<h3>Background:</h3> Societal utilities represent population values for health states and are important to assess the health economic impact of rheumatic diseases, such as Spondyloarthritis (SpA). Utilities can be derived from disease specific or generic patient reported health instruments measuring health related functioning and quality of life (HR-QoL). It is suggested that generic utilities tend to be insensitive to condition-specific changes, particularly in chronic conditions [1]. Recently an algorithm was computed to convert the ASAS HI scores into utility values from a general population perspective [2]. The utility estimation of the ASAS HI (U-ASAS HI) has yet not been fully validated. <h3>Objectives:</h3> To compare the U-ASAS HI to other generic and SpA specific outcomes and to understand the relative contribution of SpA health outcomes and personal as well as country level factors to U-ASA HI. <h3>Methods:</h3> An ancillary analysis of the ASAS HI international validation study, an observational study from 23 participating countries. Utilities aim to express the HR-QoL on a scale of 0 to 1, where 0 represents death and 1 signifies perfect health. Patients with SpA who completed the self-reported ASAS-HI, EQ5D-5L, and SF36 were selected for this analysis. Country-specific economic values from the World Bank (e.g. Gross Domestic Product) and the United Nations Development Programme (e.g. Human Development Index [HDI]) were included. Instrument specific algorithms were used to calculated generic and SpA specific health utilities from a general population perspective [2]. Normality was assessed using the Shapiro-Wilk test. Bivariate statistics were performed using Student's t-test and ANOVA tests, and correlation analyses between U-ASAS HI and other health outcomes were tested using Pearson's or Spearman's coefficient according to distribution. Next, multiple linear regression analysis was performed to evaluate the predictors of the U-ASAS HI. <h3>Results:</h3> 1425/1548 patients with complete data were included. The mean age was 41.6 (SD: 13.5), and the mean symptom duration was 14.4 (SD: 11.3) years. 65.1% were male, 77.5% were HLA B27 positive, 82.7% had axial SpA, and 17.3% had peripheral SpA. EQ-5D mean was 0.68 (SD: 0.22), SF-36 PSC mean was 47.18 (SD 11.38), SF-36 MSC mean was 39.31 (SD: 10.48), ASAS-HI mean was 6.58 (SD: 4.31). The U-ASAS HI was 0.42 (SD: 0.29). Univariate correlations revealed an inverse moderate-to-large correlation for BASFI, BASDAI, and ASDAS (Pearson r= -0.683, -0.700, -0.617; p&lt;0.001) and a positive moderate-to-large correlation for EQ-5D, SF-36 PSC, and SF-36 MSC (Pearson r= 0.691, 0.602, 0.705; p&lt;0.001) (Figure 1). In the multivariate linear regression analysis (Figure 2), the U-ASAS HI values were higher (better) in patients with a high educational level and higher HDI (p&lt;0.001). Lower (worse) values were in patients with higher ASDAS (p&lt;0.001), BASFI (p&lt;0.001), BASDAI q5 (p&lt;0.001), and in males (p=0.006). Interestingly, the U-ASAS HI was also lower in the presence of anxiety or depression (EQ-5D q5, p&lt;0.001) and a higher Rheumatic Disease Comorbidity Index (p=0.022). The adjusted model yielded an R-squared value of 0.594. <h3>Conclusion:</h3> Our study demonstrated the significant impact of personal- and country-level variables on health utilities. Notably, higher educational levels and the HDI correlated with better U-ASAS HI, while factors such as disease activity, decreased functionality, and pain contributed worsened utility. Gender differences were observed, and the presence of anxiety or depression further diminishes U-ASAS HI. This comprehensive analysis sheds light on the multifaceted determinants of valuation of health states in SpA, providing valuable insights on individual and country socioeconomic characteristics. <h3>REFERENCES:</h3> [1] Sawhney TG, et al. doi: 10.36469/001c.83387. [2] Essers I, et al. doi: 10.1136/rmdopen-2018-000872. <h3>Acknowledgements:</h3> The Assessment of Spondyloarthritis international Society (ASAS) supported Omar-Javier Calixto by a research fellowship grant. <h3>Disclosure of Interests:</h3> Omar-Javier Calixto Consultant of Janssen, Uta Kiltz Consultant of: AbbVie, Amgen, Biogen, Chugai, Eli Lilly, Gilead, GSK, Grünenthal, Hexal, Janssen, MSD, Novartis, Pfizer, Roche, UCB, Grant/research support from: AbbVie, Amgen, Biogen, Chugai, Eli Lilly, Gilead, GSK, Grünenthal, Hexal, Janssen, MSD, Novartis, Pfizer, Roche, UCB, Wilson Bautista-Molano Consultant of: Abbvie, Eli Lilly, Janssen, and Novartis, Annelies Boonen Honoraria for lectures or consulting fees from Pfizer, Novartis, UCB, Abbvie and Galapagos; all to her department, Received research grants from Abbvie, Essers Ivette: None declared, Xenofon Baraliakos Consultant of: AbbVie, Chugai, Eli Lilly, Galapagos, Janssen, MSD, Novartis, Pfizer, Roche, and UCB, Grant/research support from: AbbVie, MSD, and Novartis.