What are the pros and cons of central lab versus point-of-care (POC) troponin testing?

AIn the emergency department (ED), POC testing for cardiac troponin I or T can be attractive due to its speed. However, labs need to account for many other crucial factors in addition to turnaround time (TAT) when choosing a method.

In the case of assay sensitivity and specificity, it has been reported that all detectable levels of cardiac troponin are associated with negative outcomes (J Am Coll Cardiol 2017;70:2226-36); therefore, the superiority of central laboratory testing in these areas is an essential consideration. Regarding commutability, another shortcoming of POC is that initial results must be rebaselined with the central lab method in patients tested serially over time. POC devices are also often operated by busy non-laboratory clinical personnel, which leads to a documented increase in error rates associated with patient identification, sample handling, testing, and reporting.

Overall, central lab testing has advantages over POC in all areas save TAT (Pract Lab Med 2016;4:22-9)—and in-lab TAT can be improved through aggressive, coordinated interdisciplinary action.

What is a reasonable TAT for in-lab troponin testing?

A commonly cited TAT target is 60 minutes from the time of blood collection to the reporting of results through the lab information system (LIS) (Clin Chem 2018; doi: 10.1373/clinchem.2017.277186), or an even more challenging 60 minutes or less (e.g., 45 minutes) from order to result (Arch Pathol Lab Med 2004;128).

How did your institution reduce TAT for in-lab testing?

The clock starts ticking the moment an order is placed, so at Asante Rogue Regional Medical Center (ARRMC), we’ve placed phlebotomists in the ED who are alerted via mobile device as soon as a troponin ED order comes in. A phlebotomist collects the sample either by venipuncture (preferred) or through an IV started by a nurse, then inverts the sample appropriately before sending it to the lab via a pneumatic tube system.

An alarm sounds once the sample arrives in the lab. The lab specimen processor receives the sample in the LIS then places the sample in a stat centrifuge, starting an audible timer while issuing a verbal handoff to a technologist. Once the sample is spun, the technologist bypasses the automation line and manually loads the sample into the analyzer. An ED trackboard monitors time-sensitive metrics, displaying information such as patient identification, test name, time collected, time received, and time to result countdown (set to 30 minutes from receipt), with all information turning from black to red when overdue.

With which other departments did you coordinate on this initiative?

We worked closely with our ED leadership team (medical director, nursing, and monitor techs), lab phlebotomy team, and processing and technical staff, initially meeting on a weekly basis to change our culture of ordering, collecting, processing, and testing. We tracked key delays in each of these areas as well as hemolysis, inadequate sample mixing, and short draws—all metrics that are continuously monitored to this day. A side benefit of this effort has been greatly improved communication and cooperation between the lab, ED, and cardiologists. Additionally, ED test orders, test parameters, and trackboards were built by our LIS team per specifications from the central laboratory.

What were the results of this initiative?

We’ve maintained high-quality in-lab troponin testing (CV <10% at the 99th percentile upper reference limit) at a lower cost than POC with excellent TAT metrics with the benefit of commutability of results from the ED to the Critical Care Unit. Recent TAT data has shown our median receipt to result to be 20 minutes and a median order to result to be 50 minutes. ARRMC was also recognized this year as number 1 in the U.S. for medical excellence in interventional coronary care by the CareChex hospital and health system rating organization.

Jack Montgomery, MLS(ASCP)CM, is the chemistry technical specialist at Asante Rogue Regional Medical Center in Medford, Oregon. +Email: [email protected]