OP0223 CLINICAL AND IMAGING OUTCOMES OF DIFFERENT PHENOTYPES OF AXIAL SPONDYLOARTHRITIS: 5-YEAR ANALYSIS OF THE DESIR COHORT
Authors: A. Sepriano, S. Ramiro, D. Van der Heijde, A. Moltó, C. Gaujoux-Viala, M. Dougados, R. Landewé
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> We have previously identified three phenotypes of axial spondyloarthritis (axSpA) by latent class analysis.[1] One phenotype, that we labelled as 'Axial', was characterized by HLA-B27 positivity plus typical abnormalities on axial imaging. The second included patients with inflammatory back pain (IBP) and peripheral features ('IBP+Peripheral') and the third had patients with risk factors for axSpA (HLA-B27 and family history) but a low likelihood of other SpA features ('At risk'). Prognostic information can help clinicians in managing axSpA. However, whether there are prognostic dissimilarities across these phenotypes of axSpA is yet unclear. <h3>Objectives:</h3> To compare the long-term outcomes of three phenotypes of axSpA. <h3>Methods:</h3> Patients with axSpA from the DESIR cohort were grouped according to the three previously identified phenotypes at baseline. Clinical data was collected at baseline, every 6 months up to 2 years and then yearly up to 5 years. Radiographs of the spine and sacroiliac joints (SIJ) and magnetic resonance imaging (MRI) of the spine and SIJ were obtained at baseline, 2 and 5 years. Each image was scored by three central readers. Clinical outcomes, measured in each visit, included disability (BASFI), mobility (BASMI) and quality of life (QoL; short form 36 physical (SF36 PCS) and mental (SF36 MCS) component scores). Imaging outcomes included inflammatory (SPARCC score) and structural lesions (number of fatty lesions) on MRI of the spine and SIJ and structural lesions on radiographs of spine (mSASSS) and SIJ (mNY grade). The association between phenotype membership at baseline, operationalized as a categorical variable with the 'Axial' class as reference, and each outcome over time was tested in multivariable GEE models. An interaction between class and treatment with bDMARDs at 1 year was tested, and if significant (p&lt;0.15) the effect of class on each outcome was tested separately in treated and untreated patients. <h3>Results:</h3> In total, 576 patients ('Axial': 110; 'IBP+Peripheral': 137; 'At risk': 329) were included. Patients from the 'Axial' class were more often male (80%) than those from the 'IBP+Peripheral' (43%) and 'At risk' (40%) classes. At baseline, inflammatory and structural lesions on axial imaging were more common in the 'Axial' than in the other classes (e.g., mean SPARCC on spine MRI: 7.6 vs 0.7-0.9; and mSASSS 0.9 vs 0.3 in both). Nonetheless, disability at baseline was lower in the 'Axial' class (mean BASFI: 2.7) than in 'IBP+Peripheral' (BASFI: 3.4) and 'At risk' class (BASFI: 2.9). Impairment in spinal mobility was limited in all classes and quality of life was similarly impaired across classes at baseline (SF36 PCS range: 37-41; SF36 MCS: 39-43). The multivariable analysis showed that the 'At risk' patients had worse disability and QoL than 'Axial' patients over time (Table 1). For instance, 'At risk' patients had on average 0.4 more points in BASFI over time than 'Axial' patients [β (95% CI): 0.4 (0.2; 0.7)]. Of note, the difference in BASFI between the 'At risk' and 'Axial' phenotypes was higher in patients receiving bDMARDs than in those not (β=0.6 vs 0.5, interaction p-value: 0.076), since BASFI improved more in 'Axial' (ΔBASFI: -1.3) than in 'At risk' (ΔBASFI: -0.9) treated patients. A similar interaction between class and bDMARDs was found for the SF-36 PCS but not for the other outcomes. There were no differences in disability, mobility and QoL between 'Axial' and 'IBP+Peripheral' patients. All imaging outcomes over time were worse in the 'Axial' phenotype than in the others (Table 2). <h3>Conclusion:</h3> Patients with 'axSpA at risk' show worse self-reported outcomes over time and are less likely to benefit from anti-inflammatory treatment than those with a classical axSpA phenotype. Rheumatologists might need to tailor treatment strategies according to the phenotype of axSpA and should be particularly vigilant in their indication of targeted DMARDs in patients without objective signs of inflammation. <h3>REFERENCES:</h3> [1] Sepriano et al. Ann Rheum Dis. 2020. <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> Alexandre Sepriano Abbvie, Lilly, Abbvie, Novartis, UCB, Sofia Ramiro AbbVie, Eli Lilly, Galapagos, Janssen, MSD, Novartis, Pfizer, UCB, Sanofi, Désirée van der Heijde AbbVie, Argenx, Bayer, BMS, Galapagos, Gilead, Glaxo-Smith-Kline, Janssen, Lilly, Novartis, Pfizer, Takeda, UCB Pharma and is Director of Imaging Rheumatology bv., Anna Moltó AbbVie, Biogen, BMS, Gilead, Galapagos, Janssen, Lilly, Novartis, MSD, Pfizer, UCB Pharma, Cécile Gaujoux-Viala AbbVie; Amgen; Biogen;Boehringer Ingelheim, Bristol-Myers Squibb; Celgene; Eli Lilly; Galapagos; Gilead Sciences, Inc.; Janssen; Medac; Merck-Serono; Mylan; Nordic Pharma; Novartis; Pfizer; Roche; Sandoz; Sanofi; and UCB Pharma, Maxime Dougados AbbVie, BMS, Galapagos, Janssen, Lilly, Novartis, Pfizer, UCB Pharma, Merck, Robert Landewé AbbVie, BMS, Celgene, Eli-Lilly, Galapagos, Gilead, Glaxo-Smith-Kline, Janssen, Merck, Novartis, Pfizer, Roche, UCB and is Director of Rheumatology Consultancy bv.