POS0005 A TWO-YEAR COMPARISON OF BACK PAIN AND MORNING STIFFNESS BETWEEN AXIAL SPONDYLOARTHRITIS AND CHRONIC BACK PAIN PATIENTS IN THE SPONDYLOARTHRITIS CAUGHT EARLY (SPACE) COHORT
Authors: A. Bento Da Silva, S. Ramiro, M. Van Lunteren, M. L. Marques, C. Fongen, M. G. H. Van de Sande, R. Ramonda, S. Exarchou, D. Van der Heijde, F. A. Van Gaalen
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Treatment of axial spondyloarthritis (axSpA) has been shown to improve symptoms of the disease such as back pain (BP) and morning stiffness (MS). As a result, early referral of patients suspected of having axSpA is strongly recommended. However, little data is available on the disease course of early axSpA in clinical practice, particularly in comparison to referred patients who have chronic BP (CBP) but not axSpA. <h3>Objectives:</h3> To compare spinal symptoms at baseline and after 2 years (2y) in early axSpA and non-axSpA CBP patients. <h3>Methods:</h3> The population consisted of adults (≥16 years) with CBP lasting ≥3 months and ≤2y and starting &lt;45 years of age, included in the SPondyloArthritis Caught Early (SPACE) cohort. Patients had a diagnosis of axSpA or non-axSpA given by the treating rheumatologist at 2y, with a high level of confidence.[1] At baseline and 2y, patients reported the intensity of BP (overall and at night) and MS in the previous week on a numeric rating scale (NRS) ranging from 0 (no symptoms) to 10 (unbearable symptoms). For MS duration, a NRS ranging from 0 (0 hours) to 10 (≥2 hours) was used. For the assessment of each outcome, only patients with data available at both timepoints were included. Paired t-test was used to compare baseline and 2y results within groups. For the comparison between groups (axSpA vs non-axSpA), linear regression models with the 2y outcome were built, adjusting for the baseline value of the respective outcome (equivalent to modelling a 2y change in the outcome), age, gender and use of nonsteroidal anti-inflammatory drugs. <h3>Results:</h3> A total of 434 patients (303 axSpA; 131 non-axSpA) had undergone baseline and 2y visits. Data was available at both timepoints on ≥1 of the assessed outcomes in 267 axSpA and 110 non-axSpA patients. AxSpA (vs non-axSpA) patients were more frequently male (52% vs 25%) and had more SpA features (mean [SD]: 5 [2] vs 3 [1]). Age (mean [SD]: 29 [8] vs 31 [8] years) and symptom duration (mean [SD]: 13 [7] vs 13 [7] months) were similar between groups. Overall, at baseline, higher levels of spinal symptoms were observed in non-axSpA (vs axSpA) patients (<b>Figure</b> 1). After 2y, BP and MS significantly improved in both groups (mean [SD] improvement axSpA vs non-axSpA: overall BP 1.4 [2.5] vs 1.6 [2.4]; BP at night 1.4 [2.9] vs 1.0 [2.7]; MS intensity 1.6 [3.2] vs 1.9 [2.9]; MS duration 1.2 [3.0] vs 1.5 [3.1]; all p≤0.001). However, substantial symptoms persisted at 2y, mainly in non-axSpA patients. In adjusted multivariable linear regression analysis, axSpA (vs non-axSpA) was an independent predictor of lower BP at night at 2y (Figure 2, β [95% CI] -0.85 [-1.47; -0.23]; p=0.007). No significant differences were found for overall BP, MS intensity or MS duration. <h3>Conclusion:</h3> Overall, non-axSpA (vs axSpA) patients experience worse spinal symptoms. After 2 years, although BP and MS significantly improve in both groups, substantial symptoms persist, mainly in non-axSpA patients. AxSpA is an independent predictor of a larger improvement in BP at night, but not in overall BP or MS. <h3>REFERENCES:</h3> [1] Marques ML <i>et al. Ann Rheum Dis 2024</i> (epub ahead of print). <h3>Acknowledgements:</h3> The authors would like to acknowledge the Assessment of Spondyloarthritis International Society (ASAS) for having supported Ana Bento da Silva research fellowship. <h3>Disclosure of Interests:</h3> Ana Bento da Silva: None declared, Sofia Ramiro AbbVie, Eli Lilly, Janssen, MSD, Novartis, Pfizer, UCB, Sanofi, AbbVie, Galapagos, MSD, Novartis, Pfizer, UCB, Miranda van Lunteren: None declared, Mary Lucy Marques: None declared, Camilla Fongen: None declared, Marleen G.H. van de Sande Janssen, Novartis, UCB, Beneke, Janssen, Novartis, Abbvie, UCB, Janssen, Novartis, UCB, Roberta Ramonda: None declared, Sofia Exarchou Amgen, Janssen, Novartis, UCB Pharma, Désirée van der Heijde Abbvie, ArgenX, BMS, Galapagos, GSK, Jansen, Lilly, Novartis, Pfizer, Takeda, UCB Pharma. Director Imaging Rheumatology bv., F. A. van Gaalen Novartis, BMS, AbbVie, Galapagos, Janssen, Lily, UCB, Pfizer, Stichting ASAS, Novartis, UCB.