Both MMP-9 and the MMP-9/TIMP-1 ratio were statistically greater in COPD patients in GOLD stages 3 and 4 (p = 0.003; p ≤ 0.001) and were also higher in the patients with AECOPD ≥ 2 but failed to reach statistical significance (Table 6). Here, MMP9 is linked to chronic obstructive pulmonary disease.