Baseline characteristics associated with cumulative psoriasis over 6 years of follow-up in 589 axSpA patients
| Psoriasis over 6 years of follow-up (N=158) | No psoriasis over 6 years of follow-up (N=431) | Multivariable analysis: OR (95% CI) | |
| Age (years), mean (SD) | 33.7 (8.6) | 33.9 (8.9) | |
| Male gender, n (%) | 67 (42.4) | 203 (47.1) | |
| Symptom duration (years), mean (SD) | 1.4 (0.8) | 1.5 (0.9) | |
| Ethnicity (Caucasian), n (%) | 151 (95.6) | 382 (88.6) | 4.08 (1.62 to 12.61) |
| Body mass index (kg/m²), mean (SD) | 24.5 (4.7) | 23.7 (3.8) | 1.02 (0.97 to 1.08) |
| Past history or current symptoms of | |||
| Peripheral arthritis, n (%) | 59 (37.3) | 102 (23.7) | 1.26 (0.72 to 2.16) |
| Dactylitis, n (%) | 35 (22.2) | 43 (10.0) | 2.59 (1.36 to 4.91) |
| Family history of psoriasis, n (%) | 56 (35.4) | 60 (13.9) | 3.17 (1.95 to 5.17) |
| ASDAS-CRP, mean (SD) | 2.8 (0.9) | 2.6 (1.0) | |
| BASDAI, mean (SD) (0–100) | 47.7 (19.3) | 42.6 (20.4) | 0.99 (0.98 to 1.01) |
| BASFI, mean (SD) (0–100) | 35.7 (23.1) | 27.2 (22.6) | 1.01 (0.99 to 1.03) |
| Tender joint count, mean (SD) (0–53) | 4.0 (6.8) | 2.5 (4.9) | 1.01 (0.97 to 1.06) |
| Swollen joint count, mean (SD) (0–28) | 0.3 (1.2) | 0.1 (0.7) | 1.05 (0.83 to 1.40) |
| MASES enthesitis index, mean (SD)(0–13) | 3.2 (3.5) | 2.4 (2.8) | 1.03 (0.95 to 1.13) |
| HAQ-AS, mean (SD)(0–3) | 0.77 (0.52) | 0.61 (0.51) | |
| ASQoL, mean (SD)(0–18) | 10.2 (4.9) | 8.7 (4.9) | 1.0 4(0.97 to 1.12) |
| SF36, mean (SD) | |||
| Physical Component Summary (PCS) (0–100) | 38.6 (8.8) | 40.9 (9.1) | 1.00 (0.97 to 1.04) |
| Mental Component Summary (MCS) (0–100) | 40.9 (11.5) | 40.4 (10.9) | |
| MRI sacroiliitis (local reading), n (%) | 54 (35.1) | 156 (37.0) | |
| Modified New York radiographic criteria (local reading), yes, n (%) | 21 (13.5) | 80 (18.8) | 0.80 (0.42 to 1.47) |
| Radiographic coxitis (local reading), n (%) | 5 (3.2) | 30 (7.0) | 0.66 (0.20 to 1.82) |
| mSASSS (central reading), mean (SD)(0–72) | 0.51 (1.9) | 0.45 (1.4) | |
| HLA B27 positivity, n (%) | 91 (57.6) | 266 (62.0) | |
| CRP (mg/L), mean (SD) | 8.5 (13.6) | 8.0 (13.9) | 0.99 (0.97 to 1.01) |
| csDMARDs, n (%) | 28 (17.7) | 54 (12.5) | 1.19 (0.64 to 2.18) |
Data were missing in <5% patients for symptom duration, body mass index, ASDAS-CRP, BASDAI, BASFI, tender joint count, swollen joint count, MASES enthesitis index, HAQ-AS, ASQoL, PCS, MCS, MRI sacroiliitis, Modified New York radiographic criteria, radiographic coxitis, HLA B27 and CRP. Data were missing in 42 (7.1%) patients for mSASSS. P values were <0.20 for all variables entered in the multivariable analysis; they were >0.05 for: body mass index, modified New York radiographic criteria, radiographic coxitis, csDMARDs. P values for HAQ-AS and ASDAS-CRP were <0.05 but they were not included in the multivariable analysis because of collinearity (HAQ-AS and BASFI on the one hand, and ASDAS-CRP and BASDAI on the other hand, were collinear. One variable from each of these groups (namely, BASFI and BASDAI) were entered in the next analyses.
Values in bold are significant values at p-value <0.05 in multivariable analysis
ASDAS-CRP, Ankylosing Spondylitis Disease Activity Score-C reactive protein; ASQoL, Ankylosing Spondylitis Quality of Life Scale; axSpA, axial spondyloarthritis; BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; BASFI, Bath Ankylosing Spondylitis Functional Index; csDMARDs, conventional synthetic disease modifying anti-rheumatic drugs; HAQ-AS, Health Assessment Questionnaire for axSpA; MASES, Maastricht Ankylosing Spondylitis Enthesis Score; mSASSS, modified Stoke Ankylosing Spondylitis Spine Score; SF36, Short Form 36 Health Survey.