How long can chronic obstructive pulmonary disease live in the middle and late stages

Moderate COPD was defined as forced expiratory volume in one second less than 70% and forced expiratory volume in one second 50%~80% of predicted value, with or without cough and expectoration, while severe COPD was defined as forced expiratory volume in one second less than 70% and forced expiratory volume in one second 30%~50% of predicted value, with or without cough, expectoration and dyspnea. In the case of extremely severe COPD, where the forced expiratory volume in one second is less than 30% of the predicted value or where the forced expiratory volume in one second is less than 50% of the predicted value, but is associated with chronic respiratory failure, the patient will survive for less than five years if the patient does not receive continuous proper home oxygen therapy, which is more than 15 hours of continuous low-flow regular oxygen every night.