Results from ELISA of the plasma indicated that in the validation cohort, TIMP-1 level in COPD-PH patients was significantly higher (COPD vs. COPD-PH, 39.40 ± 3.493 vs. 44.48 ± 7.795 ng/mL, P < 0.01, Figure 2A). This evidence concerns the gene TIMP1 and chronic obstructive pulmonary disease.