Ab0878 in What Extent Cervical and/or Lumbar Mobility Explain Function and Quality of Life in Patients With Axial Spondyloarthritis? Results From the Castro Registry

Background: Patients with longstanding axial spondyloarthritis (axSpA) may suffer from an impairment of spinal mobility, potentially affecting their function and quality of life. However, there is limited research objectively assessing whether reduced cervical and/or lumbar mobility contributes to functional and quality of life impairment and the magnitude of these associations. Objectives: a)To evaluate the extent to which spinal mobility (cervical and/or lumbar) explains function (BASFI) and quality of life (ASAS-HI) b)To identify individual movements independently associated with these outcomes (BASFI and ASAS-HI) Methods: This cross-sectional analysis is derived from the CASTRO registry (Cordoba Axial SpondyloArthritis Task force, Registry and Outcomes), encompassing adult patients diagnosed with axSpA and fulfilling the ASAS classification criteria. Both cervical and lumbar mobility (rotation, lateral flexion, anterior flexion, and extension) were evaluated using Inertial Sensors, which objectively measure the range of movement in Inertial Measurement Units (IMUs). A focused Principal Component Analysis (PCA) was used to assess correlations between BASFI and ASAS-HI with the cervical and lumbar movements. Then, univariate and multivariate linear regressions were conducted to quantify the variability of BASFI and ASAS-HI explained by cervical and lumbar mobility, using the determination coefficient R2. Finally, individual cervical and lumbar movements independently associated with BASFI and ASAS-HI were identified through multivariate linear regressions. Results: A total of 156 patients (70.5% male, mean age 48 years old) were analyzed, with 83.3% exhibiting radiographic sacroiliitis and a mean disease duration of 22.2 (12.9) years. The PCA (Figure 1A) showed a correlation between reduced cervical and lumbar movements and BASFI scores, being more pronounced with cervical rotation (r = -0.440) and cervical flexion (r = -0.410). Linear regressions demonstrated that 19.9% (R2=0.199) and 11.3% (R2=0.113) of BASFI score variability were explained by cervical and lumbar mobility, respectively. The individual movement independently associated with BASFI score was the reduction of cervical rotation (β -0.30 (95%IC -0.59 to -0.02)). For ASAS-HI, the PCA (Figure 1B) showed a correlation between diminished cervical and lumbar movements and ASAS-HI scores, being more pronounced with cervical rotation (r = -0.320) and lumbar rotation (r = -0.260). Multivariate linear regressions showed that 12% (R2=0.120) and 11.4% (R2=0.114) of the ASAS-HI variability were explained by the cervical and lumbar mobility, respectively. Individual movements independently associated with ASAS-HI score included the reduction of cervical rotation (β -0.05 (95%IC -0.09 to -0.00)), lumbar flexion (β 0.06 (95%IC 0.00 to 0.12)), lumbar rotation (β -0.09 (95%IC -0.13 to -0.03)) and lumbar extension (β 0.10 (95%IC 0.02 to 0.18)). Conclusion: This study showed that the reduction of cervical mobility, particularly cervical rotation, was independently associated with a worsening in function (BASFI) among patients with axSpA. While lumbar mobility also influenced function, its impact was comparatively less pronounced than that of cervical mobility. Conversely, the deterioration in quality of life (ASAS-HI) was similarly explained by impairments in both cervical and lumbar mobility. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests: Clementina López-Medina UCB, Abbvie, Janssen, Novartis, Lilly, UCB, Novartis, Abbvie and Lilly, UCB, Abbvie and Lilly, María Lourdes Ladehesa-Pineda Pfizer, María Ángeles Puche-Larrubia: None declared, María Carmen Ábalos-Aguilera: None declared, Desiree Ruíz-Vilchez: None declared, Ignacio Gómez-García: None declared, Cristina Gonzalez-Navas: None declared, Garrido Castro Juan Luis: None declared, Eduardo Collantes-Estevez Lilly, Novartis, Lilly, Lilly, Abbvie, UCB.