THU0231 Do degree of family relationship and ethnicity impact the association between a positive family history for spondyloarthritis and presence of hla-b27? results from the worldwide asas cohort
Authors: M. van Lunteren, A. Sepriano, R. Landewé, J. Sieper, M. Rudwaleit, D. van der Heijde, F.A. van Gaalen
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> The ASAS definition of a positive family history (PFH) of spondyloarthritis (SpA) consists of the following diseases in first (FDR)- or second-degree relatives (SDR): ankylosing spondylitis (AS), acute anterior uveitis (AAU), reactive arthritis (ReA), inflammatory bowel disease (IBD), and psoriasis. In two European cohorts (SPACE and DESIR) a PFH of AS and AAU, but not a PFH of ReA, IBD, and psoriasis, were associated with HLA-B27 carriership in patients suspected of axSpA<sup>1</sup>. However, it is unknown what the role of the degree of family relationship or ethnicity is. <h3>Objectives</h3> To investigate the impact of the degree of family relationship and ethnicity on the association between the current ASAS definition of a PFH and the presence of HLA-B27 in an international cohort of patients suspected of axSpA. <h3>Methods</h3> Baseline data from patients suspected of axSpA in the worldwide ASAS cohort were analysed. Univariable analyses were performed. Each disease (AS, AAU, psoriasis, IBD, ReA) in a PFH according to ASAS expert opinion was a determinant in separate models with HLA-B27 carriership as outcome. Analyses were stratified for FDR, SDR, and self-reported ethnicities (white, Asian, and other). Analyses were repeated in multivariable models. <h3>Results</h3> In total, 594 patients suspected of axSpA were analysed. Patients had a mean age (SD) of 33.7 (11.7) years, 46% were male, had a mean symptom duration of 7.1 (9.0) years, had 3.5 (2.2) SpA features including HLA-B27 and imaging, 52% were HLA-B27 positive, 20% had sacroiliitis according to the mNY criteria, and 32% had active inflammation on MRI-SI. Sixty-two percent of the patients were diagnosed as axSpA and of these diagnosed patients 83% fulfilled the ASAS axSpA criteria. A PFH was reported by 23% of the patients; a PFH of AS was the most (15%) and PFH of AAU (1%) the least often reported family history among all patients. Any PFH was associated with HLA-B27 carriership in patients with a PFH in FDR, whites, and Asians but not in SDR. A PFH of AS was positively associated with HLA-B27 carriership in all subgroups (<b>table 1</b>). A PFH of AAU, ReA, IBD, or psoriasis was never positively associated with HLA-B27 carriership. In the multivariate analysis, similar results were found. <h3>Conclusions</h3> In the international ASAS cohort, a PFH of AS, but not of AAU, ReA, IBD, or psoriasis, was associated with HLA-B27 carriership in both first- and second-degree of family members and self-reported white and Asian ethnicity in patients suspected of axSpA. These data, in combination with data from two European cohorts, show that a PFH of AS and possibly also a PFH of AAU could be valuable in the general practice or other low SpA prevalence settings for identifying patients who are HLA-B27 positive and therefore have an increased risk of axSpA. <h3>Reference</h3> [1] Ez-Zaitouni, et al. AR&amp;T2017;19(1):118. <h3>Disclosure of Interest</h3> None declared