Relationship of ultraviolet light exposure and cutaneous and systemic disease activity in youth with childhood-onset systemic lupus: Results from the Childhood Arthritis and Rheumatology Research Alliance Registry.

Objective: To investigate the association between sun exposure measured by ultraviolet light index (UVI) 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. Methods: We reviewed data on rash and disease activity from Systemic Lupus Erythematosus Disease Activity Index 2000 (SLEDAI-2K) scores from cSLE CARRA Registry participants with visits between 2010 and 2019 and obtained 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 to examine an association between UVI/season and rash / SLEDAI-2K score, adjusting for age, sex, race and income. Results: Among 1222 participants, with a mean of 2.3 visits/participant, 437 visits (15%) had rash and 860 (30%) had SLEDAI-2K score ≥ 5. There were no associations between UVI during the month prior to visit, or the month of the visit and odds of rash or elevated systemic activity. However, fall season was associated with increased odds of rash (OR = 1.59, p = 0.04), but there not increased disease activity. Conclusion: While we found no association between UVI and rash or UVI and disease activity, further studies directly measuring UVI may help further understand whether a relationship exists between sun exposure and SLE disease activity and whether this is an area that continues to require clinical attention.