Background Axial spondyloarthritis include non-radiographic spondyloarthritis (nr-SpA) and ankylosing spondylitis (AS); they reveal the extent of sacroiliitis assessed by conventional x-ray or MRI (1). The natural history of nr-SpA follows various evolution patterns; smoking, male gender, high levels of inflammatory markers or initial radiographic lesions are among predictor factors of progression to AS (2).

Objectives The objective of the present study was to compare features related to progression of nr-SpA patients versus AS patients undergoing biological therapy with an anti-TNF agent.

Methods This was an observational, cross-sectional study including 94 patients with nr-SpA and AS under continuous anti-TNF therapy for at least six months. SPSS 20.0 was used to analyze data with a P value of 0.05.

Results Out of the selected study group, 69 patients were diagnosed with AS having a mean age of 44.8±10.8, while 25 patients had nr-SpA. Patients with nr-SpA were aged 32.1±6.6 years old and 40% of them were women, a rate significantly than in the AS group (P=0.05). Mean age at disease onset was 30.7 years for the AS subgroup versus only 23.8 years for patients with nr-SpA (P<0.001). AS patients presented a significantly higher value of the BMI compared to nr-SpA (27 versus 24.7 kg/m^2, P<0.001). 91% of patients had positive HLA B27 and 7.4% had a positive family history of SpA, with no significant differences between the two subgroups. A higher level of CRP was noticed in AS patients (P=0.038).In the study cohort the time interval from symptom onset to establishing a diagnosis was of 39.9±55.6 months, with a mean delay interval of 2.32 years for patients with nr-SpA and higher, of 3.5 for patients with AS (P=0.01).

Conclusions The nr-SpA group had a considerably higher percentage of females compared to the AS subgroup. AS patients presented higher values of CRP at follow-up visits as opposed to nr-SpA patients. There were no significant differences between nr-SpA and AS patients regarding BASDAI or PtGA scores, smoking status or frequency of uveitis. The presence of HLA B27 did not differ between the two subgroups, thus it might not be a reliable predictive factor of progression.

References

1. Akgul O, Ozgocmen S. Classification criteria for spondyloarthropathies. World J Orthop. 2011;2(12):107–115.

2. Wendling D, Non-radiographic spondyloarthritis: A theoretical concept or a real entity? Jt Bone Spine 2012;79(6):531–533. doi:10.1016/j.jbspin.2012.06.009.

References

Disclosure of Interest None declared