Table 2 Characteristics of RA patients stratified by urinary Na/K ratio

(N = 336)

n = 112 (33.3%)

n = 112 (33.3%)

n = 112 (33.3%)

P value *

Age, year

60.0 ± 13.2

62.4 ± 11.8

63.1 ± 11.0

0.143

Male sex, n (%)

10 (8.92)

22 (19.64)

25 (22.32)

0.001

Body mass index, kg/m²

22.0 ± 3.1

22.6 ± 3.7

23.4 ± 4.1

0.011

Smoking habit, n (%)

7 (6.25)

11 (9.82)

10 (8.93)

0.547

Daily salt intake (g/day)

6.09 ± 1.36

7.67 ± 1.44

9.66 ± 2.04

<  0.001

 Serum Cre, mg/dL

0.69 ± 0.16

0.72 ± 0.27

0.66 ± 0.16

0.081

 eGFR, ml/min/1.73m²

72.9 ± 18.2

73.0 ± 18.3

77.8 ± 17.2

0.01

 CRP, mg/dL

0.32 ± 0.73

0.33 ± 0.65

0.45 ± 1.19

0.46

 RF, IU/mL

100.3 ± 302.5

142.5 ± 279.4

131.4 ± 289.0

0.246

 anti-CCP antibody, U/mL

201.8 ± 435.8

242.8 ± 446.3

223.5 ± 444.2

0.216

 MMP-3, ng/mL

73.8 ± 73.7

93.5 ± 86.0

96.3 ± 105.2

0.302

 Disease duration, year

9.66 ± 9.62

10.91 ± 9.82

11.16 ± 9.32

0.117

 DAS28-ESR

2.40 ± 0.83

2.53 ± 0.96

2.74 ± 1.08

0.025

 DAS28-CRP

1.92 ± 0.73

2.01 ± 0.79

2.22 ± 1.00

0.042

 SBP (Branchial), mmHg

120.4 ± 16.5

121.2 ± 16.4

126.9 ± 18.5

0.009

 DBP (Branchial), mmHg

69.2 ± 10.5

69.3 ± 11.3

72.9 ± 13.1

0.043

 Hypertension, n (%)

25 (22.3)

37 (33.0)

48 (42.9)

0.0011

 MTX use, n (%)

90 (80.3)

80 (71.4)

76 (67.9)

0.035

 Biological agent use, n (%)

63 (56.3)

55 (49.1)

56 (50.0)

0.386

 Prednisolone use, n (%)

17 (15.2)

23 (20.5)

30 (26.8)

0.04