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

Abstract

The terms Spondyloarthritis and spondyloarthropathy (Spa) are used to define a group of diseases with related clinical characteristics and genetics. 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. 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. 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). The frequency of anti-CCP positivity was higher in SpA patients than in healthy controls.