Associations between short-term PM2.5 and smoke exposure and blood cholesterol concentrations among MI survivors
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Introduction:
Elevated blood cholesterol concentrations are a cardiovascular disease (CVD) risk factor and can be an indicator of metabolic dysfunction, particular for those with a prior cardiovascular event, e.g. myocardial infarction (MI). However, few studies have explored associations between air pollution and blood cholesterol concentrations among individuals with a prior cardiovascular event.
Methods:
We examined associations between blood cholesterol concentrations and particulate air pollution (PM2.5) and smoke exposure in a cohort of 5,683 MI survivors. Measurements of low-density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), and total cholesterol were extracted from electronic health records spanning 2004-2016 along with patient address, demographics, and smoking status. Daily smoke exposure was assessed at the zip code level using the NOAA hazard mapping system data. PM2.5 was assessed using 1x1km resolution daily modeled concentrations while daily meteorology was determined based on the nearest National Oceanic and Atmospheric Administration (NOAA) monitoring station. We adjusted for age, sex, race, temperature, relative humidity, smoking status, area-level socioeconomic status using data from the 2010 US Census, and a spline term for time since study start. We examined associations based on exposure on the day of measurement and up to 4 days prior as well as the 5-day average exposure.
Results
We observed a decrease in HDL-C in association with 5-day average PM2.5 exposure (β = -0.66mg/dL per 10 µg/m3 increase in PM2.5, 95% confidence interval = -1.24, -0.08) and smoke exposure (β = -0.76mg/dL per additional smoke day; 95% confidence interval = -1.44, -0.10). We also observed a decrease in total cholesterol in association with both 5-day average smoke exposure and PM2.5. No associations were observed for LDL-C.
Discussion
Short-term exposure to air pollution is associated with a decrease in cardioprotective HDL-C among MI survivors. These results may help to understand environmental risks among clinically vulnerable individuals.