Abstract BACKGROUND AND AIMS Although the high prevalence of symptoms experienced by haemodialysis patients is recognized, how these symptoms change over time is poorly understood, and could have implications for clinical practice and research. This study investigates the change in symptom burden over time with standard care using the POS-S renal questionnaire. METHOD Three times a week haemodialysis patients participating in a stepped wedge cluster randomized trial (SHAREHD) reported the severity of the 17 POS-S Renal symptoms (none, mild, moderate, severe and overwhelming) at baseline, 6, 12 and 18 months. Patients reporting moderate or worse for each of these symptoms at baseline were identified. Symptoms were categorized by the absolute change in population prevalence of individuals in the ‘severe’ group, estimated using multi-level mixed effects ordered probit regression adjusting for age, sex, time on HD and Charlson Comorbidity Score. To assess change within individuals, the proportion of patients changing their symptom score every 6 months was estimated, with >35% of patients remaining in the ‘severe’ category used to class a symptom as more stable. RESULTS 552 patients completed 1724 questionnaires across the four timepoints. Across all 17 symptoms with moderate or worse symptom severity at baseline, the majority of the change in population symptom prevalence occurred in the ‘severe’ category with moderate category remaining stable and mild/none prevalence increasing. The change in prevalence of the ‘severe’ category was 10%–20% >18 months in difficult sleeping, weakness, anxious, depression, shortness of breath, poor mobility, skin changes, drowsiness, pain, poor appetite, restless leg experienced an absolute improvement. Meanwhile greater absolute improvements in prevalence of 21–40% were observed in constipation, diarrhoea, sore mouth, pruritus, vomiting and nausea. Most of the symptoms with larger changes in population prevalence of the ‘severe’ category were associated with only 22–28% of patients remaining in the severe category at any one time. But larger prevalence change was driven by 9–18% difference between the proportion of patients moving out of severe compared with those moving into this category. Despite less change (10%–20%) in population prevalence of the ‘severe’ category in other symptoms, there was still a large degree of within patient movement that was relatively balanced in and out of the severe category. Examples include depression, skin changes and drowsiness, which had 75–80% movement both in and out of severe category each 6 months period, but maintained relatively static prevalence over time. All symptoms had >50% of patients in the severe group change their severity >6 months. CONCLUSION In response to standard care, the prevalence and movement in and out of the severe category can help characterize the longitudinal behavior of symptoms. More dramatic changes at the population and patient level in some symptoms could have a significant impact for clinical trial design as improvements are observed with standard care, which could be interpreted as a placebo effect. Symptom severity changes in more than 50% of patients within 6 months, arguing for routine measurement of symptom-based PROMS in haemodialysis population to identify individuals requiring intervention. Funded by VIFOR Pharma.