Table 1.
Characteristics of RA patients.
| CKD(+)RA | CKD(−)RA | ||
|---|---|---|---|
| Number of patients | 351 | 959 | |
| Age, years (SD) | 73.5 (8.6) | 64.2 (12.4) | * 2.99 × 10−47 |
| Male, n (%) | 73 (20.8) | 161 (16.8) | 0.1033 |
| Disease duration, years (SD) | 17.7 (12.5) | 16.3 (11.3) | * 0.0632 |
| Steinbrocker stage III and IV, n (%) | 156 (45.3) | 418 (44.1) | 0.7043 |
| Steinbrocker class 3 and 4, n (%) | 61 (17.8) | 96 (10.1) | 0.0003 |
| Body mass index, kg/m2 (SD) | 22.3 (3.9) | 21.7 (3.5) | * 0.0171 |
| Rheumatoid factor positive, n (%) | 287 (82.0) | 766 (80.5) | 0.5782 |
| Anti-citrullinated peptide antibody positive, n (%) | 303 (86.6) | 823 (86.7) | 0.9269 |
| Serum creatinine, mg/dL (SD) | 0.96 (0.25) | 0.62 (0.12) | * 2.71 × 10−82 |
| CRP, mg/L (SD) | 4.6 (7.5) | 5.1 (11.8) | * 0.3548 |
| ESR, mm/h (SD) | 30.2 (21.0) | 26.2 (21.1) | * 0.0035 |
| DAS28 | 3.0 (1.0) | 2.8 (1.1) | * 0.0125 |
| DAS28-CRP | 2.2 (0.9) | 2.2 (0.9) | * 0.3548 |
Number or average values of each group are shown. Standard deviations or percentages are shown in parentheses. Differences were tested by Fisher’s exact test using 2 × 2 contingency tables or the Student’s t-test. * The Student’s t-test was used. RA: rheumatoid arthritis; CKD: chronic kidney disease; CRP: C-reactive protein; ESR: erythrocyte sedimentation rate; DAS28: disease activity score 28.