CAT and chronic obstructive pulmonary disease: Except the variation rates of PaO2 were similar among four groups(P = 0.086), no matter regarding actual variation value or variation rate, the increase of NT-pro BNP (P<0.001;P = 0.03) and CAT score (P = 0.001;0.002) in COPD-PH-anemia group were significantly highest among four groups, whereas the decrease of PaO2 (P = 0.03;0.086) and Peak VO2 (P = 0.021;0.009) in COPD-PH-anemia group were significantly highest among four groups (Table 2).