Additionally, the serum MDA levels were positively correlated with 3-year PH incidence, and negatively correlated with 3-year survival rate in COPD patients; however, serum SOD levels were negatively correlated with 3-year PH incidence, and positively correlated with 3-year survival rate in COPD patients(54). This evidence concerns the gene SOD1 and chronic obstructive pulmonary disease.