Table 1.

Baseline clinical and laboratory data of 227 patients stratified according to GFR in NKF stagesa

ParameterGFR (ml/min per 1.73 m2)Pb
≥90 (n = 72)60 to 89 (n = 49)30 to 59 (n = 63)<30 (n = 43)
Gender (male/female; n [%])50/22 (69/31)34/15 (69/31)44/19 (70/30)26/17 (61/40)0.72
Age (yr)39.9 ± 13.246.1 ± 11.645.9 ± 11.554.4 ± 8.5<0.001
BMI (kg/m2)24.0 ± 3.325.6 ± 3.825.4 ± 3.326.1 ± 4.80.02
Current smokers (n [%])18 (25)11 (22)11 (18)9 (21)0.97
Systolic BP (mmHg)134 ± 21140 ± 24139 ± 19137 ± 190.21
Diastolic BP (mmHg)84 ± 1388 ± 1588 ± 1488 ± 130.20
Serum creatinine (mg/dl)1.14 ± 0.22 (0.95, 1.11, 1.30)1.54 ± 0.45 (1.25, 1.43, 1.70)2.31 ± 0.79 (1.70, 2.18, 2.80)3.63 ± 1.27 (2.73, 3.50, 4.61)<0.001
GFR (ml/min per 1.73 m2)120 ± 28 (97, 110, 132)74 ± 9 (65, 71, 81)44 ± 7 (38, 44, 50)19 ± 7 (12, 18, 26)<0.001
Proteinuria (g/24 h per 1.73 m2)0.60 ± 0.66 (0.13, 0.36, 0.82)1.10 ± 1.10 (0.16, 0.57, 1.93)1.08 ± 0.94 (0.27, 0.81, 1.83)1.03 ± 0.81 (0.36, 0.89, 1.52)0.004
Serum albumin (g/dl)4.70 ± 0.384.46 ± 0.504.55 ± 0.384.53 ± 0.340.01
hsCRP (mg/L)0.21 ± 0.270.32 ± 0.330.23 ± 0.210.35 ± 0.380.01
FGF23 c-terminal (rU/ml)57 ± 43 (36, 46, 63)81 ± 52 (45, 69, 99)187 ± 194 (67, 108, 230)456 ± 475 (127, 285, 584)<0.001
FGF23 intact (pg/ml)29 ± 28 (27, 56, 83)40 ± 37 (25, 43, 57)43 ± 26 (19, 30, 44)77 ± 83 (12, 23, 36)<0.001
Calcium (mmol/L)2.37 ± 0.11 (2.30, 2.36, 2.43)2.40 ± 0.30 (2.30, 2.37, 2.43)2.34 ± 0.15 (2.27, 2.37, 2.44)2.34 ± 0.20 (2.23, 2.32, 2.46)0.63
Phosphate (mmol/L)1.02 ± 0.42 (0.85, 0.97, 1.10)1.01 ± 0.29 (0.86, 0.97, 1.18)1.08 ± 0.23 (0.92, 1.03, 1.18)1.32 ± 0.24 (1.19, 1.29, 1.55)<0.001
Ca × P (mg2/dl2)2.40 ± 0.92 (2.02, 2.26, 2.58)2.42 ± 0.69 (1.89, 2.39, 2.81)2.52 ± 0.51 (2.16, 2.47, 2.83)3.10 ± 0.63 (2.74, 2.98, 3.52)<0.001
Parathormone (pmol/L)3.8 ± 1.5 (2.7, 3.5, 4.9)6.8 ± 4.3 (4.6, 5.8, 7.6)12.0 ± 9.5 (5.3, 9.5, 17.0)27.3 ± 21.6 (13.0, 21.0, 38.0)<0.001
Use of vitamin D (n [%])0 (0)4 (8)13 (21)13 (30)<0.001
Use of phosphate binder (n [%])0 (0)2 (4)3 (5)7 (16)0.002
  • a Data are means ± SD and 25th, 50th (median), and 75th percentiles for skewed variables where appropriate. BMI, body mass index; FGF23, fibroblast growth factor 23; hsCRP, high-sensitivity C-reactive protein; NKF, National Kidney Foundation.

  • b P values are for comparison across all four groups obtained from the Kruskal-Wallis test, one-way ANOVA, and χ2 test, as appropriate.