Society of General Internal Medicine Position Statement on Social Risk and Equity in Medicare's Mandatory Value-Based Payment Programs.

The Affordable Care Act (2010) and Medicare Access and CHIP Reauthorization Act (2015) ushered in a new era of Medicare value-based payment programs. Five major mandatory pay-for-performance programs have been implemented since 2012 with increasing positive and negative payment adjustments over time. A growing body of evidence indicates that these programs are inequitable and financially penalize safety-net systems and systems that care for a higher proportion of racial and ethnic minority patients. Payments from penalized systems are often redistributed to those with higher performance scores, which are predominantly better-financed, large, urban systems that serve less vulnerable patient populations - a "Reverse Robin Hood" effect. This inequity may be diminished by adjusting for social risk factors in payment policy. In this position statement, we review the literature evaluating equity across Medicare value-based payment programs, major policy reports evaluating the use of social risk data, and provide recommendations on behalf of the Society of General Internal Medicine regarding how to address social risk and unmet health-related social needs in these programs. Immediate recommendations include implementing peer grouping (stratification of healthcare systems by proportion of dual eligible Medicare/Medicaid patients served, and evaluation of performance and subsequent payment adjustments within strata) until optimal methods for accounting for social risk are defined. Short-term recommendations include using census-based, area-level indices to account for neighborhood-level social risk, and developing standardized approaches to collecting individual socioeconomic data in a robust but sensitive way. Long-term recommendations include implementing a research agenda to evaluate best practices for accounting for social risk, developing validated health equity specific measures of care, and creating policies to better integrate healthcare and social services.

Metastatic melanoma of unknown origin mimicking neurofibromatosis.

We present an unusual case of metastatic melanoma in a young patient with imaging appearance resembling neurofibromatosis. A 36-year-old-man with a history of cervical radiculopathy presented with cauda equina syndrome. An MRI was performed for further evaluation demonstrating multiple intradural, extramedullary enhancing lesions in the thoracic and lumbar spine, as well as extra-axial enhancing lesions with involvement of the lateral ventricles and posterior fossa. Bilateral pulmonary masses were found on chest CT. Lung lesions were biopsied and positive for metastatic melanoma. Melanoma is the third most common primary neoplasm to produce brain metastasis and should be considered on the differential as a cause of newly detected intracranial and intraspinal masses in young patients.

Sialic acid recognition is a key determinant of influenza A virus tropism in murine trachea epithelial cell cultures.

Influenza A virus interacts with specific types of sialic acid during attachment and entry into susceptible cells. The precise amino acids in the hemagglutinin protein that control sialic acid binding specificity and affinity vary among antigenic subtypes. For H3 subtypes, amino acids 226 and 228 are critical for differentiating between alpha2,3- and alpha2,6-linked forms of sialic acid (SA). We demonstrate that position 190 of the HA from A/Udorn/307/72 (H3N2) plays an important role in the recognition of alpha2,3-SA, as changing the residue from a glutamic acid to an aspartic acid led to alteration of red blood cell hemagglutination and a complete loss of replication in differentiated, murine trachea epithelial cell cultures which express only alpha2,3-SA. This amino acid change had a minimal effect on virus replication in MDCK cells, suggesting subtle changes in receptor recognition by the H3 hemagglutinin can lead to significant alterations in cell and species tropism.

The RNA binding domain of influenza A virus NS1 protein affects secretion of tumor necrosis factor alpha, interleukin-6, and interferon in primary murine tracheal epithelial cells.

Primary differentiated respiratory epithelial cell cultures closely model the in vivo environment and allow for studies of innate immune responses generated specifically by epithelial cells, the primary cell type infected by human influenza A virus strains. We used primary murine tracheal epithelial cell (mTEC) cultures to investigate antiviral and cytokine responses to influenza A virus infection, focusing on the contribution of the RNA binding domain of the NS1 protein. rWSN NS1 R38A replication is attenuated in mTEC cultures; however, viral antigen is detected predominantly in ciliated cells, similar to wild-type virus. NS1 and NS1 R38A proteins display a primarily cytoplasmic localization in infected mTEC cultures. Increased production of tumor necrosis factor alpha, interleukin-6, and beta interferon is observed during rWSN NS1 R38A infection, and cytokines are secreted in a directional manner. Cytokine pretreatment of mTEC cultures and Vero cells suggest that rWSN NS1 R38A is more sensitive to the presence of antiviral/inflammatory cytokines than wild-type virus. Our results demonstrate that the RNA binding domain is a critical regulator of both cytokine production and cytokine sensitivity during influenza A virus infection of primary tracheal epithelial cells.

Influenza A virus infection of primary differentiated airway epithelial cell cultures derived from Syrian golden hamsters.

The ability of several different influenza A virus strains to infect and replicate in primary, differentiated airway epithelial cell cultures from Syrian golden hamsters was investigated. All virus strains tested replicated equivalently in the cultures and displayed a preference for infecting nonciliated cells. This tropism correlated with the expression of both alpha2,3- and alpha2,6-linked sialic acid on the nonciliated cells. In contrast, the ciliated cells did not have detectable alpha2,6-linked sialic acid and expressed only low amounts of alpha2,3-linked sialic acid. In contrast to clinical isolates, laboratory strains of influenza A virus infected a limited number of ciliated cells at late times post-infection. The presence of alpha2,3- and alpha2,6-linked sialic acid residues on the same cell type suggests that Syrian golden hamsters and differentiated airway epithelial cell cultures derived from hamsters may provide a system for studying the reassortment of influenza A virus strains which utilize different forms of sialic acid as a primary virus receptor.

Influenza virus receptor specificity and cell tropism in mouse and human airway epithelial cells.

Recent human infections caused by the highly pathogenic avian influenza virus H5N1 strains emphasize an urgent need for assessment of factors that allow viral transmission, replication, and intra-airway spread. Important determinants for virus infection are epithelial cell receptors identified as glycans terminated by an alpha2,3-linked sialic acid (SA) that preferentially bind avian strains and glycans terminated by an alpha2,6-linked SA that bind human strains. The mouse is often used as a model for study of influenza viruses, including recent avian strains; however, the selectivity for infection of specific respiratory cell populations is not well described, and any relationship between receptors in the mouse and human lungs is incompletely understood. Here, using in vitro human and mouse airway epithelial cell models and in vivo mouse infection, we found that the alpha2,3-linked SA receptor was expressed in ciliated airway and type II alveolar epithelial cells and was targeted for cell-specific infection in both species. The alpha2,6-linked SA receptor was not expressed in the mouse, a factor that may contribute to the inability of some human strains to efficiently infect the mouse lung. In human airway epithelial cells, alpha2,6-linked SA was expressed and functional in both ciliated and goblet cells, providing expanded cellular tropism. Differences in receptor and cell-specific expression in these species suggest that differentiated human airway epithelial cell cultures may be superior for evaluation of some human strains, while the mouse can provide a model for studying avian strains that preferentially bind only the alpha2,3-linked SA receptor.

Dendritic cells respond to influenza virus through TLR7- and PKR-independent pathways.

Natural interferon-producing cells (IPC) secrete type I IFN (IFN-alpha and -beta) in response to influenza virus. This process is independent of viral replication and is mediated by Toll-like receptor 7 (TLR7), which recognizes single-stranded RNA (ssRNA). DC also express TLR7 but its function in DC response to influenza virus is unknown. To address this, we compared the DC and IPC responses to influenza virus and ssRNA oligoribonucleotides (ORN) that activate TLR7. When stimulated by ORN in vitro and in vivo, DC matured and produced inflammatory cytokines but not IFN-alpha. DC did secrete IFN-alpha in response to influenza virus. However, this response was independent of TLR7 signaling and required viral replication but not dsRNA-activated protein kinase (PKR). We conclude that DC and IPC are hard-wired to secrete IFN-alpha via different pathways, reflecting their complementary but distinct roles in anti-viral immunity.