Patients’ characteristics
| OA | RA | ||
| (n=17) | (n=20) | p Value | |
| Age (years) | 78±4.94 | 65.8±10.6 | <0.01‡ |
| Female (%) | 14 (82.4) | 16 (80) | 0.999§ |
| CRP (mg/dL) | 0.0.69±0.079¶ | 1.845±1.88 | <0.01‡ |
| ESR (mm/hour) | 24.4±14.6# | 47.3±35.0 | 0.014‡ |
| DAS28-ESR | 4.25±1.12 | ||
| RF (U/mL) | 73.5 (18.6 to 189.1) | ||
| ACPA positive (%) | 19 (95) | ||
| OA grading* | |||
| Grade I or II (%) | 1 (5.9) | ||
| Grade III or IV (%) | 16 (94.1) | ||
| RA stage† | |||
| Stage I or II (%) | 7 (35) | ||
| Stage III or IV (%) | 13 (65) |
Data are presented as mean±SD, n (%) or median (IQR).
*The Kellgren-Lawrence Grading Scale.
†The Steinbrocker Staging system.
‡Data was not available in one patient.
§Data was not available in two patients.
¶Fisher’s exact test.
#Welch’s t-test.
Notably, the level of TNF-α in RA synovial fluid had a tendency of positive correlation with the level of NRDC (p=0.054), suggesting the causative role of NRDC in TNF-α elevation (figure 4C). We next analysed the association of NRDC levels in RA synovial fluid with the patients’ clinical condition. Interestingly, NRDC levels showed a significant but modest correlation with CRP levels, but no correlations with other factors including ESR, disease activity (disease activity score 28 (DAS28)-ESR), RF or ACPA (figure 4D and data not shown). These data suggested that NRDC could be a unique synovial fluid marker for the differential diagnosis of late RA and late OA.