Table 1 Baseline characteristics of the study participants from NHANES 2007-2016, weighted

Age, years, (median, IQR)

55.00 (47.00,64.00)

55.00(48.00, 64.00)

56.00(46.00, 68.00)

0.009

Female, n (%)

6898 (52.27)

6043 (51.16)

855 (66.68)

<0.001

Race, n (%)

<0.001

Mexican American

2122 (6.68)

1920 (6.49)

202 (9.14)

Other Hispanic

1535 (4.70)

1400 (4.60)

135 (5.93)

Non-Hispanic White

5761 (73.08)

5417 (74.92)

344 (49.23)

Non-Hispanic Black

2617 (9.03)

2040 (7.58)

577 (27.91)

Other race

1322 (6.51)

1188 (6.41)

134 (7.79)

Marital status, n (%)

<0.001

Having a partner

8660 (70.39)

7872 (71.03)

788 (62.07)

Others

4697 (29.61)

4093 (28.97)

604 (37.93)

PIR, n (%)

<0.001

<1.3

3735 (16.50)

3254 (15.80)

481 (25.63)

\(>=\)1.3, <3.0

3695 (24.33)

3296 (24.01)

399 (28.55)

\(>=\)3.0

4831 (53.05)

4455 (54.22)

376 (37.83)

Education level, n (%)

<0.001

< high school

3738 (16.47)

3284 (15.90)

454 (23.87)

high school

2955 (22.09)

2654 (22.19)

301 (20.75)

> high school

6664 (61.44)

6027 (61.91)

637 (55.39)

Alcohol intake, n (%)

<0.001

no

3637 (21.03)

3132 (20.26)

505 (31.08)

yes

8772 (72.80)

8003 (73.71)

769 (60.88)

Smoking status,n (%)

<0.001

never

6904 (51.86)

6101 (51.26)

803 (59.72)

now

2589 (18.32)

2391 (18.77)

198 (12.52)

former

3864 (29.82)

3473 (29.97)

391 (27.76)

Moderate-vigorous physical activity,n (%)

5003 (41.58)

4569 (41.94)

434 (36.90)

<0.001

Body mass index,kg/m\(^{2}\), n (%)

<0.001

<25.0 kg/m\(^{2}\)

3154 (24.47)

2802 (24.33)

352 (26.37)

25.0-29.9 kg/m\(^{2}\)

4578 (35.03)

4172 (35.53)

406 (28.50)

\(\ge\)30.0 kg/m\(^{2}\)

5495 (39.71)

4884 (39.41)

611 (43.60)

High waist circumference, n (%)

8264 (62.51)

7393 (62.56)

871 (61.85)

<0.001

Phosphorus, mmol/L, (median, IQR)

1.20 (1.10, 1.32)

1.20 (1.10, 1.32)

1.23 (1.10, 1.36)

0.008

Calcium, mmol/L, (median, IQR)

2.35 (2.30, 2.40)

2.35 (2.30, 2.40)

2.33 (2.25, 2.38)

<0.001

Serum iron, umol/L, (median, IQR)

14.70 (11.3, 18.80)

15.00 (11.60, 19.20)

9.00 (5.40, 13.10)

<0.001

Albumin, g/dL, (median, IQR)

4.30 (4.10, 4.50)

4.30 (4.10, 4.50)

4.10 (3.90, 4.30)

<0.001

Uric acid, umol/L, (median, IQR)

321.20 (267.70, 380.70)

321.20 (267.70, 380.70)

309.30 (243.90, 386.60)

0.295

UACR, mg/g, (median, IQR)

6.94 (4.64, 12.54)

6.82 (4.62, 12.19)

8.92 (5.21, 23.28)

<0.001

eGFR, ml/min/1.73m2, (median, IQR)

88.78 (75.24, 100.19)

88.89 (75.79, 99.97)

86.90 (64.86, 104.75)

<0.001

serum 25-hydroxyvitamin D,nmol/L, (median, IQR)

71.00 (53.70,88.40)

71.50 (54.50, 88.70)

61.80 (42.60, 84.40)

<0.001

Serum Klotho, pg/mL, (median, IQR)

798.00 (657.20, 980.20)

800.20 (659.70, 980.70)

761.50 (619.70, 967.20)

0.127

Red blood cell, MillionCells/uL, (median, IQR)

4.63 (4.33, 4.94)

4.66 (4.38, 4.96)

4.08 (3.78, 4.41)

<0.001

Hemoglobin, g/dl, (median, IQR)

14.20 (13.30, 15.10)

14.30 (13.60, 15.20)

11.60 (10.90, 11.90)

<0.001

Mean cell volume, fL, (median, IQR)

90.30 (87.30, 93.30)

90.50 (87.60, 93.40)

85.30 (78.10, 90.60)

<0.001

Mean cell hemoglobin, pg, (median, IQR)

30.80 (29.60, 32.00)

30.90 (29.80, 32.00)

28.40 (25.40, 30.70)

<0.001

Red cell distribution width, (median, IQR)

13.00 (12.50, 13.70)

13.00 (12.50, 13.60)

14.60 (13.40, 16.10)

<0.001

Energy intake, kcal, (median, IQR)

875.00 (3026.00, 4892.00)

3904.00 (3044.00, 4923.00)

3495.00 (2711.00, 4499.00)

<0.001

Protein intake, g, (median, IQR)

152.22(117.29, 195.76)

153.47 (118.11, 197.16)

137.08 (103.14, 176.54)

<0.001

DFE deficiency, (median, IQR)

774 (4.91)

654 (4.67)

120 (8.00)

<0.001

Vitamin B12 deficiency, n (%)

638 (3.85)

549 (3.69)

89 (5.94)

<0.001

Iron intake deficiency, n (%)

639 (4.16)

549 (4.03)

90 (5.80)

0.002

Angina, n (%)

418 (2.69)

352 (2.51)

66 (5.02)

<0.001

Heart attack, %

756 (4.57)

639 (4.40)

117 (6.89)

<0.001

Congestive heart failure, n (%)

513 (2.88)

390 (2.49)

123 (8.05)

<0.001

Coronary heart disease, n (%)

673(4.31)

568 (4.05)

105 (7.74)

<0.001

Stroke, n%

627( 3.53)

505 (3.22)

122 (7.59)

<0.001

Hypertension, n (%)

7185 (48.43 )

6274 (47.58)

911 (59.38)

<0.001

Hyperlipidemia, n (%)

10687(79.94)

9637 (80.27)

1050 (75.64)

0.001

Diabetes, n (%)

3421(19.34)

2898 (18.40)

523 (31.45)

<0.001

Chronic kidney disease, n (%)

2688 (16.10)

2176 (14.91)

512 (31.53)

<0.001

Cancer, n (%)

1559(13.48)

1380 (13.39)

179 (14.56)

0.580

Rheumatoid arthritis, n (%)

943(5.46)

801 (5.18)

142 (9.06)

<0.001