Table 3. Baseline demographic and clinical characteristics of KNOW-CKD participants according to CKD stages.
| Characteristics | CKD stage | P | P for trend | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Stage 1 (n = 265) | Stage 2 (n = 419) | Stage 3a (n = 403) | Stage 3b (n = 484) | Stage 4 (n = 522) | stage 5 (n = 145) | ||||
| Age, yr | 43.2 ± 11.7 | 50.5 ± 11.7 | 54.9 ± 11.7 | 56.7 ± 11 | 57.2 ± 11.1 | 55.7 ± 11.4 | < 0.001* | < 0.001 | |
| Age (category), yr | 20 to 29 | 37 (14.0) | 16 (3.8) | 8 (2.0) | 5 (1.0) | 9 (1.7) | 2 (1.4) | < 0.001† | < 0.001 |
| 30 to 39 | 69 (26.0) | 63 (15.0) | 43 (10.7) | 29 (6.0) | 32 (6.1) | 12 (8.3) | |||
| 40 to 49 | 74 (27.9) | 106 (25.3) | 70 (17.4) | 96 (19.8) | 79 (15.1) | 24 (16.6) | |||
| 50 to 59 | 59 (22.3) | 136 (32.5) | 126 (31.3) | 138 (28.5) | 167 (32.0) | 45 (31.0) | |||
| 60 to 69 | 24 (9.1) | 80 (19.1) | 115 (28.5) | 150 (31.0) | 160 (30.7) | 49 (33.8) | |||
| 70 to 75 | 2 (0.8) | 18 (4.3) | 41 (10.2) | 66 (13.6) | 75 (14.4) | 13 (9.0) | |||
| Gender | < 0.001† | 0.719 | |||||||
| Male | 127 (47.9) | 277 (66.1) | 276 (68.5) | 307 (63.4) | 314 (60.2) | 68 (46.9) | |||
| Female | 138 (52.1) | 142 (33.9) | 127 (31.5) | 177 (36.6) | 208 (39.8) | 77 (53.1) | |||
| Monthly income, KRW | < 0.001† | ||||||||
| < 1,500,000 | 70 (27.9) | 108 (26.7) | 98 (25.0) | 101 (21.5) | 96 (18.9) | 18 (12.8) | |||
| 1,500,000 to 4,500,000 | 146 (58.2) | 230 (56.9) | 222 (56.6) | 256 (54.5) | 245 (48.1) | 76 (53.9) | |||
| > 4,500,000 | 35 (13.9) | 66 (16.3) | 72 (18.4) | 113 (24.0) | 168 (33.0) | 47 (33.3) | |||
| Educational attainment | < 0.001† | ||||||||
| Illiteracy | 1 (0.4) | 2 (0.5) | 3 (0.7) | 4 (0.8) | 4 (0.8) | 1 (0.7) | |||
| Graduated elementary school | 9 (3.8) | 26 (7.2) | 33 (9.4) | 56 (13.1) | 67 (14.7) | 22 (17.6) | |||
| Graduated middle school | 19 (8.1) | 31 (8.6) | 30 (8.5) | 61 (14.3) | 64 (14.0) | 17 (13.6) | |||
| Graduated high school | 78 (33.1) | 103 (28.5) | 113 (32.1) | 150 (35.1) | 160 (35.1) | 49 (39.2) | |||
| Graduated college or more | 129 (48.7) | 199 (47.5) | 173 (42.9) | 156 (32.2) | 161 (30.8) | 36 (24.8) | |||
| Smoking | < 0.001† | 0.009 | |||||||
| Never smoker | 173 (65.3) | 226 (54.1) | 194 (48.4) | 253 (52.5) | 271 (52.2) | 85 (59.4) | |||
| Current smoker | 42 (15.8) | 69 (16.5) | 78 (19.5) | 66 (13.7) | 76 (14.6) | 18 (12.6) | |||
| Former smoker | 50 (18.9) | 123 (29.4) | 129 (32.2) | 163 (33.8) | 172 (33.1) | 40 (28.0) | |||
| Comorbid disease | |||||||||
| Coronary artery disease | 2 (0.8) | 10 (2.4) | 17 (4.2) | 33 (6.8) | 48 (9.2) | 8 (5.5) | < 0.001† | < 0.001 | |
| Peripheral vascular disease | 3 (1.1) | 7 (1.7) | 18 (4.5) | 16 (3.3) | 29 (5.6) | 5 (3.4) | 0.006† | 0.002 | |
| Cerebrovascular disease | 6 (2.3) | 15 (3.6) | 28 (6.9) | 32 (6.6) | 45 (8.6) | 9 (6.2) | 0.003† | < 0.001 | |
| Diabetes | 40 (15.1) | 87 (20.8) | 119 (29.5) | 192 (39.7) | 249 (47.7) | 68 (46.9) | < 0.001† | < 0.001 | |
| Hypertension | 225 (84.9) | 399 (95.2) | 394 (97.8) | 475 (98.1) | 515 (98.7) | 142 (97.9) | < 0.001† | < 0.001 | |
| Congestive heart failure | 1 (0.4) | 2 (0.5) | 1 (0.2) | 7 (1.4) | 19 (3.6) | 4 (2.8) | 0.001‡ | < 0.001 | |
| Arrhythmia | 5 (1.9) | 9 (2.1) | 11 (2.7) | 9 (1.9) | 19 (3.6) | 3 (2.1) | 0.498† | 0.157 | |
| Age-adjusted modified CCI | < 0.001† | < 0.001 | |||||||
| Low (≤ 3) | 257 (97.0) | 352 (84.0) | 186 (46.2) | 176 (36.4) | 155 (29.7) | 48 (33.1) | |||
| Moderate (4–5) | 7 (2.6) | 54 (12.9) | 141 (35.0) | 185 (38.2) | 207 (39.7) | 58 (40.0) | |||
| High (6–7) | 1 (0.4) | 11 (2.6) | 63 (15.6) | 109 (22.5) | 131 (25.1) | 32 (22.1) | |||
| Very high (8–9) | 0 (0.0) | 2 (0.5) | 13 (3.2) | 14 (2.9) | 29 (5.6) | 7 (4.8) | |||
| Etiology of CKD | < 0.001† | 0.011 | |||||||
| GN | 131 (49.4) | 180 (43.0) | 163 (40.4) | 158 (32.6) | 138 (26.4) | 40 (27.6) | |||
| DN | 13 (4.9) | 44 (10.5) | 72 (17.9) | 131 (27.1) | 198 (37.9) | 61 (42.1) | |||
| HTN | 11 (4.2) | 48 (11.5) | 95 (23.6) | 112 (23.1) | 118 (22.6) | 25 (17.2) | |||
| PKD | 94 (35.5) | 118 (28.2) | 52 (12.9) | 45 (9.3) | 42 (8.0) | 13 (9.0) | |||
| Unclassified | 16 (6.0) | 29 (6.9) | 21 (5.2) | 38 (7.9) | 26 (5.0) | 6 (4.1) | |||
| BMI, kg/m2 | 24.2 ± 3.8 | 24.6 ± 3.4 | 24.7 ± 3.3 | 24.8 ± 3.2 | 24.4 ± 3.4 | 24.2 ± 3.4 | 0.068* | 0.838 | |
| BMI category, kg/m2 | 0.084† | 0.949 | |||||||
| < 18.5 (underweight) | 8 (3.0) | 8 (1.9) | 9 (2.3) | 8 (1.7) | 16 (3.1) | 5 (3.5) | |||
| 18.5 to 22.9 (normal) | 97 (36.6) | 123 (29.6) | 103 (26.1) | 120 (25.2) | 164 (31.6) | 47 (32.9) | |||
| 23.0 to < 24.9 (overweight) | 60 (22.6) | 97 (23.4) | 116 (29.4) | 153 (32.1) | 123 (23.7) | 36 (25.2) | |||
| 25.0 to 30.0 (obese I) | 82 (30.9) | 159 (38.3) | 141 (35.8) | 169 (35.4) | 180 (34.7) | 47 (32.9) | |||
| ≥ 30.0 (obese II) | 18 (6.8) | 28 (6.7) | 25 (6.3) | 27 (5.7) | 36 (6.9) | 8 (5.6) | |||
| BP variables, mmHg | |||||||||
| Systolic BP | 126.6 ± 14.3 | 126.4 ± 14.7 | 126.5 ± 15.7 | 126.8 ± 15.5 | 129.7 ± 17.6 | 135.1 ± 20.0 | < 0.001* | < 0.001 | |
| Diastolic BP | 78.6 ± 10.5 | 78.3 ± 11.3 | 76.6 ± 10.3 | 76.0 ± 10.5 | 76.4 ± 12.1 | 77.4 ± 11.8 | 0.050* | 0.003 | |
| Pulse pressure | 48.0 ± 10.4 | 48.1 ± 9.8 | 49.9 ± 12.3 | 50.8 ± 12.2 | 53.4 ± 12.8 | 57.7 ± 14.8 | < 0.001* | < 0.001 | |
| Creatinine, mg/dL | 0.7 ± 0.1 | 1.0 ± 0.2 | 1.3 ± 0.2 | 1.7 ± 0.3 | 2.7 ± 0.6 | 4.8 ± 1.6 | < 0.001* | < 0.001 | |
| Cystatin C, mg/L | 0.75 ± 0.14 | 1.02 ± 0.20 | 1.33 ± 0.22 | 1.77 ± 0.33 | 2.61 ± 0.52 | 3.86 ± 0.71 | < 0.001* | < 0.001 | |
| eGFR, mL/min/1.73 m2 | |||||||||
| MDRD study equation | 110.9 ± 20.6 | 73.3 ± 8.6 | 52.2 ± 4.3 | 37.3 ± 4.2 | 23.1 ± 4.4 | 11.8 ± 2.4 | < 0.001* | < 0.001 | |
| CKD-EPI creatinine equation | 110.9 ± 10.4 | 80.9 ± 10.7 | 56 ± 5.2 | 39.2 ± 4.8 | 23.7 ± 4.8 | 11.8 ± 2.5 | < 0.001* | < 0.001 | |
| CKD-EPI cystatin equation | 109.5 ± 16.2 | 80.7 ± 19.2 | 55.7 ± 12.5 | 38.1 ± 10.2 | 22.9 ± 7.6 | 13.3 ± 3.2 | < 0.001* | < 0.001 | |
| Urine protein/24 hr, mg/day | 621 ± 1,084 | 753 ± 1,481 | 1,088 ± 1,814 | 1,338 ± 1,927 | 2,062 ± 2,645 | 2,717 ± 3,171 | < 0.001* | < 0.001 | |
| ACEI or ARB therapy | 205 (77.4) | 369 (88.3) | 354 (88.3) | 421 (87.2) | 437 (83.9) | 121 (84.0) | 0.006† | ||
| Lipid profile, mg/dL | |||||||||
| Total cholesterol | 185.3 ± 38.1 | 179.5 ± 35.7 | 173.3 ± 35.9 | 170.6 ± 39.3 | 169.6 ± 42.3 | 168.9 ± 42.8 | < 0.001* | < 0.001 | |
| LDL cholesterol | 107.3 ± 33.1 | 102.3 ± 30.5 | 96.5 ± 30.4 | 92.3 ± 30.2 | 92.7 ± 32.4 | 93.7 ± 34.4 | < 0.001* | < 0.001 | |
| HDL cholesterol | 56.9 ± 15.6 | 52.6 ± 15.6 | 49.6 ± 14.1 | 47.2 ± 14.3 | 45.3 ± 14.7 | 45.3 ± 16.6 | < 0.001* | < 0.001 | |
| Triglycerides | 136.7 ± 86.6 | 148.5 ± 84.3 | 158.1 ± 100.2 | 166.4 ± 106.9 | 168.1 ± 107.7 | 150.7 ± 77.5 | < 0.001* | < 0.001 | |
| Hemoglobin, g/dL | 14.0 ± 1.5 | 14.1 ± 1.7 | 13.5 ± 1.9 | 12.7 ± 1.8 | 11.5 ± 1.5 | 10.5 ± 1.2 | < 0.001* | < 0.001 | |
| Serum calcium, mg/dL | 9.2 ± 0.4 | 9.3 ± 0.4 | 9.2 ± 0.4 | 9.2 ± 0.5 | 9.0 ± 0.5 | 8.5 ± 0.8 | < 0.001* | < 0.001 | |
| Serum phosphorus, mg/dL | 3.5 ± 0.5 | 3.5 ± 0.6 | 3.5 ± 0.5 | 3.6 ± 0.6 | 3.9 ± 0.7 | 4.7 ± 0.8 | < 0.001* | < 0.001 | |
| iPTH, pg/mL | 40.2 ± 17.4 | 43.0 ± 21.1 | 51.9 ± 29.7 | 61.6 ± 31.2 | 104.7 ± 70.8 | 240.8 ± 214.1 | < 0.001* | < 0.001 | |
| 25(OH)D, ng/mL | 16.3 ± 6.4 | 18.5 ± 7.4 | 18.8 ± 8.0 | 18.0 ± 7.9 | 17.6 ± 8.6 | 16.3 ± 8.3 | < 0.001* | 0.066 | |
Values are mean ± SD or No. (%).
KNOW-CKD = KoreaN Cohort Study for Outcomes in Patients With Chronic Kidney Disease, SD = standard deviation, GN = glomerulonephritis, DN = diabetic nephropathy, HTN = hypertensive nephropathy, PKD = polycystic kidney, KRW = South Korean Won rates, BMI = body mass index, CCI = Charlson comorbidity index, BP = blood pressure, eGFR = estimated glomerular filtration rate, MDRD = Modification of Diet in Renal Disease, CKD-EPI = chronic kidney disease epidemiology collaboration, ACEI = angiotensin converting enzyme inhibitor, ARB = angiotensin receptor blocker, CKD = chronic kidney disease, LDL = low-density lipoprotein, HDL = high-density lipoprotein, iPTH = intact parathyroid hormone, 25(OH)D = 25-hydroxyvitamin D.
*P value evaluated by Kruskal-Wallis test; †P value evaluated by χ2 test; ‡P value evaluated by Fisher's exact test.