Abstract A85: Distance to mammography facilities modifies the effect of patient navigation on breast cancer screening adherence among female black Medicare beneficiaries in Baltimore City.
Authors: Torres Aracelis Z. , Phelan Darcy F. , Pollack Craig E. , Bone Lee , Wenzel Jennifer , Howerton Mollie , Shapiro Gary R. , Garza Mary A. , Johnson Lawrence , Castillo-Salgado Carlos , Ford Jean G. 
Published: August 2014

Abstract
Introduction: Medicare beneficiaries, especially those from racial/ethnic minority populations, underutilize benefits for cancer screening. There is growing evidence that patient navigation helps overcome barriers to screening; however there is limited data on which subgroups benefit most from navigation. The Cancer Prevention and Treatment Demonstration (CPTD) was a randomized controlled trial that assessed the effect of patient navigation on cancer screening among Black Medicare beneficiaries in Baltimore, Maryland. We investigated whether patient navigation's effect on female participants' breast cancer screening adherence varied by distance between residence and mammography facilities.
Methods: Utilizing two sampling methods, 2,593 participants were enrolled into the CPTD trial with recruitment beginning in October 2006 and follow-up ending in December 2010. This analysis focuses on 1,856 Black female participants and utilizes baseline data as well as three follow-up surveys and exit data. The geographic software ArcGIS 10.0 spatially analyzed each participant's address relative to her three nearest mammography facilities in Baltimore City. With Stata 12.1, bivariate analyses assessed the independent effects of baseline demographics and other health variables on mammography screening adherence. While controlling for these factors, multivariable logistic regression models provided adjusted odds ratios (aORs) for the association between adherence and patient navigation. Adherence was having a mammogram within a year of the questionnaire being conducted. To assess the outcome's sensitivity, two definitions were used: 1) non-adherent at baseline and initiated adherence during follow-up; and 2) adherent at any point during follow-up regardless of baseline status. These models were stratified to assess heterogeneity based on whether or not participants were on average within two miles from their three closest facilities.
Results: There were no significant differences in adherence at baseline between the intervention and control arms. Among women who lived on average less than two miles from the three closest facilities, those in the patient navigation arm were more likely to be non-adherent at baseline and become adherent during follow-up than those in the control arm (aOR 2.12; 95% CI 1.08 - 4.18). Among those who lived two or more miles away, women in the patient navigation arm had a stronger effect on adherence initiation than did women in the control arm (aOR 2.67; 95% CI 1.21 - 5.90). For adherence at any point during the study, patient navigation was effective among those who lived less than an average of two miles but was not significantly different than controls (aOR 1.47; 95% CI 0.95 - 2.27). In comparison, those randomized to patient navigation were more likely to adhere at any point in the study than control participants if they lived further from facilities (aOR 1.89; 95% CI 1.15 - 3.10).
Conclusions: Our results suggest that among Black female Medicare beneficiaries in Baltimore City, the effect of patient navigation on mammography screening adherence was stronger for those further from facilities. These findings indicate that patient navigation might be helpful among those with more pronounced logistical barriers, including physical distance from health services. Additionally, the analyses suggest potential uses for geographic software in assessing the effectiveness of patient navigation and other community-based interventions.
Citation Format: Aracelis Z. Torres, Darcy F. Phelan, Craig E. Pollack, Lee Bone, Jennifer Wenzel, Mollie Howerton, Gary R. Shapiro, Mary A. Garza, Lawrence Johnson, Carlos Castillo-Salgado, Jean G. Ford. Distance to mammography facilities modifies the effect of patient navigation on breast cancer screening adherence among female black Medicare beneficiaries in Baltimore City. [abstract]. In: Proceedings of the Fifth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2012 Oct 27-30; San Diego, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(10 Suppl):Abstract nr A85.