ObjectiveTo estimate the prevalence and incidence of SLE in Sweden using a recent patient cohort, and to estimate the proportion and survival of patients with moderate-to-severe disease defined from register data.MethodsThis observational cohort study utilized data from national registries. Adult patients were included if they had at least two secondary care visits with a primary diagnosis of SLE from 1 July 2005 to 31 December 2020.Incident patients were defined as those with no prior visits for SLE in at least the previous 4 years. Disease severity was defined using an algorithm based on previous studies.1 2 Overall survival was defined for incident patients from date of first SLE visit (presumed diagnosis date) until death, stratified by severity in the year after diagnosis.ResultsIn total, 10,186 patients were identified, of which 5,076 were diagnosed after 2006. Prevalence increased from 2006 to 2019. The estimated point prevalence of adult SLE was 93.8 per 100,000 on 31 December 2019, and the estimated average incidence rate between 2015 and 2019 was 4.1 per 100,000 (figure 1). Of incident patients (mean age 49.9, 85% females), 61% had a clinical presentation of moderate-to-severe SLE at some point during the year following diagnosis, however patients can transition between severity states over time. The proportion of patients with moderate-to-severe disease stabilised at around 45% by 4 years after diagnosis until the end of follow-up. Compared to mild SLE patients, moderate-to-severe patients had poorer survival. After 10 years, patients with severe SLE in the year following diagnosis had an 80% survival probability compared to 86% for those with mild SLE (HR 1.49, P<0.001). Patients with moderate SLE had an 81% survival probability (HR vs. mild 1.42, P<0.001) (figure 2).ConclusionsThe estimated incidence and prevalence of SLE in Sweden is consistent with previous studies. This is the first study to evaluate moderate-to-severe SLE in Sweden from registers. Previous research has shown that survival in SLE is poorer than for controls, and we show that survival is poorer in patients presenting with moderate-to-severe disease than in mild disease, highlighting the importance of improving care for this patient group.AcknowledgementsThis study was sponsored by AstraZeneca.References Garris C, Jhingran P, Bass D, et al. Healthcare utilization and cost of systemic lupus erythematosus in a US managed care health plan. J Med Econ 2013;16:667–77. Samnaliev M, Barut V, Weir S, et al. Health care utilization and costs in adults with systemic lupus erythematosus in the United Kingdom: A real-world observational retrospective cohort study. EULAR European E-Congress of Rheumatology. Online2020.Abstract O6 Figure 1Incidence and prevalence of SLE (per 100 000)Abstract O6 Figure 2Kaplan-Meier for mortality by disease severity