Table 1 Descriptive characteristics between study participants with impaired and non-impaired eGFR groups

Age, median (IQR), year

73 (13)

61 (17)

1.09 (1.07, 1.11) ^***

Male (%)

63 (28.00)

689 (48.59)

1.88 (1.36, 2.60) ^***

BMI, median (IQR), kg/m²

24.72 (4.11)

24.14 (4.12)

  < 18.5

12 (5.33)

55 (3.88)

2.34 (1.11, 4.93) ^*

 18.5–24

70 (31.11)

644 (45.42)

Reference

 24–27

83 (36.89)

469 (33.07)

1.62 (1.13, 2.33) ^**

  > = 27

60 (26.67)

250 (17.63)

2.64 (1.76, 3.97) ^***

 Elementary school or lower

83 (37.22)

321 (22.75)

Reference

 High school

89 (39.91)

625 (44.29)

0.98 (0.68, 1.40)

 College or higher

51 (22.87)

465 (32.96)

0.73 (0.48, 1.11)

Smokers (%)

1103 (45.78)

480 (33.85)

1.19 (0.86, 1.65)

Secondhand smoking exposure (%)

69 (30.67)

524 (37.16)

0.92 (0.67, 1.28)

Alcohol drinkers (%)

76 (33.78)

429 (30.25)

0.83 (0.59, 1.17)

Hypertension

135 (60.00)

413 (29.13)

2.21 (1.62, 3.01) ^***

Type 2 Diabetes

49 (21.78)

122 (8.60)

2.45 (1.65, 3.63) ^***

Uric acid, median (IQR), mg/dL

6.10 (2.40)

5.30 (1.80)

1.48 (1.33, 1.66) ^***

  < 7

148 (66.07)

1231 (87.43)

Reference

  > =7

76 (33.93)

177 (12.57)

3.20 (2.24, 4.56) ^***

Insulin, median (IQR), μU/mL

10.05 (10.70)

7.30 (6.70)

1.03 (1.02, 1.03) ^***

HOMA-IR, median (IQR)

2.42 (3.30)

1.66 (1.88)

1.06 (1.04, 1.08) ^***

  < 1.9

80 (35.71)

798 (56.68)

Reference

  > =1.9

144 (64.29)

610 (43.32)

2.20 (1.61, 3.00) ^***

TC/HDL ratio, median (IQR)

4.43 (1.35)

4.13 (1.44)

1.20 (1.02, 1.40) ^*

  < 4

165 (73.66)

1088 (76.94)

Reference

  > =4

59 (26.34)

326 (23.06)

1.06 (0.75, 1.51)

Folate in plasma, median (IQR), ng/mL

8.68 (9.36)

9.79 (8.20)

0.98 (0.96, 1.01)

  < 6

67 (29.78)

302 (21.30)

1.54 (1.09, 2.17) ^***

  > =6

158 (70.22)

1116 (78.70)

Reference

8-OHdG, median (IQR), ng/mg creatinine

4.45 (3.57)

4.89 (3.97)

1.02 (0.98, 1.05)