Yeohan Song

Social Network Analysis of Patient Sharing Among Hospitals in Orange County, California

OBJECTIVES We applied social network analyses to determine how hospitals within Orange County, California, are interconnected by patient sharing, a system which may have numerous public health implications. METHODS Our analyses considered 2 general patient-sharing networks: uninterrupted patient sharing (UPS; i.e., direct interhospital transfers) and total patient sharing (TPS; i.e., all interhospital patient sharing, including patients with intervening nonhospital stays). We considered these networks at 3 thresholds of patient sharing: at least 1, at least 10, and at least 100 patients shared. RESULTS Geographically proximate hospitals were somewhat more likely to share patients, but many hospitals shared patients with distant hospitals. Number of patient admissions and percentage of cancer patients were associated with greater connectivity across the system. The TPS network revealed numerous connections not seen in the UPS network, meaning that direct transfers only accounted for a fraction of total patient sharing. CONCLUSIONS Our analysis demonstrated that Orange Countys 32 hospitals were highly and heterogeneously interconnected by patient sharing. Different hospital populations had different levels of influence over the patient-sharing network.

Universal Methicillin‐Resistant Staphylococcus aureus (MRSA) Surveillance for Adults at Hospital Admission: An Economic Model and Analysis

BACKGROUND Methicillin-resistant Staphylococcus aureus (MRSA) transmission and infections are a continuing problem in hospitals. Although some have recommended universal surveillance for MRSA at hospital admission to identify and to isolate MRSA-colonized patients, there is a need for formal economic studies to determine the cost-effectiveness of such a strategy. METHODS We developed a stochastic computer simulation model to determine the potential economic impact of performing MRSA surveillance (ie, single culture of an anterior nares specimen) for all hospital admissions at different MRSA prevalences and basic reproductive rate thresholds from the societal and third party-payor perspectives. Patients with positive surveillance culture results were placed under isolation precautions to prevent transmission by way of respiratory droplets. MRSA-colonized patients who were not isolated could transmit MRSA to other hospital patients. RESULTS The performance of universal MRSA surveillance was cost-effective (defined as an incremental cost-effectiveness ratio of less than

Modeling the Spread of Methicillin-Resistant Staphylococcus aureus (MRSA) Outbreaks throughout the Hospitals in Orange County, California

50,000 per quality-adjusted life-year) when the basic reproductive rate was 0.25 or greater and the prevalence was 1% or greater. In fact, surveillance was the dominant strategy when the basic reproductive rate was 1.5 or greater and the prevalence was 15% or greater, the basic reproductive rate was 2.0 or greater and the prevalence was 10% or greater, and the basic reproductive rate was 2.5 or greater and the prevalence was 5% or greater. CONCLUSIONS Universal MRSA surveillance of adults at hospital admission appears to be cost-effective at a wide range of prevalence and basic reproductive rate values. Individual hospitals and healthcare systems could compare their prevailing conditions (eg, the prevalence of MRSA colonization and MRSA transmission dynamics) with the benchmarks in our model to help determine their optimal local strategies.

Epidemiologic and Economic Effect of Methicillin-resistant Staphylococcus aureus in Obstetrics

BACKGROUND Since hospitals in a region often share patients, an outbreak of methicillin-resistant Staphylococcus aureus (MRSA) infection in one hospital could affect other hospitals. METHODS Using extensive data collected from Orange County (OC), California, we developed a detailed agent-based model to represent patient movement among all OC hospitals. Experiments simulated MRSA outbreaks in various wards, institutions, and regions. Sensitivity analysis varied lengths of stay, intraward transmission coefficients (β), MRSA loss rate, probability of patient transfer or readmission, and time to readmission. RESULTS Each simulated outbreak eventually affected all of the hospitals in the network, with effects depending on the outbreak size and location. Increasing MRSA prevalence at a single hospital (from 5% to 15%) resulted in a 2.9% average increase in relative prevalence at all other hospitals (ranging from no effect to 46.4%). Single-hospital intensive care unit outbreaks (modeled increase from 5% to 15%) caused a 1.4% average relative increase in all other OC hospitals (ranging from no effect to 12.7%). CONCLUSION MRSA outbreaks may rarely be confined to a single hospital but instead may affect all of the hospitals in a region. This suggests that prevention and control strategies and policies should account for the interconnectedness of health care facilities.

Long-Term Care Facilities: Important Participants of the Acute Care Facility Social Network?

OBJECTIVE: To quantify the epidemiologic and economic burden of methicillin-resistant Staphylococcus aureus (MRSA) infections in the obstetric population, identify main factors influencing the magnitude of disease, and evaluate the cost-effectiveness of MRSA screening and decolonization. METHODS: A cost-effectiveness decision analytic model was constructed for estimations from both the societal and third party–payer perspectives. Probabilities were derived from prior studies when available. Cost data came from the Healthcare Cost and Utilization Project, medication wholesale prices, and the Centers for Medicare & Medicaid Services. Sensitivity analysis was conducted to assess the effect of variables across a range of values. RESULTS: Approximately 14,294 pregnant or postpartum women experience an invasive MRSA infection in the United States annually. The majority of invasive MRSA infections are mastitis (n=8,880). The annual economic effect of MRSA infections is projected to be approximately

The Potential Economic Value of a Staphylococcus aureus Vaccine among Hemodialysis Patients

8.7 million and approximately

Quantifying Interhospital Patient Sharing as a Mechanism for Infectious Disease Spread

8.0 million from the societal and payer perspectives, respectively. Sensitivity analyses demonstrate that the prevalence of MRSA, incidence of mastitis, and rate of cesarean deliveries were key driving factors for the estimations. CONCLUSION: Methicillin-resistant S aureus is an important emerging pathogen responsible for a modest burden of puerperal infections and associated costs. Universal screening and decolonization efforts do not currently seem to be cost-effective. LEVEL OF EVIDENCE: III

Simulation Shows Hospitals That Cooperate On Infection Control Obtain Better Results Than Hospitals Acting Alone

Background Acute care facilities are connected via patient sharing, forming a network. However, patient sharing extends beyond this immediate network to include sharing with long-term care facilities. The extent of long-term care facility patient sharing on the acute care facility network is unknown. The objective of this study was to characterize and determine the extent and pattern of patient transfers to, from, and between long-term care facilities on the network of acute care facilities in a large metropolitan county. Methods/Principal Findings We applied social network constructs principles, measures, and frameworks to all 2007 annual adult and pediatric patient transfers among the healthcare facilities in Orange County, California, using data from surveys and several datasets. We evaluated general network and centrality measures as well as individual ego measures and further constructed sociograms. Our results show that over the course of a year, 66 of 72 long-term care facilities directly sent and 67 directly received patients from other long-term care facilities. Long-term care facilities added 1,524 ties between the acute care facilities when ties represented at least one patient transfer. Geodesic distance did not closely correlate with the geographic distance among facilities. Conclusions/Significance This study demonstrates the extent to which long-term care facilities are connected to the acute care facility patient sharing network. Many long-term care facilities were connected by patient transfers and further added many connections to the acute care facility network. This suggests that policy-makers and health officials should account for patient sharing with and among long-term care facilities as well as those among acute care facilities when evaluating policies and interventions.

The Regional Healthcare Ecosystem Analyst (RHEA): a simulation modeling tool to assist infectious disease control in a health system

Staphylococcus aureus infections are a substantial problem for hemodialysis patients. Several vaccine candidates are currently under development, with hemodialysis patients being one possible target population. To determine the potential economic value of an S. aureus vaccine among hemodialysis patients, we developed a Markov decision analytic computer simulation model. When S. aureus colonization prevalence was 1%, the incremental cost-effectiveness ratio (ICER) of vaccination was ≤

Modeling the regional spread and control of vancomycin-resistant enterococci

25,217/quality-adjusted life year (QALY). Vaccination became more cost-effective as colonization prevalence, vaccine efficacy, or vaccine protection duration increased or vaccine cost decreased. Even at 10% colonization prevalence, a 25% efficacious vaccine costing