Multicentre evaluation of the Premier Hb9210 HbA1c analyser

Evaluation of the Premier Hb9210 instrument for HbA1c determination

Background: Glycated hemoglobin measurements are a valuable tool for long-term blood glucose monitoring and the diagnosis of diabetes. Its widespread use has been made possible due to the development of new analytical methods with improved performances and standardization with reference materials. The aim of the present study was to evaluate the Trinity Biotech Premier Hb9210 analyzer for the measurement of HbA1c.Methods: The precision was assessed using the CLSI EP-15A3 and EP-10A3 protocols. The latter was also used to investigate linearity, carryover, and linear drift. The comparison study was performed between Premier Hb910 and Tosoh HLC-723 G8 through Passing-Bablok regression and the Bland-Altman plot. The Fleiss Kappa index was used to assess the degree of agreement. The interference of Hb variants was investigated using samples with Hb variants S, C, D, E, J, and Seville.Results: Within-run and between-run imprecision fell between 0.37% and 1.16%. No statistically significant nonlinearity, carry-over, and/or drift were observed. The resulting regression line of the Passing-Bablok analysis was y = 0.00 + 1.00x. The Pearson correlation coefficient was 0.997. In the Bland-Altman plot, the relative bias was 0.01%. The overall Fleiss Kappa index was 0.9. No interference from hemoglobin variants was observed.Conclusion: The Premier Hb9210 demonstrated a high degree of automation, reproducibility, good agreement, minimal carry-over effect, and excellent linearity across the wide range of HbA1c levels commonly found in diabetic patients and was not influenced by Hb variants.

Impact of haemoglobin variants on the use of haemoglobin A1c for the diagnosis and monitoring of diabetes: a contextualised review

HbA1c is the established test for monitoring glycaemic control in diabetes, and intervention trials studying the impact of treatment on glycaemic control and risk of complications focus predominantly on this parameter in terms of evaluating the glycaemic outcomes. It is also the main parameter used when targets for control are being individualised, and more recently, it has been used for the diagnosis of type 2 diabetes. For laboratories performing this test and clinicians utilising it in their decision-making process, a thorough understanding of factors that can impact on the accuracy, and appropriate interpretation of the test is essential. The changing demographic in the Irish population over the last two decades has brought this issue sharply into focus. It is therefore timely to review the utility, performance and interpretation of the HbA1c test to highlight factors impacting on the results, specifically the impact of haemoglobin variants, and the impact of these factors on its utilisation in clinical practice.

HbA1c and biomarkers of diabetes mellitus in Clinical Chemistry and Laboratory Medicine: ten years after

Since its discovery in the late 1960s, HbA_1c has proven to be a major biomarker of diabetes mellitus survey and diagnosis. Other biomarkers have also been described using classical laboratory methods or more innovative, non-invasive ones. All biomarkers of diabetes, including the historical glucose assay, have well-controlled strengths and limitations, determining their indications in clinical use. They all request high quality preanalytical and analytical methodologies, necessitating a strict evaluation of their performances by external quality control assessment trials. Specific requirements are needed for point-of-care testing technologies. This general overview, which describes how old and new tools of diabetes mellitus biological survey have evolved over the last decade, has been built through the prism of papers published in Clinical Chemistry and Laboratory Medicine during this period.

Protein glycation - biomarkers of metabolic dysfunction and early-stage decline in health in the era of precision medicine

Protein glycation provides a biomarker in widespread clinical use, glycated hemoglobin HbA1c (A1C). It is a biomarker for diagnosis of diabetes and prediabetes and of medium-term glycemic control in patients with established diabetes. A1C is an early-stage glycation adduct of hemoglobin with glucose; a fructosamine derivative. Glucose is an amino group-directed glycating agent, modifying N-terminal and lysine sidechain amino groups. A similar fructosamine derivative of serum albumin, glycated albumin (GA), finds use as a biomarker of glycemic control, particularly where there is interference in use of A1C. Later stage adducts, advanced glycation endproducts (AGEs), are formed by the degradation of fructosamines and by the reaction of reactive dicarbonyl metabolites, such as methylglyoxal. Dicarbonyls are arginine-directed glycating agents forming mainly hydroimidazolone AGEs. Glucosepane and pentosidine, an intense fluorophore, are AGE covalent crosslinks. Cellular proteolysis of glycated proteins forms glycated amino acids, which are released into plasma and excreted in urine. Development of diagnostic algorithms by artificial intelligence machine learning is enhancing the applications of glycation biomarkers. Investigational glycation biomarkers are in development for: (i) healthy aging; (ii) risk prediction of vascular complications of diabetes; (iii) diagnosis of autism; and (iv) diagnosis and classification of early-stage arthritis. Protein glycation biomarkers are influenced by heritability, aging, decline in metabolic, vascular, renal and skeletal health, and other factors. They are applicable to populations of differing ethnicities, bridging the gap between genotype and phenotype. They are thereby likely to find continued and expanding clinical use, including in the current era of developing precision medicine, reporting on multiple pathogenic processes and supporting a precision medicine approach.

Unexpected HbA1c results in the presence of three rare hemoglobin variants

Hemoglobin (Hb) variants, characterized by structural abnormalities in the globin chains, are among the most common inherited disorders. It has been shown that Hb variant remains an important cause of erroneous HbA_1c results. Thus, it is important to be aware of the extent of the interference of each Hb variant encountered to avoid reporting unreliable results. However, the effects of many types of Hb variants on the measurement of HbA_1c remain unclear. Here, we describe three rare Hb variants, Hb J-Tashikuergan [HBA2: c.59 C > A], Hb Pyrgos [HBB: c.251G > A], and Hb Hope [HBB: c.410 G > A], which lead to extremely high values (>25%) determined by Variant II Turbo 2.0. We further investigated their effects on HbA_1c measurement by an HPLC system (Bio-Rad D100), a CE system (Sebia Capillarys 3 TERA), a boronate affinity chromatography system (Premier Hb9210), and an immunoassay method (Roche Diagnostics), and found that these Hb variants severely interfered with HbA_1c measurement by Variant II Turbo 2.0 and Bio-Rad D100. This study demonstrates that patients with abnormally high HbA_1c levels should be highly suspected of carrying Hb variants. When the HbA_1c results are considered unreliable, other indicators such as glycated albumin may be a possible alternative to HbA_1c in diabetic patients.

Potential of MALDI-TOF mass spectrometry to overcome the interference of hemoglobin variants on HbA1c measurement

Objectives

Hemoglobin (Hb) variants remain an important cause of erroneous HbA1c results. We present an approach to overcome the interference of Hb variants on HbA1c measurements using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS).

Methods

Samples containing or not containing Hb variants were analyzed for HbA1c using an MALDI-TOF MS system (QuanTOF) and a boronate affinity comparative method (Ultra2). For QuanTOF, two sets of HbA1c values were obtained through α- and β-chain glycation.

Results

A robust correlation between the glycation degrees of the α- and β-chains was found, and HbA1c values derived from α- and β-chain glycation correlated well with the Ultra2 results. Statistically significant differences (p<0.01) were found for all the Hb variants tested. When using the conventional β-chain glycation to determine HbA1c, clinically significant differences were only found among samples containing β-chain variants detected by QuanTOF (i.e., Hb J-Bangkok, Hb G-Coushatta, and Hb G-Taipei). In contrast, based on α-chain glycation, no clinically significant differences were found for these three variants.

Conclusions

In addition to conventional β-chain glycation, α-chain glycation can be used to calculate HbA1c values. The interference of Hb variants on HbA1c quantification can be overcome by employing the glycation of the globin chain without a genetic variant to estimate HbA1c values.

Determinants of diagnostic discordance for non-diabetic hyperglycaemia and Type 2 diabetes using paired glycated haemoglobin measurements in a large English primary care population: cross-sectional study

AIM

To investigate factors influencing diagnostic discordance for non-diabetic hyperglycaemia and Type 2 diabetes.

METHODS

Some 10 000 adults at increased risk of diabetes were screened with HbA_1c and fasting plasma glucose (FPG). The 2208 participants with initial HbA_1c ≥ 42 mmol/mol (≥ 6.0%) or FPG ≥ 6.1 mmol/l were retested after a median 40 days. We compared the first and second HbA_1c results, and consequent diagnoses of non-diabetic hyperglycaemia and Type 2 diabetes, and investigated predictors of discordant diagnoses.

RESULTS

Of 1463 participants with non-diabetic hyperglycaemia and 394 with Type 2 diabetes on first testing, 28.4% and 21.1% respectively had discordant diagnoses on repeated testing. Initial diagnosis of non-diabetic hyperglycaemia and/or impaired fasting glucose according to both HbA_1c and FPG criteria, or to FPG only, made reclassification as Type 2 diabetes more likely than initial classification according to HbA_1c alone. Initial diagnosis of Type 2 diabetes according to both HbA_1c and FPG criteria made reclassification much less likely than initial classification according to HbA_1c alone. Age, and anthropometric and biological measurements independently but inconsistently predicted discordant diagnoses and changes in HbA_1c .

CONCLUSIONS

Diagnosis of non-diabetic hyperglycaemia or Type 2 diabetes with a single measurement of HbA_1c in a screening programme for entry to diabetes prevention trials is unreliable. Diagnosis of non-diabetic hyperglycaemia and Type 2 diabetes should be confirmed by repeat testing. FPG results could help prioritise retesting. These findings do not apply to people classified as normal on a single test, who were not retested.

The global impact of the International Federation of Clinical Chemistry and Laboratory Medicine, Education and Management Division: engaging stakeholders and assessing HbA1c quality in a multicentre study across China

Background Diabetes mellitus is a major global issue and high quality testing is essential for the diagnosis and treatment of the disease. The IFCC Committee for the Education in the Utility of Biomarkers in Diabetes (C-EUBD) plays a global role in improving knowledge and understanding around diabetes testing. This paper describes a multi-stakeholder approach, to improving diagnostic and therapeutic testing for diabetes, using a multicentre study in China as an example of the global impact of the group. Methods Educational workshops were developed to support the scientific aims of the study in which 30 centres around China received identical, fresh frozen whole blood samples with values assigned using IFCC secondary reference methods and undertook precision (EP-5) and trueness studies. Performance was assessed using sigma metrics. Results A successful multi-stakeholder group was developed and sustained throughout the study through several educational workshops, which enabled the formation of a long-term collaboration with key opinion leaders and policy makers in China. All 30 centres showed good performance with within and between laboratory coefficient of variations (CVs) below 3% in SI units at both low and high haemoglobin A1c (HbA1c) levels. All individual laboratories met the criteria of a sigma of two or more at a total allowable error (TAE) of 5 mmol/mol (0.46% NGSP). Conclusions The study led to a successful multi-partner approach to improving diabetes testing in China. All centres involved in the study meeting the published IFCC quality criteria, paving the way for future clinical trials and an expanded role for HbA1c testing across the country.

HbA1c method performance: The great success story of global standardization

Diagnosing and monitoring the treatment of people with diabetes is a global issue and uses considerable resources in laboratories and clinics worldwide. Hemoglobin A1c (HbA1c) has been the mainstay of monitoring glycemic control in people with diabetes for many years and more recently it has been advocated as a diagnostic tool for type 2 diabetes mellitus (T2DM). Good analytical performance is key to the successful use of any laboratory test, but is critical when using the test to diagnose disease, especially when the potential number of diagnoses could exceed 500 million people. Very small variations in bias or increased imprecision could lead to either a missed diagnosis or overdiagnosis of the disease and given the scale of the global disease burden, this could mean erroneous categorization of potentially millions of people. Fundamental to good performance of diagnostic testing is standardization, with defined reference materials and measurement procedures. In this review, we discuss the historical steps to first harmonize HbA1c testing, followed by the global standardization efforts and provide an update on the current situation and future goals for HbA1c testing.

Discordance in glycemic categories and regression to normality at baseline in 10,000 people in a Type 2 diabetes prevention trial

The world diabetes population quadrupled between 1980 and 2014 to 422 million and the enormous impact of Type 2 diabetes is recognised by the recent creation of national Type 2 diabetes prevention programmes. There is uncertainty about how to correctly risk stratify people for entry into prevention programmes, how combinations of multiple 'at high risk' glycemic categories predict outcome, and how the large recently defined 'at risk' population based on an elevated glycosylated haemoglobin (HbA1c) should be managed. We identified all 141,973 people at highest risk of diabetes in our population, and screened 10,000 of these with paired fasting plasma glucose and HbA1c for randomisation into a very large Type 2 diabetes prevention trial. Baseline discordance rate between highest risk categories was 45.6%, and 21.3-37.0% of highest risk glycaemic categories regressed to normality between paired baseline measurements (median 40 days apart). Accurate risk stratification using both fasting plasma glucose and HbA1c data, the use of paired baseline data, and awareness of diagnostic imprecision at diagnostic thresholds would avoid substantial overestimation of the true risk of Type 2 diabetes and the potential benefits (or otherwise) of intervention, in high risk subjects entering prevention trials and programmes.

Measurement of HbA1c and HbA2 by Capillarys 2 Flex Piercing HbA1c programme for simultaneous management of diabetes and screening for thalassemia

Introduction

Thalassemia could interfere with some assays for haemoglobin A_1c (HbA_1c) measurement, therefore, it is useful to be able to screen for thalassemia while measuring HbA_1c. We used Capillarys 2 Flex Piercing (Capillarys 2FP) HbA_1c programme to simultaneously measure HbA_1c and screen for thalassemia.

Materials and methods

Samples from 498 normal controls and 175 thalassemia patients were analysed by Capillarys 2FP HbA_1c programme (Sebia, France). For method comparison, HbA_1c was quantified by Premier Hb9210 (Trinity Biotech, Ireland) in 98 thalassaemia patients samples. For verification, HbA_1c from eight thalassaemia patients was confirmed by IFCC reference method.

Results

Among 98 thalassaemia samples, Capillarys 2FP did not provide an HbA_1c result in three samples with HbH due to the overlapping of HbBart’s with HbA_1c fraction; for the remaining 95 thalassaemia samples, Bland-Altman plot showed 0.00 ± 0.35% absolute bias between two systems, and a significant positive bias above 7% was observed only in two HbH samples. The HbA_1c values obtained by Capillarys 2FP were consistent with the IFCC targets (relative bias below ± 6%) in all of the eight samples tested by both methods. For screening samples with alpha (α-) thalassaemia silent/trait or beta (β-) thalassemia trait, the optimal HbA₂ cut-off values were ≤ 2.2% and > 2.8%, respectively.

Conclusions

Our results demonstrated the Capillarys 2FP HbA_1c system could report an accurate HbA_1c value in thalassemia silent/trait, and HbA₂ value (≤ 2.2% for α-thalassaemia silent/trait and > 2.8% for β-thalassemia trait) and abnormal bands (HbH and/or HbBart’s for HbH disease, HbF for β-thalassemia) may provide valuable information for screening.

A comparative evaluation of the analytical performances of Capillarys 2 Flex Piercing, Tosoh HLC-723 G8, Premier Hb9210, and Roche Cobas c501 Tina-quant Gen 2 analyzers for HbA1c determination

INTRODUCTION

Haemoglobin A_1c (HbA_1c) is widely used in the management of diabetes. Therefore, the reliability and comparability among different analytical methods for its detection have become very important.

MATERIALS AND METHODS

A comparative evaluation of the analytical performances (precision, linearity, accuracy, method comparison, and interferences including bilirubin, triglyceride, cholesterol, labile HbA_1c (LA_1c), vitamin C, aspirin, fetal haemoglobin (HbF), and haemoglobin E (Hb E)) were performed on Capillarys 2 Flex Piercing (Capillarys 2FP) (Sebia, France), Tosoh HLC-723 G8 (Tosoh G8) (Tosoh, Japan), Premier Hb9210 (Trinity Biotech, Ireland) and Roche Cobas c501 (Roche c501) (Roche Diagnostics, Germany).

RESULTS

A good precision was shown at both low and high HbA_1c levels on all four systems, with all individual CVs below 2% (IFCC units) or 1.5% (NGSP units). Linearity analysis for each analyzer had achieved a good correlation coefficient (R² > 0.99) over the entire range tested. The analytical bias of the four systems against the IFCC targets was less than ± 6% (NGSP units), indicating a good accuracy. Method comparison showed a great correlation and agreement between methods. Very high levels of triglycerides and cholesterol (≥ 15.28 and ≥ 8.72 mmol/L, respectively) led to falsely low HbA_1c concentrations on Roche c501. Elevated HbF induced false HbA_1c detection on Capillarys 2FP (> 10%), Tosoh G8 (> 30%), Premier Hb9210 (> 15%), and Roche c501 (> 5%). On Tosoh G8, HbE induced an extra peak on chromatogram, and significantly lower results were reported.

CONCLUSIONS

The four HbA_1c methods commonly used with commercial analyzers showed a good reliability and comparability, although some interference may falsely alter the result.

Methods, units and quality requirements for the analysis of haemoglobin A1c in diabetes mellitus

The formation of glycohemoglobin, especially the hemoglobin A_1c (HbA_1c) fraction, occurs when glucose becomes coupled with the amino acid valine in the β-chain of Hb; this reaction is dependent on the plasma concentration of glucose. Since the early 1970s it has been known that diabetics display higher values OF HbA_1C because they have elevated blood glucose concentrations. Thus HbA_1c has acquired a very important role in the treatment and diagnosis of diabetes mellitus. After the introduction of the first quantitative measurement OF HbA_1C, numerous methods for glycohemoglobin have been introduced with different assay principles: From a simple mini-column technique to the very accurate automated high-pressure chromatography and lastly to many automated immunochemical or enzymatic assays. In early days, the results of the quality control reports for HbA_1c varied extensively between laboratories, therefore in United States and Canada working groups (WG) of the Diabetes Controls and Complications Trial (DCCT) were set up to standardize the HbA_1c assays against the DCCT/National Glycohemoglobin Standardization Program reference method based on liquid chromatography. In the 1990s, the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) appointed a new WG to plan a reference preparation and method for the HBA_1c measurement. When the reference procedures were established, in 2004 IFCC recommended that all manufacturers for equipment used in HbA_1c assays should calibrate their methods to their proposals. This led to an improvement in the coefficient of variation (CV%) associated with the assay. In this review, we describe the glycation of Hb, methods, standardization of the HbA_1c assays, analytical problems, problems with the units in which HbA_1c values are expressed, reference values, quality control aspects, target requirements for HbA_1c, and the relationship of the plasma glucose values to HbA_1c concentrations. We also note that the acceptance of the mmol/mol system for HbA_1c as recommended by IFCC, i.e., the new unit and reference ranges, are becoming only slowly accepted outside of Europe where it seems that expressing HbA_1c values either only in per cent units or with parallel reporting of percent and mmol/mol will continue. We believe that these issues should be resolved in the future and that it would avoid confusion if mmol/mol unit for HbA_1c were to gain worldwide acceptance.

Detection of abnormal glucose tolerance in Africans is improved by combining A1C with fasting glucose: the Africans in America Study

OBJECTIVE

Abnormal glucose tolerance is rising in sub-Saharan Africa. Hemoglobin A1c by itself and in combination with fasting plasma glucose (FPG) is used to diagnose abnormal glucose tolerance. The diagnostic ability of A1C in Africans with heterozygous variant hemoglobin, such as sickle cell trait or hemoglobin C trait, has not been rigorously evaluated. In U.S.-based Africans, we determined by hemoglobin status the sensitivities of 1) FPG ≥5.6 mmol/L, 2) A1C ≥ 5.7% (39 mmol/mol), and 3) FPG combined with A1C (FPG ≥5.6 mmol/L and/or A1C ≥5.7% [39 mmol/mol]) for the detection of abnormal glucose tolerance.

RESEARCH DESIGN AND METHODS

An oral glucose tolerance test (OGTT) was performed in 216 African immigrants (68% male, age 37 ± 10 years [mean ± SD], range 20-64 years). Abnormal glucose tolerance was defined as 2-h glucose ≥7.8 mmol/L.

RESULTS

Variant hemoglobin was identified in 21% (46 of 216). Abnormal glucose tolerance occurred in 33% (72 of 216). When determining abnormal glucose tolerance from the OGTT (2-h glucose ≥7.8 mmol/L), sensitivities of FPG for the total, normal, and variant hemoglobin groups were 32%, 32%, and 33%, respectively. Sensitivities for A1C were 53%, 54%, and 47%. For FPG and A1C combined, sensitivities were 64%, 63%, and 67%. Sensitivities for FPG and A1C and the combination did not vary by hemoglobin status (all P > 0.6). For the entire cohort, sensitivity was higher for A1C than FPG and for both tests combined than for either test alone (all P values ≤ 0.01).

CONCLUSIONS

No significant difference in sensitivity of A1C by variant hemoglobin status was detected. For the diagnosis of abnormal glucose tolerance in Africans, the sensitivity of A1C combined with FPG is significantly superior to either test alone.