Background Axial SpondyloArthritis (axSpA) is a heterogeneous disease. The likelihood of diagnosis varies depending upon the presence of the specific SpA-features. It is debated whether additional examinations (i.e. HLA-B27 testing and imaging of the sacroiliac joints (SIJ)) should be performed in patients with a low suspicion of axSpA (0-1 present SpA-features) after clinical examination, physical examination, CRP/ESR measurement.
Objectives To investigate if HLA-B27 testing and imaging of the SIJ is useful in young patients with back pain and maximally 1 SpA feature.
Methods The SPACE cohort includes patients with chronic back pain (CBP; ≥3 months ≤2 years, onset <45 years) recruited from 5 participating centres across Europe. All patients underwent full diagnostic work-up: MRI and x-rays SIJ, HLA-B27 testing and assessment of all other SpA-features. Patients were classified according to the ASAS axSpA-criteria and according to the clinical rheumatologist diagnosis.
Results In this analysis, 133 patients were included. Of the 38/133 (28.6%) patients without SpA-features; 4/38 (10.5%) were classified according to the ASAS-axSpA criteria after additional investigations (table). Three of them were also diagnosed as axSpA by the rheumatologist. Four additional patients were diagnosed axSpA but did not fulfil the ASAS axSpA criteria. Of the 95/133 (71.4%) patients with 1 SpA-feature; 22/95 (23.2%) patients fulfilled the ASAS criteria via the imaging arm. SpA features in these patients were: 7 IBP, 5 IBD, 4 positive family history for SpA, 3 good response to NSAIDs, 2 raised CRP/ESR, 1 enthesitis. Seventeen of these 22 patients were also diagnosed as axSpA by the rheumatologist. Six additional patients were diagnosed axSpA but did not fulfil the ASAS axSpA criteria.
Conclusions In patients with CBP and maximally 1 SpA feature after medical history, physical examination and CRP/ESR measurement, subsequent HLA-B27 testing and imaging led to fulfilment of the ASAS axSpA-criteria in 11% and 23%, respectively. In addition axSpA was the clinical diagnosis in almost twenty percent of this group. Therefore, in patients with maximally 1 SpA feature, axSpA cannot be ruled out without additional imaging and/or HLA-B27 testing.
Disclosure of Interest None declared