title: Long-term Coarse Particulate Matter Exposure and Heart Rate Variability in the Multi-ethnic Study of Atherosclerosis.
abstract: BACKGROUND
  Reduced heart rate variability, a marker of impaired cardiac autonomic function, has been linked to short-term exposure to airborne particles. This research adds to the literature by examining associations with long-term exposures to coarse particles (PM10-2.5).
  
  
  METHODS
  Using electrocardiogram recordings from 2,780 participants (45-84 years) from three Multi-ethnic Study of Atherosclerosis sites, we assessed the standard deviation of normal to normal intervals and root-mean square differences of successive normal to normal intervals at a baseline (2000-2002) and follow-up (2010-2012) examination (mean visits/person = 1.5). Annual average concentrations of PM10-2.5 mass, copper, zinc, phosphorus, silicon, and endotoxin were estimated using site-specific spatial prediction models. We assessed associations for baseline heart rate variability and rate of change in heart rate variability over time using multivariable mixed models adjusted for time, sociodemographic, lifestyle, health, and neighborhood confounders, including copollutants.
  
  
  RESULTS
  In our primary models adjusted for demographic and lifestyle factors and site, PM10-2.5 mass was associated with 1.0% (95% confidence interval [CI]: -4.1, 2.1%) lower standard deviation of normal to normal interval levels per interquartile range of 2 μg/m. Stronger associations, however, were observed before site adjustment and with increasing residential stability. Similar patterns were found for root-mean square differences of successive normal to normal intervals. We found little evidence for associations with other chemical species and with the rate of change in heart rate variability, though endotoxin was associated with increasing heart rate variability over time.
  
  
  CONCLUSIONS
  We found only weak evidence that long-term PM10-2.5 exposures are associated with lowered heart rate variability. Stronger associations among residentially stable individuals suggest that confirmatory studies are needed.
authors.affiliation: From the aDepartment of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI; bDivision of Public Health Sciences, Wake Forest University, Wake Forest, NC; cInstitute for Minority Health Research, University of Illinois at Chicago and Department of Preventive Medicine, Northwestern University, Chicago, IL; dDivision of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, MN; eDepartment of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA; fDepartment of Biostatistics, University of Washington, Seattle, WA; gDepartment of Occupational and Environmental Health, University of Iowa, Iowa City, IA; hDepartments of Medicine and Epidemiology, University of Washington, Seattle, WA; and iDepartment of Civil and Environmental Engineering, University of Washington, Seattle, WA.
authors.forename: Richa
authors.initials: R
authors.lastname: Adhikari
authors.forename: Jennifer
authors.initials: J
authors.lastname: D'Souza
authors.forename: Elsayed Z
authors.initials: EZ
authors.lastname: Soliman
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Burke
authors.forename: Martha L
authors.initials: ML
authors.lastname: Daviglus
authors.forename: David R
authors.initials: DR
authors.lastname: Jacobs
authors.forename: Sung Kyun
authors.initials: SK
authors.lastname: Park
authors.forename: Lianne
authors.initials: L
authors.lastname: Sheppard
authors.forename: Peter S
authors.initials: PS
authors.lastname: Thorne
authors.forename: Joel D
authors.initials: JD
authors.lastname: Kaufman
authors.forename: Timothy V
authors.initials: TV
authors.lastname: Larson
authors.forename: Sara Dubowsky
authors.initials: SD
authors.lastname: Adar
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001342:Autonomic Nervous System Diseases / Q000453:epidemiology* / Q000503:physiopathology; D015331:Cohort Studies; D004562:Electrocardiography; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D005260:Female; D006331:Heart Diseases / Q000453:epidemiology* / Q000503:physiopathology; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D052638:Particulate Matter; D012307:Risk Factors
chemical_list: D052638:Particulate Matter