severity of COPD GOLD Stage 4 Rena Wang, Oliver He https://www.webmd.com/lung/copd/gold-criteria-for-copd https://www.ncbi.nlm.nih.gov/books/NBK580644/table/ch1.tab1/ GOLD Stage 4 represents very severe, end-stage COPD, characterized by lung function (FEV1) less than 30% of predicted capacity. It involves chronic, debilitating breathing difficulties, frequent flare-ups, and often requires long-term oxygen therapy. Management focuses on improving quality of life, using medications, pulmonary rehab, and potentially lung-volume reduction surgery.