Fig. 2
From: Cell-free DNA levels associate with COPD exacerbations and mortality
cf-mtDNA levels are higher in participants classified as GOLD stage I/II while cf-nDNA levels are higher in participants classified as GOLD stage IV. Baseline (A) cf-mtDNA and (B) cf-nDNA levels were assessed in participants with COPD who were classified as GOLD stage I/II (n = 944), III (n = 893), or IV (n = 290). The results are presented as median, with the box indicating Q1 and Q3 quartiles and the whiskers indicating range. To format the y-axis, we used the natural logarithmic scale of data and then transformed it back to nominal data for ease of interpretation. Statistical analysis was performed using ANOVA with Bonferroni post hoc pairwise comparison. *P value < 0.05, ***P value < 0.001. cf-mtDNA = cell-free mitochondrial DNA; cf-nDNA = cell-free nuclear DNA; COPD = chronic obstructive pulmonary disease; GOLD = Global Initiative for Obstructive Lung Disease