Conference Coverage

California wildfires caused uptick in clinic visits for atopic dermatitis, itch



During the deadliest wildfire in California’s history in 2018, dermatology clinics 175 miles away at the University of California, San Francisco, experienced an increase in the number of pediatric and adult visits for pruritus and atopic dermatitis associated with air pollution created from the wildfire, according to research presented at the annual meeting of the Society for Investigative Dermatology, held virtually.

In patients with and without atopic dermatitis (AD), “acute exposure to poor air quality associated with a wildfire event can increase the number of visits for itch,” Raj Fadadu, a medical student at the University of California, San Francisco, said in his presentation.

Not many studies have examined this potential association, but includes those that have found significant positive associations between exposure to air pollution and pruritus, the development of AD, and exacerbation of AD (J Allergy Clin Immunol. 2014 Nov;134[5]:993-9). Another study found outpatient visits for patients with eczema and dermatitis in Beijing increased as the level of particulate matter, nitrogen dioxide, and sulfur dioxide concentrations increased (Environ Sci Process Impacts. 2019 Jan 23;21[1]:163-73).

Mr. Faduda and colleagues set out to determine whether the number of appointments for and severity of skin disease increased as a result of the 2018 Camp Fire, which started in Paradise, Calif., using measures of air pollution and clinic visits in years where California did not experience a wildfire event as controls. Using the National Oceanic and Atmospheric Administration Hazard Mapping System for fire and smoke, the researchers graphed smoke plume density scores and particulate matter (PM2.5) concentrations in the area. They then calculated the number of UCSF dermatology clinic visits for AD/eczema, and measured severity of skin disease with appointments for itch symptoms, and the number of prescribed medications during that time using ICD-10 codes.

The Camp Fire rapidly spread over a period of 17 days, between Nov. 8 and 25, 2018, during which time, PM2.5 particulate matter concentrations increased 10-fold, while the NOAA smoke plume density score sharply increased. More pediatric and adult patients also seemed to be visiting clinics during this time, compared with several weeks before and several weeks after the fire, prompting a more expanded analysis of this signal, Mr. Fadadu said.

He and his coinvestigators compared data between October 2015 and February 2016 – a period of time where there were no wildfires in California – with data in 2018, when the Camp Fire occurred. They collected data on 3,448 adults and 699 children across 3 years with a total of 5,539 adult appointments for AD, 924 pediatric appointments for AD, 1,319 adult itch appointments, and 294 pediatric itch appointments. Cumulative and exposure lags were used to measure the effect of the wildfire in a Poisson regression analysis.

They found that, during the wildfire, pediatric AD weekly clinic visits were 1.75 times higher (95% confidence interval, 1.21-2.50) and pediatric itch visits were 2.10 times higher (95% CI, 1.44-3.00), compared with weeks where there was no fire. During the wildfire, pediatric AD clinic visits increased by 8% (rate ratio, 1.08; 95% CI, 1.04-1.12) per 10 mcg/m3 increase in PM2.5 concentration.

In adults, clinic visits for AD were 1.28 times higher (95% CI, 1.08-1.51) during the wildfire, compared with nonfire weeks. While there was a positive association between pollution exposure and adult AD, “this effect is less than what we observed” for pediatric AD visits, said Mr. Fadadu. Air pollution was positively associated with the development of itch symptoms in adults and more prescriptions for AD medications, but the results were not statistically significant.

“This may be explained by the fact that 80% of pediatric itch patients carried an AD diagnosis, while in contrast, only half of the adult itch patients also have a diagnosis of AD,” he said.

While there are several possible limitations of the research, including assessment of air pollution exposure, Mr. Fadadu said, “these results can inform how dermatologists counsel patients during future episodes of poor air quality, as well as expand comprehension of the broader health effects of climate change that can significantly impact quality of life.”

This study was funded by the UCSF Summer Explore Fellowship, Marguerite Schoeneman Award, and Joint Medical Program Thesis Grant.

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