Multiple models for outbreak decision support in the face of uncertainty.

Policymakers must make management decisions despite incomplete knowledge and conflicting model projections. Little guidance exists for the rapid, representative, and unbiased collection of policy-relevant scientific input from independent modeling teams. Integrating approaches from decision analysis, expert judgment, and model aggregation, we convened multiple modeling teams to evaluate COVID-19 reopening strategies for a mid-sized United States county early in the pandemic. Projections from seventeen distinct models were inconsistent in magnitude but highly consistent in ranking interventions. The 6-mo-ahead aggregate projections were well in line with observed outbreaks in mid-sized US counties. The aggregate results showed that up to half the population could be infected with full workplace reopening, while workplace restrictions reduced median cumulative infections by 82%. Rankings of interventions were consistent across public health objectives, but there was a strong trade-off between public health outcomes and duration of workplace closures, and no win-win intermediate reopening strategies were identified. Between-model variation was high; the aggregate results thus provide valuable risk quantification for decision making. This approach can be applied to the evaluation of management interventions in any setting where models are used to inform decision making. This case study demonstrated the utility of our approach and was one of several multimodel efforts that laid the groundwork for the COVID-19 Scenario Modeling Hub, which has provided multiple rounds of real-time scenario projections for situational awareness and decision making to the Centers for Disease Control and Prevention since December 2020.

Omicron Subvariants: Clinical, Laboratory, and Cell Culture Characterization.

BACKGROUND: The variant of concern Omicron has become the sole circulating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant for the past several months. Omicron subvariants BA.1, BA.2, BA.3, BA.4, and BA.5 evolved over the time, with BA.1 causing the largest wave of infections globally in December 2021-January 2022. This study compared the clinical outcomes in patients infected with different Omicron subvariants and the relative viral loads and recovery of infectious virus from upper respiratory specimens. METHODS: SARS-CoV-2-positive remnant clinical specimens, diagnosed at the Johns Hopkins Microbiology Laboratory between December 2021 and July 2022, were used for whole-genome sequencing. The clinical outcomes of infections with Omicron subvariants were compared with infections with BA.1. Cycle threshold (Ct) values and the recovery of infectious virus on the VeroTMPRSS2 cell line from clinical specimens were compared. RESULTS: BA.1 was associated with the largest increase in SARS-CoV-2 positivity rate and coronavirus disease 2019 (COVID-19)-related hospitalizations at the Johns Hopkins system. After a peak in January, cases decreased in the spring, but the emergence of BA.2.12.1 followed by BA.5 in May 2022 led to an increase in case positivity and admissions. BA.1 infections had a lower mean Ct value when compared with other Omicron subvariants. BA.5 samples had a greater likelihood of having infectious virus at Ct values <20. CONCLUSIONS: Omicron subvariants continue to be associated with a relatively high rate of polymerase chain reaction (PCR) positivity and hospital admissions. The BA.5 infections are more while BA.2 infections are less likely to have infectious virus, suggesting potential differences in infectibility during the Omicron waves.

Epidemiology and Clinical Outcomes of Community-Acquired Acute Kidney Injury in the Emergency Department: A Multisite Retrospective Cohort Study.

RATIONALE & OBJECTIVE: The prevalence of community-acquired acute kidney injury (CA-AKI) in the United States and its clinical consequences are not well described. Our objective was to describe the epidemiology of CA-AKI and the associated clinical outcomes. STUDY DESIGN: Retrospective cohort study. SETTING & PARTICIPANTS: 178,927 encounters by 139,632 adults at 5 US emergency departments (EDs) between July 1, 2017, and December 31, 2022. PREDICTORS: CA-AKI identified using KDIGO (Kidney Disease: Improving Global Outcomes) serum creatinine (Scr)-based criteria. OUTCOMES: For encounters resulting in hospitalization, the in-hospital trajectory of AKI severity, dialysis initiation, intensive care unit (ICU) admission, and death. For all encounters, occurrence over 180 days of hospitalization, ICU admission, new or progressive chronic kidney disease, dialysis initiation, and death. ANALYTICAL APPROACH: Multivariable logistic regression analysis to test the association between CA-AKI and measured outcomes. RESULTS: For all encounters, 10.4% of patients met the criteria for any stage of AKI on arrival to the ED. 16.6% of patients admitted to the hospital from the ED had CA-AKI on arrival to the ED. The likelihood of AKI recovery was inversely related to CA-AKI stage on arrival to the ED. Among encounters for hospitalized patients, CA-AKI was associated with in-hospital dialysis initiation (OR, 6.2; 95% CI, 5.1-7.5), ICU admission (OR, 1.9; 95% CI, 1.7-2.0), and death (OR, 2.2; 95% CI, 2.0-2.5) compared with patients without CA-AKI. Among all encounters, CA-AKI was associated with new or progressive chronic kidney disease (OR, 6.0; 95% CI, 5.6-6.4), dialysis initiation (OR, 5.1; 95% CI, 4.5-5.7), subsequent hospitalization (OR, 1.1; 95% CI, 1.1-1.2) including ICU admission (OR, 1.2; 95% CI, 1.1-1.4), and death (OR, 1.6; 95% CI, 1.5-1.7) during the subsequent 180 days. LIMITATIONS: Residual confounding. Study implemented at a single university-based health system. Potential selection bias related to exclusion of patients without an available baseline Scr measurement. Potential ascertainment bias related to limited repeat Scr data during follow-up after an ED visit. CONCLUSIONS: CA-AKI is a common and important entity that is associated with serious adverse clinical consequences during the 6-month period after diagnosis. PLAIN-LANGUAGE SUMMARY: Acute kidney injury (AKI) is a condition characterized by a rapid decline in kidney function. There are many causes of AKI, but few studies have examined how often AKI is already present when patients first arrive to an emergency department seeking medical attention for any reason. We analyzed approximately 175,000 visits to Johns Hopkins emergency departments and found that AKI is common on presentation to the emergency department and that patients with AKI have increased risks of hospitalization, intensive care unit admission, development of chronic kidney disease, requirement of dialysis, and death in the first 6 months after diagnosis. AKI is an important condition for health care professionals to recognize and is associated with serious adverse outcomes.

Administration of a ß-Lactam Prior to Vancomycin as the First Dose of Antibiotic Therapy Improves Survival in Patients With Bloodstream Infections.

BACKGROUND: Prompt initiation of antibiotic therapy improves the survival of patients with bloodstream infections (BSIs). We sought to determine if the sequence of administration of the first dose of antibiotic therapy (ie, ß-lactam or vancomycin, if both are deemed necessary and cannot be administered simultaneously) impacts early mortality for patients with BSI. METHODS: We conducted a multicenter, observational study of patients ≥13 years with BSIs to evaluate the association of the sequence of antibiotic administration with 7-day mortality using inverse probability of treatment weighting (IPTW) incorporating propensity scores. Propensity scores were generated based on demographics, Pitt bacteremia score, intensive care unit status, highest lactate, highest white blood cell count, Charlson comorbidity index, severe immunocompromise, administration of active empiric therapy, combination therapy, and time from emergency department arrival to first antibiotic dose. RESULTS: Of 3376 eligible patients, 2685 (79.5%) received a ß-lactam and 691 (20.5%) received vancomycin as their initial antibiotic. In the IPTW cohort, exposed and unexposed patients were similar on all baseline variables. Administration of a ß-lactam agent prior to vancomycin protected against 7-day mortality (adjusted odds ratio [aOR], 0.48 [95% confidence interval {CI}, .33-.69]). Similar results were observed when evaluating 48-hour mortality (aOR, 0.45 [95% CI, .24-.83]). Administration of vancomycin prior to a ß-lactam was not associated with improved survival in the subgroup of 524 patients with methicillin-resistant Staphylococcus aureus BSI (aOR, 0.93 [95% CI, .33-2.63]). CONCLUSIONS: For ill-appearing patients likely to be experiencing a BSI, prioritizing administration of a ß-lactam over vancomycin may reduce early mortality, underscoring the significant impact of a relatively simple practice change on improving patient survival.

Latino Household Transmission of Severe Acute Respiratory Syndrome Coronavirus 2.

We assessed temporal changes in the household secondary attack rate of severe acute respiratory syndrome coronavirus 2 and identified risk factors for transmission in vulnerable Latino households of Baltimore, Maryland. The household secondary attack rate was 45.8%, and it appeared to increase as the alpha variant spread, highlighting the magnified risk of spread in unvaccinated populations.

Infection With the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Delta Variant Is Associated With Higher Recovery of Infectious Virus Compared to the Alpha Variant in Both Unvaccinated and Vaccinated Individuals.

BACKGROUND: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant of concern (VOC) B.1.617.2 (Delta) displaced B.1.1.7 (Alpha) and is associated with increases in coronavirus disease 2019 (COVID-19) cases, greater transmissibility, and higher viral RNA loads, but data are lacking regarding the infectious virus load and antiviral antibody levels in the nasal tract. METHODS: Whole genome sequencing, cycle threshold (Ct) values, infectious virus, anti-SARS-CoV-2 immunoglobulin G (IgG) levels, and clinical chart reviews were combined to characterize SARS-CoV-2 lineages circulating in the National Capital Region between January and September 2021 and differentiate infections in vaccinated and unvaccinated individuals by the Delta, Alpha, and B.1.2 (the predominant lineage prior to Alpha) variants. RESULTS: The Delta variant displaced the Alpha variant to constitute 99% of the circulating lineages in the National Capital Region by August 2021. In Delta infections, 28.5% were breakthrough cases in fully vaccinated individuals compared to 4% in the Alpha infected cohort. Breakthrough infections in both cohorts were associated with comorbidities, but only Delta infections were associated with a significant increase in the median days after vaccination. More than 74% of Delta samples had infectious virus compared to <30% from the Alpha cohort. The recovery of infectious virus with both variants was associated with low levels of local SARS-CoV-2 IgG. CONCLUSIONS: Infection with the Delta variant was associated with more frequent recovery of infectious virus in vaccinated and unvaccinated individuals compared to the Alpha variant but was not associated with an increase in disease severity in fully vaccinated individuals. Infectious virus was correlated with the presence of low amounts of antiviral IgG in the nasal specimens.

Evaluation of Metagenomic and Targeted Next-Generation Sequencing Workflows for Detection of Respiratory Pathogens from Bronchoalveolar Lavage Fluid Specimens.

Next-generation sequencing (NGS) workflows applied to bronchoalveolar lavage (BAL) fluid specimens could enhance the detection of respiratory pathogens, although optimal approaches are not defined. This study evaluated the performance of the Respiratory Pathogen ID/AMR (RPIP) kit (Illumina, Inc.) with automated Explify bioinformatic analysis (IDbyDNA, Inc.), a targeted NGS workflow enriching specific pathogen sequences and antimicrobial resistance (AMR) markers, and a complementary untargeted metagenomic workflow with in-house bioinformatic analysis. Compared to a composite clinical standard consisting of provider-ordered microbiology testing, chart review, and orthogonal testing, both workflows demonstrated similar performances. The overall agreement for the RPIP targeted workflow was 65.6% (95% confidence interval, 59.2 to 71.5%), with a positive percent agreement (PPA) of 45.9% (36.8 to 55.2%) and a negative percent agreement (NPA) of 85.7% (78.1 to 91.5%). The overall accuracy for the metagenomic workflow was 67.1% (60.9 to 72.9%), with a PPA of 56.6% (47.3 to 65.5%) and an NPA of 77.2% (68.9 to 84.1%). The approaches revealed pathogens undetected by provider-ordered testing (Ureaplasma parvum, Tropheryma whipplei, severe acute respiratory syndrome coronavirus 2 [SARS-CoV-2], rhinovirus, and cytomegalovirus [CMV]), although not all pathogens detected by provider-ordered testing were identified by the NGS workflows. The RPIP targeted workflow required more time and reagents for library preparation but streamlined bioinformatic analysis, whereas the metagenomic assay was less demanding technically but required complex bioinformatic analysis. The results from both workflows were interpreted utilizing standardized criteria, which is necessary to avoid reporting nonpathogenic organisms. The RPIP targeted workflow identified AMR markers associated with phenotypic resistance in some bacteria but incorrectly identified blaOXA genes in Pseudomonas aeruginosa as being associated with carbapenem resistance. These workflows could serve as adjunctive testing with, but not as a replacement for, standard microbiology techniques.

Decreased Use of Broad-Spectrum Antibiotics During the Coronavirus Disease 2019 Epidemic in South Korea.

BACKGROUND: Early in the coronavirus disease 2019 (COVID-19) pandemic, there was a concern over possible increase in antibiotic use due to coinfections among COVID-19 patients in the community. Here, we evaluate the changes in nationwide use of broad-spectrum antibiotics during the COVID-19 epidemic in South Korea. METHODS: We obtained national reimbursement data on the prescription of antibiotics, including penicillin with ß-lactamase inhibitors, cephalosporins, fluoroquinolones, and macrolides. We examined the number of antibiotic prescriptions compared with the previous 3 years in the same period from August to July. To quantify the impact of the COVID-19 epidemic on antibiotic use, we developed a regression model adjusting for changes of viral acute respiratory tract infections (ARTIs), which are an important factor driving antibiotic use. RESULTS: During the COVID-19 epidemic in South Korea, the broad-spectrum antibiotic use dropped by 15%-55% compared to the previous 3 years. Overall reduction in antibiotic use adjusting for ARTIs was estimated to be 14%-30%, with a larger impact in children. CONCLUSIONS: Our study found that broad-spectrum antibiotic use was substantially reduced during the COVID-19 epidemic in South Korea. This reduction can be in part due to reduced ARTIs as a result of stringent public health interventions including social distancing measures.

Racial and ethnic disparities in hospital observation in Maryland.

OBJECTIVES: Hospital observation is a key disposition option from the emergency department (ED) and encompasses up to one third of patients requiring post-ED care. Observation has been associated with higher incidence of catastrophic financial costs and has downstream effects on post-discharge clinical services. Yet little is known about the non-clinical determinants of observation assignment. We sought to evaluate the impact of patient-level demographic factors on observation designation among Maryland patients. METHODS: We conducted a retrospective analysis of all ED encounters in Maryland between July 2012 and January 2017 for four priority diagnoses (heart failure, chronic obstructive pulmonary disease [COPD], pneumonia, and acute chest pain) using multilevel logistic models allowing for heterogeneity of the effects across hospitals. The primary exposure was self-reported race and ethnicity. The primary outcome was the initial status assignment from the ED: hospital observation versus inpatient admission. RESULTS: Across 46 Maryland hospitals, 259,788 patient encounters resulted in a disposition of inpatient admission (65%) or observation designation (35%). Black (adjusted odds ratio [aOR]: 1.19; 95% confidence interval [CI]: 1.16-1.23) and Hispanic (aOR: 1.11; 95% CI: 1.01-1.21) patients were significantly more likely to be placed in observation than white, non-Hispanic patients. These differences were consistent across the majority of acute-care hospitals in Maryland (27/46). CONCLUSION: Black and Hispanic patients in Maryland are more likely to be treated under the observation designation than white, non-Hispanic patients independent of clinical presentation. Race agnostic, time-based status assignments may be key in eliminating these disparities.

Resource utilization across the continuum of HIV care: An emergency department-based cohort study.

BACKGROUND: The objective of this study was to determine the healthcare resource utilization for people living with HIV (PLWH) presenting to the emergency department (ED) across the HIV Care Continuum. METHODS: This prospective study enrolled PLWH presenting to an urban ED between June 2016 and March 2017. Subjects were categorized as being linked to care, retained in care, on antiretroviral therapy (ART), and virally suppressed (<200 copies/ml). Data on ED visit rates, duration of stay, and hospital admission rates were compared to local metrics. RESULTS: Overall, 94.3% of 159 enrollees had been linked to care, 75.5% retained in care, 81.1% on ART, and 62.8% virally suppressed. Compared to the general population of the city and of the ED, participants had a higher ED visit rate (3.0 v. 1.2 visits per person-per year) in the past two years, a higher median duration of ED stay (12.6 v. 7.6 h), and a higher hospital admission rate (36.5% v. 24.9%) during their index ED visit. Viral suppression was negatively associated with admission (OR = 0.35, 95% CI: 0.17, 0.72). Forty-eight (30.2%) participants who had at least eight ED visits in the past two years were more likely to have a diagnosed mental health disorder (79.2% v. 62.2%, p=0.036). CONCLUSIONS: Our results showed that PLWH use more ED resources than the general population and a better engagement in HIV care is linked to lesser ED resource utilization for PLWH, indicating the importance of improved HIV care engagement in healthcare utilization management.

Global increase and geographic convergence in antibiotic consumption between 2000 and 2015.

Tracking antibiotic consumption patterns over time and across countries could inform policies to optimize antibiotic prescribing and minimize antibiotic resistance, such as setting and enforcing per capita consumption targets or aiding investments in alternatives to antibiotics. In this study, we analyzed the trends and drivers of antibiotic consumption from 2000 to 2015 in 76 countries and projected total global antibiotic consumption through 2030. Between 2000 and 2015, antibiotic consumption, expressed in defined daily doses (DDD), increased 65% (21.1-34.8 billion DDDs), and the antibiotic consumption rate increased 39% (11.3-15.7 DDDs per 1,000 inhabitants per day). The increase was driven by low- and middle-income countries (LMICs), where rising consumption was correlated with gross domestic product per capita (GDPPC) growth (P = 0.004). In high-income countries (HICs), although overall consumption increased modestly, DDDs per 1,000 inhabitants per day fell 4%, and there was no correlation with GDPPC. Of particular concern was the rapid increase in the use of last-resort compounds, both in HICs and LMICs, such as glycylcyclines, oxazolidinones, carbapenems, and polymyxins. Projections of global antibiotic consumption in 2030, assuming no policy changes, were up to 200% higher than the 42 billion DDDs estimated in 2015. Although antibiotic consumption rates in most LMICs remain lower than in HICs despite higher bacterial disease burden, consumption in LMICs is rapidly converging to rates similar to HICs. Reducing global consumption is critical for reducing the threat of antibiotic resistance, but reduction efforts must balance access limitations in LMICs and take account of local and global resistance patterns.

Early Prediction of Acute Kidney Injury in the Emergency Department With Machine-Learning Methods Applied to Electronic Health Record Data.

STUDY OBJECTIVE: Acute kidney injury occurs commonly and is a leading cause of prolonged hospitalization, development and progression of chronic kidney disease, and death. Early acute kidney injury treatment can improve outcomes. However, current decision support is not able to detect patients at the highest risk of developing acute kidney injury. We analyzed routinely collected emergency department (ED) data and developed prediction models with capacity for early identification of ED patients at high risk for acute kidney injury. METHODS: A multisite, retrospective, cross-sectional study was performed at 3 EDs between January 2014 and July 2017. All adult ED visits in which patients were hospitalized and serum creatinine level was measured both on arrival and again with 72 hours were included. We built machine-learning-based classifiers that rely on vital signs, chief complaints, medical history and active medical visits, and laboratory results to predict the development of acute kidney injury stage 1 and 2 in the next 24 to 72 hours, according to creatinine-based international consensus criteria. Predictive performance was evaluated out of sample by Monte Carlo cross validation. RESULTS: The final cohort included 91,258 visits by 59,792 unique patients. Seventy-two-hour incidence of acute kidney injury was 7.9% for stages greater than or equal to 1 and 1.0% for stages greater than or equal to 2. The area under the receiver operating characteristic curve for acute kidney injury prediction ranged from 0.81 (95% confidence interval 0.80 to 0.82) to 0.74 (95% confidence interval 0.74 to 0.75), with a median time from ED arrival to prediction of 1.7 hours (interquartile range 1.3 to 2.5 hours). CONCLUSION: Machine learning applied to routinely collected ED data identified ED patients at high risk for acute kidney injury up to 72 hours before they met diagnostic criteria. Further prospective evaluation is necessary.

Risk of Acute Kidney Injury Associated With Medication Administration in the Emergency Department.

BACKGROUND: Patients who develop acute kidney injury (AKI) have a 2-fold increased risk for major adverse events within 1 year. An estimated 19-26% of all cases of hospital-acquired AKI may be attributable to drug-induced kidney disease (DIKD). Patients evaluated in the emergency department (ED) are often prescribed potentially nephrotoxic drugs, yet the role of ED prescribing in DIKD is unknown. OBJECTIVE: We sought to measure the association between ED medication administration and development of AKI. METHODS: This was a retrospective 5-year cohort analysis at a single center. Patients with a serum creatinine measurement at presentation in the ED and 24-168 h later were included. Outcome was incidence of AKI as defined by Kidney Disease Improving Global Outcomes criteria in the 7 days after ED evaluation. Medication administration risk was estimated using Cox proportional hazards model. RESULTS: There were 46,965 ED encounters by 30,407 patients included in the study, of which 6461 (13.8%) patients met the criteria for AKI. For hospitalized patients, administration of a potentially nephrotoxic medication was associated with increased risk of AKI (hazard ratio [HR] 1.30 [95% confidence interval {CI} 1.20-1.41]). Diuretics were associated with the largest risk of AKI (HR 1.64 [95% CI 1.52-1.78]), followed by angiotensin-converting enzyme inhibitors (HR 1.39 [95% CI 1.26-1.54]) and antibiotics (HR 1.13 [95% CI 1.05-1.22]). For discharged patients, administration of antibiotics was strongly associated with increased risk of AKI (HR 3.19 [95% CI 1.08-9.43]). CONCLUSION: ED administration of potentially nephrotoxic medications was associated with an increased risk of AKI in the following 7 days. Diuretics, angiotensin-converting enzyme inhibitors, and antibiotics were independently associated with increased risk of AKI. Nephroprotective practices in the ED may mitigate kidney injury and long-term adverse outcomes.

National Costs Associated With Methicillin-Susceptible and Methicillin-Resistant Staphylococcus aureus Hospitalizations in the United States, 2010-2014.

Background: Infections caused by methicillin-resistant Staphylococcus aureus (MRSA) have been associated with worse patient outcomes and higher costs of care than methicillin-susceptible (MSSA) infections. However, since prior studies found these differences, the healthcare landscape has changed, including widespread dissemination of community-associated strains of MRSA. We sought to provide updated estimates of the excess costs of MRSA infections. Methods: We conducted a retrospective analysis using data from the National Inpatient Sample from the Agency for Healthcare Research and Quality for the years 2010-2014. We calculated costs for hospitalizations, including MRSA- and MSSA-related septicemia and pneumonia infections, as well as MRSA- and MSSA-related infections from conditions classified elsewhere and of an unspecified site ("other infections"). Differences in the costs of hospitalization were estimated using propensity score-adjusted mortality outcomes for 2010-2014. Results: In 2014, estimated costs were highest for pneumonia and sepsis-related hospitalizations. Propensity score-adjusted costs were significantly higher for MSSA-related pneumonia ($40725 vs $38561; P = .045) and other hospitalizations ($15578 vs $14792; P < .001) than for MRSA-related hospitalizations. Similar patterns were observed from 2010 to 2013, although crude cost differences between MSSA- and MRSA-related pneumonia hospitalizations rose from 25.8% in 2010 to 31.0% in 2014. Compared with MSSA-related hospitalizations, MRSA-related hospitalizations had a higher adjusted mortality rate. Conclusions: Although MRSA infections had been previously associated with higher hospitalization costs, our results suggest that, in recent years, costs associated with MSSA-related infections have converged with and may surpass costs of similar MRSA-related hospitalizations.

The Mortality Burden of Multidrug-resistant Pathogens in India: A Retrospective, Observational Study.

BACKGROUND: The threat posed by antibiotic resistance is of increasing concern in low- and middle-income countries (LMICs) as their rates of antibiotic use increase. However, an understanding of the burden of resistance is lacking in LMICs, particularly for multidrug-resistant (MDR) pathogens. METHODS: We conducted a retrospective, 10-hospital study of the relationship between MDR pathogens and mortality in India. Patient-level antimicrobial susceptibility test (AST) results for Enterococcus spp., Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp. were analyzed for their association with patient mortality outcomes. RESULTS: We analyzed data on 5103 AST results from 10 hospitals. The overall mortality rate of patients was 13.1% (n = 581), and there was a significant relationship between MDR and mortality. Infections with MDR and extensively drug resistant (XDR) E. coli, XDR K. pneumoniae, and MDR A. baumannii were associated with 2-3 times higher mortality. Mortality due to methicillin-resistant S. aureus (MRSA) was significantly higher than susceptible strains when the MRSA isolate was resistant to aminoglycosides. CONCLUSIONS: This is one of the largest studies undertaken in an LMIC to measure the burden of antibiotic resistance. We found that MDR bacterial infections pose a significant risk to patients. While consistent with prior studies, the variations in drug resistance and associated mortality outcomes by pathogen are different from those observed in high-income countries and provide a baseline for studies in other LMICs. Future research should aim to elucidate the burden of resistance and the differential transmission mechanisms that drive this public health crisis.

Emergency Department Utilization Among the Uninsured During Insurance Expansion in Maryland.

STUDY OBJECTIVE: We analyzed the effect of insurance expansion on emergency department (ED) utilization among the uninsured in Maryland, which expanded Medicaid eligibility and created health insurance exchanges in 2014. METHODS: This was a retrospective analysis of statewide administrative claims for July 2012 to December 2015. We used coarsened exact matching to pair uninsured and insured (Medicaid, Medicare, commercial, and other) adult Maryland residents who visited an ED or were hospitalized at baseline (July 2012 to December 2013). We compared ED utilization between these groups after insurance expansion (January 2014 to December 2015), using a difference-in-differences quasi-experimental design. Nonreturning patients from the baseline period were included in the post-insurance expansion rates as having zero visits. RESULTS: Matching yielded 178,381 pairs. In the 12 months before insurance expansion, the baseline uninsured group visited the ED at a rate of 26.1 per 100 patient-quarters versus 28.2 among the insured group (relative rate=0.93). In the 24 months after insurance expansion, 45% of the baseline uninsured returned to an ED, of whom 33% returned uninsured, 40% returned with Medicaid, and 21% returned with commercial insurance. After insurance expansion, with 55% of patients in each group not returning, the ED visit rate for both the baseline uninsured and insured groups was 15.9 per 100 patient-quarters (relative rate=1.00). This 8% relative increase from baseline in ED visits among the uninsured group was driven primarily by increases in higher-acuity visits. Uninsured patients from high-poverty zip codes (N=34,964 pairs) increased their ED utilization by 15% after insurance expansion, whereas baseline uninsured patients with no comorbidities (N=94,330 pairs) showed a 3% decrease. CONCLUSION: Insurance expansion in Maryland was associated with a modest relative increase in ED visits among the uninsured, driven by increases in higher-acuity visits. It remains unclear whether insurance coverage helped the uninsured address their unmet medical needs.

Is Antimicrobial Resistance a Bigger Problem in Tertiary Care Hospitals Than in Small Community Hospitals in the United States?

Large tertiary care hospitals (TCHs) are thought to have higher antimicrobial resistance (AMR) rates when compared to small community hospitals (SCHs) as they provide care to patients with higher disease severity. However, we found no systematic differences in AMR rates between TCHs and SCHs in the United States.

Trends in Methicillin-Resistant Staphylococcus aureus Hospitalizations in the United States, 2010-2014.

Data from the National Inpatient Sample show that the decrease in hospitalizations related to methicillin-resistant Staphylococcus aureus (MRSA) infections between 2010 and 2014 primarily reflected declines in skin and soft tissue infections. Hospitalizations related to invasive MRSA remained largely unchanged.

Categorical Risk Perception Drives Variability in Antibiotic Prescribing in the Emergency Department: A Mixed Methods Observational Study.

BACKGROUND: Adherence to evidence-based antibiotic therapy guidelines for treatment of upper respiratory tract infections (URIs) varies widely among clinicians. Understanding this variability is key for reducing inappropriate prescribing. OBJECTIVE: To measure how emergency department (ED) clinicians' perceptions of antibiotic prescribing risks affect their decision-making. DESIGN: Clinician survey based on fuzzy-trace theory, a theory of medical decision-making, combined with retrospective data on prescribing outcomes for URI/pneumonia visits in two EDs. The survey predicts the categorical meanings, or gists, that individuals derive from given information. PARTICIPANTS: ED physicians, residents, and physician assistants (PAs) who completed surveys and treated patients with URI/pneumonia diagnoses between August 2014 and December 2015. MAIN MEASURES: Gists derived from survey responses and their association with rates of antibiotic prescribing per visit. KEY RESULTS: Of 4474 URI/pneumonia visits, 2874 (64.2%) had an antibiotic prescription. However, prescribing rates varied from 7% to 91% for the 69 clinicians surveyed (65.2% response rate). Clinicians who framed therapy-prescribing decisions as a categorical choice between continued illness and possibly beneficial treatment ("why not take a risk?" gist, which assumes antibiotic therapy is essentially harmless) had higher rates of prescribing (OR 1.28 [95% CI, 1.06-1.54]). Greater agreement with the "antibiotics may be harmful" gist was associated with lower prescribing rates (OR 0.81 [95% CI, 0.67-0.98]). CONCLUSIONS: Our results indicate that clinicians who perceive prescribing as a categorical choice between patients remaining ill or possibly improving from therapy are more likely to prescribe antibiotics. However, this strategy assumes that antibiotics are essentially harmless. Clinicians who framed decision-making as a choice between potential harms from therapy and continued patient illness (e.g., increased appreciation of potential harms) had lower prescribing rates. These results suggest that interventions to reduce inappropriate prescribing should emphasize the non-negligible possibility of serious side effects.

The Effect of Medicaid Expansion on Utilization in Maryland Emergency Departments.

STUDY OBJECTIVE: A proposed benefit of expanding Medicaid eligibility under the Patient Protection and Affordable Care Act (ACA) was a reduction in emergency department (ED) utilization for primary care needs. Pre-ACA studies found that new Medicaid enrollees increased their ED utilization rates, but the effect on system-level ED visits was less clear. Our objective was to estimate the effect of Medicaid expansion on aggregate and individual-based ED utilization patterns within Maryland. METHODS: We performed a retrospective cross-sectional study of ED utilization patterns across Maryland, using data from Maryland's Health Services Cost Review Commission. We also analyzed utilization differences between pre-ACA (July 2012 to December 2013) uninsured patients who returned post-ACA (July 2014 to December 2015). RESULTS: The total number of ED visits in Maryland decreased by 36,531 (-1.2%) between the 6 quarters pre-ACA and the 6 quarters post-ACA. Medicaid-covered ED visits increased from 23.3% to 28.9% (159,004 additional visits), whereas uninsured patient visits decreased from 16.3% to 10.4% (181,607 fewer visits). Coverage by other insurance types remained largely stable between periods. We found no significant relationship between Medicaid expansion and changes in ED volume by hospital. For patients uninsured pre-ACA who returned post-ACA, the adjusted visits per person during 6 quarters was 2.38 (95% confidence interval 2.35 to 2.40) for those newly enrolled in Medicaid post-ACA compared with 1.66 (95% confidence interval 1.64 to 1.68) for those remaining uninsured. CONCLUSION: There was a substantial increase in patients covered by Medicaid in the post-ACA period, but this did not significantly affect total ED volume. Returning patients newly enrolled in Medicaid visited the ED more than their uninsured counterparts; however, this cohort accounted for only a small percentage of total ED visits in Maryland.