Karen F. Miller

Decreasing Lab Turnaround Time Improves Emergency Department Throughput and Decreases Emergency Medical Services Diversion: A Simulation Model

BACKGROUND The effect of decreasing lab turnaround times on emergency department (ED) efficiency can be estimated through system-level simulation models and help identify important outcome measures to study prospectively. Furthermore, such models may suggest the advantage of bedside or point-of-care testing and how they might affect efficiency measures. OBJECTIVES The authors used a sophisticated simulation model in place at an adult urban ED with an annual census of 55,000 patient visits. The effect of decreasing turnaround times on emergency medical services (EMS) diversion, ED patient throughput, and total ED length of stay (LOS) was determined. METHODS Data were generated by using system dynamics analytic modeling and simulation approach on 90 separate days from December 2, 2007, through February 29, 2008. The model was a continuous simulation of ED flow, driven by real-time actual patient data, and had intrinsic error checking to assume reasonable goodness-of-fit. A return of complete laboratory results incrementally at 120, 100, 80, 60, 40, 20, and 10 minutes was compared. Diversion calculation assumed EMS closure when more than 10 patients were in the waiting room and 100% ED bed occupancy had been reached for longer than 30 minutes, as per local practice. LOS was generated from data insertion into the patient flow stream and calculation of time to specific predefined gates. The average accuracy of four separate measurement channels (waiting room volume, ED census, inpatient admit stream, and ED discharge stream), all across 24 hours, was measured by comparing the area under the simulated curve against the area under the measured curve. Each channels accuracy was summed and averaged for an overall accuracy rating. RESULTS As lab turnaround time decreased from 120 to 10 minutes, the total number of diversion days (maximum 57 at 120 minutes, minimum 29 at 10 minutes), average diversion hours per day (10.8 hours vs. 6.0 hours), percentage of days with diversion (63% vs. 32%), and average ED LOS (2.77 hours vs. 2.17 hours) incrementally decreased, while average daily throughput (104 patients vs. 120 patients) increased. All runs were at least 85% accurate. CONCLUSIONS This simulation model suggests compelling improvement in ED efficiency with decreasing lab turnaround time. Outcomes such as time on EMS diversion, ED LOS, and ED throughput represent important but understudied areas that should be evaluated prospectively. EDs should consider processes that will improve turnaround time, such as point-of-care testing, to obtain these goals.

Low Numeracy Is Associated With Increased Odds of 30-Day Emergency Department or Hospital Recidivism for Patients With Acute Heart Failure

Background— More than 25% of Medicare patients hospitalized for heart failure are readmitted within 30 days. The contributions of numeracy and health literacy to recidivism for patients with acute heart failure (AHF) are not known. Methods and Results— A cohort of patients with acute heart failure who presented to 4 emergency departments between January 2008 and September 2011. Research assistants administered subjective measures of numeracy and health literacy; 30-day follow-up was performed by phone interview. Recidivism was defined as any unplanned return to the emergency department or hospital within 30 days of the index emergency department visit for AHF. Multivariable logistic regression adjusting for patient age, sex, race, insurance status, hospital site, days eligible for recidivism, chronic kidney disease, abnormal hemoglobin, and low ejection fraction evaluated the relation between numeracy and health literacy with 30-day recidivism. Of the 709 patients included in the analysis, 390 (55%) had low numeracy skills and 258 (37%) had low literacy skills. Low numeracy was associated with increased odds of recidivism within 30 days (adjusted odds ratio, 1.41; 95% confidence interval, 1.00–1.98; P=0.048). For low health literacy, adjusted odds ratio of recidivism was 1.17 (95% confidence interval, 0.83–1.65; P=0.37). Conclusions— Low numeracy was associated with greater odds of 30-day recidivism. Further investigation is warranted to determine whether addressing numeracy and health literacy may reduce 30-day recidivism for patients with acute heart failure.

Galectin 3 complements BNP in risk stratification in acute heart failure

Background: Galectin 3 (G3) is a mediator of fibrosis and remodeling in heart failure. Methods: Patients diagnosed with and treated for Acute Heart Failure Syndromes were prospectively enrolled in the Decision Making in Acute Decompensated Heart Failure multicenter trial. Results: Patients with a higher G3 had a history of renal disease, a lower heart rate and acute kidney injury. They also tended to have a history of HF and 30-day adverse events compared with B-type natriuretic peptide. Conclusion: In Acute Heart Failure Syndromes, G3 levels do not provide prognostic value, but when used complementary to B-type natriuretic peptide, G3 is associated with renal dysfunction and may predict 30-day events.

Elevated urinary neutrophil gelatinase-associated lipocalcin after acute heart failure treatment is associated with worsening renal function and adverse events

Reliable detectors of worsening renal function (WRF) in Emergency Department (ED) patients with acute heart failure (AHF) are limited. We hypothesized that initial urinary neutrophil gelatinase‐associated lipocalcin (NGAL) levels, and changes in urinary NGAL levels after initial ED AHF therapy, would be associated with WRF and adverse events.

A multicenter comparison of established and emerging cardiac biomarkers for the diagnostic evaluation of chest pain in the emergency department.

BACKGROUND The aim of this study is to assess the role of novel biomarkers for the diagnostic evaluation of acute coronary syndrome (ACS). METHODS Among 318 patients presenting to an emergency department with acute chest discomfort, we evaluated the diagnostic value of 5 candidate biomarkers (amino terminal pro-B-type natriuretic peptide [NT-proBNP], ischemia modified albumin, heart fatty acid binding protein, high-sensitivity troponin I [hsTnI], and unbound free fatty acids [FFAu]) for detecting ACS, comparing their results with that of conventional troponin T (cTnT). RESULTS Sixty-two subjects (19.5%) had ACS. The sensitivity and negative predictive values of NT-proBNP (73%, 90%) and hsTnI (57%, 89%) were higher than that of cTnT (22%, 84%). Unbound free fatty acids had the highest overall combination of sensitivity (75%), specificity (72%), and negative predictive values (92%) of all the markers examined. A significant increase in the C-statistic for cTnT resulted from the addition of results for NT-proBNP (change 0.09, P = .001), hsTnI (change 0.13, P < .001), and FFAu (change 0.15, P < .001). In integrated discrimination improvement and net reclassification improvement analyses, NT-proBNP, hsTnI, and FFAu added significant diagnostic information to cTnT; when changing the diagnostic criterion standard for ACS to hsTnI, FFAu still added significant reclassification for both events and nonevents. In serial sampling (n = 180), FFAu added important reclassification information to hsTnI. CONCLUSION Among emergency department patients with symptoms suggestive of ACS, neither ischemia modified albumin nor heart fatty acid binding protein detected or excluded ACS, whereas NT-proBNP, hsTnI, or FFAu added diagnostic information to cTnT. In the context of hsTnI results, FFAu measurement significantly reclassified both false negatives and false positives at baseline and in serial samples.

Risk stratification in acute heart failure: rationale and design of the STRATIFY and DECIDE studies.

BACKGROUND A critical challenge for physicians facing patients presenting with signs and symptoms of acute heart failure (AHF) is how and where to best manage them. Currently, most patients evaluated for AHF are admitted to the hospital, yet not all warrant inpatient care. Up to 50% of admissions could be potentially avoided and many admitted patients could be discharged after a short period of observation and treatment. Methods for identifying patients that can be sent home early are lacking. Improving the physicians ability to identify and safely manage low-risk patients is essential to avoiding unnecessary use of hospital beds. METHODS Two studies (STRATIFY and DECIDE) have been funded by the National Heart Lung and Blood Institute with the goal of developing prediction rules to facilitate early decision making in AHF. Using prospectively gathered evaluation and treatment data from the acute setting (STRATIFY) and early inpatient stay (DECIDE), rules will be generated to predict risk for death and serious complications. Subsequent studies will be designed to test the external validity, utility, generalizability and cost-effectiveness of these prediction rules in different acute care environments representing racially and socioeconomically diverse patient populations. RESULTS A major innovation is prediction of 5-day as well as 30-day outcomes, overcoming the limitation that 30-day outcomes are highly dependent on unpredictable, post-visit patient and provider behavior. A novel aspect of the proposed project is the use of a comprehensive cardiology review to correctly assign post-treatment outcomes to the acute presentation. CONCLUSIONS Finally, a rigorous analysis plan has been developed to construct the prediction rules that will maximally extract both the statistical and clinical properties of every data element. Upon completion of this study we will subsequently externally test the prediction rules in a heterogeneous patient cohort.

Identification of Emergency Department Patients With Acute Heart Failure at Low Risk for 30-Day Adverse Events : The STRATIFY Decision Tool

OBJECTIVES No prospectively derived or validated decision tools identify emergency department (ED) patients with acute heart failure (AHF) at low risk for 30-day adverse events who are thus potential candidates for safe ED discharge. This study sought to accomplish that goal. BACKGROUND The nearly 1 million annual ED visits for AHF are associated with high proportions of admissions and consume significant resources. METHODS We prospectively enrolled 1,033 patients diagnosed with AHF in the ED from 4 hospitals between July 20, 2007, and February 4, 2011. We used an ordinal outcome hierarchy, defined as the incidence of the most severe adverse event within 30 days of ED evaluation (acute coronary syndrome, coronary revascularization, emergent dialysis, intubation, mechanical cardiac support, cardiopulmonary resuscitation, and death). RESULTS Of 1,033 patients enrolled, 126 (12%) experienced at least one 30-day adverse event. The decision tool had a C statistic of 0.68 (95% confidence interval: 0.63 to 0.74). Elevated troponin (p < 0.001) and renal function (p = 0.01) were significant predictors of adverse events in our multivariable model, whereas B-type natriuretic peptide (p = 0.09), tachypnea (p = 0.09), and patients undergoing dialysis (p = 0.07) trended toward significance. At risk thresholds of 1%, 3%, and 5%, we found 0%, 1.4%, and 13.0% patients were at low risk, with negative predictive values of 100%, 96%, and 93%, respectively. CONCLUSIONS The STRATIFY decision tool identifies ED patients with AHF who are at low risk for 30-day adverse events and may be candidates for safe ED discharge. After external testing, and perhaps when used as part of a shared decision-making strategy, it may significantly affect disposition strategies. (Improving Heart Failure Risk Stratification in the ED [STRATIFY]; NCT00508638).

Soluble ST2 as a Diagnostic and Prognostic Marker for Acute Heart Failure Syndromes.

OBJECTIVES: We investigated the association of sST2 with diagnostic and prognostic outcomes and assessed whether it aids B-natriuretic peptide (BNP) in diagnosing and predicting outcomes in emergency department (ED) patients with suspected AHFS. METHODS: We recruited patients who presented to the ED of 3 tertiary hospitals with signs or symptoms of AHFS and met modified Framingham criteria for AHFS. Outcome measures were a final diagnosis of AHFS and 5-and 30-day adverse events. RESULTS: In the 295 subjects with sST2 available, the median sST2 was 0.20 ng/ml (IQR=0.10, 0.34). Although unadjusted analyses indicated sST2 was significantly associated with the diagnosis of AHFS (p=0.02), this was not so in the adjusted analysis (p=0.33). Moderately low diagnostic utility was noted with an AUC of 0.62 (95% CI=0.56, 0.69). Similar sST2 test characteristics were seen when BNP was restricted between 100 and 500 pg/ml. While sST2 was associated with AHFS readmission at 30-days (p=0.04), in the adjusted analyses it was not associated with adverse events. CONCLUSION: In patients with signs or symptoms of AHFS, unadjusted analyses indicated that sST2 was significantly associated with the diagnosis of AHFS and with 30-day AHFS recidivism. However, the associations did not carry over to adjusted analyses, and sST2 did not add significant information with regard to explaining the diagnostic and prognostic variability of BNP.

The AFFORD Clinical Decision Aid to Identify Emergency Department Patients With Atrial Fibrillation at Low Risk for 30-Day Adverse Events

There is wide variation in the management of patients with atrial fibrillation (AF) in the emergency department (ED). We aimed to derive and internally validate the first prospective, ED-based clinical decision aid to identify patients with AF at low risk for 30-day adverse events. We performed a prospective cohort study at a university-affiliated tertiary-care ED. Patients were enrolled from June 9, 2010, to February 28, 2013, and followed for 30 days. We enrolled a convenience sample of patients in ED presenting with symptomatic AF. Candidate predictors were based on ED data available in the first 2 hours. The decision aid was derived using model approximation (preconditioning) followed by strong bootstrap internal validation. We used an ordinal outcome hierarchy defined as the incidence of the most severe adverse event within 30 days of the ED evaluation. Of 497 patients enrolled, stroke and AF-related death occurred in 13 (3%) and 4 (<1%) patients, respectively. The decision aid included the following: age, triage vitals (systolic blood pressure, temperature, respiratory rate, oxygen saturation, supplemental oxygen requirement), medical history (heart failure, home sotalol use, previous percutaneous coronary intervention, electrical cardioversion, cardiac ablation, frequency of AF symptoms), and ED data (2 hours heart rate, chest radiograph results, hemoglobin, creatinine, and brain natriuretic peptide). The decision aids c-statistic in predicting any 30-day adverse event was 0.7 (95% confidence interval 0.65, 0.76). In conclusion, in patients with AF in the ED, Atrial Fibrillation and Flutter Outcome Risk Determination provides the first evidence-based decision aid for identifying patients who are at low risk for 30-day adverse events and candidates for safe discharge.

Atrial fibrillation and flutter outcomes and risk determination (AFFORD): design and rationale.

BACKGROUND Atrial fibrillation (AF) is the most common sustained arrhythmia affecting over 700,000 individuals in Japan and 2.2 million in the USA. The proper management of patients with AF is critical due to the well-documented association with heart failure and stroke. A strategy to better define the emergency department (ED) management, admission decisions, and spectrum of risk from low to high is needed. METHODS AND SUBJECTS The atrial fibrillation and flutter outcomes and risk determination investigation is a prospective, observational cohort study to develop a multivariable clinical prediction rule that accurately estimates risk for adverse outcomes in patients presenting to the ED with symptomatic AF. We will enroll 430 patients at 2 sites who present to the ED with symptomatic AF defined as a new or established diagnosis of AF or atrial flutter that require ED evaluation for a complaint thought related to their rhythm disturbance. The studys endpoint is to develop an accurate, objective, internally validated, reliable clinical prediction rule to risk-stratify ED patients presenting with AF exacerbations. The rule will incorporate patient history and examination findings and laboratory studies obtained upon ED presentation, as well as trends over the first 2 h of care. This investigations primary outcome is the incidence of any AF-related adverse event at 5 days and 30 days. We expect to complete the study by the end of 2014. The study was registered at Clinicaltrials.gov NCT01138644.