Relationship of regional ultraviolet index data with rash and systemic disease activity in youth with childhood-onset systemic lupus: results from the Childhood Arthritis and Rheumatology Research Alliance Registry

To investigate the association between ultraviolet light index (UVI), as a marker for UV exposure, and seasonality with rash and systemic disease activity in youth with childhood-onset systemic lupus (cSLE) from the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry. We reviewed data on rash and disease activity from Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2 K) scores from cSLE CARRA Registry participants with visits between 2010 and 2019 and obtained zipcode level UVI data from the National Oceanic and Atmospheric Administration (NOAA). Our main exposures were UVI and season during the month of visit and one month prior to visit. We used mixed-effects logistic regression models to examine associations between regional UVI (by zipcode)/season and odds of rash and severe SLEDAI-2 K score (≥ 5 vs. 0–4), adjusting for age, sex, race and income. Among 1222 participants, with a mean of 2.3 visits per participant, 437 visits (15