Table 1 Clinical characteristics and laboratory assessments of the study groups

Age (years)

63.89 ± 12.94†

57.18 ± 11.95‡

43.12 ± 12.27

 < 0.001

Female (n, %)

152, 95.6%

403, 93.9%

668, 95.4%

0.500

Creatinine (μmol/L)

127.75 ± 108.03†

76.68 ± 8.31‡

63.40 ± 7.98

 < 0.001

Urea (mmol/L)

7.857 ± 3.643†

5.13 ± 1.35‡

4.39 ± 1.23

 < 0.001

Potassium (mmol/L)

4.028 ± 0.575†

3.99 ± 0.35‡

3.88 ± 0.364

 < 0.001

Sodium (mmol/L)

142.00 (140.00–144.00)†

141.56 (140.00–143.00)‡

140.14 (138.92–142.00)

 < 0.001

Chlorine (mmol/L)

106.624 ± 3.855†

105.56 ± 2.27‡

105.01 ± 2.35

 < 0.001

FPG (mmol/L)

5.29 (4.91–5.84)†

5.22 (4.87–5.58)‡

4.98 (4.71–5.34)

 < 0.001

ANA-positive (n, %)

149 (93.7%)

640 (91.4%)

398 (92.8%)

0.584

N = 114

N = 555

N = 356

SSA-positive (n, %)

61 (53.5%)†

338 (60.9%) ‡

248 (69.7%)

0.002

SSB-positive (n, %)

34 (29.8%)

154 (27.7%)

88 (24.7%)

0.459

nRNP (n, %)

0.131

negative

109 (95.6%)

516 (93.1%)

322 (90.4%)

positive

5 (4.4%)

38 (6.9%)

34 (9.6%)

Scl-70 (n, %)

0.098

negative

110 (96.5%)

548 (98.7%)

353 (99.2%)

positive

4 (3.5%)

7 (1.3%)

3 (0.8%)

Jo-1 (n, %)

‡

0.002

negative

112 (98.2%)

554 (99.8%)

346 (97.2%)

positive

2 (1.8%)

1 (0.2%)

10 (2.8%)

rRNP (n, %)

0.602

negative

109 (97.3%)

536 (96.8%)

331 (95.7%)

positive

3 (2.7%)

18 (3.2%)

15 (4.3%)