POS0953 PERIPHERAL ARTHRITIS AND HIGHER DISEASE ACTIVITY LEAD TO MORE FUNCTIONAL IMPAIRMENT IN AXIAL SPONDYLOARTHRITIS: LONGITUDINAL ANALYSIS FROM ESPAXIA

Background:Preserving functional ability is among the main goals when treating patients with axSpA. Higher disease activity, reduced axial mobility, and increase spinal radiographic damage, and smoking status have shown to be longitudinally associated with functional worsening. The presence of peripheral arthritis has also been associated with worse functional ability during follow-up, though not in a true longitudinal analysis.Objectives:To investigate whether peripheral arthritis together with disease activity independently contribute to functional impairment over time in patients with axSpA and to evaluate if there are contextual factors modifying this relationship.Methods:Patients with axSpA from the ESPAXIA cohort were followed-up annually over 7 years. Physical function was assessed by the self-reported questionnaire BASFI, disease activity by ASDAS and peripheral arthritis was also recorded. The association between BASFI (outcome), peripheral arthritis and ASDAS (main variables of interest) over time was tested in generalized estimating equations (GEE) models. Models were autoregressive, i.e. adjusted for BASFI 1 year earlier, to allow for a truly longitudinal interpretation. Interactions between each of ASDAS and peripheral arthritis with contextual factors were tested.Results:185 patients were included (77 % male, mean age 42 (SD 13), mean disease duration 9.4 (SD 9.6) years. Mean baseline ASDAS was 2.3 (1.4), mean BASFI 3.9 (2.7) and 17% presented peripheral arthritis during the first visit. After a mean of 3.7 (2.4) years of follow-up, ASDAS and peripheral arthritis independently contributed to explaining BASFI changes over time. Contextual factors did not modify either of the relationships. A true longitudinal relation was proved with the autoregressive GEE model, showing that, adjusted for age, gender, spinal mobility and use of NSAIDs, an increase of one ASDAS unit led to a BASFI 0.48 units higher (ß 0.48 [95% CI 0.39-0.57]), and the presence of peripheral arthritis, to a BASFI 0.44 units higher (ß 0.44 [0.08-0.8]) (Table 1). A gradient was found for ASDAS disease activity states: ASDAS low disease activity (vs ASDAS inactive disease) with an increase in BASFI of 0.67 (0.35-0.98) units compared to ASDAS very high disease activity (vs ASDAS inactive disease) with a BASFI increase of 2.30 (1.90-2.72) units. (Figure 1) No interaction was found between peripheral arthritis and disease activity on BASFI, and similarly, no interactions were found between either ASDAS or peripheral arthritis with age, gender, educational level, smoking status, job type or comorbidities on BASFI.Table 1.Factors longitudinally associated with BASFIAssessmentModel with ASDAS continuousß (95% CI)n=179Model with ASDAS categoricalß (95% CI)n=179Previous BASFI (0-10)0.47 (0.41 to 0.52) †0.44 (0.39 to 0.50)†Age (years)0.007 (-0.005 to 0.02)0.008 (-0.004 to 0.02)Male gender (vs female gender)-0.42 (-0.79 to -0.06) †-0.38 (-0.74 to -0.02)†Peripheral arthritis0.44 (0.08 to 0.80) †0.38 (0.03 to 0.74) †ASDAS-CRP0.48 (0.39 to 0.57) †-ASDAS-CRP categoricalModerate vs inactive disease-0.67 (0.35 to 0.98) †High vs inactive disease-1.70 (1.37 to 2.02) †Very high vs inactive disease-2.30 (1.90 to 2.72) †BASMI (0-10)0.32 (0.24 to 0.41) †0.32 (0.23 to 0.40) †NSAIDs (%)0.38 (0.09 to 0.66) †0.37 (0.09 to 0.64) †† Significant at p<0.05.Figure 1.Longitudinal relationship between ASDAS and BASFIConclusion:Peripheral arthritis and higher disease activity independently lead to more functional impairment in axSpA. Contextual factors do not modify these relationships.Disclosure of Interests:Dafne Capelusnik Speakers bureau: BMS, Grant/research support from: Pfizer, Sofia Ramiro Speakers bureau: Lilly, MSD, Novartis, UCB, Consultant of: AbbVie, Lilly, MSD, Novartis, UCB, Sanofi, Grant/research support from: MSD, Emilce Edith Schneeberger Speakers bureau: Abbvie, BMS, Janssen, Eli Lilly, Boehringer Ingelheim, Pfizer, Grant/research support from: Pfizer, Gustavo Citera Speakers bureau: Abbvie, BMS, Janssen, Pfizer, Grant/research support from: Pfizer, BMS, Janssen