Classification of Airflow Limitation Based on <i>z</i> -Score Underestimates Mortality in Patients with Chronic Obstructive Pulmonary Disease

Abstract

In patients with COPD, the AL classification based on z-score predicts worse mortality than those based on percentage of predicted. It is possible that the z-score underestimates AL severity in patients older than 60 years of age with severe functional impairment.