title: Population-density and county-level variation in breast cancer mortality rates among white women residing in the Northeastern and Southern United States.
abstract: OBJECTIVE
  We assessed the contribution of variation in risk factor prevalence to population-density and county-level variation in breast cancer mortality rates.
  
  
  METHODS
  In 1995 we collected risk factor information in a telephone interview of a random digit dialed sample of: (1) 1241 women from counties in the upper and lower tertiles of population density as of 1970 in the Northeast and South of the United States (Design A); (2) 2492 women from counties in the upper and lower tertiles of 1970-1979 breast cancer mortality rates in the four populations from Design A, and; (3) 276 women in Nassau County in New York State. We calculated 1990-94 mortality ratios (MRs) adjusted for breast cancer risk factors.
  
  
  RESULTS
  The high/low population-density fully-adjusted MRs in women > or = 55 years were 1.01 (95% CI 0.9-1.2) and 1.00 (95% CI 0.8-1.2). The fully-adjusted MRs for high versus low mortality counties ranged from 0.95 (95% CI 0.8-1.2) to 1.29 (95% CI 1.0-1.6) in women > or = 55 years.
  
  
  CONCLUSIONS
  Differences in risk factor prevalence explained higher rates in high-density versus low-density areas in older women. Modest elevations in the adjusted high/low breast cancer MRs among older women in certain groups of counties may reflect unidentified risk factors but more likely are due to chance.
authors.affiliation: Department of Biostatistics and Epidemiology, School of Public Health and Health Sciences, University of Massachusetts, Amherst, MA 01003, USA. ssturgeon@schoolph.umass.edu
authors.forename: Susan R
authors.initials: SR
authors.lastname: Sturgeon
authors.forename: Barry I
authors.initials: BI
authors.lastname: Graubard
authors.forename: Catherine
authors.initials: C
authors.lastname: Schairer
authors.forename: Mary
authors.initials: M
authors.lastname: McAdams
authors.forename: Robert N
authors.initials: RN
authors.lastname: Hoover
authors.forename: Mitchell H
authors.initials: MH
authors.lastname: Gail
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D001943:Breast Neoplasms / Q000401:mortality*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009511:New England / Q000453:epidemiology; D016017:Odds Ratio; D011156:Population Density; D015995:Prevalence; D012307:Risk Factors; D012959:Socioeconomic Factors; D015144:Southeastern United States / Q000453:epidemiology; D044465:White People / Q000706:statistics & numerical data*; D016387:Women's Health