Emphysema: Stages and Prognosis
Doctors describe the severity and progression of emphysema with staging systems. Although everyone with emphysema is unique, emphysema staging can help with prognosis. However, no emphysema staging system can accurately predict what will happen to any individual person with emphysema.
Pulmonary Function Affects Emphysema Prognosis
Emphysema staging requires pulmonary function testing (PFTs). Doctors use PFTs to follow the lung capacity in people with emphysema. During PFTs, a person with emphysema breathes and blows air through a tube while airflow is measured. A person's emphysema prognosis is in large part determined by PFTs.
The lung damage in emphysema creates small air pockets in the lungs, where air becomes trapped. The trapped air makes it difficult for people with emphysema to blow out forcefully. The more air that is trapped, the worse lung function becomes. Over time, this makes it harder to breathe with emphysema, and pulmonary function test results decline.
The GOLD Emphysema Staging System
One major emphysema staging system is called GOLD. It was created by an expert group called the Global Initiative for Chronic Obstructive Lung Disease.
The major factor in GOLD emphysema staging is the amount of air a person with emphysema can forcefully exhale in one second. This is called the forced expiratory volume, or FEV1.
GOLD emphysema staging is as follows:
Stage I, Mild emphysema: FEV1 greater than or equal to 80% of normal
Stage II, Moderate emphysema: FEV1 less than 80%, but greater than or equal to 50% of normal
Stage III, Severe emphysema: FEV1 less than 50%, but greater than or equal to 30% of normal
Stage IV, Very severe emphysema: FEV1 less than 30% of normal, OR less than 50% of normal with low blood oxygen levels
GOLD emphysema staging is well established and widely used. However, GOLD emphysema staging does not include other areas of functioning that are important, such as how people living with emphysema feel.
The BODE Emphysema Staging System
Emphysema affects more than the ability to blow air through a tube. The BODE index, another emphysema staging system, measures emphysema's impact on multiple areas in life:
- Body mass index (B), or weight adjusted for height
- Airflow limitation (O for obstruction), measured by pulmonary function tests.
- Breathlessness (D for dyspnea), assessed by a questionnaire.
Exercise capacity (E), measured by how far a person with emphysema can walk in six minutes.
The BODE index does a slightly better job at determining emphysema prognosis than GOLD criteria.