Ab0879 Post-Partum Spondyloarthritis and Response to Anti-Tnfa: Results From a Single-Center Study and the French National Health Data System Database

Background: Female spondyloarthritis (SpA) has distinctive features compared with male SpA, and 18 to 28% of these SpAs occur in the post-partum period [1]. Post-partum is associated with musculoskeletal remodelling and IL-17 secreting cells activation, two key factors in the development of SpA [2]. We hypothesized that post-partum SpA might manifest as predominant enthesitic involvement and be less dependent on HLA-B27 and TNFa. Objectives: To investigate the characteristics of SpA occurring in the post-partum period and their response to anti-TNFa. Methods: We performed́ a case-control, retrospective, observational, monocentric study using Rouen University Hospital's data warehouse. Dates of delivery and symptom onset were available for 154 SpA patients. Characteristics were compared between our cases (SpA occurring in the post-partum period) and controls (SpA occurring remote from delivery). Next, data from the French National Health Data System (NHDS) database were cross-referenced with the national birth register to identify SpA that were reported in the post-partum period. Data from January 1, 2017 to January 1, 2021 were analysed. Results: We We identified 58 cases and 96 controls. Post-partum SpA were proportionally less associated with HLA-B27 (37.3% vs. 52.3%, p-value: 0.040), had more anterior chest wall pain (74.1% vs. 54.7%, p-value: 0.008) and psoriasis (37.9% vs. 16.8%, p-value: 0.006). They were just as likely as controls to have a biological inflammatory syndrome at the time of diagnosis, but less so at the time of introduction of the first bDMARD (22.2% vs. 48.1%, p-value: 0.003). Regarding sacro-iliac joints, there was less radiographic damage (4% vs. 18.6%, p-value: 0.009) and MRI sacro-iliitis (30.6% vs. 47.4%, p-value: 0.033) in post-partum SpA. Anti-TNFa retention rate in the post-partum group was 45.6% at 12 months, versus 71.2% in our controls (Odd ratio: 2.56 [95% CI: 1.34 - 4.95]). Multivariate survival analysis found a hazard ratio for bDMARD discontinuation 2.43 (95% CI: 1.62 - 3.65) within the first two years of treatment. In the NHDS, 423 patients were identified as post-partum SpA between 2017 and 2021 and they received 560 anti-TNFa. In these women, retention rate of anti-TNFa was low with 51% (95% CI: 0.47 – 0.55) of patients still taking anti-TNFa 6 months after the initiation and 30% (95% CI: 0.26 – 0.34) after 12 months. Conclusion: Our study highlighted a phenotype singular to post-partum SpA with more anterior chest wall pain, more psoriasis and less association with HLA-B27 and less MRI damage. While the non-radiographic SpA retention rate for anti-TNFa is 73% [3], the rates of 45.6% on the post-partum SpA from the retrospective cohort and 30% from the NHDS suggest a poorer response to these treatments. This poor retention rate of anti-TNFa was unchanged in the sub-population stratified by increased CRP or MRI sacroiliitis. REFERENCES: [1] Wallenius M, Skomsvoll JF, Irgens LM, et al. Postpartum onset of rheumatoid arthritis and other chronic arthritides: results from a patient register linked to a medical birth registry. Ann Rheum Dis. 2010;69:332–6. [2] Watad A, Bridgewood C, Russell T, et al. The Early Phases of Ankylosing Spondylitis: Emerging Insights From Clinical and Basic Science. Frontiers in Immunology. 2018;9. [3] Ørnbjerg LM, Brahe CH, Askling J, et al. Treatment response and drug retention rates in 24 195 biologic-naïve patients with axial spondyloarthritis initiating TNFi treatment: routine care data from 12 registries in the EuroSpA collaboration. Annals of the Rheumatic Diseases. 2019;78:1536–44. Acknowledgements: NIL. Disclosure of Interests: Baptiste de Maleprade: None declared, Elie Lacroix: None declared, Julien Grosjean: None declared, Olivier Vittecoq AbbVie, Bristol-Myers Squibb, Gilead, Lilly, Merck, Novartis, Pfizer, Roche- Chugai, Mylan and Sanofi, Novartis, Pfizer, Merck and Bristol-Myers Squibb, Thierry LEQUERRÉ AbbVie, Boehringer Ingelheim, BMS, Fresenius, Galapagos, Lilly, MEDAC, MSD, Nordic Pharma, Novartis, Pfizer, Roche – Chugai, UCB.