Comparison of clinical and laboratory features between patients with ankylosing spondylitis and non-radiolographic axial spondyloarthritis

Objective To analyze and compare the clinical and laboratory features between patients with ankylosing spondylitis (AS) and nonradiographic axial spondyloarthritis (nr-axSpA). Methods One hundred and forty-one patients with AS and 73 cases with nr-axSpA were recruited. Clinical and laboratory indexes of individuals were recorded in detail, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and Ankylosing Spondylitis Disease Activity Score (ASDAS) crp were calculated. Spondyloarthritis research consortium of Canada (SPARCC) score standard was used to evaluate the degree of bone marrow edema in sacr-oiliac joint under magnetic resonance imaging scanning. T test, rank test and χ2 test were used for statistical analysis. Results The average age of patients with AS was obviously higher than that of patients with nr-axSpA (t=4.962, P 0.05). 21.6% (21 cases) of patients with AS had peripheral swollen joints, which was higher than that in nr-axSpA (2.2%, χ2=8.861, P=0.003). Forty cases in AS had tender joints (41.2%), only 6 patients in nr-axSpA had tender joints (13.3%, χ2=11.458, P 0.05). Percentage of patients with occipit-to-wall distance higher than 0 cm in AS was higher than that in nr-axSpA, and the mean distance of fingers to ground in AS was also higher than that in nr-axSpA (χ2=19.844, P<0.01; Z=5.724, P<0.01). Chest expansion degree and Schboer's test in AS was much lower than that in nr-axSpA, respectively (Z=3.083, P=0.002; Z=5.103, P<0.01). BASFI in AS was higher than that in nr-axSpA (Z=5.840, P<0.01). The ratio of joint function in AS was obviously worse than that in nr-axSpA (χ2=11.369, P=0.01). Conclusion Compared to patients with nr-axSpA, AS patients are male predominant, and have severer inflammation in clinical and laboratory findings and are worse in functional status. Key words: Spondylitis, ankylosing; Disease attributes; Nonradiographic axial spondyloarthritis