HbA1c: performance of the Sebia Capillarys 2 Flex Piercing

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.

Misleading HbA1c Measurement in Diabetic Patients with Hemoglobin Variants

BACKGROUND AND OBJECTIVES

Hemoglobin A1c (HbA1c) is widely used for the monitoring and management of diabetes mellitus. The aim of this study is to investigate the influence of hemoglobin (Hb) variants on the measurement of HbA1c.

MATERIALS AND METHODS

HbA1c levels of 845 blood samples obtained from diabetic patients with various hemoglobin types were measured using a turbidimetric inhibition immunoassay and capillary electrophoresis.

RESULTS

Of 845 patients with diabetes, 65.7% (555/845) have the normal hemoglobin type (A₂A) and 34.3% (290/845) have various abnormal hemoglobin types, including heterozygous HbE 30.2% (255/845), homozygous HbE 1.9 % (16/845), Hb Constant Spring (CS) trait 1.4% (12/845), CSEA Bart's 0.2% (2/845), and beta-thalassemia trait 0.6% (5/845). In most of the patients with diabetes, HbA1c levels determined by two different methods, inhibition immunoassay and capillary electrophoresis, gave strong positive correlation (R = 0.901, P < 0.001), except for those with homozygous HbE (N = 16) and CSEA Bart's (N = 2). In all 18 patients with homozygous HbE and CSEA Bart's, the HbA1c was undetectable by capillary electrophoresis, meaning that their estimated average glucose was undeterminable, although their HbA1c levels could be measured using an inhibition immunoassay. The discrepancy of HbA1c results obtained from two different methods is noted in patients without HbA.

CONCLUSIONS

We have demonstrated the erroneous nature of HbA1c measurement in patients with hemoglobin variants, especially in those without HbA expression. Therefore, in the population with a high prevalence of hemoglobinopathies, hemoglobin typing should be considered as basic information prior to HbA1c measurement.

False measurement of glycated hemoglobin in patients without hemoglobin A

Background: Hemoglobin (Hb) A1c, a biochemical marker widely used in monitoring diabetes mellitus, can be quantitatively measured by various examining systems. However, significant errors still exist. In the present study, we evaluated the HbA1c level in five patients with compound heterozygotes by five different examining systems and our goal is to identify the existence of erroneous HbA1c measurement.Methods: Blood samples collected from normal (no hemoglobin variants) and abnormal (compound heterozygotes) patients were analyzed by capillary electrophoresis technique and sequence analysis. The samples without HbA expression via above methods were further analyzed for HbA1c by ion exchange HPLC Variant II/ Variant II Turbo 2.0 (VII and VII-T 2.0), boronate affinity HPLC, capillary electrophoresis, and Tinaquant immunoassay.Results: HbA1c expression were unexpectedly detected in the compound heterozygous samples by using additional examining systems: The HPLC VII and VII-T 2.0 detected HbA1c expression in two of five samples and failed to detect the abnormal HbA2 expression; the CE system detected HbA1c expression in one of five samples with abnormal HbA2 expression; the Ultra2 and PPI system detected the HbA1c expression of all samples without abnormal HbA2Conclusions: Five human samples without HbA expression were additionally detected with HbA1c expression with or without abnormal HbA2 expression by five analysis systems and the different examining assay potentially affected the test results. These results demonstrated that the limitations of current examining systems for monitoring patients with hemoglobin disorders highlighting the further improvement in the method of clinical HbA examination.

Capillarys 2 Flex Piercing: Analytical performance assessment according to CLSI protocols for HbA1c quantification

HbA_1c is used for monitoring diabetic balance. In this paper we report an assessment of the analytical performances of Capillarys 2 Flex Piercing (C2FP) for HbA_1c measurement using CE (Capillary Electrophoresis). CLSI (Clinical and Laboratory Standard Institute) protocols are used for the evaluation of apparatus performances: precision, linearity, method comparison, trueness and common interferences. HbA_1c CVs average in intra-assay was 1.6% between run imprecision CV ranged from 0.1 to 1.8%. The linearity was demonstrated between 4.7 and 15.0%. The comparison study revealed that Bland Altman plot mean difference was equal to -0.03 (CI 95% (-0.05 to -0.0003)) and Passing-Bablok regression intercept was -0.05, CI95%(-0.13 -  -0.05); slope: 1.00, CI95%[1.00-1.01]. A strong correlation (r > 0.99) was proved. No significant effects of hemoglobin variants were seen with CE on HbA_1c measurement. No problem related to sample-to-sample carry over was noted. No interferences of LA_1c and cHb were observed. CE allowed quantification of HbA_1c even at low level of total hemoglobin (40 g/L) in contrast to HPLC. Furthermore, this analyzer offered the opportunity of quantifying the HbA₂ simultaneously with HbA_1c . This evaluation showed that C2FP is a convenient system for the control of diabetes and the detection of hemoglobinopathies.

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.

Multicentre evaluation of the Premier Hb9210 HbA1c analyser

BACKGROUND

The accurate and precise quantification of HbA1c is essential for the diagnosis and routine monitoring of patients with diabetes. We report an evaluation of the Trinity Biotech Premier Hb9210 analyser (Bray, Ireland/Kansas City, MO, USA), a boronate affinity chromatography-based high performance liquid chromatography (HPLC) system for the measurement of glycated haemoglobin.

METHODS

We evaluated the analytical performance of the Hb9210 as part of a multicentre evaluation. The effect of haemoglobin variants, other potential interferences and the performance in comparison to both the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) and National Glycohemoglobin Standardization Program (NGSP) reference systems, was assessed. Most of the centres participating also act as reference laboratories for both the IFCC standardisation network for HbA1c and the NGSP.

RESULTS

The combined data from all centres showed total coefficients of variation (CV) of 2.71%, 2.32% and 2.14% at low, medium and high values, respectively, for mmol/mol (SI units) and 1.62%, 1.59% and 1.68% for % (NGSP units), which are well below the recommended upper limits of 3% CV for mmol/mol (SI units) and 2% CV for % (NGSP). The analyser showed a good correlation to HbA1c methods currently used in clinical practice and the IFCC reference method procedure. Haemoglobin variants AC, AS, AE and AD do not affect the measurement of HbA1c. Overall the Hb9210 performs well across the whole analytical range.

CONCLUSIONS

The Hb9210 performs well and is suitable for clinical application in the analysis of HbA1c.

Evaluation of hemoglobin A1c measurement by Capillarys 2 electrophoresis for detection of abnormal glucose tolerance in African immigrants to the United States

BACKGROUND

Hemoglobin A1c (HbA1c) is used to monitor long-term glycemic control in individuals with diabetes, guide therapy, predict the risk of microvascular complications, and more recently to diagnose diabetes. An automated liquid-flow capillary electrophoresis method was recently developed to measure HbA1c using the Capillarys 2 Flex Piercing instrument.

METHODS

Analytical evaluation was performed at 2 clinical centers. A clinical analysis was conducted in 109 African-born individuals, 24% of whom have variant hemoglobin (HbAS or HbAC). Abnormal glucose tolerance (which includes both diabetes and prediabetes) was defined as 2h glucose of ≥ 140 mg/dl (7.8 mmol/l) during an oral glucose tolerance test.

RESULTS

Interlaboratory CVs were ≤ 2.1%. The method showed satisfactory correlation with 2 other analyzers that measure HbA1c by high-performance liquid chromatography. Neither labile HbA1c, carbamylated hemoglobin, uremia, bilirubin nor common hemoglobin variants (HbC/HbS/HbE) interfered. Forty-five individuals (41%) had abnormal glucose tolerance. The sensitivity of HbA1c for diagnosing abnormal glucose tolerance was 38%, 36% and 42% for total, normal and variant hemoglobin groups, respectively.

CONCLUSIONS

The analytical performance of HbA1c on the Capillarys 2 is suitable for clinical application. Variant hemoglobin in Africans did not interfere with the detection of abnormal glucose tolerance by HbA1c measured on the Capillarys 2.

Erroneous HbA1c measurements in the presence of β-thalassemia and common Chinese hemoglobin variants

HbA

Blood samples from normal patients, patients with β-thalassemia, patients exhibiting heterozygosity, and patients exhibiting homozygosity were analyzed using ion-exchange HPLC (Variant II Turbo, Bio-Rad and Adams A

Samples from patients with β-thalassemia produced significant positive biases on the Variant II Turbo system compared to the other three systems. For heterozygous βA/βE patients, a good agreement was observed between Capillarys 2 Flex Piercing and Ultra

β-Thalassemia can cause errors in HbA

Evaluation of the Sebia CAPILLARYS 2 flex piercing for the measurement of HbA(1c) on venous and capillary blood samples

OBJECTIVES

We evaluated the Sebia CAPILLARYS 2 Flex Piercing (Cap 2FP; Sebia, Lisses, France) for measurement of hemoglobin A1c (HbA1c) on venous and capillary blood samples.

METHODS

We analyzed whole-blood samples and control materials with the Cap 2FP and Tosoh G8 (Tosoh Corporation, Tokyo, Japan). Capillary blood samples were analyzed on the Cap 2FP on different storage conditions and were compared with venous samples.

RESULTS

Both instruments achieved total imprecision of less than 2.5% (International Federation of Clinical Chemistry units). Bias was 1 mmol/mol or less and 4 mmol/mol or less for the Cap 2FP and Tosoh G8, respectively. The Cap 2FP was not prone to common interferences. The Tosoh G8 showed significant bias only for carbamylated hemoglobin and did not completely separate hemoglobin D and hemoglobin E. On the Cap 2FP, storage of capillary blood at room temperature showed no significant bias. There was good agreement with venous blood.

CONCLUSIONS

The Cap 2FP and Tosoh G8 perform excellently for HbA1c determination. Capillary blood can be analyzed on the Cap 2FP as an acceptable alternative to venous blood and point-of-care testing. Home collection and central analysis of capillary blood could contribute to a reduction of health care costs without reducing quality of HbA1c determination.

Performances of capillary electrophoresis and HPLC methods in HbA1c determination: diagnostic accuracy in HbS and HbD-Iran variants' presence

BACKGROUND

Glycated hemoglobin (HbA1c) provides a useful estimate of mean glycemia in patients with diabetes and is directly related to risks for diabetes complications. The aim of this study is to compare a capillary electrophoresis method and two high-performance liquid chromatography (HPLC) cation-exchange analyzers (Variant II (Bio-Rad Laboratories, Inc., Hercules, CA) and G8 (Tosoh Biosciences, San Francisco, CA)) to identify the most reliable method in Hb variants' presence.

METHODS

Measurements of HbA1c were carried out in blood samples from 200 Tor Vergata Hospital patients, using G8 Tosoh, and from 107 San Filippo Neri Hospital patients, using Variant II Bio-Rad methods. All samples were analyzed by Capillarys 2 Flex Piercing (FP; Sebia, Lisses, France).

RESULTS

There was a good concordance between the results of capillary electrophoresis and HPLC methods (R(2) = 0.99, P < 0.0001 for G8 HPLC; R(2) = 0.99, P < 0.0001 for Variant II HPLC). During the study, we observed that some Hb variants, HbS and HbD-Iran, can alter the HbA1c level.

CONCLUSIONS

Since the HbA1c test is now recommended for diagnosing diabetes, and minimal variation of the concentration affects the clinical therapy, it is very important that the results are reliable and interference-free. Capillarys 2-FP analyzer is suitable for this purpose and sometimes it showed some advantages with respect to the HPLC analyzers tested, especially when Hb variants are present.