Comparing Shared Patient Networks Across Payers.

BACKGROUND: Measuring care coordination in administrative data facilitates important research to improve care quality. OBJECTIVE: To compare shared patient networks constructed from administrative claims data across multiple payers. DESIGN: Social network analysis of pooled cross sections of physicians treating prevalent colorectal cancer patients between 2003 and 2013. PARTICIPANTS: Surgeons, medical oncologists, and radiation oncologists identified from North Carolina Central Cancer Registry data linked to Medicare claims (N = 1735) and private insurance claims (N = 1321). MAIN MEASURES: Provider-level measures included the number of patients treated, the number of providers with whom they share patients (by specialty), the extent of patient sharing with each specialty, and network centrality. Network-level measures included the number of providers and shared patients, the density of shared-patient relationships among providers, and the size and composition of clusters of providers with a high level of patient sharing. RESULTS: For 24.5% of providers, total patient volume rank differed by at least one quintile group between payers. Medicare claims missed 14.6% of all shared patient relationships between providers, but captured a greater number of patient-sharing relationships per provider compared with the private insurance database, even after controlling for the total number of patients (27.242 vs 26.044, p < 0.001). Providers in the private network shared a higher fraction of patients with other providers (0.226 vs 0.127, p < 0.001) compared to the Medicare network. Clustering coefficients for providers, weighted betweenness, and eigenvector centrality varied greatly across payers. Network differences led to some clusters of providers that existed in the combined network not being detected in Medicare alone. CONCLUSION: Many features of shared patient networks constructed from a single-payer database differed from similar networks constructed from other payers' data. Depending on a study's goals, shortcomings of single-payer networks should be considered when using claims data to draw conclusions about provider behavior.

Breast cancer sentinel node metastases: histopathologic detection and clinical significance.

BACKGROUND: Lymphatic mapping with sentinel lymphadenectomy (LM/SL) is an accurate and less morbid means of determining the tumor status of the axilla in breast cancer patients than standard level I and II axillary lymph node dissection (ALND). This review addresses the handling and pathologic examination of the sentinel node (SN), the clinical significance of tumor within the SN, and the risk factors for non-SN tumor involvement. METHODS: The seminal works that have addressed pathologic examination of ALND specimens and SN specimens are summarized, and the important studies attempting to identify predictors of non-SN metastases in patients with a tumor-involved SN are reviewed. RESULTS: Standard single-section hematoxylin-eosin (H&E) examination is inadequate for reliable detection of axillary or SN metastases. Large studies appropriately powered to detect a survival difference for patients with micrometastatic disease are reviewed. The current data on the clinical significance of micrometastatic nodal disease is inconclusive. While several strong predictors of non-SN tumor involvement have been identified, none is reliable enough to allow omission of ALND in patients with a tumor-involved SN. CONCLUSIONS: Routine examination of the SN specimen should include serial sections with H&E stain. Ongoing prospective clinical trials should help to define the clinical significance of SN micrometastases. Furthermore, these trials could help identify predictors of non-SN metastasis that would allow a subset of patients with a tumor-involved SN to avoid the morbidity of ALND.

Biophysical characteristics of anti-Gal(alpha)1-3Gal IgM binding to cell surfaces: implications for xenotransplantation.

BACKGROUND: Natural antibodies directed against cell surface carbohydrates are thought to be vital to host defense and to initiate the rejection of xenografts and ABO-incompatible allografts. The biophysical properties underlying the association and dissociation of these antibodies from cell surfaces is incompletely understood. We investigated those properties for the binding of Galalpha1-3Gal antibodies to porcine endothelial cell surfaces, because such interactions might be relevant to the clinical application of xenotransplantation. RESULTS AND CONCLUSIONS: The initial rate of binding of anti-Galalpha1-3Gal antibodies to endothelial cells was found to depend on antibody concentration, antibody diffusion, and antigen concentration. The presence of an intact glycocalyx had a greater impact on antibody binding than mobility of antigen in cell membranes. Disruption of glycocalyx increased the amount of antibody bound at equilibrium by more than 50%. Although the binding of anti-Galalpha1-3Gal antibodies to cell surfaces could be inhibited by soluble Galalpha1-3Gal, once bound, some anti-Galalpha1-3Gal could not be dissociated by competitive inhibitors of binding or by denaturation of the bound Ig with chaotropic reagents, but could be dissociated by reduction of disulfide bonds, suggesting that attachment to cell surfaces was, at least in part, by means other than specific reaction with the epitope.