Table 1: Spirometric classification of COPD     Stage of COPD   FEV1 % Predicted 0   At risk   Normal   I   Mild   > 80%   II   Moderate   50 - < 80%   III   Severe   30 - < 50%   IV     Very severe   < 30 %                 FEV1 : forced expiratory volume in one second; FVC : forced vital capacity.