POS0242 ROLE OF HLA-B27 CARRIERSHIP IN PERIPHERAL SPONDYLOARTHRITIS: DATA FROM ASAS PERSPA STUDY
Authors: M. Arévalo, C. López-Medina, V. Navarro-Compán, M. Moreno, M. Llop Vilaltella, J. Calvet, J. Gratacos-Masmitja, M. Dougados
Journal: Annals of the Rheumatic Diseases (2021)

Background: HLA-B27 is well known for its role in conferring susceptibility to spondyloarthritis (SpA), and several studies evaluating its association to axial SpA phenotype have been published. However, there is few evidence about its influence in patients affected with peripheral SpA (pSpA). In this sense we find ASAS perSpA registry suitable for this purpose. Objectives: To identify phenotypical differences in pSpA patients regarding HLA-B27 status. Methods: Data from all patients fulfilling ASAS pSpA criteria with HLA-B27-testing result available included in the ASAS perSpA study were used for this analysis. Socio-demographic and disease characteristics were collected. A descriptive and comparative analysis was performed between HLA-B27 positive and negative patients, using a simple logistic regression for all variables to assess their association to HLA-B27 positivity. Results were considered significant when p &lt;0.05. A multivariate model was also performed including significant (p&lt;0.1) and the most relevant clinical variables in agreement of medical criteria. Results: Among the 4465 patients included in the registry, 555 fulfilled ASAS pSpA criteria and of them 286 had the HLA-B27 typing available. HLA-B27 was positive in 118 (41.3%) and negative in 168 (58.7%). Results are listed in Table 1. No differences were observed for gender distribution (males 55.1% in HLA-B27 positive vs 49.4% in HLA-B27 negatives). HLA-B27 positive patients were significantly younger, presented a younger disease onset, had significantly higher prior axial involvement, radiographic sacroiliitis and higher root joint involvement. On the other hand, HLA-B27 negative patients showed longer disease duration with a higher diagnosis delay. Around half of the patients in both groups showed a mono or oligoarticular pattern without differences regarding HLA-B27 status, however, psoriatic arthritis (PsA) and peripheral joint damage was significantly higher in HLA-B27 negative patients. Also psoriasis and inflammatory bowel disease (IBD) were more frequent in HLA-B27 negative patients compared to positive ones, and acute anterior uveitis (AAU) was significantly more frequent in HLA-B27 positive patients without differences in number of AAU episodes lifelong. Finally, obesity and concomitant fibromyalgia were both more common in HLA-B27 negatives. No significant differences were found for the rest of variables evaluated. Table 1. HLA-B27+ (N = 118) HLA-B27- (N = 168) N/mean %/SD N/mean %/SD p Obesity (BMI &gt;30) 14 11,9% 44 26,3% 0,003 Men 65 55,1% 83 49,4% 0,344 Family history 44 37,3% 52 31,0% 0,265 Axial involvement 62 52,5% 42 25,0% &lt;0.001 Radiographic sacroilitis 30 28,3% 25 16,8% 0,029 Psoriathic arthritis 23 19,5% 112 72,6% &lt;0.001 Reactive arthritis 5 4,2% 3 1,8% 0,229 IBD arthritis 1 0,9% 8 4,8% 0,098 Mono/oligoarticular pattern 59 54,6% 76 51,0% 0,566 Root joint involvement 52 44,1% 54 32,1% 0,04 Tarsitis 22 18,6% 16 9,5% 0,028 Enthesitis 62 52,5% 69 41,1% 0,056 Dactylitis 31 26,3% 51 30,4% 0,452 Peripheral structural damage 9 7,6% 41 24,4% &lt;0.001 Psoriasis 21 17,8% 125 74,4% &lt;0.001 AAU 21 17,8% 7 4,2% &lt;0.001 IBD 2 1,7% 13 7,7% 0,039 Fibromyalgia 15 13,2% 43 26,7% 0,008 Age (y) 42,7 14,8 52,2 13,4 &lt;0.001 Age onset (y) 33,9 13,7 38,3 14,5 0,013 Dx delay (m) 4,7 8,2 7,7 9,8 0,009 Disease duration (y) 9,06 10,2 14,2 11,6 &lt;0.001 BASDAI 3,9 2,2 4,4 2,4 0,06 CRP 16,9 25,1 12 27,3 0,148 ASDAS-CRP 2,7 1,2 2,7 1,1 0,876 AAU number of episodes 6,8 8,4 2,1 1,7 0,265 In the multivariate analysis, age at disease onset (OR 0.96, CI95% 0.94-0.98), disease duration (OR 0.96, CI95% 0.92-0.99), PsA (OR 0.28, CI95% 0.09-0.85), presence of psoriasis (OR 0.22, CI95% 0.07-0.64), IBD related arthritis (OR 0.03, CI95% 0.01-0.19), AAU (OR 3.63, CI95% 1.22-11.9) and tarsitis (OR 2.61, CI95% 1.01-6.98) were the most important variables independently associated to HLA-B27 status. Conclusion: Presence of HLA-B27 in pSpA patients was associated to a higher axial and root joint involvement, an earlier disease onset and presence of AAU, but not to PsA, psoriasis and IBD that were higher in HLA-B27 negative patients. Disclosure of Interests: Marta Arévalo Speakers bureau: Abbvie, Nordic Pharma, Clementina López-Medina: None declared, Victoria Navarro-Compán: None declared, Mireia Moreno Speakers bureau: Abbvie, Novartis, UCB, Bristol and AMGEN, María LLop Vilaltella Speakers bureau: Novartis, Joan Calvet: None declared, Jordi Gratacos-Masmitja Speakers bureau: During the course of the year, I have received funding for courses and conferences or as an advisor and speaker from MSD, Pfizer, AbbVie, Janssen Cilag, Novartis, Celgene, and Lilly., Maxime Dougados: None declared