Wildfire smoke increases cardiac arrest risk
The risk for out-of-hospital cardiac arrest increases with wildfire smoke exposure, according to a study published in the Journal of the American Heart Association.
This risk is most pronounced in people with lower socioeconomic status, according to the study.
“These findings show direct evidence of cardiovascular clinical events to be associated with wildfire smoke exposure,” Sumi Hoshiko, MPH, research scientist at the Environmental Health Investigations Branch of the Center for Healthy Communities at the California Department of Public Health, told Healio. “Clinicians should be aware of these risks, particularly relevant for their patients with underlying cardiorespiratory conditions. These include patients with ischemic heart disease, heart failure, cerebrovascular disease and asthma.”
Cardiac arrest in California
Caitlin G. Jones, MS, a fellow in the chronic disease control branch of the California Department of Public Health in Richmond, and colleagues analyzed data from 5,336 patients (58% aged at least 65 years; 36% women) with out-of-hospital cardiac arrest in 14 California counties from 2015 to 2017. Counties included in this study had wildfires that burned at least 50,000 acres for at least 50 days.
“This study used a surveillance dataset that recorded cardiac arrests occurring outside of a hospital setting, so it was able to capture events that would not be included in other studies, as most studies of health effects of wildfire smoke have relied on hospital admissions and emergency department data,” Hoshiko said in an interview. “Since out-of-hospital cardiac arrest is highly fatal, most out-of-hospital cardiac arrest patients do not survive long enough to be admitted to the hospital, so this provided a more comprehensive picture of the health impact of wildfire smoke.”
Other data were assessed including smoke plume density, daily mean temperature, relative humidity and socioeconomic status. Each day that an out-of-hospital cardiac arrest occurred was matched by the day of the week with 4 control days at 1, 2, 3 and 4 weeks before the cardiac event occurred. Patients were also categorized by age (19 to 34 years, 35 to 64 years and 65 years), sex and socioeconomic status for secondary subgroup analyses.
Of the patients included in the study, 16.4% experienced wildfire smoke exposure.
The link between out-of-hospital cardiac arrest and heavy smoke exposure was significant at lag days 0 (OR = 1.56; 95% CI, 1.05-2.33), 2 (OR = 1.7; 95% CI, 1.18-2.45) and 3 (OR = 1.48; 95% CI, 1.02-2.13).
Patients with lower and higher socioeconomic status had an elevated risk for out-of-hospital cardiac arrest with exposure to heavy smoke. Significant positive associations were observed for patients with higher socioeconomic status with heavy smoke exposure at lag days 0 (OR = 1.59; 95% CI, 1.02-2.49) and 2 (OR = 1.6; 95% CI, 1.07-2.4). ORs were similar for heavy smoke density in patients with low socioeconomic status, although it was not statistically significant at lag day 0 (OR = 1.47; 95% CI, 0.62-3.51) or lag day 2 (OR = 2.25; 95% CI, 0.9-5.61).
The lower socioeconomic status group had elevated ORs for nearly all lag days at light and medium smoke densities, which was also not statistically significant. The higher socioeconomic status group had a consistently negative effect at these smoke densities, which was statistically significant for medium smoke density at lag day 2 (OR = 0.78; 95% CI, 0.61-0.98).
Both men and women had increases in out-of-hospital cardiac arrest under heavy smoke conditions, especially in women at lag day 0 (OR = 2.02; 95% CI, 1.1-3.7) and in men at lag day 2 (OR = 1.67; 95% CI, 1.08-2.59).
Heavy smoke conditions also increased the risk for out-of-hospital cardiac arrest across age groups. Patients aged 35 to 64 years had the highest risk at lag day 0 (OR = 1.91; 95% CI, 1.07-3.42), whereas patients aged at least 65 years had a stronger association between the two factors at lag day 2 (OR = 2.12; 95% CI, 1.31-3.46) and lag day 3 (OR = 1.67; 95% CI, 1.02-2.72).
Advice for cardiologists
“Although wildfire smoke, unlike behavioral factors such as smoking, is not under individual control, personal interventions take on greater importance in order to reduce exposures during times of wildfires,” Hoshiko told Healio. “Cardiologists can help patients become aware of their risk and encourage them to consider preparing. During a smoky period, measures can be taken to reduce exposures both indoors and out.” – by Darlene Dobkowski
For more information:
Sumi Hoshiko, MPH, can be reached at sumi@hoshiko@cdph.ca.gov.
Disclosures: The authors report no relevant financial disclosures.