Oral glucocorticoid dose patterns and organ damage in systemic lupus erythematosus – a nationwide cohort study

BACKGROUND: Evaluating the relationship between glucocorticoid (GC) exposure and organ damage in systemic lupus erythematosus (SLE) is challenging since GC dose varies over time. It is unclear which exposure time window captures the full impact of GC usage. METHODS: We studied a nationwide cohort of individuals with newly diagnosed SLE 2006-2022 with follow-up until January 2024 through a linkage of Swedish national registers. Long-term oral GC exposure was assessed from pharmacy dispensations to identify which dosing patterns had the strongest association with organ damage overall, and within the ocular, cardiovascular, peripheral vascular, gastrointestinal, diabetes, and malignancy domains. We used Weighted Cumulative Exposure models to estimate the weights of the average daily dose at different time points and determine the relative importance of exposure on organ damage accrual, adjusted for confounders. RESULTS: Among 3749 patients with newly diagnosed SLE (82.1% female, median age 48.0 years), the increased risk of first organ damage overall associated with GC dosing was well-captured by the past 2 years (adjusted HR=1.42 [95%CI 1.31-1.53] for 5 mg/day), and fairly well captured by the past 1 year (adjusted HR=1.34 [95%CI 1.23-1.42] for 5 mg/day). For cardiovascular damage, dose patterns over the past 3 years substantially contributed to the associated increased risk. CONCLUSIONS: In evaluations of overall organ damage in SLE, GC exposure during at least the previous year should be considered to capture the associated increased risk. For cardiovascular damage, the time window for assessing GC exposure and disease activity should be extended to the last 3 years.