The Best of Both Worlds: Eliminating Creatine Kinase-Muscle/Brain (CK-MB) Testing in the Emergency Department Leads to Lower Costs Without Missed Clinical Diagnoses.

The 2014 American Heart Association/American College of Cardiology (AHA/ACC) clinical guidelines recommend cardiac troponin as a superior biomarker to creatine kinase (CK) and creatine kinase-muscle/brain (CK-MB) for the detection of acute coronary syndrome (ACS), namely myocardial infarction and unstable angina. In April 2018, our Emergency Department (ED) transitioned from using standard troponin to using high-sensitivity troponin T, and adopted a clinical guideline consistent with the AHA/ACC. The guideline recommended high-sensitivity troponin T without CK/CK-MB testing in the majority of clinical situations, limiting CK/CK-MB testing to two specific clinical cases: 1) estimated glomerular filtration rate (eGFR) value <15 mL/min, or 2) recent acute coronary syndrome (ACS) event. Per our ED's policy, a "negative" troponin T was defined as being below the limit of detection (LOD) (i.e., <6 ng/L); such a value obtained at least 3 hours after symptom onset "ruled out" an ACS event and did not require a repeat troponin. The goal of this retrospective study was to determine whether the guideline limiting CK-MB testing missed clinically-significant cardiac outcomes (ACS or new diagnosis of coronary artery disease [CAD]) or was associated with mortality. Pre-implementation data (July 1, 2017 - December 31, 2017) was compared with post-implementation data (July 1, 2018 - December 31, 2018). After guideline introduction, CK/CK-MB ordering decreased by nearly 90%, while troponin ordering increased by nearly 20%, likely due to the introduction in June 2018 of high-sensitivity troponin T, which yielded numerous intermediate/indeterminate-range results that prompted repeat testing. Fewer than 1.5% of patients with a "negative" troponin (below the LOD) and a "positive" CK-MB (above the upper limit of normal [ULN]) had ACS or new-diagnosis CAD; patients with either diagnosis did not expire during their hospital stay or within 30 days of their index visit. CK-MB Index, which has a higher specificity than CK, only found ACS or new CAD among 0.8% of positive results. Considering both decreased CK/CK-MB and increased troponin ordering, the net annual direct cost savings in cardiac biomarker testing was extrapolated to $12,700. Had our institution not transitioned to higher cost high-sensitivity troponin ($2.054/unit) from standard troponin ($1.65/unit), and had the rate of troponin ordering increased solely proportionate to the rate of ED visit increase (2% year-over-year) rather than increase nearly 20% (likely due to the transition to high-sensitivity troponin), then the total six-month direct costs on troponin testing would have been $14,632 instead of $21,267.12, and annual direct cost savings would have been $18,945.80 instead of $12,700. The new ED clinical guideline did not result in a significant number of missed ACS or new-diagnosis CAD, and was associated with direct cost savings. These savings probably underestimate total savings, as the reduced number of "false-positive" CK-MB results likely prevented additional costs, such as hospitalization, specialty consultation, coronary calcium CT, echocardiogram, cardiac stress test, and coronary artery catheterization.

Increased Emergency Department Hallway Length of Stay is Associated with Development of Delirium.

INTRODUCTION: Our study aimed to determine 1) the association between time spent in the emergency department (ED) hallway and the development of delirium and 2) the hospital location of delirium development. METHODS: This single-center, retrospective chart review included patients 18+ years old admitted to the hospital after presenting, without baseline cognitive impairment, to the ED in 2018. We identified the Delirium group by the following: key words describing delirium; orders for psychotropics, special observation, and restraints; or documented positive Confusion Assessment Method (CAM) screen. The Control group included patients not meeting delirium criteria. We used a multivariable logistic regression model, while adjusting for confounders, to assess the odds of delirium development associated with percentage of ED LOS spent in the hallway. RESULTS: A total of 25,156 patients met inclusion criteria with 1920 (7.6%) meeting delirium criteria. Delirium group vs. Control group patients spent a greater percentage of time in the ED hallway (median 50.5% vs 10.8%, P<0.001); had longer ED LOS (median 11.94 vs 8.12 hours, P<0.001); had more ED room transfers (median 5 vs 4, P<0.001); and had longer hospital LOS (median 5.0 vs 4.6 days, P<0.001). Patients more frequently developed delirium in the ED (77.5%) than on inpatient units (22.5%). The relative odds of a patient developing delirium increased by 3.31 times for each percent increase in ED hallway time (95% confidence interval, 2.85, 3.83). CONCLUSION: Patients with delirium had more ED hallway exposure, longer ED LOS, and more ED room transfers. Understanding delirium in the ED has substantial implications for improving patient safety.