Features of coxitis in spondyloarthritis

According to an epidemiological study, hip joint involvement was detected in 12–56% of patients with axial spondyloarthritis (axSpA) in Russia. Data on the incidence of coxitis in patients with axial psoriatic arthritis (axPsA) are lacking. The aim of the study was to compare radiographic changes in the hip joints in patients with axial spondyloarthritis and axial psoriatic arthritis and to evaluate the relationship between coxitis and disease activity. Material and methods. The study included 222 patients with a mean age of 35.7±12.7 years. The first group included 108 patients who met the 2009 ASAS (Assessment of SpondyloArthritis International Society) criteria for axSpA or the 1984 criteria for ankylosing spondylitis (AS); The second group included 114 patients with axPsA who met the CASPAR (ClASsification for Psoriatic ARthritis) criteria. Signs of axial involvement in psoriatic arthritis (PsA) were determined using instrumental imaging methods. Diagnosis required the presence of radiologically reliable sacroiliitis (SI), i.e., bilateral stage ≥II or unilateral stage ≥III according to Kellgren, or active sacroiliitis according to magnetic resonance imaging. The presence of at least one syndesmophyte (paraspinal ossificate) in the cervical (CS) or lumbar (LS) spine, as well as ankylosis of the facet joints of the CS, were also taken into account. The mean age of disease onset was 26.3±20.3 years; HLA-B27 was detected in 54% of patients. The diagnosis of coxitis was established based on a pelvic X-ray and calculation of the Bath Ankylosing Spondylitis Radiology Hip Index (BASRI hip) for each joint. Results. Radiographic evidence of coxitis was detected in 52 of the 222 patients included in the study, including 22 patients with AS and 30 patients with axPsA. Patients with axPsA were older than those with axSpA (median age 32 years and 45 years, respectively; p