Innovations in HbA1c analysis: finding the balance between speed and accuracy. An investigation of a potential new Secondary Reference Measurement Procedure for the IFCC

OBJECTIVES

The escalating prevalence of diabetes worldwide has resulted in a dramatic increase in the number of people who need testing, which in turn necessitates faster HbA1c measurement. The Tosoh GR01 addresses the need for fast turnaround times of whilst offering pragmatic steps to maintain result accuracy in a single instrument by offering two distinct operating modes: Short Mode (SM) and Long Mode (LM). The aim of this study was to evaluate all relevant aspects of the performance of the Tosoh GR01 with a view to accepting the instrument as a future Secondary Reference Measurement Procedure (SRMP) for the IFCC.

METHODS

Certified Clinical & Laboratory Standards Institute (CLSI) Evaluation Protocols (EP) were used to evaluate precision (EP-5), accuracy (EP-9), linearity (EP-6), carry-over (EP-10) and the effect of hemoglobin variants and other potential interferences.

RESULTS

Both modes demonstrated CVs <0.6 % in SI units and <0.4 % in NGSP units at 46 mmol/mol (6.4 %) and 75 mmol/mol (9.0 %) and passed both National Glycohemoglobin Standardization Program (NGSP) and International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) certification procedures when compared with 7 IFCC Certified Secondary Reference Measurement Procedures (SRMP). Sigma for both modes was >6 when using the results of EP-5 and EP-9 at an HbA1c concentration of 50 mmol/mol (6.7 %). Neither mode showed any interference with common Hb-variants except for HbAE when HbA1c was >65 mmol/mol. In the SM HbAS, HbAD and HbAC were recognized but no result was reported.

CONCLUSIONS

There is a good balance between speed and accuracy for determining HbA1c with the Tosoh GR01 in both analytical modes and the device is suitable for use as an IFCC SRMP.

Achievement of Target Gain Larger than Unity in an Inertial Fusion Experiment

On December 5, 2022, an indirect drive fusion implosion on the National Ignition Facility (NIF) achieved a target gain G_{target} of 1.5. This is the first laboratory demonstration of exceeding "scientific breakeven" (or G_{target}>1) where 2.05 MJ of 351 nm laser light produced 3.1 MJ of total fusion yield, a result which significantly exceeds the Lawson criterion for fusion ignition as reported in a previous NIF implosion [H. Abu-Shawareb et al. (Indirect Drive ICF Collaboration), Phys. Rev. Lett. 129, 075001 (2022)PRLTAO0031-900710.1103/PhysRevLett.129.075001]. This achievement is the culmination of more than five decades of research and gives proof that laboratory fusion, based on fundamental physics principles, is possible. This Letter reports on the target, laser, design, and experimental advancements that led to this result.

The risk of clinical misinterpretation of HbA1c: Modelling the impact of biological variation and analytical performance on HbA1c used for diagnosis and monitoring of diabetes

BACKGROUND

The validity of clinical interpretation of HbA1c depends on the analytical performance of the method and the biological variation of HbA1c in patients. The contribution of non-glucose related factors to the biological variation of HbA1c (NGBVA1c) is not known. This paper explores the cumulative impact of analytical errors and NGBVA1c on the risk of misinterpretation.

METHODS

A model has been developed to predict the risk of misinterpretation of HbA1c for diagnosis and monitoring with variables for analytical performance and levels of NGBVA1c.

RESULTS

The model results in probabilities of misinterpretation for a given HbA1c.

EXAMPLE

for an HbA1c 43 mmol/mol (6.1%), bias 1 mmol/mol (0.09%), CV 3% (2%) used for diagnosis, the probabilities of misinterpretation range from 1 to 19% depending on the contribution of NGBVA1c to the biological variation of HbA1c.

CONCLUSIONS

In addition to analytical bias and imprecision, NGBVA1c contributes to the risk of misinterpretation, but the relative impact is different per clinical application of HbA1c. For monitoring, imprecision is the predominating factor, for diagnosis both biological variation and analytical bias. Given the increasing use of HbA1c for diagnosis, increase of knowledge on NGBVA1c, decrease of analytical bias, and awareness of the risk of misinterpretation are required.

Lawson Criterion for Ignition Exceeded in an Inertial Fusion Experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion.

Age and vitamin D affect the magnitude of the antibody response to the first dose of the SARS-CoV-2 BNT162b2 vaccine

Background

Most approved vaccines utilise a two-dose strategy. To enable larger groups of patients to receive the first dose, the UK government increased the gap between the two doses from three to twelve weeks. Here we report on the immunogenicity of the first dose, including effect of age and vitamin D status on these levels over an 8 week-period.

Methods

Blood samples were collected from healthcare workers (HCW) receiving their first BNT162b2 vaccine dose between January and February 2021. Antibody (Ab) production was measured, prior to and weekly for 4 weeks post immunization, and a final measurement was performed at 8 weeks. Serum vitamin D concentrations were also measured at baseline.

Findings

Immunization of 97 HCW induced an Ab response that peaked 3•2 weeks post immunization to decrease thereafter. Ab levels remained positive at 8 weeks. IgG peak concentration was negatively associated with age (β=-0•440, p<0.001). Response to immunization was also significantly affected by vitamin D status (p=0•022), on average 29•3% greater peak value in individuals with 25(OH)D>50nmol/L. No other variable showed significant effect.

Interpretation

The first dose of BNT162b2 produced Ab levels that remained positive after 8 weeks. Peak was greater in younger subjects and 25(OH)D>50nmol/L was beneficial. Booster campaigns should take into consideration vitamin D status which is at its highest following a period of sunshine exposure or following oral supplementation (400-1000IU daily).

Funding

Abbott Diagnostics Ltd supplied the kits used to quantify the anti-SARS -CoV-2 Spike IgG and technical support as well as provided financial support for sample collections.

Diagnosing type 2 diabetes using Hemoglobin A1c: a systematic review and meta-analysis of the diagnostic cutpoint based on microvascular complications

AIMS

Diabetic microvascular complications of retinopathy, nephropathy and neuropathy may occur at hemoglobin A1c levels (HbA1c) below the 6.5% (48 mmol/mol) diagnostic threshold. Our objective was to assess the validity of the HbA1c diagnostic cutpoint of 6.5% based upon published evidence of the prevalence of retinopathy, nephropathy and neuropathy as markers of diabetes.

METHODS

Data Sources PubMed, Embase, Cochrane, Scopus and CINAHL from 1990-March 2019, grey literature sources. Study Selection All studies reported after 1990 (to ensure standardized HbA1c values) where HbA1c levels were presented in relation to prevalence of retinopathy, nephropathy or neuropathy in subjects not known to have diabetes. Data Extraction Studies were screened independently, data abstracted, and risk of bias appraised. Data Synthesis Data were synthesized using HbA1c categories of < 6.0% (< 42 mmol/mol), 6.0-6.4% (42-47 mmol/mol) and ≥ 6.5% (≥ 48 mmol/mol). Random-effects meta-analyses were conducted for retinopathy, nephropathy and neuropathy prevalence stratified by HbA1c categories. Random-effects multivariable meta-regression was conducted to identify predictors of retinopathy prevalence and sources of between-study heterogeneity.

RESULTS

Pooled mean prevalence was: 4.0%(95% CI: 3.2-5.0%) for retinopathy, 10.5% (95% CI: 4.0-19.5%) for nephropathy, 2.5% (95% CI: 1.1-4.3%) for neuropathy. Mean prevalence when stratified for HbA1c < 6.0%, 6.0-6.4% and ≥ 6.5% was: retinopathy: 3.4% (95% CI: 1.8-5.4%), 2.3% (95% CI: 1.6-3.2%) and 7.8%(95% CI: 5.7-10.3%); nephropathy: 7.1% (95% CI: 1.7-15.9%), 9.6% (95% CI: 0.8-26.4%) and 17.1% (95% CI: 1.0-46.9%); neuropathy: 2.1% (95% CI: 0.0-6.8%), 3.4% (95% CI: 0.0-11.6%) and 2.8% (95% CI: 0.0-12.8%). Multivariable meta-regression showed HbA1c ≥ 6.5% (OR: 4.05; 95% CI: 1.92-8.57%), age > 55 (OR: 3.23; 95% CI 1.81-5.77), and African-American race (OR: 10.73; 95% CI: 4.34-26.55), to be associated with higher retinopathy prevalence. Marked heterogeneity in prevalence estimates was found across all meta-analyses (Cochran's Q-statistic p < 0.0001).

CONCLUSIONS

The prevalence of nephropathy and moderate retinopathy was increased in subjects with HbA1c values ≥ 6.5% confirming the high specificity of this value for diagnosing T2DM; however, at HbA1c < 6.5% retinopathy increased at age > 55 years and, most strikingly, in African-Americans, suggesting there may be excess microvascular complication prevalence (particularly nephropathy) in individuals below the diabetes diagnostic threshold.

Performance of SARS-CoV-2 serology tests: Are they good enough?

In the emergency of the SARS-CoV-2 pandemic, great efforts were made to quickly provide serology testing to the medical community however, these methods have been introduced into clinical practice without the complete validation usually required by the regulatory organizations. SARS-CoV-2 patient samples (n = 43) were analyzed alongside pre-pandemic control specimen (n = 50), confirmed respiratory infections (n = 50), inflammatory polyarthritis (n = 22) and positive for thyroid stimulating immunoglobulin (n = 30). Imprecision, diagnostic sensitivity and specificity and concordance were evaluated on IgG serologic assays from EuroImmun, Epitope Diagnostics (EDI), Abbott Diagnostics and DiaSorin and a rapid IgG/IgM test from Healgen. EDI and EuroImmun imprecision was 0.02–14.0% CV. Abbott and DiaSorin imprecision (CV) ranged from 5.2%–8.1% and 8.2%–9.6% respectively. Diagnostic sensitivity of the assays was 100% (CI: 80–100%) for Abbott, EDI and EuroImmun and 95% (CI: 73–100%) for DiaSorin at ≥14 days post PCR. Only the Abbott assay had a diagnostic specificity of 100% (CI: 91–100%). EuroImmun cross-reacted in 3 non-SARS-CoV-2 respiratory infections and 2 controls. The DiaSorin displayed more false negative results and cross-reacted in six cases across all conditions tested. EDI had one cross-reactive sample. The Healgen rapid test showed excellent sensitivity and specificity. Overall, concordance of the assays ranged from 76.1% to 97.9%. Serological tests for SARS-CoV-2 showed good analytical performance. The head-to-head analysis of samples revealed differences in results that may be linked to the use of nucleocapsid or spike proteins. The point of care device tested demonstrated adequate performance for antibody detection.

Experience of point-of-care HbA1c testing in the English National Health Service Diabetes Prevention Programme: an observational study

INTRODUCTION

To report the observations of point-of-care (POC) glycated hemoglobin (HbA1c) testing in people with non-diabetic hyperglycemia (NDH; HbA1c 42-47 mmol/mol (6.0%-6.4%)), applied in community settings, within the English National Health Service Diabetes Prevention Programme (NHS DPP).

RESEARCH DESIGN AND METHODS

A service evaluation assessing prospectively collected national service-level data from the NHS DPP, using data from the first referral received in June 2016-October 2018. Individuals were referred to the NHS DPP with a laboratory-measured HbA1c in the NDH range and had a repeat HbA1c measured at first attendance of the program using one of three POC devices: DCA Vantage, Afinion or A1C Now+. Differences between the referral and POC HbA1c and the SD of the POC HbA1c were calculated. The factors associated with the difference in HbA1c and the association between POC HbA1c result and subsequent attendance of the NHS DPP were also evaluated.

RESULTS

Data from 73 703 participants demonstrated a significant mean difference between the referral and POC HbA1c of -2.48 mmol/mol (-0.23%) (t=157, p<0.001) with significant differences in the mean difference between devices (F(2, 73 700)=738, p<0.001). The SD of POC HbA1c was 4.46 mmol/mol (0.41%) with significant differences in SDs between devices (F(2, 73 700)=1542, p<0.001). Participants who were older, from more deprived areas and from Asian, black and mixed ethnic groups were associated with smaller HbA1c differences. Normoglycemic POC HbA1c versus NDH POC HbA1c values were associated with lower subsequent attendance at behavioral interventions (58% vs 67%, p<0.001).

CONCLUSION

POC HbA1c testing in community settings was associated with significantly lower HbA1c values when compared with laboratory-measured referrals. Acknowledging effects of regression to the mean, we found that these differences were also associated with POC method, location, individual patient factors and time between measurements. Compared with POC HbA1c values in the NDH range, normoglycemic POC HbA1c values were associated with lower subsequent intervention attendance.

Are hemoglobin A1c point-of-care analyzers fit for purpose? The story continues

Objectives

Point-of-care (POC) analyzers are playing an increasingly important role in diabetes management but it is essential that we know the performance of these analyzers in order to make appropriate clinical decisions. Whilst there is a growing body of evidence around the more well-known analyzers, there are many ‘new kids on the block’ with new features, such as displaying the presence of potential Hb-variants, which do not yet have a proven track record.

Methods

The study is a comprehensive analytical and usability study of six POC analyzers for HbA1c using Clinical and Laboratory Standards Institute (CLSI) protocols, international quality targets and certified International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) and National Glycohemoglobin Standardization Program (NGSP) Secondary Reference Measurement Procedures (SRMP). The study includes precision (EP-5 and EP-15), trueness (EP-9), linearity (EP-6), sample commutability (fresh, frozen and lyophilized), interference of Hb-variants (fresh and frozen samples).

Results

Only two of the six analyzers performed to acceptable levels over the range of performance criteria. Hb-variant interference, imprecision or variability between lot numbers are still poor in four of the analyzers.

Conclusions

This unique and comprehensive study shows that out of six POC analyzers studied only two (The Lab 001 and Cobas B101) met international quality criteria (IFCC and NGSP), two (A1Care and Innovastar) were borderline and two (QuikReadgo and Allegro) were unacceptable. It is essential that the scientific and clinical community are equipped with this knowledge in order to make sound decisions on the use of these analyzers.

Analysis: Investigating the quality of POCT devices for HbA1c, what are our next steps?

There are a growing number of publications evaluating the performance of HbA1c point-of-care testing (POCT) devices when compared to routine laboratory instruments, but is this what we need from future studies? Here we describe the current understanding of the performance of POCT for HbA1c, which areas need further studies, and the key requirements for future publications based on performance evaluations of these devices. These include studies in clinical settings, performance measured against internationally standardized reference methods, and the need to evaluate new to the market devices that do not currently have a detailed performance history. In addition we highlight the need for external quality assessment schemes that are designed to support POCT in a wide range of clinical settings.

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.

EurA1c: The European HbA1c Trial to Investigate the Performance of HbA1c Assays in 2166 Laboratories across 17 Countries and 24 Manufacturers by Use of the IFCC Model for Quality Targets

BACKGROUND

A major objective of the IFCC Committee on Education and Use of Biomarkers in Diabetes is to generate awareness and improvement of HbA1c assays through evaluation of the performance by countries and manufacturers.

METHODS

Fresh whole blood and lyophilized hemolysate specimens manufactured from the same pool were used by 17 external quality assessment organizers to evaluate analytical performance of 2166 laboratories. Results were evaluated per country, per manufacturer, and per manufacturer and country combined according to criteria of the IFCC model for quality targets.

RESULTS

At the country level with fresh whole blood specimens, 6 countries met the IFCC criterion, 2 did not, and 2 were borderline. With lyophilized hemolysates, 5 countries met the criterion, 2 did not, and 3 were borderline. At the manufacturer level using fresh whole blood specimens, 13 manufacturers met the criterion, 8 did not, and 3 were borderline. Using lyophilized hemolysates, 7 manufacturers met the criterion, 6 did not, and 3 were borderline. In both country and manufacturer groups, the major contribution to total error derived from between-laboratory variation. There were no substantial differences in performance between groups using fresh whole blood or lyophilized hemolysate samples.

CONCLUSIONS

The state of the art is that 1 of 20 laboratories does not meet the IFCC criterion, but there are substantial differences between country and between manufacturer groups. Efforts to further improve quality should focus on reducing between-laboratory variation. With some limitations, fresh whole blood and well-defined lyophilized specimens are suitable for purpose.

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.

Evaluation of Four HbA1c Point-of-Care Devices Using International Quality Targets: Are They Fit for the Purpose?

BACKGROUND

Point-of-care (POC) testing is becoming increasingly valuable in health care delivery, and it is important that the devices used meet the same quality criteria as main laboratory analyzers. While external quality assessment (EQA) provides a great tool for assessing quality, many POC devices are not enrolled in these schemes and standard laboratory evaluations are needed to assess performance.

METHODS

The Clinical and Laboratory Standards Institute (CLSI) protocols EP-5 and EP-9 were applied to investigate imprecision, accuracy and bias. We assessed bias using the mean of 4 certified secondary reference measurement procedures (SRMPs).

RESULTS

The Afinion2™ and the Quo-Lab had CVs of ≤1.7 and ≤2.4% respectively in IFCC SI units (≤1.2 and ≤1.7% NGSP) and a bias ≤2 mmol/mol (≤0.2% NGSP) at 48 and 75 mmol/mol (6.5 and 9.0% NGSP). Sigma for the Afinion2 was 5.8 and for the Quo-Lab 4.0. Both methods passed the NGSP criteria with 2 instruments when compared with 4 individual SRMPs. The HbA1c 501 had a CV of 3.4% and 2.7% in IFCC SI units (2.1% and 1.7% NGSP) and a bias ≤2.4 mmol/mol (≤0.2% NGSP) and passed the NGSP criteria with 2 instruments compared with 4 individual SRMPs except for instrument 2 compared with the Tosoh G8. Sigma was 2.1. The A1Care had a sigma of 1.4 and failed all criteria mainly due to a high CV (6.2% and 4.1% in IFCC SI units [4.1% and 2.9% NGSP] at 48 and 75 mmol/mol [6.5 and 9.0% NGSP]).

CONCLUSIONS

The analytical performance was excellent for the Afinion2 and the Quo-Lab, acceptable for the HbA1c 501 and unacceptable for the A1Care according to different used criteria, demonstrating that whilst performance is improving there are still areas for considerable improvement.

Evaluating new HbA1c methods for adoption by the IFCC and NGSP reference networks using international quality targets

BACKGROUND

As a reference laboratory for HbA1c, it is essential to have accurate and precise HbA1c methods covering a range of measurement principles. We report an evaluation of the Abbott Enzymatic (Architect c4000), Roche Gen.3 HbA1c (Cobas c513) and Tosoh G11 using different quality targets.

METHODS

The effect of hemoglobin variants, other potential interferences and the performance in comparison to both the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) and the National Glycohemoglobin Standardization Program (NGSP) reference systems was assessed using certified evaluation protocols.

RESULTS

Each of the evaluated HbA1c methods had CVs <3% in SI units and <2% in NGSP units at 46 mmol/mol (6.4%) and 72 mmol/mol (8.7%) and passed the NGSP criteria when compared with six secondary reference measurement procedures (SRMPs). Sigma was 8.6 for Abbott Enzymatic, 3.3 for Roche Cobas c513 and 6.9 for Tosoh G11. No clinically significant interference was detected for the common Hb variants for the three methods.

CONCLUSIONS

All three methods performed well and are suitable for clinical application in the analysis of HbA1c. Partly based on the result of this study, the Abbott Enzymatic method on the Architect c4000 and the Roche Gen.3 HbA1c on the Cobas c513 are now official, certified IFCC and NGSP SRMPs in the IFCC and NGSP networks. Sigma metrics quality criteria presented in a graph distinguish between good and excellent performance.

Performance of point-of-care HbA1c test devices: implications for use in clinical practice - a systematic review and meta-analysis

BACKGROUND

Point-of-care (POC) devices could be used to measure hemoglobin A1c (HbA1c) in the doctors' office, allowing immediate feedback of results to patients. Reports have raised concerns about the analytical performance of some of these devices. We carried out a systematic review and meta-analysis using a novel approach to compare the accuracy and precision of POC HbA1c devices.

METHODS

Medline, Embase and Web of Science databases were searched in June 2015 for published reports comparing POC HbA1c devices with laboratory methods. Two reviewers screened articles and extracted data on bias, precision and diagnostic accuracy. Mean bias and variability between the POC and laboratory test were combined in a meta-analysis. Study quality was assessed using the QUADAS2 tool.

RESULTS

Two researchers independently reviewed 1739 records for eligibility. Sixty-one studies were included in the meta-analysis of mean bias. Devices evaluated were A1cgear, A1cNow, Afinion, B-analyst, Clover, Cobas b101, DCA 2000/Vantage, HemoCue, Innovastar, Nycocard, Quo-Lab, Quo-Test and SDA1cCare. Nine devices had a negative mean bias which was significant for three devices. There was substantial variability in bias within devices. There was no difference in bias between clinical or laboratory operators in two devices.

CONCLUSIONS

This is the first meta-analysis to directly compare performance of POC HbA1c devices. Use of a device with a mean negative bias compared to a laboratory method may lead to higher levels of glycemia and a lower risk of hypoglycaemia. The implications of this on clinical decision-making and patient outcomes now need to be tested in a randomized trial.

Relationship between HbA1c and cancer in people with or without diabetes: a systematic review

AIM

To identify the relationship between HbA1c and cancers in people with or without diabetes.

BACKGROUND

Cancer is a major public health problem, accounting for 8.2 million deaths worldwide in 2012. HbA1c level has been associated with the risk of developing certain cancers, although the existing evidence is conflicting.

METHODS

EMBASE, MEDLINE, CINAHL and the Cochrane Library were searched. Eligible articles included randomized controlled trials, cohort studies, case-control studies, systematic reviews and meta-analyses. Participants of either sex, with or without Type 1 or 2 diabetes, were included. The studies were assessed using the Scottish Intercollegiate Guidelines Network (SIGN) criteria by two independent assessors. No meta-analysis was performed because of the heterogeneity of results.

RESULTS

A total of 19 studies from 1006 met the inclusion criteria, of which 14 were cohort studies and five were nested case-control studies. Eight studies investigated outcomes for all cancer sites. Four of these studies reported that higher HbA1c levels were associated with higher incidence and/or mortality risk for all cancers. One study observed a U-shaped relationship between HbA1c and cancer incidence and mortality. Increasing HbA1c levels were associated with increasing risk of developing colorectal, pancreatic, respiratory and female genital tract cancers. No increased risk was observed for breast cancer, gastrointestinal or urological malignancies.

CONCLUSION

HbA1c appears to be associated with cancer incidence and/or cancer mortality, but further studies are needed to fully understand the complex relationship between HbA1c and cancer.

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.

The effect of anaemia and abnormalities of erythrocyte indices on HbA1c analysis: a systematic review

AIMS/HYPOTHESIS

The use of HbA1c for the diagnosis of diabetes is now widely advocated despite caveats to its use. Anaemia is cited as a major confounder to this use; however, the effect of erythrocyte indices and to what degree anaemia influences HbA1c levels is not known.

METHODS

A systematic electronic database search of MEDLINE, EMBASE, the Cumulative Index to Nursing & Allied Health Literature (CINAHL) and the Cochrane Library was conducted for relevant articles published between January 1990 and May 2014. Included studies had at least one measurement of HbA1c and glucose, and a least one index of haematinic deficiency, involving non-pregnant adults, not known to have diabetes.

RESULTS

A total of 12 articles from 544 were included. The majority of studies focused on iron deficiency anaemia (IDA) and, in general, demonstrated that the presence of iron deficiency with or without anaemia led to an increase in HbA1c values compared with controls, with no concomitant rise in glucose indices. Data on the effects of other indices of erythrocyte abnormalities on HbA1c are limited but show a possible decrease in HbA1c values with non-iron deficiency forms of anaemia.

CONCLUSIONS/INTERPRETATION

HbA1c is likely to be affected by iron deficiency and IDA with a spurious increase in HbA1c values; conversely, non-IDA may lead to a decreased HbA1c value. This may lead to confusion when diagnosing diabetes using HbA1c. This review clearly identifies the need for more evidence, especially in identifying the types and degrees of anaemia likely to have significant impact on the reliability of HbA1c.

Investigation of 2 models to set and evaluate quality targets for hb a1c: biological variation and sigma-metrics

BACKGROUND

A major objective of the IFCC Task Force on Implementation of HbA1c Standardization is to develop a model to define quality targets for glycated hemoglobin (Hb A1c).

METHODS

Two generic models, biological variation and sigma-metrics, are investigated. We selected variables in the models for Hb A1c and used data of external quality assurance/proficiency testing programs to evaluate the suitability of the models to set and evaluate quality targets within and between laboratories.

RESULTS

In the biological variation model, 48% of individual laboratories and none of the 26 instrument groups met the minimum performance criterion. In the sigma-metrics model, with a total allowable error (TAE) set at 5 mmol/mol (0.46% NGSP), 77% of the individual laboratories and 12 of 26 instrument groups met the 2σ criterion.

CONCLUSIONS

The biological variation and sigma-metrics models were demonstrated to be suitable for setting and evaluating quality targets within and between laboratories. The sigma-metrics model is more flexible, as both the TAE and the risk of failure can be adjusted to the situation-for example, requirements related to diagnosis/monitoring or international authorities. With the aim of reaching (inter)national consensus on advice regarding quality targets for Hb A1c, the Task Force suggests the sigma-metrics model as the model of choice, with default values of 5 mmol/mol (0.46%) for TAE and risk levels of 2σ and 4σ for routine laboratories and laboratories performing clinical trials, respectively. These goals should serve as a starting point for discussion with international stakeholders in the field of diabetes.

IFCC standardised HbA(1c): should the world be as one?

The central importance of HbA(1c) in monitoring glycaemic control was highlighted by the Diabetes Control and Complications Trial (DCCT) which showed that improved glycaemic control, as monitored by HbA(1c), delayed the onset of diabetic complications. Following this publication the issue of international standardisation of glycated haemoglobin (GHb) measurements became an important objective. The lack of international standardisation resulted in several countries developing National Standardisation Programmes. The International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) Working Group on HbA(1c) Standardisation has established a reference measurement procedure (HPLC-MS or HPLC-CE) for HbA(1c) embracing the concept of metrological traceability. The reference method is anchored to a global network of 15 approved reference laboratories; this confers sustainability and a low level of uncertainty. Essential elements of a comprehensive reference measurement system additionally include the definition of the measurand and the unit of measurement. HbA(1c) is defined as haemoglobin (Hb) molecules having a stable adduct of glucose to the N-terminal valine of the β chain [Hb β chain (Blood) - N-(1-deoxyfructos-1-yl) Hb β chain] and that mmol/mol be used as the unit of measurement. These developments will result in improvements in inter-method and inter-laboratory agreement. Additionally, global acceptance of standardisation based on metrologically sound principles will enable clinical goals and diagnostic guidelines to be developed that can be adopted by all countries.

Control of the attosecond synchronization of XUV radiation with phase-optimized mirrors

We report on the advanced amplitude and phase control of attosecond radiation allowed by specifically-designed multilayer XUV mirrors. We first demonstrate that such mirrors can compensate for the intrinsic chirp of the attosecond emission over a large bandwidth of more than 20 eV. We then show that their combination with metallic foils introduces a third-order dispersion that is adjustable through the mirror's incidence angle. This results in a controllable beating allowing the radiation to be shaped from a single to a series of sub-100 as pulses.

Audit of internal quality control practice and processes in the south-east of England and suggested regional standards

Background

Internal quality control (IQC) has a long and well-established role in clinical biochemistry laboratories. However, despite the duration of use, and the publication of several articles detailing best practice, the implementation and use of IQC vary significantly between institutions. Consequently, the North Thames Audit and Quality Assurance Group undertook a region-wide audit of current IQC practice in 2006.

Methods

On aspects of IQC testing, interpretation and laboratory processes, 54 laboratories in the region were audited.

Results

Audit data showed significant variability in all aspects of practice, including IQC frequency, use of appropriate material, statistical processing and grades of staff involved.

Conclusions

Some of the variation in practice may affect the effectiveness of laboratory IQC, and thus the adequacy of a laboratory to monitor system performance. Consequently, a set of proposed regional standards have been developed and disseminated, prior to re-audit at a future date.

The effect of potassium EDTA on the stability of parathyroid hormone in whole blood

BACKGROUND

The stability of parathyroid hormone (PTH) in whole blood has not been well characterized. Previous studies show EDTA plasma samples to be more stable than serum samples.

METHODS

Blood from 17 haemodialysis patients and five healthy volunteers was collected into serum separator tubes (SSTs) and potassium EDTA tubes (EDTA-Ts) and incubated at room temperature before separation and storage for PTH analysis using the Bayer Advia Centaur.

RESULTS

Initial PTH concentrations were 7% higher (95% confidence interval [CI] 2-16%, P=0.016) in EDTA-Ts compared to the SSTs in the renal cohort. PTH concentrations in SSTs were significantly lower after 8 (10%, 95% CI 3-17%) and 20 h (22%, 95% CI 11-31%) but did not change significantly in EDTA-Ts (P=0.1543). PTH concentration in EDTA-Ts from healthy volunteers was also independent of incubation time (P=0.1165).

CONCLUSION

The greater stability of PTH in whole blood anticoagulated with potassium EDTA allows PTH analysis to be offered to sites such as satellite clinics and primary care sites which do not have centrifugation and refrigeration facilities.

ET nursing education in Australia

Australia is comparable in size to the United States, but its population is far smaller, approximately 17 million. Australia is technologically advanced and has a high standard of health care, in which ET nursing has always been considered a specialist nursing role. Although Australia is historically linked with England, formation of closer ties with geographic neighbors, such as Southeast Asia, New Zealand, and the Pacific nations, is ongoing. This article describes some relevant aspects of the Australian context and considers the past, present, and expected future trends for ET nurse education in Australia, from the first program in 1971 to current World Council of Enterostomal Therapy-recognized programs teaching students from as far away as Japan, Israel, Singapore, Malaysia, New Zealand, China, Russia, and New Guinea. The content of the programs has progressively broadened in recognition of the expanded scope of practice, and this trend will undoubtedly continue. ET nursing should remain, however, a distinct nursing specialty practice in Australia.

Propionyl-L-carnitine limits chronic ventricular dilation after myocardial infarction in rats

To determine whether propionyl-L-carnitine (PLC) administration ameliorates ventricular remodeling after myocardial infarction, we performed coronary occlusion in rats and examined the long-term effects of the drug 19-24 wk after surgery. In view of the well-established role of angiotensin-converting enzyme (ACE) inhibitors in the reduction of ventricular dilation after infarction, the therapeutic impact of oral PLC (60 mg/kg) was compared with that of enalapril (1 mg/kg). Infarct size measured planimetrically was found to be comparable in untreated, PLC-treated, and enalapril-treated rats, averaging 40-46% of the left ventricular free wall. Heart weight was increased 14, 16, and 11% with no treatment, with PLC, and with enalapril, respectively. The relationship between left ventricular filling pressure and chamber volume demonstrated that PLC and enalapril significantly prevented the expansion in cavitary size after infarction. These protective influences were observed throughout the range of filling pressures measured, from 0 to 30 mmHg. At a uniform reference point of filling pressure of 4 mmHg, untreated infarcted hearts showed an expansion in ventricular volume of 2.17-fold (P < 0.0001). Corresponding increases in this parameter after PLC and enalapril were 36 and 43%, respectively, both not statistically significant. Moreover, PLC was capable of reducing the alterations in myocardial compliance associated with myocardial infarction. In conclusion, PLC reduces the magnitude of decompensated eccentric hypertrophy produced by myocardial infarction in a manner similar to that found with ACE inhibition.

Hemodynamic and metabolic activities of propionyl-L-carnitine in rats with pressure-overload cardiac hypertrophy

Evidence has been put forth that a number of human and experimental cardiomyopathies are associated with a lower myocardial carnitine content. This study was performed to test the hypothesis that the correction of carnitine derivative, propionyl-L-carnitine (PLC), may improve cardiac function. Repeated administration of PLC was compared to saline with respect to cardiac function in rats with pressure-overload cardiac hypertrophy and low myocardial carnitine levels. Cardiac hypertrophy was induced by abdominal aorta constriction in rats. Separate groups of rats were used for (a) determination of myocardial carnitine content, (b) evaluation of in vivo hemodynamics, and (c) evaluation of performance and metabolic state of Langendorff perfused hearts. Results showed the following: (i) The myocardial carnitine content was inversely correlated to cardiac hypertrophy (r = 0.68, p less than 0.05) and PLC treatment (50 mg/kg i.a. for 4 days) restored it to normal values (ii) The PLC effect on cardiac function was significantly and directly related to cardiac hypertrophy [correlations between heart weight and percent changes in cardiovascular parameters: cardiac output (CO), p less than 0.001; cardiac work (CW), p less than 0.01, stroke volume (SV) and stroke work (SW), p less than 0.02]. In animals with heart weight greater than 1,400 mg, the effect of PLC on CO, CW, SV, SW, and total peripheral resistance (TPR) was significantly different from that of saline (CO, CW, SV, and SW, p less than 0.005 each; TPR, p less than 0.05). The effect was observed 24 h after the first PLC administration and significantly diminished following a 4 day suspension of the treatment. (iii) Perfused hearts from PLC-treated rats displayed a significantly lower left ventricular end-diastolic pressure (p less than 0.01) and greater relaxation rate (p less than 0.05) than those from control rats. Moreover, in PLC-treated hearts, the content of creatine phosphate, ATP, and total adenine nucleotides (ATP+ADP+AMP; TAN) was significantly increased (CP, p less than 0.05; ATP and TAN, p less than 0.01 vs. control). These data show that PLC exerts a stimulatory activity on hearts with hypertrophy and low carnitine content, implying that carnitine deficiency may contribute to the depression of cardiac function in this model.

Effects of intravenous endothelin on hemodynamics and cardiac contractility in conscious Milan normotensive rats

The effects of endothelin-1 (ET-1) on hemodynamics and cardiac contractility were compared with the responses to angiotensin I (AI) and phenylephrine (PE) in Milan normotensive rats. Intravenous (i.v.) injection of ET-1 (0.8 nmol/kg) initially decreased mean blood pressure (MBP), total peripheral resistance (TPR), and dP/dt (-28 +/- 2, -34.8 +/- 3.7, and -9.4 +/- 1.3%, p less than 0.01, respectively), and increased heart rate (HR), cardiac output (CO), and the velocity of myocardial anterior wall shortening (dL/dt) (11.8 +/- 2.1, 10.4 +/- 2.9, and 28.3 +/- 8.3% p less than 0.05, respectively). These effects were followed by a sustained increase in MBP and TPR and a decrease in CO. As compared with AI (0.25 nmol/kg) and PE (35 nmol/kg), which produced a similar degree of increase in TPR, the reduction in CO induced by ET-1 was more prominent (-25 +/- 2 by ET-1 vs. -14 +/- 2 by AI and -14 +/- 3% by PE, p less than 0.05, respectively). Moreover, ET-1 induced a significant decrease in dP/dt, shortening fraction (SF), and dL/dt (-6.1 +/- 1.6, -35.0 +/- 3.8, and -38.6 +/- 5.5%, p less than 0.01, respectively), whereas these indexes of left ventricle performance were not affected by either AI or PE. Furthermore, the reduction in SF induced by ET-1 was mainly due to the decrease in myocardial diastolic segment length, suggesting reduction in diastolic filling volume.(ABSTRACT TRUNCATED AT 250 WORDS)

The early results of porous-coated total shoulder arthroplasty

A porous-coated total shoulder arthroplasty of the authors' design was investigated over a period of six years. Thirteen of the first 21 arthroplasties, with an average follow-up period of three years, revealed the difficulty of proving stability by either bony or fibrous tissue ingrowth or both. With the exception of two patients (one glenoid and one humeral component), there was no gross evidence of radiographic loosening. Clinically, the early results were encouraging, but long-term follow-up observations are necessary before definitive conclusions are possible.

The Canadian experience with pulsed magnetic fields in the treatment of ununited tibial fractures

A clinical survey of 56 patients was conducted at four different centers in Canada to evaluate the effect of extremely low frequency pulsed magnetic fields (PMF) on ununited fractures of the tibia. All ten patients with delayed union and 84% of the 44 patients with nonunion healed. One case with a traumatic pseudarthrosis and one with a congenital pseudarthrosis failed to respond to treatment. These results compare favorably to those reported by others using a system with different pulse characteristics. Prolonged immobilization is necessary and poses problems of rehabilitation. Nonunions with a gap between the tibial fragments and pseudarthroses are better treated with bone grafting and internal fixation prior to electrical stimulation.

Syme's amputation in adults: a long-term review

A retrospective study was undertaken in two patient populations to establish the failure rate of Syme's amputation. Failure was defined as an amputation requiring revision to a more proximal level. For traumatic lesions of the foot the failure rate was 29% and for dysvascular lesions it was 41%. The long-term functional results in 55 patients who underwent Syme's amputation for traumatic, dysvascular or congenital lesions were studied. Overall, 73% had good function. The ideal Syme's stump, where the fat pad is centred securely over the distal tibia, was noted in only 22% of patients. The authors conclude that, in the past, technical details may have been overemphasized, because in this study the functional results of Syme's amputation were more dependent on prosthetic fitting. This type of amputation is not recommended for patients with dysvascular lesions because of the high failure rate.

Fractures and soft tissue injuries of the feet and ankle

An accurate clinical diagnosis of foot and ankle pain can be made by a history, physical examination and routine X-rays of the affected part. Each problem has a specific treatment; however, fractures and dislocations around the foot and ankle can be thought of in an organized fashion by proper physical examination and then the appropriate treatment. Fractures and soft tissue injuries can be treated rationally by understanding the mechanism of injury and the possibility of subsequent deformity. This article classifies specific injuries as a group and indicates a treatment program for each problem.

Infection rate following first-time joint implants in 1978 at the new England baptist hospital: a preliminary report

Followup of 390 first-time joint implants performed at the New England Baptist Hospital in 1978 was undertaken by means of chart review and postoperative letters to the patients and operating surgeons. There were three superficial and one deep infection. An overall infection rate of 1.03% was determined.

Successful surgical decompression of spinal extradural metastases of liposarcoma

Two patients with metastatic liposarcoma to the spine developed neurologic deficits that were successfully reversed by laminectomy and partial tumor resections. Recurrences at later dates were treated similarly with comparable outcomes. Paraplegia was forestalled for approximately two years by each of the surgical interventions.

Effect of altitude on oxygen binding by hemoglobin and on organic phosphate levels

The relationship between oxygen dissociation and 2,3-diphosphoglycerate (2,3-DPG) in the red cell has been studied in subjects moving from low to high altitude and vice versa. Within 24 hr following the change in altitude there was a change in hemoglobin affinity for oxygen; this modification therefore represents an important rapid adaptive mechanism to anoxia. A parallel change occurred in the organic phosphate content of the red cell. While this study does not provide direct evidence of a cause-effect relationship, the data strongly suggest that with anoxia, the observed rise in organic phosphate content of the red cell is responsible for increased availability of oxygen to tissues.