Abstract P3-10-03: Socioeconomic disparities in needle biopsy prior to breast cancer surgery across physician referral networks
Authors: Killelea BK , Herrin J , Soulos PR , Pollack CE , Forman HP , Yu J , Xu X , Tannenbaum S , Wang S , Gross CP 
Published: March 2017

Abstract
Introduction
Although needle biopsy (NB) is recommended prior to breast cancer surgery, the use of NB has been shown to vary according to patient socioeconomic status (SES), operating surgeon, and geographic region. We hypothesized that surgeons who work in the same peer referral network (defined by patient sharing) might have similar practice patterns with regard to NB, and that the magnitude of SES disparities might vary across networks. We therefore examined: 1) SES disparities in the receipt of NB, 2) variation in NB across networks, and 3) whether the association between SES and NB varied across networks.
Methods
We used the SEER database and 5% Medicare sample to examine all patients with a new diagnosis of breast cancer from 2004 through 2006. We used Medicare claims to construct peer groups of physicians based on patient-sharing ties. Patients were assigned to peer groups based on the surgeon who performed their definitive surgery. We defined a patient as having low SES if she was in the lowest quintile of area-level income. We used hierarchical generalized linear models (HGLM) to assess the association between low SES and receipt of NB, including random effects for the surgeon, peer group, and Hospital Referral Region (HRR). We then allowed the low SES effect to vary across peer groups in order to determine whether the association between SES and NB varied across groups.
Results
In the full sample of 14,552 patients, 9,498 (65%) received needle biopsy. In bivariable analysis, patients in the lowest income quintile were less likely to receive NB compared to all other patients (59% vs 67%, p&lt;.001). The majority of the variance (59%) in NB use was at the patient level, 22% was at the surgeon level, and 13.7% at the peer group level. The use of NB varied substantially across peer groups, with a median of 69% (interquartile range [51%, 84%]). Even after accounting for physician, peer group, and HRR variation, patients in the lowest stratum of SES were significantly less likely to have received NB compared to all other patient (OR = 0.88; p=.04). Finally, we found that the association between SES and NB varied significantly across referral networks (P&lt;0.05)
Conclusions
Patients with low SES are significantly less likely to receive NB prior to breast cancer surgery, and moreover the magnitude of this SES-related disparity varies significantly according to which referral networks are providing care. Future policies to increase NB rates and standardize care for all breast cancer patients may consider the implications of how care for patients with low SES varies across surgical provider networks.Introduction
Although needle biopsy (NB) is recommended prior to breast cancer surgery, the use of NB has been shown to vary according to patient socioeconomic status (SES), operating surgeon, and geographic region. We hypothesized that surgeons who work in the same peer referral network (defined by patient sharing) might have similar practice patterns with regard to NB, and that the magnitude of SES disparities might vary across networks. We therefore examined: 1) SES disparities in the receipt of NB, 2) variation in NB across networks, and 3) whether the association between SES and NB varied across networks.
Methods
We used the SEER database and 5% Medicare sample to examine all patients with a new diagnosis of breast cancer from 2004 through 2006. We used Medicare claims to construct peer groups of physicians based on patient-sharing ties. Patients were assigned to peer groups based on the surgeon who performed their definitive surgery. We defined a patient as having low SES if she was in the lowest quintile of area-level income. We used hierarchical generalized linear models (HGLM) to assess the association between low SES and receipt of NB, including random effects for the surgeon, peer group, and Hospital Referral Region (HRR). We then allowed the low SES effect to vary across peer groups in order to determine whether the association between SES and NB varied across groups.
Results
In the full sample of 14,552 patients, 9,498 (65%) received needle biopsy. In bivariable analysis, patients in the lowest income quintile were less likely to receive NB compared to all other patients (59% vs 67%, p&lt;.001). The majority of the variance (59%) in NB use was at the patient level, 22% was at the surgeon level, and 13.7% at the peer group level. The use of NB varied substantially across peer groups, with a median of 69% (interquartile range [51%, 84%]). Even after accounting for physician, peer group, and HRR variation, patients in the lowest stratum of SES were significantly less likely to have received NB compared to all other patient (OR = 0.88; p=.04). Finally, we found that the association between SES and NB varied significantly across referral networks (P&lt;0.05)
Conclusions
Patients with low SES are significantly less likely to receive NB prior to breast cancer surgery, and moreover the magnitude of this SES-related disparity varies significantly according to which referral networks are providing care. Future policies to increase NB rates and standardize care for all breast cancer patients may consider the implications of how care for patients with low SES varies across surgical provider networks.
Citation Format: Killelea BK, Herrin J, Soulos PR, Pollack CE, Forman HP, Yu J, Xu X, Tannenbaum S, Wang S, Gross CP. Socioeconomic disparities in needle biopsy prior to breast cancer surgery across physician referral networks [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-10-03.