April 13, 2017 — A study published recently in the American Association for Clinical Chemistry’s (AACC) Journal of Applied Laboratory Medicine describes the creation of a first-of-its-kind patient sample bank that could improve consistency among blood tests used to diagnose heart attacks and advance care for cardiac patients.
In the emergency room, a blood test for cardiac troponin — a protein released when cardiac cells are damaged — is used to identify chest pain patients who are having a heart attack so that they can be treated as quickly as possible. Specifically, a heart attack is diagnosed when a patient’s troponin concentrations exceed those found in the 99th percentile of a healthy reference population. However, the 99th percentile cutoff value varies for different troponin tests because each test manufacturer uses a different reference population. Therefore, there is a need to have samples available from one healthy reference population so that all manufacturers can use the same population to determine a universal 99th percentile cutoff for troponin. This will help to ensure that cardiac patients receive the same diagnosis and quality of care regardless of what hospital they go to and what troponin test is used.
This study examines the universal sample bank of ethnically and geographically diverse healthy subjects that AACC created to ensure that cardiac patients have consistent quality of diagnosis and care. Participants were recruited from among attendees of the 2015 AACC Annual Meeting & Clinical Lab Expo, the world’s largest conference for laboratory medicine, as well as at the University of Maryland. From those individuals who met initial eligibility criteria, 60 mL of blood was collected and tested for hemoglobin A1c, N-terminal pro–B-type natriuretic peptide and creatinine. These tests were used to exclude participants with uncontrolled diabetes, renal insufficiency, and heart disease, including most asymptomatic cardiac conditions.
In total, 808 individuals were included in the sample bank: 402 females and 406 males who are 60 percent Caucasian, 26 percent African or African American, 11 percent Asian or Pacific Islander, and 3 percent other. This sample bank and its associated data provides a unique opportunity for diagnostic manufacturers to generate a reliable 99th percentile value that applies to all troponin tests, which in turn could prevent delays in heart attack patients receiving critical treatment.
“The 99th percentiles can now be assessed by assay manufacturers and laboratories using the same patient population,” said senior paper author Robert Christenson, Ph.D., of the University of Maryland School of Medicine. “This enables establishing and applying clinical decision points in an effective and consistent manner. [Additionally,] this sample bank can and likely will be used for the determination of reference ranges for other clinical laboratory tests.”
For more information: www.aacc.org