Different Stages of COPD

Chronic obstructive pulmonary disease, or COPD, is a progressive disease of the lungs that causes difficulty breathing. The disease affects more than 12 million people in the United States, making it the fourth leading cause of death, according to the National Heart, Lung and Blood Institute. It is a progressive disease that gets worse over time, and is diagnosed in stages, from Stage 1 to Stage 4, with Stage 4 representing the most advanced stage of the disease.

Stage I

Stage I COPD is mild COPD; in this stage, there is some impairment in airflow, but it is not noticeable, according to frost.com. Coughing or mucus might be present, but are not abnormally so. In pulmonary function tests, COPD International estimates that individuals in this stage have 80 percent or more of their normal lung function.

Stage II

Stage II COPD is moderate disease, and people with this stage can have moderate or severe shortness of breath during exertion, which may or may not be accompanied by a cough or mucus. It is typically at this stage that individuals often seek medical help because of persistent symptoms. Pulmonary function tests show about 50 to 80 percent of normal lung functioning.

Stage III

Severe COPD is Stage III, and in this stage, individuals have more pronounced shortness of breath, with or without a cough or mucus, which tends to be persistent and worsen over time. Symptoms at this point start interfering with quality of life may cause fatigue, and individuals may have difficulty exercising, according to COPD International. Lung functioning is at about 30 to 50 percent.

Stage IV

The last stage of COPD is Stage IV, and is the most severe. In this stage, quality of life is significantly impaired because of symptoms, and the shortness of breath and restricted airflow are so pronounced that they can be life-threatening. Pulmonary function tests show less than 30 percent of lung functioning. If an individual has less than 50 percent of lung functioning, but has chronic respiratory failure, a diagnosis of Stage IV COPD may be diagnosed.

About this Author

After graduating with a bachelor’s degree in psychology and women’s studies, Jaime Herndon pursued a Master of Science in clinical health psychology, and recently completed her M.P.H. in maternal-child health from UNC. Her interests include women’s cancers, pediatric oncology, and women’s health.