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Urban vs. rural residence and outcomes in older breast cancer patients.

BACKGROUND
20% of the US population resides in rural areas, yet is served by 3% of oncologists, and 7% of non-oncology specialists. Access to care issues can be compounded by lower socioeconomic status (SES) in rural areas, yet this issue is unexplored among older patients with breast cancer.


METHODS
Using SEER-Medicare, 109,608 patients diagnosed at ≥65y with breast cancer between 2000 and 2011 were identified. Residence status was combined with Federal Poverty levels: urban (high-, medium- and low-poverty); rural (high-, medium- and low-poverty). Five-year overall survival (OS) and healthcare utilization (HCU: visits to primary care provider [PCP], oncologist, non-oncology specialist, emergency department) were examined using urban/low-poverty as reference. The residence, HCU, mortality association was examined using mediation and moderation analyses.


RESULTS
Median age was 76y; 12.5% were rural, 15.6% high-poverty. 5y OS: 5y OS was 69.8% for rural and 70.9% for urban. Both urban- and rural/high-poverty patients had a 1.2-fold increased mortality hazard. Rural/high-poverty patients had a higher rate of PCP (Y1: IRR=1.23; Y2-Y5: IRR=1.19) and ED visits (Y1: IRR=1.82; Y2-Y5: IRR=1.43), but lower non-oncology specialist visit rates (Y1: IRR=0.74; Y2-Y5: IRR=0.71). Paucity of non-oncology specialist visits mediated 23%-57% of excess mortality risk. The interaction between residence/SES and paucity of non-oncology specialist visits accounted for 49%-92% of excess mortality risk experienced by rural/high-poverty patients vs. urban/low-poverty.


CONCLUSIONS
Urban-rural residence mortality differences among older breast cancer patients are highly predicated by poverty level.


IMPACT
Rural/high-poverty patients demonstrate less use of non-oncology specialists compared to urban/low-poverty, with disparities moderated by specialist use.