Table 2.
Demographic, clinical, and biochemical characteristics of the different groups of study participants
| Patients with axSpA (n = 41) | Women with postpartum buttock/pelvic pain (n = 46) | Patients with disc herniation (n = 25) | Healthy subjects (n = 92) | |
|---|---|---|---|---|
| Demographic feature | ||||
| Age, years | 30.9 (6.41) | 32.6 (3.25 )† | 35.2 (5.70)† | 34 (6.42)† |
| Male sex, no. (%) | 26 (63.4) | 0 (0)§ | 11 (44.0) | 45 (48.9) |
| HLA-B27 positive, no. (%) | 33 (80.5) | 5 (10.9)§ | 0 (0)§ | 6 (6.5)§ |
| CRP, mg/ liter | 11.4 (13.5) | 1.66 (2.06)§ | 2.19 (3.28)§ | 1.71 (3.01)§ |
| Body mass index, kg/m2 | 23.1 (2.95) | 25.0 (4.39) | 26.1 (4.03) | 24.50 (3.45) |
| No. of childbirths if woman | 1.7 (0.8) | 1.5 (0.8) | 1.6 (0.9) | 2.14 (1.13) |
| Years since last childbirth if woman | 4.9 (4.6) | 0.7 (0.3) | 9.1 (7.0) | 7 (6.8) |
| Symptom duration, years | 8 (5.6) | 1 (0.8)§ | 0.8 (0.4)§ | NA |
| Smoking status, no (%) | ||||
| Daily smoker | 10 (24.4) | 2 (4.3) | 12 (48.0) | 12 (13) |
| Occasional smoker | 9 (22.0) | 6 (13.0) | 4 (16.0) | 11 (12) |
| Never smoked | 13 (31.7) | 25 (54.3) | 7 (28.0) | 62 (67.4) |
| Previous smoker | 8 (19.5) | 13 (28.3) | 2 (8.0) | 7 (7.6) |
| Physical activity (%) | ||||
| Light | 11 (26.8) | 7 (15.2) | 9 (36.0) | 17 (18.5) |
| Moderate | 11 (26.8) | 29 (63.0) | 7 (28.0) | 23 (25) |
| Heavy | 13 (31.7) | 8 (17.4) | 6 (24.0) | 21 (22.8) |
| Most heavy | 6 (14.6) | 2 (4.3) | 3 (12.0) | 31 (33.7) |
| Inflammatory back pain, no. (%) | 41 (100) | 11 (23.9)§ | 3 (12.0)§ | 0 (0) |
| Medical history of SpA features, no (%) | ||||
| Arthritis | 12 (29.3) | 0 (0)§ | 1 (4.0) | 0 (0) |
| Enthesitis | 6 (14.6) | 1 (2.2)† | 0 (0) | 9 (9.8) |
| Uveitis | 9 (22.0) | 0 (0)§ | 0 (0) | 0 (0)§ |
| Psoriasis | 1 (2.4) | 0 (0) | 0 (0) | 0 (0) |
| Inflammatory bowel disease, no. (%) | 4 (9.8) | 0 (0) | 0 (0) | 0 (0)‡ |
| Clinical examination | ||||
| SJC ≥ 1, no. (%) | 1 (2.4%) | NA | NA | NA |
| TJC ≥ 1, no. (%) | 2 (4.8%) | NA | NA | NA |
| Pain | 3.9.8 (25.1) | NA | NA | NA |
| Physician global VAS score | 4.3 (2.7) | NA | NA | NA |
| BASDAI score | 4 (2,1) | NA | NA | NA |
| BASFI score | 2.7 (2.1) | NA | NA | NA |
| BASMI score | 1.2 (1.7) | 0.3 (0.7)§ | 0.5 (0.6) | 2.85 (7.19)§ |
| SPARCC SI joint score | ||||
| Inflammation score (0–48) | 10.8 (10.7) | 3.88 (5.7)‡ | 0.3 (0.9)§ | 0.41 (1.01)§ |
| SSS fat lesion score (scale 0–40) | 12 (11.1) | 0.5 (2.3)§ | 0.3 (1.0)§ | 0.6 (2)§ |
| SSS erosion score (scale 0–40) | 5.2 (4.8) | 0.5 (2.2)§ | 0.02 (0.1)§ | 0.05 (0.2)§ |
| SSS backfill score (scale 0–20) | 4.8 (5.6) | 0 (0)§ | 0 (0)§ | 0 (0)§ |
| SSS ankylosis score (scale 0–20) | 3.5 (6.0) | 0 (0)§ | 0 (0)§ | 0 (0)§ |
| Extracellular biomarkers levels, ng/ml | ||||
| C1M | 84.3 (85.7) | 36.7 (20.2) | 42.4 (28.1) | 34.20 (20.98) |
| C2M | 23.97 (6.98) | 28.12 (9.70) | 27.65 (19.25) | 23.16 (6.60) |
| T2CM | 5.56 (1.35) | 5.66 (1.66) | 5.96 (1.44) | 5.71 (2.60) |
| C3M | 15.6 (3.95) | 14.0 (1.90) | 13.9 (4.46) | 13.84 (3.04) |
| C4M | 34.9 (10.2) | 27.5 (4.59) | 28.0 (8.64) | 28.03 (8.74)§ |
| C6M | 20.5 (5.75) | 17.2 (2.83) | 19.4 (4.85) | 16.89 (4.52)§ |
| C10C | 2570 (462) | 2610 (450) | 2530 (632) | 2557.12 (593.15) |
| COL10NC | 9.15 (5.81) | 9.33 (13.2) | 8.32 (4.95) | 9.78 (5.32) |
| PROM | 0.30 (0.09) | 0.26 (0.09) | 0.27 (0.08) | 0.26 (0.08) |
| VICM | 5.80 (4.36) | 3.85 (2.63)‡ | 3.65 (3.09) | 3.65 (2.38) |
| CRPM | 11.9 (2.87) | 11.0 (5.16)‡ | 12.9 (12.4) | 10.42 (2.55)‡ |
| PRO-C2 | 22.39 (6.27) | 25.47 (10.30) | 21.88 (6.91) | 27.10 (20.93) |
| PRO-C3 | 10.2 (2.52) | 11.2 (2.87) | 11.2 (3.70) | 11.40 (2.79)‡ |
| PRO-C4 | 7370.07 (763.99) | 6811.70 (687.48)§ | 7083.46 (1149.44) | 6491.39 (834.36)§ |
| PRO-C6 | 6.94 (2.45) | 7.93 (3.51) | 7.61 (2.87) | 6.11 (1.36) |
Except where indicated otherwise, mean ± SD is presented. Kruskal-Wallis rank test was used with patients with patients with axSpA as the reference group. Significance is shown as †p< 0.05, ‡p< 0.01, and §p< 0.001
Abbreviations: CRP C-reactive protein, NA not applicable, SJC swollen joint count, TJC tender joint count, SPARCC Spondyloarthritis Research Consortium of Canada, VAS visual analog scale (each scale 0–10), BASDAI Bath Ankylosing Spondylitis Disease Activity Index (scale 0–10), BASFI Bath Ankylosing Spondylitis Functional Index (scale 0–10), BASMI Bath Ankylosing Spondylitis Metrology Index (scale 0–10), SSS SI joint structural lesion score, C1M metalloproteinase (MMP)-degraded type I collagen, C2M metalloproteinase (MMP)-degraded type II collagen, T2CM MMP-1 and MMP-13-mediated degradation of type II collagen, C3M MMP-degraded type III collagen, C4M MMP-degraded type IV collagen, C6M MMP-degraded type VI collagen, CRPM C-reactive protein metabolite, PROM MMP-1 and MMP-13-mediated degradation of prolargin, VICM citrullinated and MMP-degraded vimentin, PRO-C2 pro-peptide of type II collagen, PRO-C3 pro-peptide of type III collagen, PRO-C4 pro-peptide of type IV collagen, PRO-C6 pro-peptide of type VI collagen