Differences between familial and sporadic early spondyloarthritis: results from the ESPERANZA cohort.

OBJECTIVES: To describe and evaluate clinical and imaging differences between patients with familial and sporadic early spondyloarthritis (SpA).

METHODS: This was a cross-sectional study analysing the baseline dataset from ESPERANZA, a national programme developed for the early identification of patients with SpA. Patients fulfilling SpA ASAS classification criteria were included. Familial SpA was defined according to the ASAS/ESSG criteria as the presence in first- or second-degree relatives of any of the following: ankylosing spondylitis, psoriasis, uveitis, reactive arthritis, and inflammatory bowel disease. Socio-demographic and disease characteristics, disease activity, metrology and laboratory and imaging data were compared by descriptive and bivariate statistics.

RESULTS: A total of 377 patients were included - 64% men, mean age 32, and mean disease duration 12 months. Out of these, 132 (35%) patients (101 axial and 31 peripheral SpA) were familial forms. In patients with axial SpA, statistically significant differences (p<0.05) were found between familial and sporadic forms regarding age at symptoms onset (29.4±9.2 vs. 31.5±10 years), HLA B27 positivity (83% vs. 71%), BASMI (1.2± 13 vs. 1.6 1.2) and sacroiliitis on magnetic resonance imaging (36% vs. 47%), respectively. In patients with peripheral SpA, there were no significant differences for any of the variables analysed.

CONCLUSIONS: Familial axial SpA presents symptoms at a younger age, is more frequently HLA-B27 positive and shows better spinal mobility than sporadic axial SpA; this latter presenting sacroiliitis on MRI more frequently than familial axial SpA. Apparently, no differences exist in the expression of familial or sporadic peripheral SpA.