Introduction Patient perception and perspective have become relevant in individualised therapy planning in MDS. Thus, integration of patient-reported outcomes (PRO), including health-related quality of life (HRQoL), in studies and in clinical practice is essential. We demonstrated recently pronounced impairments in HRQoL in patients with MDS (Stauder et al., Leukemia 2018). However, longitudinal data on aspects of HRQoL in MDS are rare.Objectives 1. To describe longitudinal changes of HRQoL in MDS and 2. To compare the time course in different patient subgroups to define patients at high risk of deterioration of HRQoL.Methods The EUMDS Registry is a prospective, non-interventional longitudinal study, enrolling newly diagnosed patients with IPSS low or intermediate-1 MDS from 143 haematology centres in 17 European countries and Israel. HRQOL was assessed by EQ-5D questionnaire. Patients were selected, if they fully completed the EQ-5D score (five dimensions and VAS) at baseline and at 6 and 12 months, resulting in a total of 743 subjects at 86 centres in 15 countries. Differences in response for the five EQ-5D dimensions between patients subgroups were evaluated using chi-squareMcNemar tests. For EQ-VAS, the mean score with standard deviation was calculated. Wilcoxon's signed ranks tests were conducted to identify changes over time between HRQOL values at baseline and at 6, 12 months.Results•Moderate/severe impairments at initial diagnosis were observed in the dimensions mobility (39.4%), self-care (10.2%), usual activities (32.6%), pain discomfort (46.6%) and anxiety/depression (36.7%).•As compared with baseline a pronounced increase in moderate/severe problems was observed at 12 months in the dimensions self-care (10.2% (baseline) vs 15.5% (12 mo); p=0.003) and in usual activities (32.6% vs 40.6%; p=0.001). In contrast, self-reported mobility, pain and anxiety/depression did not change significantly. Decrease in VAS over time revealed a trend toward significance (75 vs. 70; p=0.056).•More pronounced impairment of HRQOL was most significantly observed in patients of advanced age: 60-75 yrs in self-care 8.3% vs 14.3% (p=0.016) and in usual activities 28% vs 35.7% (p=0.032); in persons 75+ years in self-care 14.2% vs 19.8% (p=0.058) and in usual activities 48.7% vs 50.3% (p=0.003). Similarly, VAS significantly decreased in the latter group from 70 to 66 (p=0.038).•Increases in impairments were most prominent in male patients in self-care (9.7 vs 16.7%; p=0.002) and in usual activities (29.4 vs 38.7%; p=0.003), whereas in women HRQoL at the different time points was not significantly different.•Pronounced decreases in HRQoL aspects was observed in anemic patients (Hb-levels <10g/dl) at initial diagnosis: mobility 47.4 vs 55.2% (p=0.06), self-care 13.5 vs 21.1% (p=0.015), usual activities 41.3 vs 52.7% (p=0.006), pain/discomfort 43.3 vs 55.6% (p=0.058) and VAS (70 vs 68; p=0.051). A reduction in HRQoL was observed even in patients with a Hb-level ≥10 g/dl in the dimension self-care (7.9 vs 12.1%; p=0.042).•Pronounced decreases in problems in HRQoL were observed in anemic patients (Hb<10 g/dL) who received transfusions in self-care (18.1% vs 25.6%; p=0.029), in usual activities (43.6% vs 61.5%; p=0.038), and in VAS (67.3 vs 61.9; p=0.003).•Transfusion dependent patients were at high risk to develop impairments in VAS (70 vs 64; p=0.006) and in most dimensions of EQ-5D (mobility 50.2 vs 62%, p=0.017), self-care (8.8 vs 11.5%, p=0.017), usual activities (41.6 vs 62.9%, p=0.01) and pain/discomfort (48.3 vs 58.5%, p=0.038).Conclusions Low-risk MDS patients report relevant restrictions in distinct dimensions at initial diagnosis. A relevant drop in HRQoL is observed at 12 months particularly in self-care and in usual activities. Patients of advanced age, males and those with initial low Hb-levels most frequently reported declines in HRQoL. Transfusion-need represents a relevant predictor of deterioration of HRQoL. These analyses form the basis to identify vulnerable patients and to tailor individualized interventions and treatment approaches. Analyses are planned to unravel the role of intervention therapies on observed changes in HRQoL. DisclosuresStauder:Teva: Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees. Fenaux:Celgene: Honoraria, Research Funding; Jazz: Honoraria, Research Funding; Roche: Honoraria; Otsuka: Honoraria, Research Funding; Janssen: Honoraria, Research Funding. Garelius:novartis: Honoraria. Efficace:Incyte: Consultancy; Amgen: Consultancy; TEVA: Consultancy; Bristol Meyers Squibb: Consultancy; Orsenix: Consultancy; Seattle Genetics: Consultancy; Lundbeck: Research Funding; TEVA: Research Funding; AMGEN: Research Funding. de Witte:Amgen: Consultancy, Research Funding; Celgene: Honoraria, Research Funding; Novartis: Research Funding.