Table 1 Participant characteristics

Sex, n (%) male

178 (70.6 %)

250 (58.1 %)

63 (48.5 %)

491 (60.5 %)

<0.001

Age, years

52 (43.5, 62)

50 (40,60)

56 (47,62)

52 (42,61)

<0.001

BMI, kg/m²

28 (3.9)

26.3 (4.6)

27.5 (5)

27 (4.5)

<0.001

Systolic blood pressure, mmHG

133 ± 14.7

133 ± 17.9

134 ± 16.7

133 ± 16.7

0.60

 Caucasian

224 (89 %)

365 (84.9 %)

100 (76.9 %)

689 (85 %)

0.03

 African American

15 (6.0 %)

37 (8.6 %)

12 (9.2 %)

64 (8 %)

 Other

13 (5.0 %)

28 (6.5 %)

18 (13.9 %)

59 (7 %)

 Baseline eGFRcys (ml/min/1.73 m²)

33.4 (12.8)

31.5 (12.6)

28 (11.3)

31.5 (12.6)

<0.001

 Baseline eGFRcr (ml/min/1.73 m²)

34.4 (12.6)

32.9 (12.7)

30.2 (11)

32.9 (12.5)

0.007

 Baseline mGFR (ml/min/1.73 m²)

35.1 (11.7)

32.8 (11.9)

30.0 (10.2)

33.1 (11.7)

<0.001

 mGFR ≤29 ml/min/1.73 m²

86 (34.1 %)

198 (46.0 %)

75 (57.7 %)

359 (44.2 %)

<0.001

 mGFR 30–44 ml/min/1.73 m²

100 (39.7 %)

141 (32.8 %)

42 (32.3 %)

283 (34.9 %)

 mGFR ≥45 ml/min/1.73 m²

66 (26.2 %)

91 (21.2 %)

13 (10.0 %)

170 (20.9 %)

 Serum creatinine, mg/dl

2.29 (0.89)

2.37 (0.94)

2.35 (0.82)

2.3 (0.90)

0.36

 Serum cystatin C, mg/L, N = 797

2.11 ± 0.66

2.22 ± 0.67

2.36 ± 0.67

2.21 ± 0.67

0.001

 Proteinuria, mg/L, N = 786

1.09 ± 1.75

1.1 ± 1.58

1.16 ± 1.91

1.11 ± 1.69

0.87

 C-reactive protein^, mg/dL

0.24 (0.11,0.47)

0.20 (0.10,0.61)

0.31 (0.13, 0.71)

0.23 (0.11, 0.6)

0.07

 Albumin, g/dL

4.03 (0.30)

4.02 (0.35)

4.0 (0.31)

4.02 (0.33)

0.77

 Hematocrit, g/dl

40 (4.5)

38.6 (5.2)

38.1 (4.4)

38.8 (4.92)

0.004

 Diabetes mellitus

12 (4.8 %)

18 (4.2 %)

12 (9.2 %)

42 (5.2 %)

0.07

 Coronary artery disease

22 (8.7 %)

35 (8.1 %)

17 (13.1 %)

74 (9.1 %)

0.22

 Hypertension

214 (84.9 %)

355 (82.6 %)

112 (86.2 %)

681 (84 %)

0.53

 Polycystic kidney disease

53 (21 %)

99 (23 %)

21 (16.2 %)

173 (21.3 %)

0.03

 Glomerular disease

119 (47 %)

169 (39.3 %)

64 (49.2)

352 (43.3)

 Other

80 (32 %)

162 (37.7 %)

45 (34.6 %)

287 (35.3 %)