Table 1. Demographic and clinical characteristics.
| Entire Cohort (n=3939) | Participants in GFR Subcohort | P-value | ||
|---|---|---|---|---|
| Yes (n=1433) | No (n=2506) | |||
| mGFR | ||||
| including first clearance period (mL/min/1.73 m2) | - | 49.0 ±21.0) | - | - |
| excluding first clearance period (mL/min/1.73 m2) | - | 48.0 ±19.9) | - | - |
| Age (y) | 58.2 ±11.0) | 56.0 ±12.3) | 59.4 ±10.0) | <0.001 |
| Female gender | 1778 (45.1) | 628 (43.8) | 1150 (45.9) | 0.2 |
| Black race | 1658 (42.1) | 534 (37.3) | 1124 (44.9) | <0.001 |
| Hispanic | 497 (12.6) | 215 (15.0) | 282 (11.3) | <0.001 |
| Diabetes present | 1907 (48.4) | 689 (48.1) | 1218 (48.6) | 0.8 |
| Height (cm) | 168.8 ±9.7) | 168.9 ±9.5) | 168.8 ±9.8) | 0.7 |
| Weight (kg) | 91.5 ±23.4) | 89.4 ±21.0) | 92.8 ±24.6) | <0.001 |
| BMI (kg/m2) | 32.1 ±7.8) | 31.3 ±6.9) | 32.5 ±8.3) | <0.001 |
| Waist circumference (cm) | 105.8 ±17.6) | 103.8 ±16.1) | 107.0 ±18.3) | <0.001 |
| BIA resistance (ohm) | 463.9 ±104.4) | 467.9 ±101.3) | 461.6 ±106.2) | 0.07 |
| BIA reactance (ohm) | 54.4 ±26.0) | 54.8 ±23.6) | 54.1 ±27.2) | 0.5 |
| BIA phase angle (degrees) | 6.9 ±4.2) | 6.8 ±3.7) | 6.9 ±4.5) | 0.5 |
| Fat-free mass† (kg) | 60.5 ±15.6) | 59.8 ±15.0) | 61.0 ±15.9) | 0.03 |
| Impedance† (ohm) | 468.2 ±102.7) | 472.2 ±99.9) | 465.9 ±104.2) | 0.07 |
| Serum creatinine‡ (mg/dL) | 1.74 ±0.58) | 1.70 ±0.57) | 1.77 ±0.58) | <0.001 |
| Serum cystatin C (mg/L) | 1.52 ±0.55) | 1.46 ±0.52) | 1.55 ±0.56) | <0.001 |
| Serum albumin (g/dL) | 3.9 ±0.5) | 3.9 ±0.5) | 4.0 ±0.5) | <0.001 |
| SUN (mg/dL) | 29.6 ±13.6) | 29.3 ±13.3) | 29.9 ±13.8) | 0.2 |
| 24-h urine protein (mg/d) | 184.3 [73.1-910.0] | 210.8 [76.5-1073.1] | 171.1 [71.4-839.5] | 0.01 |
| 24-h urine creatinine (mg/dL) | 70.8 ±36.9) | 68.0 ±35.0) | 72.4 ±37.9) | <0.001 |
| 24-h urine creatinine (g/d) | 1.3 ±0.6) | 1.4 ±0.6) | 1.3 ±0.6) | 0.002 |
| UPCR (mg/g)* | 152.5 [57.5-777.8] | 160.8 [59.1-941.4] | 145.9 [56.3-724.0] | 0.08 |
| 24-h urine albumin (mg/d) | 64.3 [10.3-558.7] | 84.1 [10.8-646.7] | 57.8 [9.9-508.6] | 0.004 |
| 24-h urine urea nitrogen (g/d) | 8.6 ±4.4) | 8.8 ±4.3) | 8.5 ±4.5) | 0.08 |
| Plasma glucose (mg/dL) | 115.4 ±51.7) | 112.7 ±48.8) | 117.0 ±53.2) | 0.01 |
| Total plasma homocysteine (mg/L) | 2.0 ±0.8) | 2.0 ±0.8) | 2.1 ±0.9) | <0.001 |
| hsCRP (mg/L) | 2.6 [1.1-6.5] | 2.2 [0.9-5.2] | 2.8 [1.1-7.1] | <0.001 |
| BNP (pg/mL) | 40.6 [17.0–96.0] | 36.7 [15.4-83.6] | 43.1 [18.0-101.9] | <0.001 |
| Fibrinogen (mg/dL) | 416.9 ±121.1) | 403.8 ±118.3) | 424.4 ±122.1) | <0.001 |
| Insulin (μU/mL) | 16.3 [10.9-25.4] | 15.6 [10.5-24.6] | 16.5 [11.2-25.9] | 0.01 |
| IL-6 (pg/mL) | 1.9 [1.2-3.2] | 1.7 [1.1-2.8] | 2.0 [1.2-3.4] | <0.001 |
| TNF-α (pg/mL) | 2.2 [1.5-3.2] | 2.2 [1.5-3.3] | 2.2 [1.5-3.2] | 0.6 |
| IL-1ra (pg/ml) | 715.7 [390-1551] | 715.0 [370-1508] | 717.1 [397-1569] | 0.1 |
| Urine NGAL (ng/ml) | 14.9 [5.0-35.4] | 13.9 [5.0-32.2] | 15.5 [5.0-38.0] | 0.004 |
| Creatinine clearance (mL/min) | 58.2 ±30.5) | 61.2 ±31.1) | 56.5 ±30.0) | <0.001 |
| HOMA-IR | 6.6 ±8.7) | 6.3 ±7.7) | 6.8 ±9.2) | 0.1 |
| SI-HOMA | 0.2 [0.1-0.4] | 0.3 [0.1-0.4] | 0.2 [0.1-0.4] | 0.02 |
| Body surface area (m2) | 2.06 ±0.29) | 2.04 ±0.27) | 2.07 ±0.30) | <0.001 |
Note: unless otherwise indicated, values for continuous variables given as mean ± SD or median [25th-75th percentile], while values for categorical variables given as number (percentage).
BIA – bioelectrical impedance analysis; BMI – body mass index; BNP – brain natriuretic protein; GFR – glomerular filtration rate; HOMA-IR – homeostasis model assessment – insulin resistance; hsCRP – high-sensitivity C-reactive protein; IL-1ra – interleukin 1 receptor antagonist; IL-6 – interleukin 6; mGFR – measured GFR; NGAL – neutrophil gelatinase-associated lipocalin; SI-HOMA – homeostasis model assessment – insulin sensitivity; Sun, serum urea nitrogen; TNF-α - tumor necrosis factor α; UPCR, urine protein-creatinine ratio.
Determined from 24-h urine sample
From BIA data
Traceable to isotope dilution mass spectrometry.
Note: Conversion factors for units: creatinine in mg/dL to μmol/L, ×88.4; creatinine clearance in mL/min to mL/s, ×0.01667; serum albumin in g/dL to g/L, ×10; SUN in mg/dL to mmol/L, ×0.357; plasma glucose in g/dL to mmol/L, ×0.05551; insulin in μU/mL to pmol/L, ×6.00.