The prehospital and hospital costs of emergency care for frequent ED patients.

INTRODUCTION: Frequent emergency department (ED) use has been identified as a cause of ED overcrowding and increasing health care costs. Studies have examined the expense of frequent patients (FPs) to hospitals but have not added the cost Emergency Medical Services (EMS) to estimate the total cost of this pattern of care. METHODS: Data on 2012 ED visits to a rural Level I Trauma Center and public safety net hospital were collected through a deidentified patient database. Transport data and 2012 Medicare Reimbursement Schedules were used to estimate the cost of EMS transport. Health information, outcomes, and costs were compared to find differences between the FP and non-FP group. RESULTS: This study identified 1242 FPs who visited the ED 5 or more times in 2012. Frequent patients comprised 3.25% of ED patients but accounted for 17% of ED visits and 13.7% of hospital costs. Frequent patients had higher rates of chronic disease, severity scores, and mortality. Frequent patients arrived more often via ambulance and accounted for 32% of total transports at an estimated cost of $2.5-$3.2 million. Hospital costs attributable to FPs were $29.1 million, bringing the total cost of emergency care to $31.6-$32.3 million, approximately $25,000 per patient. CONCLUSIONS: This study demonstrates that the inclusion of a prehospital cost estimate adds approximately 10% to the cost of care for the FP population. In addition to improving care for a sick population of patients, programs that reduce frequent EMS and ED use have the potential to produce a favorable cost benefit to communities and health systems.

Alternaria alternata allergen Alt a 1: a unique ß-barrel protein dimer found exclusively in fungi.

BACKGROUND: Alternaria species is one of the most common molds associated with allergic diseases, and 80% of Alternaria species-sensitive patients produce IgE antibodies to a major protein allergen, Alt a 1. The structure and function of Alt a 1 is unknown. OBJECTIVE: We sought to obtain a high-resolution structure of Alt a 1 using x-ray crystallography and to investigate structural relationships between Alt a 1 and other allergens and proteins reported in the Protein Data Bank. METHODS: X-ray crystallography was used to determine the structure of Alt a 1 by using a custom-designed set of crystallization conditions. An initial Alt a 1 model was determined by the application of a Ta(6)Br(12)(2+) cluster and single-wavelength anomalous diffraction. Bioinformatic analyses were used to compare the Alt a 1 sequence and structure with that of other proteins. RESULTS: Alt a 1 is a unique ß-barrel comprising 11 ß-strands and forms a "butterfly-like" dimer linked by a single disulfide bond with a large (1345 Å(2)) dimer interface. Intramolecular disulfide bonds are conserved among Alt a 1 homologs. Currently, the Alt a 1 structure has no equivalent in the Protein Data Bank. Bioinformatics analyses suggest that the structure is found exclusively in fungi. Four previously reported putative IgE-binding peptides have been located on the Alt a 1 structure. CONCLUSIONS: Alt a 1 has a unique, dimeric ß-barrel structure that appears to define a new protein family with unknown function found exclusively in fungi. The location of IgE antibody-binding epitopes is in agreement with the structural analysis of Alt a 1. The Alt a 1 structure will allow mechanistic structure/function studies and immunologic studies directed toward new forms of immunotherapy for Alternaria species-sensitive allergic patients.

Structural and immunologic characterization of Ara h 1, a major peanut allergen.

Allergic reactions to peanuts and tree nuts are major causes of anaphylaxis in the United States. We compare different properties of natural and recombinant versions of Ara h 1, a major peanut allergen, through structural, immunologic, and bioinformatics analyses. Small angle x-ray scattering studies show that natural Ara h 1 forms higher molecular weight aggregates in solution. In contrast, the full-length recombinant protein is partially unfolded and exists as a monomer. The crystal structure of the Ara h 1 core (residues 170-586) shows that the central part of the allergen has a bicupin fold, which is in agreement with our bioinformatics analysis. In its crystalline state, the core region of Ara h 1 forms trimeric assemblies, while in solution the protein exists as higher molecular weight assemblies. This finding reveals that the residues forming the core region of the protein are sufficient for formation of Ara h 1 trimers and higher order oligomers. Natural and recombinant variants of proteins tested in in vitro gastric and duodenal digestion assays show that the natural protein is the most stable form, followed by the recombinant Ara h 1 core fragment and the full-length recombinant protein. Additionally, IgE binding studies reveal that the natural and recombinant allergens have different patterns of interaction with IgE antibodies. The molecular basis of cross-reactivity between vicilin allergens is also elucidated.