▪Background: Hemophilic arthropathy is a common and debilitating condition in patients with severe hemophilia A, and often leads to significant impact on the patient’s quality of life (QoL). A better understanding of the nature and extent of association between joint damage and QoL is an essential step towards evaluation of treatment effect. However, few studies have focused on the association between joint damage and QoL. This study aims to fill in the gap by examining the extent to which joint damage is correlated with QoL among patients with severe hemophilia A. The findings will enable a better assessment of treatment benefits of current and new therapies.Methods: Data from a phase III randomized, controlled, parallel trial (SPINART) was analyzed. The duration of the trial was 3 years. The analytical sample consisted of 84 patients with severe hemophilia A. Patients from both treatment arms (prophylaxis arm n = 42; on-demand arm n = 42) were pooled for this analysis. Joint damage was measured using 1) Colorado Adult Joint Assessment Scale (CAJAS) total score at baseline, year 1, 2, and 3;and 2) Magnetic Resonance Imaging (MRI) total score at baseline and year 3. In both measures, higher scores indicated worse joint damage. QoL was measured using Haemophilia Quality of Life (Haemo-QoL-A for adults) and EQ-5D at baseline, year 1, 2 and 3. Pearson correlation coefficients and the corresponding p values were calculated for each time point to assess the associations between the joint damage measures (CAJAS and MRI) and the QoL measures, including Haemo-QoL-A (total score, Physical Functioning and Role Functioning domain scores), and EQ-5D (Index score and Visual Analogue Scale (VAS) score).Results: Patients in this study had a mean age of 30.6 (SD 9.2) years and 90.5 % were White. CAJAS was negatively correlated with both of the EQ-5D scores and all three Haemo-QoL-A scores (Table 1), indicating the association between greater joint damage and worse QoL. The correlation coefficient (r) ranged from -0.34 to -0.56, and was statistically significant at all the time points assessed (all p < 0.05). The strongest correlations were found between CAJAS and EQ-5D VAS score (range of r = -0.45 to -0.48), and between CAJAS and Haemo-QoL Physical Functioning domain score (range of r = -0.45 to -0.56). The MRI total score was also negatively correlated with both QoL measures, with r ranging from -0.07 to -0.49, though not all coefficients were statistically significant. The strongest correlations were found between MRI and EQ-5D VAS, and between MRI and the Physical Functioning domain score at baseline and year 3.Conclusions: Greater joint damage is significantly correlated with lower QoL among patients with severe hemophilia A. In particular, CAJAS and MRI scores are most strongly correlated with both EQ-5D VAS and the Haemo-QoL-A (Total and Physical Functioning scores). These findings underscore the direct impact of joint damage on the physical functioning in particular and overall quality of life among patients with severe hemophilia A. [Display omitted] DisclosuresPocoski:Bayer Healthcare Pharmaceuticals: Employment. Lin:Bayer Healthcare Pharmaceuticals: Consultancy, Research Funding. Hong:Bayer Healthcare Pharmaceuticals: Employment. Kelkar:Bayer Healthcare Pharmaceuticals: Consultancy, Research Funding. Du:Bayer Healthcare Pharmaceuticals: Consultancy, Research Funding. Humphries:Bayer Healthcare Pharmaceuticals: Employment. Xie:Bayer Healthcare Pharmaceuticals: Consultancy, Research Funding.