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COPD is a common lung condition characterized by the persistent, abnormal decrease of airflow leaving the lungs. This airflow limitation is usually progressive, not fully reversible and does not change markedly over a period of several months. A breathing test known as spirometry is required to confirm a diagnosis of COPD. During a spirometry test, airflow limitation is measured and then classified according to its severity. According to the Global Initiative for Chronic Obstructive Lung Disease (GOLD) there are four COPD stages (also referred to as grades) that range from mild to very severe. The lower your spirometry test score, the more severe your COPD.
In the past, a spirometry test was the only tool used to measure COPD severity. Recently, GOLD guidelines were updated to include COPD symptoms and COPD exacerbations (periods of time when COPD symptoms worsen) when measuring COPD severity. Combining symptoms and exacerbations with spirometry results give doctors a more accurate picture as to the true severity of COPD, which can better direct COPD treatment.2
Spirometry measures forced vital capacity (FVC), the volume of air forcibly exhaled after taking the deepest breath possible and forced expiratory volume in one second (FEV1), the volume of air exhaled during the first second of the test. It then calculates FEV1/FVC, the ratio of these two measurements. The following chart demonstrates how these values are applied to COPD stages:2
Classification of Severity of
Airflow Limitation in COPD in patients with an FEV1/FVC of < 0.70:
|GOLD I||Mild COPD||FEV1 ≥ 80% of normal|
|GOLD II||Moderate COPD||FEV1 50-79% of normal|
|GOLD III||Severe COPD||FEV1 30-49% of normal|
|GOLD IV||Very Severe COPD||FEV1 < 30% of normal|
If you have GOLD I: Mild COPD, you have minor airflow limitation but you may not yet notice any COPD symptoms. Or, you may possibly have a cough with excess mucus production that you associate with smoking. Because people with GOLD I: Mild COPD rarely link COPD symptoms with lung disease, they usually don’t seek treatment at this stage.2
At this stage, your airflow limitation worsens and you may start to notice symptoms, particularly shortness of breath with increased activity along with cough and mucus production. Because symptoms start to become more problematic during GOLD II: Moderate COPD, it is at this stage that most people seek medical treatment.2
During this stage, airflow limitation significantly worsens, shortness of breath becomes more evident and COPD exacerbations are more common. You may also start to notice that physical activity becomes more difficult and that you fatigue more easily than usual.2
At this level of COPD, your quality of life may be greatly impaired and COPD exacerbations may be life-threatening. Airflow limitation is severe and may start to affect your heart and other bodily systems leading to COPD complications such as cor pulmonale and respiratory failure.2
It’s important to understand that the GOLD grading system is only meant to be used as a guideline; it’s not an exact science. What’s much more important is how you feel and how well you take care of yourself. There are some people living with GOLD IV: Very Severe COPD who take excellent care of themselves and lead a fairly normal life. On the other hand, there are those with GOLD II: Moderate COPD who are sedentary and continue to smoke who are dramatically affected by the disease.
To keep your COPD from worsening, consider the following steps:
 Institute of Medicine (US) Committee on a National Surveillance System for Cardiovascular and Select Chronic Diseases. A Nationwide Framework for Surveillance of Cardiovascular and Chronic Lung Diseases. Washington (DC): National Academies Press (US); 2011. 3, Chronic Lung Disease. Available from: https://www.ncbi.nlm.nih.gov/books/NBK83163/.
 David M. Mannino, Matthew M. Reichert and Kourtney J. Davis. Lung Function Decline and Outcomes in an Adult Population. The Am. J. Respir. Crit. Care Med., Vol 173. pp. 985-990, (2006).
 A. Anzueto. Impact of exacerbations on COPD. European Respiratory Review Jun 2010, 19 (116) 113-118; DOI: 10.1183/09059180.00002610.