Background Axial involvement in psoriatic arthritis (PsA) is a controversial issue. Lack of unanimity in the definition has led to a wide range of levels of prevalence. Moreover, although radiographic progression in patients with spondylitis (AS) is widely known, the different radiographic characteristics of both entities advise against establishing a parallelism between the evolution of the different lesions or the clinical factors which may have an influence on them.
Objectives Measure radiographic progression over four years in patients with PsA and axial involvement. Relate radiographic damage with clinical and analytical factors.
Methods Prospective study with patients diagnosed with PsA according to the CASPAR criteria. Axial involvement was defined as the presence of inflammatory back pain along with sacroiliitis and/or syndesmophytes. Patients with less of five years of evolution from the onset were included. The radiographic damage was measured with the PASRI method. The difference between both measurements was four years. The assessment was carried out by two observers. The clinical factors measured were: age, sex, peripheral involvement, smoking, use of NSAIDs (continuous vs on-demand), biological treatment, measures of activity (BASDAI), function (BASFI) and mobility (BASMI). The analytical variables measured were: VSG, PCR, B-CrossLaps, P1NP and HLA-B27. The presence of a dorsal or lumbar fracture was also assessed according to the semiquantitative Gennant method.
Results 45 patients with PsA and axial involvement were included. The average age was 53.5 years (SD: 12.9). 31 patients were men. The kappa coefficient between both raters was 0.70. Radiographic progression was higher in men (3.13 vs 1.14, p=0.04; in the multivariate analysis: p=0.04, OR: 0.61, 95%CI: 0.39–0.98) and in smokers (active and ex-mokers) (3.81 vs 1.14, p=0.04; in the multivariate analysis: p=0.04, OR: 0.61, 95%CI: 0.48–0.93). The presence of vertebral fracture was associated to patients with a higher radiographic progression (4.85 vs 1.82; p=0.001; in the multivariate analysis: p=0.008, OR: 0.59, 95%CI: 0.39–0.87). No differences were found regarding the presence of peripheral manifestations (2.32 vs 3.57, p=0.3), peripheral joints erosions (2.61 vs 3.1, p=0.4), continuous use of NSAIDs (1.67 vs 2.91, p=0.3), biological prescription (2.04 vs 3.72, p=0.3) or HLA-B27 (2.00 vs 2.79, p=0.5). A correlation was observed between radiographic progression and the initial PASRI score (p=0.001) and between progression and a lower P1NP concentration (p=0.02). Twelve patients did not show radiographic progression. These patients showed lower initial PASRI scores (5.35 vs 12.6, p=0,001; in the multivariate analysis: p=0.03; OR: 0.73, 95%CI: 0.55–0.98) and a lower P1NP concentration (38.7 vs 61.1; p=0.006: in the multivariate analysis: p=0.01; OR: 1.05, 95%CI: 1.008–1.096).
Conclusions As in patients with AS, male gender, smoking and the presence of initial damage were associated to a higher radiographic progression. These patients were associated to a higher rate of vertebral fracture and lower levels of P1NP. Radiographic progression was not associated to inflammatory parameters, peripheral manifestations or to the treatment used. 25% of the patients did not show radiographic progression
Disclosure of Interest None declared