Background/Purpose: Systemic lupus erythematosus (SLE) is a complex multisystem autoimmune disease that affects at least 300,000 people in the United States creating a substantial socioeconomic burden. The exact etiology of SLE remains largely unknown. Both genetic factors and environmental exposures have been implicated in the etiology and progression of SLE. Air pollution is one of the major environmental factors that have been proposed in the study of SLE exacerbation. Fine and ultrafine particles measuring 2.5μm (PM2.5) are major contributors to air pollution. Wildfires can increase PM2.5 significantly and affect individuals’ health negatively. Due to topographical and meteorological conditions in the central valley of California, the area is prone to air pollution and this can be well pronounced during active wildfires in the surrounding areas. In this study, we aim to study the correlation between the frequency of SLE flares and air quality measures.

Methods: This is a retrospective study. Data for SLE patients with the following criteria were collected: age 18 or above, confirmed diagnosis of SLE (by ACR 2019 criteria, tissue diagnosis, or rheumatologist-confirmed), who had an ED visit or were admitted during the year 2018 for SLE flare. The following data for Fresno county covering the year 2018 were collected using the environmental protection agency website: PM2.5, Ozone, and average daily temperature. The data were averaged for each week of the year and the counts of SLE flares were examined during each week. Pearson correlation tests were used to analyze the correlation of air quality measures with the frequency of SLE flares (Pearson correlation coefficients and 2- tailed p values were reported).

Results: A total of 432 SLE ED and inpatient encounters were reviewed, of those 257 met the study criteria for SLE with 94 SLE flares. The mean age was 40 with 93% of patients being females. Pearson correlation coefficient for the Ozone air quality index and SLE flares was found to be -0.244 (p value= 0.08). Correlation coefficient results for PM2.5 levels air quality index and average temperature were -0.103 (p value= 0.465) and -0.198 (p value= 0.155) respectively.

Conclusion: In our study, there was no statistically significant correlation between SLE flares and levels of different pollutants including PM2.5 and Ozone. There was also no statistically significant correlation between the average daily temperature and the frequency of SLE flares. We suggest there might be a signal that it is in our unique population’s genetics or cultural differences that might be paving way for their flares or their healthcare access. Our study is an important pilot to support the need for assessing the possibly unique genetic makeup in our population, considering that weather might not be the major flare trigger. Larger studies are needed to assess the association and causation between SLE flares and air pollution.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/association-of-air-pollution-with-systemic-lupus-erythematosus-disease-activity-in-the-central-valley-of-california/