Background It is possible to classify patients as having spondyloarthritis (SpA) according to the ASAS axial SpA criteria HLA-B27-arm without any signs of sacroiliitis on MRI or X-ray. The question arises whether patients fulfilling the HLA-B27-arm reflect a group of patients similar to those fulfilling the imaging-arm of the ASAS axial SpA criteria1.
Objectives To compare demographics, number of SpA-features and level of disease activity in patients fulfilling the imaging-arm to patients fulfilling the HLA-B27-arm of the ASAS axial SpA criteria.
Methods The SPondyloArthritis Caught Early (SPACE)-cohort is set-up in the Leiden University Medical Center (LUMC) aiming to diagnose and treat patients with axial spondyloarthritis (SpA) at an earlier stage. Patients with back pain (≥3 months, but ≤2 years, onset <45 years) visiting the rheumatology outpatient clinic were included. All patients of the SPACE-cohort (n=157) fulfilling the ASAS axial SpA criteria were included in this analysis (n=60). Patients were compared on demographics, presence of SpA-features and level of disease activity.
Results Of those 60 patients, 29 fulfilled the imaging-arm (11 fulfilling modified New York (mNY) criteria; 18 MRI positive only); 31 fulfilled the HLA-B27-arm. Patients fulfilling the HLA-B27-arm have significantly more often a positive family history for SpA (p=0.001), are more frequently female (p=0.04) and have a significantly shorter disease duration (p=0.02). Moreover, there was a trend toward more uveitis (p=0.09). Patients in both arms are very similar with respect to all other SpA-features and level of disease activity (BASDAI and ASDAS). Within the imaging-arm, patients with sacroiliitis on X-ray do not differ significantly from patients with sacroiliitis on MRI in any of the tested variables including symptom duration and disease activity (table; # represent p-value <0.05).
Conclusions Patients with sacroiliitis on X-ray have the same level of disease activity and symptom duration as patients with sacroiliitis on MRI only. Patients fulfilling the HLA-B27-arm are remarkably similar to patients fulfilling the imaging-arm of the ASAS axial SpA criteria, with respect to the presence of most SpA-features and level of disease activity.
Rudwaleit M et al. ARD 2009;68:777-83
Disclosure of Interest None Declared