Understanding reversals of association between cancer screening and race/ethnicity.
BACKGROUND
We used a composite variable composed of insurance status, income, and race/ethnicity to investigate access-enhancing programs as a possible reason for "reversals of association" and large percent changes (LPC), between race/ethnicity and cancer screening, when comparing the unadjusted and adjusted ORs.


METHODS
Data were from women aged 40-64 years, using the combined 2008 and 2010 Behavioral Risk Factor Surveillance System surveys. Recent mammography was within the past 2 years, and recent Pap testing was within the past 3 years. Initial analyses using all variables singly were followed by analyses that used the composite variable with the remaining covariates.


RESULTS
Analyses with race/ethnicity singly indicated reversals of association for Hispanic women and higher estimated screening for black and Hispanic women than for white women. Analyses with the composite variable found no reversals of association, but there were several LPCs for Hispanic and black women, for lower income, and for uninsured women. White, uninsured, lower income women were among those with the lowest utilization.


CONCLUSIONS
Results were consistent with the possibility that access-enhancing programs for lower income, uninsured and often non-white women can lead to overestimates of screening, reversals of association, and LPCs in multivariable analyses. Attention should be given to identifying LPCs to unadjusted ORs. Lower income, uninsured, white women are also a group at risk of extremely low mammography and Pap test utilization.


CONCLUSIONS
Combining variables to create better-targeted population subgroups may help in the interpretation of analyses that produce reversals of association and LPCs for correlates of cancer screening utilization.
Department of Behavioral and Social Sciences, Public Health Program, Brown University, Providence, RI 02912, USA. William_Rakowski@brown.edu
William
W
Rakowski
Michelle L
ML
Rogers
Gregory M
GM
Dominick
Melissa A
MA
Clark
D000328:Adult; D044383:Black People; D055088:Early Detection of Cancer / Q000706:statistics & numerical data*; D005260:Female; D006630:Hispanic or Latino; D006801:Humans; D008327:Mammography / Q000706:statistics & numerical data*; D008875:Middle Aged; D014626:Vaginal Smears / Q000706:statistics & numerical data*; D044465:White People