The COPD severity score is based on responses to survey items that comprise five domains of COPD severity: [1] degree of respiratory symptoms, [2] prior systemic corticosteroid use, [3] other COPD medication use, [4] previous hospitalization or intubation for respiratory disease, and [5] home oxygen use (Table 1) (12 (link)). The possible COPD severity score range is 0 to 35, with higher scores reflecting more severe disease. The scoring algorithm takes into account both current respiratory symptoms and the therapy necessary to achieve this symptom status. For example, a person with few respiratory symptoms who is receiving albuterol, ipratropium and salmeterol for COPD would have a higher COPD severity score than another person with comparable symptoms who was only taking albuterol and ipratropium. In developing the COPD severity score in prior published analyses, each survey item was assigned an a priori weight based on clinical aspects of the disease and its expected contribution to overall COPD severity. This weighting scheme was validated by showing that it correlated very closely with a score whose alternative weighting was derived from factor analysis with orthogonal rotation (12 (link)). Prior analyses have also demonstrated internal consistency reliability and concurrent validity (correlation with pulmonary function, physical HRQL, physical disability, and respiratory-specific HRQL) (12 (link), 13 (link), 16 ).