The expressions of BNP and Fbg protein in the control group, COPD/PH− group and COPD/PH+ group increased sequentially (P<0.001), while the expression levels of the Apelin protein in the control group, COPD/PH− group and COPD/PH + group decreased sequentially (P<0.001). Here, NPPB is linked to chronic obstructive pulmonary disease.