In clinical settings, point-of-care testing (POCT) provides rapid diagnostic information to help make clinical decisions as early as possible in the care and treatment of patients.
Ensuring that such information is quickly available optimizes the entire care process. Therefore, the potential of any POCT application can be evaluated in terms of how it contributes to decision making and the care process.
However, the potential impact of POCT measurement systems versus laboratory analytical systems needs consideration because most of the evidence regarding the effectiveness of a test would have been determined using lab-based solutions.
HbA1c Testing in Diabetes Management
Over the past few decades, HbA1c testing has become an established method in the management of diabetes and, more recently, the test has also been recognized for its role in diagnosis of the disease.
The HbA1c level not only reflects the circulating glucose concentration over the lifespan of the red blood cell, but has also been shown to predict the complications of diabetes such as cardiovascular disease.
Previously, the use of HbA1c measurement was based on laboratory-based methods such as affinity chromatography and ion exchange, with other affinity and immunological techniques following later.
According to one study of biological variation, the inter- and intra-individual difference in HbA1c between non-diabetics was 4.0% and 1.7%, respectively.
Another study showed an intra-individual difference of 1.2% in non-diabetics and 1.75% in type 1 diabetics, while the respective values for fasting blood glucose were 5% and 30%. These studies demonstrate the benefits of using HbA1c measurement in the screening and management of diabetes.
In this article, the above data was used to determine the desirable analytical goals for bias, imprecision and total error as 1.9%, 1.3%, and 3.9%, respectively.
Lestra Winters et al. used similar performance criteria and found that out of eight POCT systems for HbA1c measurement, only two satisfied the required performance criteria, while Bruns and Boyd described a poor analytical performance with respect to clinical decision making.
The report prepared by Lenters and Westra, showed variation between the laboratory reference methods even though the techniques were all controlled and calibrated in their laboratory.
More about the Analysis
With regard to the viability of POCT for HbA1c in the management of diabetes, a systematic review concluded that to date, no trial data presents sufficient evidence that a POCT system is effective for HbA1c in the management of diabetes.
However, this review was based on seven studies and used two approaches to the surrogate outcome measure, thereby limiting the opportunity for meta-analysis of the entire cohort.
Furthermore, significant heterogeneity between the patient populations existed, which also limited the opportunity for pooling data and conducting a meta-analysis. Moreover, there was a significant lack of documentation regarding the treatment protocols used and therefore no evidence that patients were stratified according to the care they received. However, there was some indication that treatment was intensified to a greater degree among those with an HbA1c level above 7.0% who were receiving POCT.
The authors highlighted key aspects in the application of POCT, which are relevant to both standard practice and research studies. These included the following:
- Patients must be stratified by their baseline HbA1c values
- A revised process of care using POCT must be defined and adhered to
- The POCT results must be discussed with patients and any treatment plans documented and implemented
Interestingly, four observational studies carried out across a total of 5700 diabetic patients where results were fed back to patients immediately, all showed considerable reductions in HbA1c levels. In fact, one of these studies showed improvement in the HbA1c level was maintained over a period of four years.
A recent systematic review of strategies to improve standards in the management of diabetes has demonstrated that quality improvement strategies regarding adherence to guidelines can contribute to improved HbA1c levels.
According to data obtained from primary care records, there is evidence to suggest that HbA1c testing has been both under-used and over-used. However, the data also suggests that patient satisfaction has improved considerably with the use of POCT and that individuals’ personal knowledge of their HbA1c levels is linked to better outcomes.
Testing HbA1c in POCT Settings
The various attributes of the HbA1c measurement are applicable not only in the management of diabetes, but also in diagnosis of the disease. Moreover, the test has been shown to perform as well as the fasting blood glucose test commonly used to screen for type 2 diabetes.
The World Health Organization has now recommended that HbA1c be used as a diagnostic measure in diabetes, with similar guidance now being followed in a number of countries.
However, a degree of caution should be employed when using the test, which should not be used in the testing of children, young people, those with suspected type 1 diabetes, pregnant women, cases of acute illness, cases of HIV infection, cases of renal failure or patients with a short duration of symptoms.
In addition, the cut-off value of 48 mmol/mol (6.5% DCCT) may not be suitable for all populations, with further research required into any populations not yet featured in the studies to date. However, patients who fall within the range of 42 – 47 mmol/mol should be considered at high risk for developing diabetes and managed with appropriate lifestyle advice and annual retesting.
Although there have been some concerns regarding the use of HbA1c in screening for diabetes in terms of cost, patient follow-up and lifestyle advice, current guidance supports the use of this test in both screening for type 2 diabetes and the management of those already diagnosed with the condition.
The use of POCT for HbA1c in the management of diabetes enables better access to testing and rapid clinical decision making, discussion, and implementation of optimized treatment. It also enables tests to be performed closer to the patient, making the process more convenient and therefore increasing the likelihood of treatment compliance.
Point-of-care HbA1c analyzers from EKF Diagnostics are certified to IFCC and NGSP international standards for point-of-care testing in the screening and monitoring of patients with diabetes.
Produced from articles authored by Professor Chris Price, Visiting Professor in Clinical Biochemistry, Department of Primary Care Health Sciences, University of Oxford and Dr Gary Dowthwaite, Product Manager, EKF Diagnostics.
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About EKF Diagnostics
The EKF range of analysers is unique in their ease of use, accuracy and portability which is why we are a trusted brand in GP surgeries, pharmacies, blood banks, sports clinics, hospitals and laboratories for the measurement of glucose, lactate, hemoglobin, hematocrit and HbA1c.
EKF Diagnostics products' reputation for quality, accuracy and ease of use stems from our beginnings as a technology business founded in Barleben in Germany in 1990. In the following years we have invested in developing a portfolio of analysers and consumables for the near patient care sector that deliver laboratory accuracy and reliability without the high costs and maintenance associated with lab devices.
In 2010 EKF Diagnostics acquired HbA1c developer Quotient Diagnostics based in Walton-on-Thames, UK and Argutus Medical in Dublin, a specialist research and distribution company engaged in kidney and liver diagnostics. The following year the company expanded further through the acquisition of Stanbio Laboratory, a manufacturer and distributor of diagnostic products with a worldwide customer base.
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