Table 1 Baseline characteristics and cell-free DNA levels of study participants
From: Cell-free DNA levels associate with COPD exacerbations and mortality
|  | COPD n = 2,052 − 2,128 | Smokers without airflow obstruction n = 298–331 | Non-smokers n = 181–243 | P valueA |
|---|---|---|---|---|
Age, median (IQR) | 64 (59–69) | 55 (48–62) | 54 (47–61) | < 0.001 |
Male, n (%) | 1,390 (65) | 183 (55) | 92 (38) | < 0.001 |
BMI, median (IQR) | 26.0 (22.6–29.5) | 26.3 (23.6–29.1) | 26.6 (23.9–30.3) | 0.008 |
White, n (%) | 2,081 (98) | 322 (97) | 237 (98) | 0.65 |
Current non-smoker, n (%) | 744 (36) | 189 (58) | -- | < 0.001 |
Packs per year, median (IQR) | 44 (30–60) | 28 (18–39) | -- | < 0.001 |
Post-bronchodilator FEV1 (%), median (IQR) | 47 (36–61) | 108 (100–117) | 116 (103–123) | < 0.001 |
FVC (%), median (IQR) | 80 (65–93) | 112 (103–121) | 118 (107–127) | < 0.001 |
Post-bronchodilator FEV1/FVC, median (IQR) | 58 (48–70) | 101 (97–106) | 104 (100–108) | < 0.001 |
cf-mtDNA (copies/µL), median (IQR) | 1,042 (262-3,266) | 1,381 (563-2,933) | 367 (91 − 1,299) | < 0.001 |
cf-nDNA (copies/µL), median (IQR) | 0.54 (0.31–0.92) | 0.34 (0.20–0.61) | 0.49 (0.29–0.80) | < 0.001 |
Eosinophil count (cells/µL), median (IQR) | 180 (110–280) | 170 (100–240) | 130 (80–210) | < 0.001 |
GOLD stage, n (%) | Â | Â | Â | Â |
 I | 1 (0.1) | -- | -- | NA |
 II | 943 (44) |  |  |  |
 III | 893 (42) |  |  |  |
 IV | 290 (14) |  |  |  |
SGRQ total score, median (IQR) | 51 (35–66) | 5 (3–11) | 2 (0–6) | < 0.001 |
BODE index, median (IQR) | 3 (2–5) | -- | -- | NA |
Borg scale, median (IQR)* | 4 (2–5) | -- | -- | NA |
Emphysema presence, n (%) | 747 (39) | 17 (5) | 0 (0) | < 0.001 |
6MWD (m), median (IQR) | 370 (300–447) | -- | -- | NA |
No. of prior exacerbations (%) | Â | Â | Â | Â |
 0 | 1,121 (53) | -- | -- | NA |
 1 | 540 (25) |  |  |  |
 2 | 266 (13) |  |  |  |
 3+ | 201 (9) |  |  |  |