Associations between short and long-term PM2.5 exposure and blood lipid concentrations in myocardial infarction survivors
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Background and Aim
Ambient particulate matter (PM2.5) increases morbidity and mortality, particularly for those with underlying chronic disease. Examining disease risk factors such as blood lipids can reveal the early stages of the pathophysiologic processes triggered by PM2.5.
Methods
We examined associations between short-term PM2.5 and blood concentrations of total cholesterol, high-density lipoprotein cholesterol (HDL), and low-density lipoprotein cholesterol (LDL) among myocardial infarction (MI) survivors (N = 8,740) seen at a University of North Carolina Healthcare System facility between January 1, 2004 and December 31, 2016. Lipid measurements were extracted from the electronic health records along with geocoded residential address, patient demographics, and disease history. Daily PM2.5 was estimated at 1x1 km resolution using an ensemble machine learning model. We used linear mixed-effects models with a random intercept for each individual to model the associations while adjusting for age, sex, race, temperature, relative humidity, socioeconomic status, and a natural spline for time since study start. We also examined annual average PM2.5 in separate models adjusted for age, race, sex and socioeconomic status. Results are presented as the regression coefficient (β, per 1 μg/m3 higher PM2.5) and associated 95% confidence interval (CI).
Results
For short-term PM2.5 exposures associations were only seen between 5-day average PM2.5 and HDL (β = -0.06; CI= -0.10, -0.02) and total cholesterol (β = -0.18; CI= -0.37, 0.01). Annual average PM2.5 was associated with total cholesterol (β = 1.57; CI= 1.05, 2.12), HDL (β = 0.57; CI= 0.42, 0.72), and LDL (β = -0.95; CI= -1.95, 0.05).
Conclusions
Short and long-term exposures to PM2.5 are associated with changes in blood lipids among MI survivors with the directions of associations varying by time period of exposure. Further evaluation of these associations may reveal important insights into the actions of PM2.5 for clinically vulnerable individuals.