Background According to the current concept, non-radiographic axial spondyloarthritis (nr-axSpA) and ankylosing spondylitis (AS) represent two stages of one disease (axial SpA). In cross-sectional studies it has been demonstrated that nr-axSpA does not differ from AS with respect to clinical signs of disease activity. Prospective studies comparing clinical course of the disease over time are, however, lacking.
Objectives To investigate the clinical course of the disease over two years in patients with nr-axSpA in comparison to AS.
Methods In total, 210 patients with early axSpA (115 with AS according to the modified New York criteria and symptom duration ≤10 years, and 95 with nr-axSpA and symptom duration ≤5 years) from the German Spondyloarthritis Inception Cohort (GESPIC) were included. Data on the radiographic course of the disease have been reported elsewhere . Clinical assessment, which included standard disease activity (BASDAI, C-reactive protein - CRP), function (BASFI) and spinal mobility (BASMI – 3 point definition) assessments as well as therapy recording, was performed at baseline and every 6 months thereafter. Starting from the visit at month 6 (6M), the ASDAS-CRP and the ASAS NSAID intake score were calculated.
Results The majority of patients were included in GESPIC and followed-up prior to marketing authorisation of TNF blockers for AS and nr-axSpA. However, 17 AS patients (14.8%) and 5 nr-axSpA patients (5.3%) received at least one prescription of a TNF blocker during 2 years of follow-up and were excluded from the further analysis. Remaining patients with nr-axSpA (n=90) did not differ from AS patients (n=98) with respect to the BASDAI and the BASFI at any time point during 2 years of follow-up (figure). AS patients had however significantly higher level of CRP at all time points but ASDAS-CRP was significantly higher in AS at 6M only (figure).
There were also no substantial differences in the treatment between two groups. Especially, there were no differences in the proportion of patients taking NSAIDs at any time point, as well as there was no difference in the NSAIDs dose/intake frequency as reflected by the NSAIDs intake score over 2 years: 33.7±28.0 in nr-axSpA vs. 34.2±28.4 in AS, p=0.9. Spinal mobility (as measured by BASMI) was generally better in nr-axSpA as compared to AS, but this difference was statistically significant only at two time points (6 and 12 months).
Conclusions Patients with nr-axSpA and AS demonstrated the same course of the disease over 2 years as evaluated by the level of symptoms, functional status and NSAIDs treatment (except anti-TNF). Higher level of CRP and worse spinal mobility might indicate higher activity of systemic inflammation and more structural damage in AS patients.
Poddubnyy D, et al. Ann Rheum Dis. 2011;70:1369-74.
Disclosure of Interest : None declared