SAN FRANCISCO – , according to investigators from Johns Hopkins University, Baltimore.
The work helps solve a longstanding mystery in systemic lupus erythematosus (SLE): why symptoms seem to come and go with the seasons.
Johns Hopkins University research previously has shown that renal flares are more common in the winter; double-stranded DNA antibodies more common in late fall; and rashes more likely in late spring.
However, “the exact reasons of why the seasonality was there remained a big question,” said lead investigator George Stojan, MD, an assistant professor of rheumatology and the codirector of the Hopkins Lupus Center.
To get a handle on the matter, Dr. Stojan and his team reviewed 1,628 patients treated at the university during 1999-2017. Using Environmental Protection Agency data, they examined atmospheric conditions within 350 km of Baltimore in the 10 days leading up to lupus visits for flares; the researchers adjusted for age, sex, income, ethnicity, rural versus urban residence, and how close patients lived to highways and airports.
“We [found] specific, strong associations between atmospheric variables and fine particulate matter concentrations ... and organ-specific lupus flares,” Dr. Stojan said. He explained why that matters in a video interview at an international congress on SLE.
In short, rash was directly associated with concentrations of ozone and inhalable, fine particulate matter less than 2.5 mcm in diameter (PM 2.5). Joint flares were associated with PM 2.5, ozone, resultant wind, and humidity.
Renal flares were inversely associated with temperature, and directly associated with wind and humidity. Pulmonary flares and serositis were associated with PM 2.5, and both hematologic and neurologic flares with wind and temperature.
The analysis was based on a per-unit basis. For example, each mcg/m3 increase in PM 2.5 increased the odds of a pulmonary flare about 4% (odds ratio, 1.042, P = .026). The other findings were mostly of smaller magnitude, but still statistically significant.
The National Institutes of Health funded the research. Dr. Stojan had no disclosures.
SOURCE: Stojan G et al. LUPUS 2019, Abstract M31.