Many disorders rely on specific measurements of blood parameters, for example, blood sugar, as an essential part of their diagnostic and treatment monitoring procedures. In the past, blood parametric tests were performed exclusively in a clinical laboratory.
HbA1c Point-of-care testing
Newer developments in testing technologies have enabled some of these, including glycated hemoglobin testing, to be performed in point-of-care settings such as clinics or doctors’ surgeries. The most significant advantage of point-of-care testing (POCT) is the time saved in making clinical decisions on patient management without having to wait for the test results to arrive from the laboratory.
Point-of-Care Testing (POCT) has taken a prominent place in the delivery of healthcare services by promising and providing quicker results. Patients who are very sick can now be rapidly and accurately assessed, while the frequency of outpatient visits is also reduced. For this reason, POCT is a valuable tool for enhancing patient care and treatment, as well as improving patient satisfaction.
Point-of-care testing (POCT) is typically performed by healthcare professionals with limited to no experience in laboratory testing, making it crucial that such tests are reproducible, straightforward, and yield reliable data.
Another important consideration is that these tests should match the quality of traditional laboratory analyzers. Unreliable results would be unusable and irrelevant despite the time savings, as decisions made on this basis could often be wrong.
HbA1c testing in clinics
One area where point-of-care testing (POCT) has proven its worth is in the diabetes clinic. High glucose levels can produce a host of serious medical complications if not corrected promptly. Therefore, monitoring blood sugar levels in diabetic patients is crucial, which requires regular measurement of glycated hemoglobin levels (HbA1C levels).
Glycated hemoglobin is hemoglobin with bound glucose molecules. This typically occurs to a limited extent in regular blood, but with a higher incidence with very high blood glucose concentrations. The HbA1C test reflects the binding of glucose to hemoglobin quantitatively. As the average lifespan of a normal red blood cell is about 120 days, the result can show the average glucose concentration in blood over the past three months.
Standardized HbA1C performance criteria have recently been issued, allowing for a direct correlation between the test results and the conclusions of the Diabetes Control and Complications Trial and the United Kingdom Prospective Diabetes Study. These trials showed that the level of HbA1C was directly related to the risk of various outcomes in diabetic patients [4].
Devices for HbA1c Point-of-care testing
A host of POCT devices are now available, and many have obtained certification of compliance to relevant regulatory criteria put forward by regulatory bodies, including CE certification, which shows that it conforms to the EU directives on health, safety, and environmental protection, and the US Food and Drug Administration (FDA) approval.
However, it is essential to understand that the certificate of compliance is based on the manufacturer’s data, which in turn is obtained under ideal operating conditions. However, this is unlikely to be the case during actual point-of-care testing (POCT) due to the wide variations in clinical conditions. Thus, there is no guarantee that the certification proves the instrument will function reliably in real-life situations [2].
One way to provide reliable assessment in real-world scenarios is through external quality assessment (EQA) tools and trials [2,3]. This is only possible for instruments that are enrolled in this type of scheme. To make it more difficult, some devices are designed to prevent any internal quality assessments to verify device calibration. Independent laboratory testing is often needed to assess the actual reliability of the data gathered by these POCT devices under the conditions of daily clinical use.
Currently, over 30 point-of-care testing (POCT) devices are available for HbA1C testing. This has led to establishing support and reference values for manufacturers, provided by the European Reference Laboratory for Glycohemglobin, so that the instruments may be evaluated for their analytical performance independently [5].
In a study, the Clinical and Laboratory Standards Institute (CLSI) protocols were applied to measure the accuracy and precision of an array of point-of-care testing (POCT) devices for HbA1C testing against the measurement procedures set out by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) as secondary reference values. These findings were published in the Journal of Diabetes Science and Technology [6].
Of the tested devices, three are based on a boronate affinity methodology: Quo-Lab® (EKF Diagnostics PLC, Cardiff, UK), Afinion2 (Abbott, Oslo, Norway), and HbA1c 501 (HemoCue Diagnostics, Ängelholm, Sweden). One uses the enzymatic protocol to determine HbA1c (A1Care (i-SENSE, Seoul, Korea).
The results for the Quo-Lab® and the Afinion2 were shown to be excellent. They both met the NGSP criteria when tested against four secondary reference measurement protocols. The HbA1c 501 achieved acceptable (borderline) analytical results, despite complying with the requirements for routine laboratory procedures. However, the A1Care instrument failed to meet any of the tested criteria and yielded results that fell below acceptable values for determining HbA1c [6].
This recent data emphasizes the importance of careful selection when choosing a POCT device. Of course, these instruments are continually innovating to achieve improved analytical performance. Yet, the danger remains that not all POCT devices may yield reliable data for HbA1C determination; thus, the evidence must be reviewed carefully before choosing an instrument for point-of-care measurements. Robust independent evaluations of POCT device accuracy, therefore, remain invaluable for assisting such decision-making and ensuring that the best patient care is provided.
References:
- [1] Patzer KH, et al. Implementation of HbA1c point of care testing in 3 German Medical Practices: impact on workflow and physician, staff, and patient satisfaction. J Diabetes Sci Technol. 2018; 3:687‑694.
- [2] NGSP website note CAP survey data. Available at: http://www.ngsp.org/CAP/CAP17c.pdf Accessed April 2018.
- [3] Centers for Medicare & Medicaid Services. Available at: https://www.cms.gov/Regulations-and-Guidance/Legislation/CLIA/Certificate_of_-Waiver_Laboratory_Project.html. Accessed April 2018.
- [4] NGSP. Harmonizing hemoglobin A1c testing. Available at: www.ngsp.org
- [5] Westgard. Available at: http://james.westgard.com/the_westgard_rules/2017/08/are-there-new-erna-lenters-westra-rulesfor-hba1c.html. Accessed April 2018.
- [6] Lenters-Westra E and English E. Evaluation of Four HbA1c Point-of-Care Devices Using International Quality Targets: Are They Fit for the Purpose? Journal of Diabetes Science and Technology 2018; Special Issue: 1–9.
