steps and recommended treatments vary by age.