Trajectories of disease severity and their clinical outcome in real-world patients with systemic lupus erythematosus.

Objective: Systemic lupus erythematosus (SLE) is characterised by variability of disease activity patterns over time. This study aimed to investigate the trajectories of SLE disease severity patterns, identify clinical and demographic variables, and assess the association between trajectories of SLE disease severity and all-cause mortality. Methods: A retrospective cohort of newly diagnosed patients with SLE was established using the Korean nationwide healthcare claims information database between 1st January 2008 and 31st December 2016. Using group-based trajectory modelling (GBTM), they were clustered based on the trajectory of SLE disease severity patterns during a two-year follow-up from the cohort entry date. We performed Cox proportional hazards models to compare the mortality between trajectories of SLE disease severity patterns. Results: A total of 8901 patients with SLE were included in the analysis from 2008 to 2016. Five distinct SLE disease severity trajectories were identified as optimal: consistently severe (4.6 %), mild-then-moderate (11.6 %), moderate-then-mild (15.1 %), consistently moderate (30.4 %), and consistently mild (38.3 %). Patients with consistently mild disease severity were more likely to be older; those with consistently severe disease severity were more likely to be male with more comorbidities than other groups. Compared to the consistently mild disease severity, the other trajectory groups showed a higher risk of all-cause mortality. Conclusion: Through GBTM, dynamic two-year severity trajectories of newly diagnosed SLE were identified. Patients' demographics and comorbidities attributed to changes in SLE severity trajectories, which may inform evidence for clinical decision-making.