Table 2 Baseline Characteristics according to Monthly Income Level
N | Total | Monthly income | P | P for trend | ||
|---|---|---|---|---|---|---|
> $ 4500 | $1500 to $4500 | < $ 1500 | ||||
1361 | 269 | 701 | 391 | |||
Age (year, mean ± SD) | 60.9 ± 6.9 | 59.0 ± 6.6 | 60.6 ± 6.9 | 62.8 ± 6.7 | < 0.001 | < 0.001 |
Male (N, %) | 860 (63.2) | 199 (74.0) | 433 (61.8) | 228 (58.3) | < 0.001 | < 0.001 |
LVH (N, %) | 413 (30.3) | 60 (22.3) | 205 (29.2) | 148 (37.9) | < 0.001 | < 0.001 |
eGFR (mL/min/1.73m2) | 45.5 ± 25.1 | 49.9 ± 24.9 | 46.5 ± 25.2 | 40.5 ± 24.3 | < 0.001 | < 0.001 |
BMI (kg/m2, mean ± SD) | 24.6 ± 3.1 | 24.6 ± 2.8 | 24.6 ± 3.2 | 24.7 ± 3.2 | 0.586 | 0.403 |
CKD stage (N, %) |  |  |  |  | < 0.001 | < 0.001 |
 Stage G1 | 112 (8.2) | 27 (10.0) | 60 (8.6) | 25 (6.4) |  |  |
 Stage G2 | 226 (16.6) | 58 (21.6) | 115 (16.4) | 53 (13.6) |  |  |
 Stage G3a | 250 (18.4) | 54 (20.1) | 145 (20.7) | 51 (13.0) |  |  |
 Stage G3b | 322 (23.7) | 60 (22.3) | 171 (24.4) | 91 (23.3) |  |  |
 Stage G4 | 352 (25.9) | 59 (21.9) | 162 (23.1) | 131 (33.5) |  |  |
 Stage G5 | 99 (7.3) | 11 (4.1) | 48 (6.8) | 40 (10.2) |  |  |
Underlying renal disease (N, %) |  |  |  |  | < 0.001 | < 0.001 |
 Diabetic nephropathy | 429 (31.8) | 59 (22.0) | 223 (32.2) | 147 (27.8) |  |  |
 Hypertensive nephropathy | 327 (24.2) | 71 (25.4) | 173 (25.0) | 83 (21.3) |  |  |
 Glomerulonephritis | 341 (25.3) | 88 (32.8) | 179 (25.8) | 74 (19.0) |  |  |
 Polycystic kidney disease | 140 (10.4) | 39 (14.6) | 63 (9.1) | 38 (9.8) |  |  |
Diabetes mellitus (N, %) | 571 (42.0) | 88 (32.7) | 291 (41.5) | 192 (49.1) | Â | Â |
bHemoglobin A1c (%, mean ± SD) | 6.9 ± 1.4 | 6.8 ± 1.2 | 6.9 ± 1.3 | 7.0 ± 1.5 | 0.293 | 0.125 |
Hypertension (N, %) | 1334 (98.0) | 268 (99.6) | 688 (98.1) | 378 (96.7) | 0.069 | 0.041 |
 Systolic blood pressure (mmHg) | 128.84 ± 16.7 | 127.0 ± 14.1 | 128.3 ± 17.3 | 131.0 ± 17.1 | 0.005a | 0.001 |
 Diastolic blood pressure (mmHg) | 75.9 ± 11.2 | 77.1 ± 10.2 | 75.6 ± 11.3 | 75.8 ± 11.5 | 0.175 | 0.224 |
Educational attainment (N, %) |  |  |  |  | < 0.001 | < 0.001 |
 College graduate or higher | 437 (32.1) | 163 (60.6) | 214 (30.5) | 60 (15.3) |  |  |
 Completed high school | 467 (34.3) | 73 (27.1) | 279 (39.8) | 115 (29.4) |  |  |
 Lower than high school | 347 (33.6) | 33 (12.3) | 208 (29.7) | 216 (55.2) |  |  |
Physical activity (N, %) |  |  |  |  | < 0.001 | < 0.001 |
 High | 287 (21.1) | 55 (20.4) | 156 (22.3) | 76 (19.4) |  |  |
 Moderate | 536 (39.4) | 137 (50.9) | 259 (36.9) | 140 (35.8) |  |  |
 Low | 538 (39.5) | 77 (28.6) | 286 (40.8) | 175 (44.8) |  |  |
Anemia (N, %) | 662 (49.1) | 101 (37.8) | 345 (49.8) | 216 (55.8) | < 0.001 | < 0.001 |
ESA (N, %) | 119 (8.7) | 12 (4.5) | 71 (10.1) | 36 (9.2) | 0.019 | 0.01 |
Serum laboratory values | ||||||
 Hemoglobin (g/dL) | 12.6 ± 2.0 | 13.2 ± 1.9 | 12.6 ± 2.0 | 12.2 ± 1.9 | < 0.001 | < 0.001 |
 Creatinine (mg/dL) | 1.9 ± 1.1 | 1.8 ± 1.0 | 1.9 ± 1.1 | 2.1 ± 1.2 | < 0.001a | < 0.001 |
 Albumin (g/dL) | 4.2 ± 0.4 | 4.2 ± 0.3 | 4.1 ± 0.4 | 4.1 ± 0.4 | 0.003a | 0.001 |
 Calcium (mg/dL) | 9.1 ± 0.5 | 9.2 ± 0.5 | 9.1 ± 0.5 | 9.1 ± 0.5 | 0.012 | 0.004 |
 Phosphorus (mg/dL) | 3.7 ± 0.7 | 3.6 ± 0.5 | 3.7 ± 0.7 | 3.8 ± 0.7 | 0.003a | 0.001 |
 Total cholesterol (mg/dL) | 170.7 ± 38.2 | 171.0 ± 37.0 | 171.4 ± 39.4 | 159.3 ± 36.8 | 0.692a | 0.508 |
 LDL (mg/dL) | 93.1 ± 31.8 | 91.1 ± 32.4 | 94.4 ± 31.9 | 92.1 ± 31.1 | 0.281 | 0.851 |
 cHDL (mg/dL) | 47.7 ± 14.6 | 49.7 ± 14.5 | 47.4 ± 14.2 | 46.9 ± 14.3 | 0.051 | 0.029 |
 dTriglyceride (mg/dL) | 159.2 ± 95.7 | 143.7 ± 101.3 | 160.6 ± 100.0 | 159.6 ± 83.4 | 0.692 | 0.585 |
 e25-OH vitamin D (ng/mL) | 18.5 ± 8.5 | 19.4 ± 8.2 | 18.7 ± 9.0 | 17.6 ± 7.9 | 0.019 | 0.006 |
f24 hour urine sodium (mmol/day) | 154.8 ± 67.7 | 157.4 ± 67.5 | 152.1 ± 66.5 | 157.8 ± 69.6 | 0.348 | 0.797 |