Population-density and county-level variation in breast cancer mortality rates among white women residing in the Northeastern and Southern United States.
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.
Sturgeon
Susan R
SR
Department of Biostatistics and Epidemiology, School of Public Health and Health Sciences, University of Massachusetts, Amherst, MA 01003, USA. ssturgeon@schoolph.umass.edu
Graubard
Barry I
BI
Schairer
Catherine
C
McAdams
Mary
M
Hoover
Robert N
RN
Gail
Mitchell H
MH
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