Specific features of axial involvement in psoriatic arthritis: data from real clinical practice

Objective. To compare clinical features in psoriatic arthritis (PsA) patients with and without axial involvement. Subjects and methods. 385 PsA patients (172 males and 213 females) from National PsA Register were examined, their diagnosis verified according to CASPAR criteria. Patients’ median age was 45 [35; 54] years, median disease duration – 5,1 [0; 8] years. Pelvis X-ray and HLA-B27 levels in addition to physical examinations were obtained in all patients. Sacroiliitis (SI) was established based on radiographic findings (rSI) including bilateral changes corresponding to at least stage II, or unilateral – corresponding to at least stage III of Kellgren-Lawrence radiographic grading scale. Patients’ radiographs were evaluated by an independent radiologist. Disease activity was assessed using the DAS28 (Disease activity score 28), DAS (Disease activity in psoriatic arthritis) and BASDAI (Bath ankylosing spondylitis disease activity index) scales. 100 mm visual analog scale (VAS) was used for assessment of pain intensity (PI) and the Patient’s Global Assessment of Disease Activity (PtGA). Patients were distributed into two groups: Group 1 included rSI(+) patients, Group 2 – patients without radiologically confirmed SI – rSI (-). Results. Group 1 included 214 (55,6%) patients with axial involvement, 106 males and 108 females, Group 2 rSI (-) – 171 (44,4%) patients, 66 males and 105 females Proportion of men was significantly higher in RSi(+) group – 49,5% vs 38,6% in rSi(-) group (Odds Ratio, OR – 1,56, 95% CI 1,6-2,4; р = 0,0324). Patient’s median age was 45 [35; 54] and 46 [34; 56] years, respectively (p=0,911). Higher rates of HLA-В27 positivity were found in group rSI(+) patients, than in rSI(-), respectively in 62 out of 126 and in 26 out of 78 patients (OR 1,9, 95% CI 1,1-3,5). Patients from RSI(+) group had more severe erosive peripheral arthritis. Median tender joint counts (TJC) were 9 [14; 18] and 6 [3; 12] (р=0,02), while radiographic feet bone erosions were found in 58 (27,1%) and 29 (17%) patients, respectively (OR 1,8, 95% CI 1,1-3,0). Disease activity was higher in rSI(+) group. Median DAS28 score was 4,3 [3,3; 5,6] and 4,05 [3,03; 4,88] (р=0,02), DAPSA – 28,40 [15,65; 43,65] and 20,0 [12,45; 30,0], (р < 0,01), BASDAI – 1,6 [0; 5,1] and 0 [0; 4,5] (р < 0,01), C-reactive protein (CRP) – 0,9 [0,4; 2,2] mg/dl and 0,8 [0,3; 1,3] mg/dl, respectively (р=0,029). PtGA VAS values were 56,5 [42,3; 70,0] mm and 50,0 [30,0; 60,0] mm (р < 0,01); physicia