Social network analysis of physician interactions: the effect of institutional boundaries on breast cancer care.

Although comparative effectiveness trials and nationally recognized clinical guidelines offer substantial guidance about ideal patient treatment, we remain largely uninformed about the patterns of care seen in everyday clinical practice. To address this gap in knowledge, we looked at registry-based data on breast cancer care at two neighboring healthcare institutions with a specific focus on whether organizational boundaries determine the physicians that a patient will see. From an initial patient-oriented data set, we developed a social network of physicians, modeling their interactions over the course of the provided treatments. Applying a mixture of visual and quantitative analyses to this network, we found evidence for strong intra-institutional ties and poignantly weak connections to physicians operating out of other healthcare centers.