Table 1 Demographic characteristics of participators at baseline
Characteristic | All participators | Tertile of blood Cd | P | ||
|---|---|---|---|---|---|
Tertile 1 (< 0.367 ppm) | Tertile 2 (0.367 ~ 1.102 ppm) | Tertile 3 (> 1.102 ppm) | |||
N | 196 | 65 | 65 | 66 | Â |
Season, n (%) | Â | Â | Â | Â | 0.375 |
 Spring | 90 (45.9) | 31 (47.7) | 32 (49.2) | 27 (40.9) |  |
 Summer | 14 (7.1) | 6 (9.2) | 5 (7.7) | 3 (4.5) |  |
 Autumn | 49 (25.0) | 19 (29.2) | 14 (21.5) | 16 (24.2) |  |
 Winter | 43 (21.9) | 9 (13.8) | 14 (21.5) | 20 (30.3) |  |
Age, years | 74.1 ± 0.52 | 75.9 ± 1.09 | 72.7 ± 1.01 | 74.2 ± 0.94 | 0.087 |
Male, n (%) | 146 (74.5) | 49 (76.6) | 45 (69.2) | 52 (78.8) | 0.474 |
Smoking status, n (%) | Â | Â | Â | Â | 0.788 |
 None | 86 (43.9) | 29 (44.6) | 28 (43.1) | 29 (43.9) |  |
 Former | 77 (39.3) | 26 (40.6) | 23 (35.4) | 28 (42.4) |  |
 Current | 33 (16.8) | 10 (15.6) | 14 (21.5) | 9 (13.6) |  |
 Smoking amount, pack-year | 45.0(20.6, 55.0) | 38.9(21.3, 43.8) | 45.0(35.0, 75.0) | 52.3(26.3, 60.0) |  < 0.001 |
Comorbidities, n (%) | Â | Â | Â | Â | Â |
 Hypertension | 92 (46.9) | 37 (56.9) | 29 (44.6) | 26 (39.4) | 0.120 |
 Diabetes mellitus | 21 (10.7) | 5 (7.7) | 8 (12.3) | 8 (12.1) | 0.654 |
 Coronary disease, | 25 (12.8) | 10 (15.4) | 8 (12.3) | 7 (10.6) | 0.801 |
 Cerebrovascular diseases | 23 (11.7) | 6 (9.2) | 8 (12.3) | 9 (13.6) | 0.788 |
Inhaled therapy for COPD, n (%) | Â | Â | Â | Â | Â |
 SABA | 67 (34.2) | 20 (30.8) | 21 (32.3) | 26 (39.4) | 0.562 |
 SAMA | 14 (7.1) | 2 (3.1) | 5 (7.7) | 7 (10.6) | 0.270 |
 LABA | 60 (30.6) | 18 (27.7) | 25 (38.5) | 17 (25.8) | 0.429 |
 LAMA | 35 (17.9) | 11 (17.2) | 14 (21.5) | 10 (15.4) | 0.636 |
 Inhaled corticosteroids | 166 (84.7) | 57 (87.7) | 52 (80.0) | 57 (86.4) | 0.510 |
Clinical parameters | Â | Â | Â | Â | Â |
 WBC (109/L) | 7.3 ± 0.21 | 5.4 ± 0.16 | 6.5 ± 0.22 | 11.2 ± 0.32 |  < 0.001 |
 Neutrophil (109/L) | 6.3 ± 0.49 | 3.5 ± 0.15 | 5.6 ± 0.92 | 9.0 ± 0.35 |  < 0.001 |
 Lymphocyte (109/L) | 1.5 ± 0.19 | 1.2 ± 0.08 | 1.5 ± 0.36 | 1.2 ± 0.08 | 0.586 |
 Monocyte (109/L) | 0.6 ± 0.02 | 0.5 ± 0.05 | 0.6 ± 0.05 | 0.9 ± 0.05 |  < 0.001 |
 Eosinophil (109/L) | 0.08(0.02, 0.18) | 0.10(0.05, 0.2) | 0.09(0.02, 0.17) | 0.07(0.01, 0.16) | 0.228 |
 Basophil (109/L) | 0.02(0.01, 0.04) | 0.02(0.01, 0.04) | 0.02(0.01, 0.04) | 0.03(0.02, 0.05) | 0.190 |
 Uric acid (μmol/L) | 301.8 ± 6.78 | 308.7 ± 13.52 | 294.7 ± 13.09 | 286.8 ± 14.41 | 0.594 |
 Urea nitrogen (mmol/L) | 6.7 ± 0.20 | 6.5 ± 0.33 | 6.9 ± 0.48 | 6.5 ± 0.33 | 0.702 |
 Creatinine (μmol/L) | 66.0(53.0, 82.0) | 62.0(50.0, 80.0) | 68.0(57.0, 86.0) | 66.0(55.0, 83.0) | 0.429 |
eGFR (mL/min) | 143.1(112.4, 172.5) | 141.7 (110.9, 169.2) | 124.3(104.1, 163.8) | 147.5(137.3, 178.7) | 0.116 |
 ALT (U/L) | 20.4 ± 1.83 | 17.0 ± 1.38 | 17.2 ± 1.01 | 29.7 ± 6.83 | 0.045 |
 AST (U/L) | 24.0 ± 0.97 | 25.8 ± 2.75 | 20.8 ± 0.84 | 26.4 ± 2.30 | 0.124 |
 IL-6 (pg/mL) | 41.6(15.6, 111.5) | 19.6(12.2, 39.0) | 40.4(18.1, 93.1) | 124.7(111.0, 193.6) |  < 0.001 |
 CRP (mg/L) | 33.7(19.0, 60.9) | 24.1(15.4, 40.2) | 42.2(23.6, 61.0) | 84.5(38.9, 150.1) |  < 0.001 |
Pulmonary function | Â | Â | Â | Â | Â |
 FVC (L) | 2.3 ± 0.09 | 2.6 ± 0.17 | 2.8 ± 0.18 | 1.5 ± 0.11 |  < 0.001 |
 FEV1 (L) | 1.9 ± 0.08 | 2.3 ± 0.18 | 2.2 ± 0.21 | 1.3 ± 0.08 |  < 0.001 |
 FEV1/FVC (%) | 62.5 ± 1.54 | 67.2 ± 3.89 | 68.3 ± 3.92 | 55.6 ± 1.89 | 0.002 |
 FEV1 (%) | 60.4 ± 2.69 | 67.2 ± 3.89 | 65.4 ± 5.95 | 40.2 ± 4.49 |  < 0.001 |