Demographic, clinical and biological data of the 25 patients finally included in the study
| RA | SpA | ||
| Number of patients | 11 | 14 | |
| Sex (M/F) | 6/5 | 9/5 | |
| Age (mean (SD) years) | 47 (16) | 35 (36) | NS |
| Disease duration (mean (SD) months) | 36 (34) | 37 (53) | NS |
| Thompson index (mean (SD)) | 210 (106) | 136 (62) | NS |
| Rheumatoid factor positive (%) | 8 (73) | 0 | |
| HLA B-27 positive (%) | 0 | 10 (71) | |
| CRP (mean (SD) mg/dl) | 4.3 (5.9) | 2.4 (3.75) | NS |
| Number of cells in synovial fluid (mean (SD) ml) | 8456 (6112) | 10727 (8699) | NS |
RA: rheumatoid arthritis. SpA: seronegative spondyloarthropathies. CRP: C reactive protein.