Page 115 - Recognizing axial spondyloarthritis - Janneke de Winter

examination included a 68-joint tender joint count and a 66-joint swollen joint count, an enthesitis score (the Maastricht Ankylosing Spondylitis Enthesitis Score (26)), a dactylitis evaluation, the linear Bath Ankylosing Spondylitis Metrology Index (27), chest expansion, and occiput-to-wall distance (22). Cutoff values of modified Schober test and chest expansion results were set at 4.5 cm and 3.6 cm, respectively (28).
Biological evaluation at baseline
Laboratory assessments included HLA–B27 testing, serum CRP levels, and erythrocyte sedimentation rate (ESR). Levels of calprotectin were determined by enzyme-linked immunosorbent assay in accordance with the instructions of the manufacturer (Hycult) (29,30).
Imaging evaluation at baseline
Radiographs of the lumbar and cervical spine and of the sacroiliac (SI) joints were obtained. Anteroposterior radiographs of the SI joints were scored according to the modified New York criteria for AS (31). Lateral and anteroposterior radiographs of the lumbar and cervical spine were scored according to the modified Stoke Ankylosing Spondylitis Spine Score (32). MRIs were performed on a 3.0T scanner (Philips Medical Systems) with sagittal T1- weighted and STIR sequences with a slice thickness of 4 mm for the spine (sagittal) and SI joints (semicoronal). Radiographs and MRIs were both scored by 1 experienced reader (RL) in a blinded manner for the presence of bone marrow edema according to the ASAS/Outcome Measures in Rheumatology definition of a positive MRI (33). In order to assess the reproducibility of the MRI scoring, we used a test-retest method. One experienced reader (RL) scored the MRIs in a blinded manner at 2 different time points, with a time lag of at least 6 months. The second reading was complemented with 18 control MRIs, 8 from patients without SpA and 10 from patients with active axial SpA (according to a rheumatologist’s opinion as well as according to the ASAS classification criteria for axial SpA (34)). MRIs of participants in the Pre-SpA cohort study were only considered positive when they were scored as positive at both time points. We quantified agreement between the first and second readings with Cohen’s kappa coefficient.
Statistical analysis
Clinical, biologic, and imaging features of SpA were reported descriptively. Data were complete except for imaging data missing for 1 first-degree relative. Symptoms of first-degree relatives were classified according to the ASAS classification criteria for axial SpA (34), the ASAS classification criteria for peripheral SpA (35), the European Spondylarthropathy Study Group (ESSG) preliminary criteria for the classification of SpA (36), the Amor criteria for SpA (37), the Classification of Psoriatic Arthritis (CASPAR) Study Group criteria for psoriatic arthritis (38), and the modified New York criteria for AS (31). A chi-square test was used to compare
THE PRE-SPA COHORT
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