Pos0506 the Longitudinal Association Between Disease Activity, Function and Health-Related Quality of Life in Axial Spondyloarthritis: Results From the Desir Cohort

Background: Health related quality of life (HRQoL) in axial spondyloarthritis (axSpA) is a broad outcome, that is thought to depend on disease-related factors as well as contextual factors. Previously, a hierarchical model was proposed where HRQoL is the overarching outcome, with all other outcomes contributing to it [1]. This model was initially developed cross-sectionally mainly in radiographic (r-axSpA); then partially validated longitudinally, but it has yet to been demonstrated whether HRQoL is indeed dependent on disease activity and function. Objectives: To investigate the longitudinal relationship between disease activity and function (independent variables) and HRQoL (dependent variable) in patients with axSpA, during a 10-year follow-up. Methods: AxSpA patients (symptom duration <3 years) enrolled in the DESIR cohort, were included. Outcomes were collected at baseline, every 6 months for the first 2 years, and yearly up to 10 years. Disease activity was assessed by ASDAS, physical function by BASFI, and HRQoL by 3 different questionnaires: SF36-MCS, SF36-PCS and ASQoL (each considered separately). The presence of axSpA features, personal and environmental factors, and therapy were collected at baseline (sex, age, HLA-B27 positivity, MRI or radiographic sacroiliitis) or over the whole follow-up (psoriasis, IBD, uveitis, enthesitis, dactylitis, peripheral arthritis, BMI, smoking, blue collar job, education, marital status, parental status, use of NSAIDs or bDMARDs, comorbidities): these variables were tested as potential confounders or effect modifiers of the relationship between ASDAS and BASFI, on one side, and HRQoL, on the other. Generalised estimating equations (GEE) models having SF36-MCS, SF36-PCS or ASQoL as outcomes, each in a separate model, and ASDAS and BASFI as main independent variables were built, first with univariable analysis followed by multivariable. Covariates that were considered, according to clinical judgment, to be important confounders (sex, age, therapy) were included by default. The final multivariable models were conducted both as simple GEE models, and as autoregressive models (i.e. corrected for the HRQoL outcome at the previous time point) in order to allow for the interpretation of a longitudinal relationship. Results were expressed as beta coefficient (Beta) and 95% confidence interval (95%CI). Results: 663 axSpA patients were included, 306 (46%) males, mean age 33.5 (8.6) years, mean disease duration 1.5 (0.9) years, 141 (22%) having r-axSpA. ASDAS and BASFI were strongly and significantly associated to SF36-MCS (Beta -2.43 [95%CI -2.84, -2.04] and 1.23 [-1.43, -1.03] respectively), SF36-PCS (-3.07 [95%CI-3.32, -2.83] and -2.24 [-2.37, -2.11]) and ASQoL (1.35 [95%CI 1.23, 1.48] and 1.16 [1.09, 1.22]) in the simple models that included only the two main independent variables. The results were confirmed in the autoregressive models including only the two main independent variables with SF36-MCS (-2.09 [95%CI -2.53, -1.65] and -1.21 [-1.43, -0.99]) SF36-PCS (-3.07 [95%CI-3.32, -2.83] and -2.24 [-2.37, -2.11]) and ASQoL (1.35 [95%CI 1.23, 1.48] and 1.16 [1.09, 1.22]) as outcome Notably, the effect size for ASDAS and BASFI varied only modestly when corrected for all relevant confounders (Table 1). Conclusion: A longitudinal relationship between disease activity and function and HRQoL has been demonstrated, even when correcting for the main contextual factors, confirming that HRQoL can be interpreted as an overarching outcome in axSpA REFERENCES: [1] Machado P, et al. Ann Rheum Dis. 2011;70:1758-64. Acknowledgements: The DESIR cohort is conducted as a programme hospitalier de recherche clinique (PHRC) with Assistance Publique–Hôpitaux de Paris as the sponsor. This cohort has also been supported via unrestricted grants from Pfizer France and the French society of Rheumatology. Disclosure of Interests: Augusta Ortolan Janssen, UCB Pharma, Novartis, Abbvie, Désirée van der Heijde AbbVie, Argenx, BMS, Galapagos, GlaxoSmithKline, Janssen, Lilly, Novartis, Pfizer, Takeda, UCB Pharma, AbbVie, Argenx, BMS, Galapagos, GlaxoSmithKline, Janssen, Lilly, Novartis, Pfizer, Takeda, UCB Pharma, Laure Gossec AbbVie, Amgen, BMS, Celltrion, Janssen, Lilly, MSD, Novartis, Pfizer, Sandoz, UCB Pharma, AbbVie, Biogen, Lilly, Novartis, UCB Pharma, Sofia Ramiro AbbVie, Eli Lilly, Galapagos, Janssen, MSD, Novartis, Pfizer, UCB, Sanofi, AbbVie, Eli Lilly, Galapagos, Janssen, MSD, Novartis, Pfizer, UCB, Sanofi.