Derivation and Validation of Thresholds Using Synthetic Data Methods for Single-Test Screening of Emergency Department Patients with Possible Acute Myocardial Infarction Using a Point-of-Care Troponin Assay.

BACKGROUND: Single-sample (screening) rule-out of acute myocardial infarction (AMI) with troponin requires derivation of a single-test screening threshold. In data sets with small event numbers, the lowest one or two concentrations of myocardial infarction (MI) patients dictate the threshold. This is not optimal. We aimed to demonstrate a process incorporating both real and synthetic data for deriving such thresholds using a novel pre-production high-precision point-of-care assay. METHODS: cTnI concentrations were measured from thawed plasma using the Troponin I Next (TnI-Nx) assay (i-STAT; Abbott) in adults on arrival to the emergency department with symptoms suggestive of AMI. The primary outcome was an AMI or cardiac death within 30 days. We used internal-external validation with synthetic data production based on clinical and demographic data, plus the measured TnI-Nx concentration, to derive and validate decision thresholds for TnI-Nx. The target low-risk threshold was a sensitivity of 99% and a high-risk threshold specificity of >95%. RESULTS: In total, 1356 patients were included, of whom 191 (14.1%) had the primary outcome. A total of 500 synthetic data sets were constructed. The mean low-risk threshold was determined to be 5 ng/L. This categorized 38% (95% CI, 6%-68%) to low-risk with a sensitivity of 99.0% (95% CI, 98.6%-99.5%) and a negative predictive value of 99.4% (95% CI, 97.6%-99.8%). A similarly derived high-risk threshold of 25 ng/L had a specificity of 95.0% (95% CI, 94.8%-95.1%) and a positive predictive value of 74.8% (95% CI, 71.5%-78.0%). CONCLUSIONS: With the TnI-Nx assay, we successfully demonstrated an approach using synthetic data generation to derive low-risk thresholds for safe and effective screening.

Glucose and Psychosocial Outcomes 12 Months Following Transition from Multiple Daily Injections to Advanced Hybrid Closed Loop in Youth with Type 1 Diabetes and Suboptimal Glycemia.

Objective: To investigate 12-month glycemic and psychosocial changes following transition from multiple daily injections (MDI) to advanced hybrid closed-loop (AHCL) therapy in youth (aged 13-25 years) with type 1 diabetes and suboptimal glycemia (glycated hemoglobin [HbA1c] ≥8.5% [69 mmol/mol]). Research Design and Methods: Prospective, single arm, dual-center study in 20 participants. Extension phase outcomes reported after 12 months, including HbA1c, time in glycemic ranges, AHCL system performance, and psychosocial questionnaires assessing quality of life, diabetes treatment, and sleep. Results: After 12 months, 19 out of 20 participants continued to use AHCL. Average time-in-range 70-180 mg/dL (3.9-10.0 mmol/L) improved from 27.6% ± 13.2% to 62.5% ± 11.4%. This translated to an average 2.5 percentage-point (27.1 mmol/mol) improvement in HbA1c from 10.5% ± 2.1% (91.2 mmol/mol) at baseline to 8.0% ± 0.9% (64.1 mmol/mol) at 12 months. Psychosocial questionnaires and very high HbA1c at study entry indicated significant diabetes-associated burden for both individuals and parents. After 12 months, improvements were observed in general and diabetes-specific health-related quality of life, as well as in diabetes treatment satisfaction. Safety data were reassuring with a diabetic ketoacidosis rate of 0.15 per participant-year after 12 months of AHCL (compared to 0.25 per participant-year in the 12 months before the study). Conclusions: After 12 months of AHCL usage, this study highlights the potential for substantial and sustained glycemic and psychosocial improvements among individuals experiencing considerable diabetes burden and suboptimal glycemia, following their switch from MDI to AHCL.

Impact of Advanced Hybrid Closed Loop on Youth With High-Risk Type 1 Diabetes Using Multiple Daily Injections.

OBJECTIVE: To evaluate glycemic outcomes in youth (aged 13-25 years) with type 1 diabetes and high-risk glycemic control (HbA1c ≥8.5% [69 mmol/mol]) on multiple daily injection (MDI) therapy after transitioning to advanced hybrid closed loop (AHCL) therapy. RESEARCH DESIGN AND METHODS: This prospective, 3-month, single-arm, dual-center study enrolled 20 participants, and all completed the study. RESULTS: HbA1c decreased from 10.5 ± 2.1% (91.2 ± 22.8 mmol/mol) at baseline to 7.6 ± 1.1% (59.7 ± 11.9 mmol/mol), and time spent in target range 70-180 mg/dL (3.9-10.0 mmol/L) increased from 27.6 ± 13.2% at baseline to 66.5 ± 9.8% after 3 months of AHCL. Two episodes of diabetic ketoacidosis attributed to infusion set failure occurred. CONCLUSIONS: AHCL has the potential to improve suboptimal glycemia in youth with type 1 diabetes previously on MDI therapy.

Validity of a Novel Point-of-Care Troponin Assay for Single-Test Rule-Out of Acute Myocardial Infarction.

Importance: Emergency department (ED) investigations of patients with suspected acute myocardial infarction (AMI) are time consuming, partly because of the turnaround time of laboratory tests. Current point-of-care troponin assays shorten test turnaround times but lack precision at lower concentrations. Development of point-of-care troponin assays with greater analytical precision could reduce the decision-making time in EDs for ruling out AMI. Objective: To determine the clinical accuracy for AMI of a single troponin concentration measured on arrival to ED with a new-generation, higher precision point-of-care assay with a 15-minute turnaround time. Design, Setting, and Participants: This observational study occurred at a single urban regional ED. Adults presenting acutely from the community to the ED with symptoms suggestive of AMI were included. Troponin concentrations were measured on ED arrival with both a novel point-of-care assay (i-STAT TnI-Nx; Abbott Point of Care) and a high-sensitivity troponin I assay (Architect hs-cTnI; Abbott Diagnostics). Main Outcomes and Measures: The primary outcome was type 1 AMI during index presentation. We compared the discrimination ability of the TnI-Nx assay with the hs-cTnI assay using the area under receiver operator characteristic curve (AUC) and sensitivity, negative predictive value, and the proportion of negative test results at thresholds with 100% sensitivity. Results: Of 354 patients (255 [72.0%] men; mean [SD] age, 62 [12] years), 57 (16.1%) experienced an AMI. Eighty-five patients (24.0%) presented to the ED less than 3 hours after symptom onset. No difference was found between the AUC of the TnI-Nx assay (0.975 [95% CI, 0.958-0.993]) and the hs-cTnI assay (0.970 [95% CI, 0.949 to 0.990]; P = .46). A TnI-Nx assay result of less than 11 ng/L identified 201 patients (56.7%) as low risk, with a sensitivity of 100% (95% CI, 93.7%-100%) and a negative predictive value of 100% (95% CI, 98.2%-100%). In comparison, an hs-cTnI assay result of less than 3 ng/L identified 154 patients (43.5%) as low risk, with a sensitivity of 100% (95% CI, 93.7%-100%) and a negative predictive value of 100% (95% CI, 97.6%-100%). Conclusions and Relevance: A novel point-of-care troponin assay that can produce a result 15 minutes after blood sampling had comparable discrimination ability to an hs-cTnI assay for ruling out AMI after a single blood test. Use in the ED may facilitate earlier decision making and could expedite the safe discharge of a large proportion of low-risk patients.