title: Smoking intensity (pack/day) is a better measure than pack-years or smoking status for modeling cardiovascular disease outcomes.
abstract: Smoking as an epidemiological exposure can be quantified in many ways including duration, intensity, pack-years, recency, and age at initiation. However, it is not clear which of these are most important for cardiovascular disease (CVD) and how they should be modeled.
  
  
  
  Using the Multi-Ethnic Study of Atherosclerosis, Cox models for time to incident CVD adjusted for age, sex, race/ethnicity, education category, and income category were compared which included various characterizations of smoking history.
  
  
  
  Duration, age at starting, time since quitting, and noncigarette forms of smoking were not independently associated with CVD, whereas baseline current intensity was associated with CVD [e.g., hard CVD hazard ratio 1 pack/d of 1.85 95% confidence interval (1.33, 2.57)]. Former smokers, regardless of duration, intensity, or recency, were not at increased risk, suggesting that risk may risk may drop precipitously from the time of quitting. For CVD events, representing smoking exposure as baseline smoking intensity produced better model fit as measured by Akaike information criterion than models using smoking status or pack-years.
  
  
  
  The association of smoking with incident CVD events was well captured by including a simple term for baseline smoking intensity.
authors: Department of Biostatistics, Collaborative Health Studies Coordinating Center, University of Washington, Building 29, Suite 210, 6200 NE 74th Street, Box 354922, Seattle, WA 98115, USA. Electronic address: rmnance@uw.edu.
authors: Robin
authors: R
authors: Nance
authors: Department of Epidemiology, Collaborative Health Studies Coordinating Center, University of Washington, Box 354922, Building 29, Suite 310, 6200 NE 74th Street, Seattle, WA 98115-8160, USA.
authors: Joseph
authors: J
authors: Delaney
authors: Johns Hopkins Ciccarone Center for the Prevention of Heart Disease, Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, 600 N. Wolfe Street, Baltimore, MD 21287, USA.
authors: John W
authors: JW
authors: McEvoy
authors: Department of Medicine, Johns Hopkins Hospital, Johns Hopkins University, 600 N. Wolfe Street, Blalock 524C, Baltimore, MD 21287, USA.
authors: Michael J
authors: MJ
authors: Blaha
authors: Division of Public Health Sciences, Wake Forest School of Medicine, Medical Center Blvd., Winston-Salem, NC 27157-1063, USA.
authors: Gregory L
authors: GL
authors: Burke
authors: Department of Environmental Health Sciences, Columbia University, 722 168th W St, Office 1105, New York, NY 10032, USA.
authors: Ana
authors: A
authors: Navas-Acien
authors: Departments of Environmental & Occupational Health Sciences, Medicine, and Epidemiology, University of Washington, 4225 Roosevelt Way NE, Suite 100, Seattle, WA 98105, USA.
authors: Joel D
authors: JD
authors: Kaufman
authors: Department of Medicine, Division of General Medicine, Presbyterian Hospital, Columbia University, 630 West 168th Street, 9-105E, New York, NY 10032, USA.
authors: Elizabeth C
authors: EC
authors: Oelsner
authors: Department of Biostatistics, Collaborative Health Studies Coordinating Center, University of Washington, Building 29, Suite 210, 6200 NE 74th Street, Box 354922, Seattle, WA 98115, USA.
authors: Robyn L
authors: RL
authors: McClelland
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002318:Cardiovascular Diseases / Q000453:epidemiology*; D015984:Causality; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology*; D013997:Time Factors
keywords: Cardiovascular disease; Cohort; Intensity; Multi-Ethnic Study of Atherosclerosis; Pack-years; Smoking