Clinical and laboratory features of patients with undifferentiated spondyloarthritis and ankylosing spondylitis

Abstract

Background: The terms Spondyloarthritis and spondyloarthropathy (Spa) are used to define a group of diseases with related clinical characteristics and genetics. Aim: To report the clinical and demographic characteristics of ankylosing spondylitis (AS) and undifferentiated spondyloarthritis (USpA) and to evaluate the frequency of cyclic citrullinated peptide antibody (anti-CCP) positivity. Material and Methods: Two hundred patients with USpA or AS, 100 control patients with a diagnosis of rheumatoid arthritis (RA) and 100 healthy volunteers were included. For each patient, their detailed medical histories, physical examination, whole blood counts, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), anti-CCP, routine biochemical tests, and HLA-B27 test results were evaluated. ASDAS and BASDAI scores and morning stiffness were used to evaluate the disease activity. Results: The presenting symptom of 73 (73%) patients in the AS group and 58 (58%) patients in the USpA group was pain in axial joints. A family history of Spa was positive in 32 patients from both groups (32%). A positive HLA-B27 was found in 55% of the AS group and 25% of the USpA group (p < 0.01 for the difference between groups). The frequency of positive HLA-B27 was significantly higher in individuals with a family history of SpA (p = 0.022). A positive Anti-CCP was found in 56% of the RA group, a significantly higher frequency compared with other groups (p < 0.001). The frequency of positive Anti-CCP in patients in AS (9%) and USpA (6%) was significantly higher than in healthy controls (p < 0.001). Conclusions: The frequency of anti-CCP positivity was higher in SpA patients than in healthy controls.