Research on point-of-care tests in outpatient care in Germany: A scoping review and definition of relevant endpoints in evaluation studies

BACKGROUND

The fast turnaround time and user-friendliness of point-of-care tests (POCTs) offer a great potential to improve outpatient health care where clinical decisions have to be made during the physician-patient encounter and time resources are limited. The aim of this scoping review is to describe the extent and nature as well as gaps in German research activities on POCT in outpatient care. In addition, we define research endpoints that should be addressed in the comprehensive evaluation of POCTs targeted for outpatient care.

METHODS

We performed a scoping review with a systematic literature search in Medline (via PubMed), Scopus, Web of Science, Cochrane library and Google Scholar for German publications on POCT with relevance to German outpatient care published from January 2005 to November 2020.

RESULTS

Our literature search identified 2,200 unique records. After literature selection 117 articles were included in this scoping review. Just over half of the articles (67/117, 57.3%) were primary research studies with original data, while one third of all the studies (33.3%) were secondary research articles (e.g., review articles). The remaining articles were clinical recommendations / position papers (7/117, 6.0%) and other types of articles (3.4%). The majority of articles focused on POCT use in infectious diseases (44/117, 37.6%), diabetic syndromes (15.4%), cardiac disease (12.0%) or coagulopathies and thrombosis (10.3%), while the remaining articles did not specify the disease (13.7%) or investigated other diseases (11.1%). Similar to international studies, most primary research studies investigated the diagnostic performance of POCT (e.g., sensitivity, specificity). Evidence beyond diagnostic accuracy remains scarce, such as the impact on therapeutic decisions and practice routines, clinical effectiveness, and user perspectives. In line with this, interventional studies (such as RCTs) on the effectiveness of POCT use in German outpatient care are limited. We define six endpoint domains that should be addressed in the evaluation of POCTs targeted for outpatient care: (i) diagnostic performance, (ii) clinical performance, (iii) time and costs, (iv) impact on clinical routines / processes, (v) perspectives of medical professionals and patients, and (vi) broader aspects.

CONCLUSION

There is considerable research activity on POCTs targeted for use in outpatient care in Germany. Data on their potential benefits beyond diagnostic accuracy is often lacking and should be addressed in future POCT research studies.

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.

Stability of Glucose Concentrations in Frozen Plasma

BACKGROUND

Conflicting information is available regarding the stability of glucose concentrations in frozen plasma samples. Clinical trials could benefit from such long-term storage because it would allow usage of a central laboratory with higher-quality laboratory analyzers in contrast to mobile analyzers in a decentralized setting.

METHODS

In this study, venous blood samples were collected in lithium-heparin gel tubes. Plasma was separated immediately after blood was drawn, and from each of the 21 plasma samples, 6 aliquots were prepared for measurement at 6 time points: immediately and after 2, 4, 6, 8, and 12 weeks. Between sampling and measurement, aliquots were stored at less than -20°C. Transport on dry ice was simulated by placing aliquots in a -80°C freezer for 5 days between weeks 8 and 12. Measurements were performed on a hexokinase-based laboratory analyzer.Average relative differences and corresponding 99% confidence intervals (CIs) were calculated between the stored aliquots' and the immediately measured aliquots' glucose concentrations. Glucose concentrations were deemed stable as long as average relative differences were ≤±2.5%.

RESULTS

Over the whole 12-weeks duration, the largest average relative difference was -1.82% (99% CI: -2.25% to -1.39%). Shorter storage durations tended to lead to less bias.

CONCLUSION

In this study, the stability of glucose concentrations in frozen plasma samples obtained with lithium-heparin gel tubes could be shown for up to 12 weeks. Future studies should be performed to assess whether this is independent of the glucose analyzer and the type of sampling tube used.

Evaluation of Trueness and Precision of a Bench-Top Laboratory Glucose Analyzer Using Reference Materials

SUPER GL compact is a bench-top analyzer for glucose, lactate, and hemoglobin concentrations. Glucose measurements in the biosensor are based on an enzymatic-amperometric reaction of glucose with glucose oxidase.In this study, trueness and precision were assessed with Standard Reference Material 965b (National Institute of Standards and Technology, Gaithersburg, MD) for 2 SUPER GL compact (S1 and S2) and 1 YSI 2300 STAT Plus (Y) device, using a protocol based on CLSI EP05-A3.Precision was similar among S1, S2, and Y. S1 and S2 exhibited negative bias at low concentrations and positive bias at high concentrations, whereas Y showed negative bias that increased with higher concentrations. Overall, SUPER GL compact's performance was comparable to that of YSI 2300 STAT Plus.

Do We Need the Replacement of YSI 2300? A View from the Clinical Laboratory

In this issue of Journal of Diabetes Science and Technology, Baumstark et al. evaluated the analytical performance of a bench-top laboratory glucose analyzer (SUPER-GL) intended for replacement for the YSI2300-STAT analyzer, that served for several decades as a comparator method in clinical and analytical studies of blood glucose monitoring systems (BGMS). The authors concluded that the SUPER-GL's overall performance is comparable to that of YSI2300-STAT, and has the potential to be a candidate comparator analyzer. However, the question is if we need to recommend as a "comparator method," a specific device, that measure glucose using the same analytical method with most BGMS. In this analysis we present our point of view hoping to generate a discussion on the necessity for such a replacement.

Magnetic Microdimer as Mobile Meter for Measuring Plasma Glucose and Lipids

With the development of designed materials and structures, a wide array of micro/nanomachines with versatile functionalities are employed for specific sensing applications. Here, we demonstrated a magnetic propelled microdimer-based point-of-care testing system, which can be used to provide the real-time data of plasma glucose and lipids relying on the motion feedback of mechanical properties. On-demand and programmable speed and direction of the microdimers can be achieved with the judicious adjustment of the external magnetic field, while their velocity and instantaneous postures provide estimation of glucose, cholesterol, and triglycerides concentrations with high temporal accuracy. Numerical simulations reveal the relationship between motility performance and surrounding liquid properties. Such technology presents a point-of-care testing (POCT) approach to adapt to biofluid measurement, which advances the development of microrobotic system in biomedical fields.

External validation and update of the early detection rule for severe hyperkalemia among patients with symptomatic bradycardia

OBJECTIVE

Chon et al. suggested a high prevalence of severe hyperkalemia (serum potassium ≥ 6.0 mEq/L with electrocardiographic [ECG] changes) among patients with symptomatic or extreme bradycardia. Despite the urgent need to detect and treat severe hyperkalemia, serum potassium result may be available too late and is often spuriously high. Meanwhile, the traditional, descriptive ECG findings of severe hyperkalemia have shown unsatisfactory diagnostic powers. To overcome these diagnostic problems, they outlined the following quantitative rules to facilitate its early detection: Maximum precordial T wave ≥ 8.5 mV (2), atrial fibrillation/junctional bradycardia (1), heart rate (HR) ≤ 42/min (1) with (original rule)/without (ECG-only rule) diltiazem medication (2), and diabetes mellitus (1). Here we report on our external validation of these rules and the resulting updates.

METHODS

This retrospective, cross-sectional study included all adults with symptomatic (HR ≤ 50/min with syncope/pre-syncope/dizziness, altered mentality, chest pain, dyspnea, general weakness, oliguria, or shock) or extreme (HR ≤ 40/min) bradycardia who visited a university emergency department from 2014 to 2019. After validating the abovementioned rules externally, we selected risk factors of severe hyperkalemia among the ECG findings and easy-to-assess clinical variables by multiple logistic regression analysis. After modelling the updated 'ECG-only' and 'ECG-plus' indices, we internally validated the better of the two by bootstrapping with 1000 iterations.

RESULTS

Among 455 symptomatic/extreme bradycardia cases (70.3 ± 13.1 years; 213 females [46.8%]), 70 (15.4%) had severe hyperkalemia. The previous ECG-only rule showed a c-statistic of 0.765 (95% CI: 0.706-0.825), Hosmer-Lemeshow test of p < 0.001, and a calibration slope of 0.719 (95% CI: 0.401-1.04). On updating, the ECG-plus index summing junctional bradycardia/atrial fibrillation (1), maximum precordial T wave≥8.0 mV (2), general weakness as the chief complaint (2), oxygen demand (1), and dialysis (2) outperformed the ECG-only index (c-statistic, 0.832; 95% CI, 0.785-0.880 vs. 0.764; 95% CI, 0.700-0.828; p = 0.011). On bootstrapping, the c-statistic was 0.832 (95% CI: 0.786-0.878). For scores ≥ 3 (positive likelihood ratio ≥ 5.0), the sensitivity and specificity were 0.514 and 0.901, respectively. For scores ≤ 1, negative likelihood ratio was ≤0.2.

CONCLUSIONS

Previous rules showed less satisfactory calibration but fair discrimination to detect severe hyperkalemia in patients with symptomatic or extreme bradycardia. We propose the ECG-plus index as the optimum tool to facilitate its early detection.

The End of the Road for the YSI 2300 Analyzer: Where Do We Go Now?

Production of the YSI 2300 STAT PLUS Glucose and l-Lactate Analyzer (YSI Incorporated, Yellow Springs, OH, United States) has been discontinued. This benchtop instrument is the most widely used device for determining the accuracy of products that measure blood glucose and interstitial fluid glucose. An alternate comparator instrument must now be identified by the diabetes diagnostics industry. The available products should be reviewed by parties interested in accurate, fast, low-cost comparator benchtop, or portable (nonstrip) methods using small sample volumes with good ease-of-use and human factors. Stakeholders include glucose monitor manufacturers, test labs, clinical chemists, diabetes clinicians, professional organizations, and regulators. This article presents features of eleven possible alternative instruments to be considered as comparator methods for measuring the accuracy of glucose monitors.

Measurement accuracy of two professional-use systems for point-of-care testing of blood glucose

Background The professional-use systems HemoCue® Glucose 201+ (HC201+) and HemoCue® Glucose 201 RT (HC201RT) are widely used for point-of-care testing (POCT) of blood glucose (BG). HC201RT utilizes unit-use microcuvettes which can be stored at room temperature, whereas HC201+ microcuvettes have to be stored at <8 °C. In this study, system accuracy of HC201+ and HC201RT was evaluated using capillary and venous blood samples. Methods For each system, two reagent system lots were evaluated within a period of 2 years based on testing procedures of ISO 15197:2013, a standard applicable for self-monitoring of blood glucose (SMBG) systems. For each reagent system lot, the investigation was performed by using 100 capillary and 95 to 99 venous blood samples. Comparison measurements were performed with a hexokinase laboratory method. Accuracy criteria of ISO 15197:2013 and POCT12-A3 were applied. In addition, bias was analyzed according to Bland and Altman, and error grid analysis was performed. Results When measuring capillary samples, both systems fulfilled accuracy requirements of ISO 15197:2013 and POCT12-A3 with the investigated reagent system lots. When measuring venous samples, only HC201+ fulfilled these requirements. Bias between HC201+ and reference measurements was more consistent over venous and capillary samples and microcuvette lots than for HC201RT. Error grid analysis showed that clinical actions might have been different depending on which system was used. Conclusions In this study, HC201+ showed a high level of accuracy irrespective of the sample type (capillary or venous). In contrast, HC201RT measurement results were markedly affected by the type of sample.

Utility of point-of-care vs reference laboratory testing for the evaluation of glucose levels

AIMS

To assess the level of agreement between point-of-care and laboratory reference glucose values in defining glycaemic status.

METHODS

We analysed 1292 overweight/obese, non-institutionalized participants, aged 40-65 years, in the San Juan Overweight Adults Longitudinal Study. Fasting venous blood glucose was determined using a point-of-care Bayer Contour Blood Glucose Meter and by Vitros System 250 instrument (laboratory). American Diabetes Association thresholds were used to classify participants into normoglycaemia (< 5.6 mmol/l), prediabetes (5.6 to 6.9 mmol/l), or diabetes groups (≥ 7 mmol/l).

RESULTS

Bland-Altman plot analysis showed a slope of 0.04 (P=0.002) for the regression between the mean difference and the average of the two methods. The slopes were significantly different from zero among people with normoglycaemia (β=-0.57, P<0.001), and prediabetes (β=-0.75, P<0.001) but not among people with diabetes (β=-0.02, P=0.68). When the prediabetes and diabetes groups were merged into one group, the slope was 0.01, and the glucose values remained similar using the two methods (P=0.76).

CONCLUSION

Point-of-care blood glucose measurement may be useful to screen people with diabetes, and to assess glucose among individuals with diabetes where blood can be drawn, but laboratory tests are unavailable or untimely.

A Review of Blood Glucose Monitor Accuracy

The aim of this study was to assess the accuracy of blood glucose monitors (BGMs) from studies reported in the medical literature. A literature review was performed of publications between 2010 and 2017 that presented data about the accuracy of BGMs using ISO 15197 2003 and/or ISO 15197 2013 as target standards. We found 58 publications describing the performance of 143 unique BGM systems, 59 of which were Food and Drug Administration (FDA) cleared. When compared with non-FDA-cleared BGMs, FDA-cleared BGMs were significantly more likely to pass both ISO 15197 2003 (OR = 2.39, CI 1.45-3.92, P < 0.01) and ISO 15197 2013 standards (OR = 2.20, CI 1.51-3.27, P < 0.01). Newer meters were more likely to pass both ISO 15197 2003 and ISO 15197 2013 standards. Many of the studies were supported by BGM manufacturers, and when compared with independent studies, an FDA-cleared BGM was significantly more likely to pass in a manufacturer-supported study for both ISO 15197 2003 (OR = 22.4, CI 8.73-21.57, P < 0.001) and ISO 15197 2013 (OR = 23.08, CI 10.16-60.03, P < 0.001). BGM accuracy should be assessed independently following regulatory clearance to ensure accurate performance. Failure to meet performance levels mandated by standards can result in deleterious clinical and economic effects.

Accuracy of a Factory-Calibrated, Real-Time Continuous Glucose Monitoring System During 10 Days of Use in Youth and Adults with Diabetes

BACKGROUND

Frequent use of continuous glucose monitoring (CGM) systems is associated with improved glycemic outcomes in persons with diabetes, but the need for calibrations and sensor insertions are often barriers to adoption. In this study, we evaluated the performance of G6, a sixth-generation, factory-calibrated CGM system specified for 10-day wear.

METHODS

The study enrolled participants of ages 6 years and up with type 1 diabetes or insulin-treated type 2 diabetes at 11 sites in the United States. Participation involved one sensor wear period of up to 10 days. Adults wore the system on the abdomen; youth of ages 6-17 years could choose to wear it on the abdomen or upper buttocks. Clinic sessions for frequent comparison with reference blood glucose measurements took place on days 1, 4-5, 7, and/or 10. Participants of ages 13 years and up underwent purposeful supervised glucose manipulation during in-clinic sessions. During the study, participants calibrated the systems once daily. However, analysis was performed on glucose values that were derived from reprocessed raw sensor data, independently of self-monitored blood glucose values used for calibration. Reprocessing used assigned sensor codes and a factory-calibration algorithm. Performance evaluation included the proportion of CGM values that were within ±20% of reference glucose values >100 mg/dL or within ±20 mg/dL of reference glucose values ≤100 mg/dL (%20/20), the analogous %15/15, and the mean absolute relative difference (MARD, expressed as a percentage) between temporally matched CGM and reference values.

RESULTS

Data from 262 study participants (21,569 matched CGM reference pairs) were analyzed. The overall %15/15, %20/20, and MARD were 82.4%, 92.3%, and 10.0%, respectively. Matched pairs from 134 adults and 128 youth of ages 6-17 years were similar with respect to %20/20 (92.4% and 91.9%) and MARD (9.9% and 10.1%). Overall %20/20 values on days 1 and 10 of sensor wear were 88.6% and 90.6%, respectively. The system's "Urgent Low Soon" (predictive of hypoglycemia within 20 min) hypoglycemia alert was correctly provided 84% of the time within 30 min before impending biochemical hypoglycemia (<70 mg/dL). The 10-day sensor survival rate was 87%.

CONCLUSION

The new factory-calibrated G6 real-time CGM system provides accurate readings for 10 days and removes several clinical barriers to broader CGM adoption.

Prevalence, Awareness, Treatment, and Control of Hypertension among Chinese First-Generation Migrants and Italians in Prato, Italy: The CHIP Study

Data on health needs of Chinese living in the South of Europe are lacking. To compare prevalence, awareness, treatment, control, and risk factors for hypertension between Chinese migrants and Italian adults, a sample of 1200 first-generation Chinese migrants and 291 native Italians aged 35–59 years living in Prato (Italy) was recruited in a community-based participatory cross-sectional survey. Primary outcome measure was hypertension, diagnosed for blood pressure values ≥ 140/90 mmHg or current use of antihypertensive medications. Associations with exposures (including age, gender, body mass index, waist, education level, total cholesterol, and triglycerides) were examined using logistic regression. When compared with Italians, Chinese had higher hypertension prevalence (27.2% versus 21.3%, p < 0.01), with comparable levels of awareness (57.4% and 48.4%) but lower treatment rates (70.6% and 90.0%, resp.). In both ethnic groups age and parental history of hypertension were predictors of awareness and treatment, body mass index being predictor of hypertension diagnosis. In Chinese participants, where the optimum cut-off point for body mass index was ≥23.9 kg/m², the sensibility and specificity prediction for hypertension were 61.7% and 59.8%, respectively (area under the ROC curve = 0.629). Implementation of specific, culturally adapted health programs for the Chinese community is now needed.

New findings on type 2 diabetes in first-generation Chinese migrants settled in Italy: Chinese in Prato (CHIP) cross-sectional survey

BACKGROUND

Chinese people are one of the fastest growing immigrant populations in Europe, and their health has become a key issue to host nations. Although type 2 diabetes (T2DM) is a big burden among migrant populations, data on Chinese immigrants in Europe are limited.

METHODS

A cross-sectional survey was performed in 2014, adopting principles of community-based participatory research to investigate T2DM, diagnosed by the American Diabetes Association fasting criteria, in Chinese first-generation migrants aged 16 to 59 years settled in Prato (Italy). Association with different factors was investigated using logistic regression.

RESULTS

Of the 1608 participants, 177 had T2DM (11.0%), 119 being newly diagnosed (7.4%). Among subjects with diabetes, 58 (32.8%) were aware of the disease; among subjects with diabetes aware of their condition, 46 (79%) were treated with glucose lowering drugs. Age-standardized (World Health Organization 2001 population) prevalence of T2DM was 9.6% (95% CI 9.1 to 10.2%), being 12.0% (95% CI 11.0 to 12.9%) in men, and 7.8% (95% CI 7.1 to 8.4%) in women. At adjusted logistic regression, diabetes was associated with hypertension, current smoking, adiposity indices (waist circumference, waist-to-hip ratio, waist-to-height ratio, and body mass index), and high triglycerides. T2DM, adiposity indices, and high triglycerides were not associated with duration of stay in Italy.

CONCLUSIONS

The high prevalence of T2DM among first-generation Chinese immigrants in Europe stresses the need for specific health programs for T2DM early diagnosis, treatment, and prevention. There is an urgent need for policies to support this group because current policies will produce major social and economic costs. Copyright © 2016 John Wiley & Sons, Ltd.

A Comparison Study Between Point-of-Care Testing Systems and Central Laboratory for Determining Blood Glucose in Venous Blood

BACKGROUND

Diabetes mellitus is a metabolic disease that is characterized by hyperglycemia. Blood glucose (BG) is helpful for the diagnosis and treatment of diabetes and an important part of the management of diabetes. Point-of-care testing (POCT) is generally used by patients themselves or medical personnel to monitor BG. The objective of this article was to evaluate the accuracy and consistency of POCT on venous blood samples and compare it with the central laboratory system to determine the reliability of POCT measurement results as diagnostic criteria.

METHOD

A total of 162 venous whole blood samples were pooled in this study, which included different concentrations and were determined by three POCT systems randomly. The results were compared with the central laboratory system, which uses the Glucose GOD-PAP method (HITACHI 7600-120). The accuracy was evaluated by the International Organization for Standardization (ISO) 15197:2013.

RESULT

Bland-Altman and Passing-Bablok regression analysis showed three POCT systems that were comparable with the reference method (0.65, 95% CI: -0.57 to 1.86, Y = -0.11 + 0.95X for ACCU-CHEK^® Performa; 0.40, 95% CI: -1.3 to 2.1, Y = 0.036 + 0.96X for ACCU-CHEK^® Active; 0.70, 95% CI: -0.44 to 1.83, Y = -0.073 + 0.95X for OneTouch ^® UltraVue). According to ISO 15197:2013, all POCT systems showed 100% of the results within 0.83 mmol/l (15 mg/dl) at BG concentrations <5.55 mmol/l (100 mg/dl); 92%, 89.2%, and 95.7% of the measurement results within 15% at BG concentrations ≥5.55 mmol/l (100 mg/dl) for ACCU-CHEK^® Performa, ACCU-CHEK^® Active, and OneTouch^® UltraVue, respectively.

CONCLUSIONS

The POCT system cannot replace the central laboratory system as a provider of a standard result in clinical diagnosis. It can only be used as a screening test.

Point-of-Care Testing

This article provides an overview of the current use of point-of-care testing (POCT) and its utility for patients’ self-management of chronic disease states. Pharmacists utilize POCT to provide rapid laboratory diagnostic results as a monitoring tool in the management of their patients and in order to improve medication outcomes. Considerations for the transition to use of POCT in the home to further improve disease management and improve health care cost-effectiveness are discussed. Devices available for home use include those suitable for management of diabetes mellitus, hypertension, congestive heart failure, and anticoagulation. Many of these devices include software capabilities enabling patients to share important health information with health care providers using a computer. Limitations and challenges surrounding implementation of home POCT for patients include reliability of instrumentation, ability to coordinate data collection, necessary training requirements, and cost-effectiveness. Looking forward, the successful integration of POCT into the homes of patients is contingent on a concerted effort made by all members of the health care team.

A model for managing and monitoring the quality of glucometers used in a high-volume clinical setting

Introduction

The aim of this study is to present a model for assuring the quality of a large number of glucometers being used in a high-volume hospital clinical setting.

Materials and methods

Internal quality-control samples and blood samples from two patients were used to determine the accuracy of 83 glucometers used at our hospital. On each glucometer three levels of control were used for glucose concentrations determination. In addition, the difference between the results from patient samples obtained with the glucometers and the hexokinase reference method were compared. The differences were assessed based on the International Organization for Standardization (ISO 15197) standards.

Results

The glucose concentrations were as follows: 2.51 ± 0.34 mmol/L for the hypo-control samples; 5.12 ± 0.32 mmol/L for the low-control samples; and 16.11 ± 1.03 mmol/L for high-control samples. All results were within the expected ranges. For Patient I, the result with the first group of 52 glucometers was 11.56 ± 0.5 mmol/L, while the result for Patient II with the second group of 31 glucometers was 10.52 ± 0.62 mmol/L. All data points of the study complied with the requirements of the Clarke error grid.

Conclusion

All quality-control and comparison assay results were appropriate for evaluating glucometers used in a high-volume hospital setting. The method used in this study can be suggested as a model for laboratory managers, especially in similar high-volume hospitals.

Atrial fibrillation in first generation Chinese migrants living in Europe: A proof of concept study

BACKGROUND

Despite the public health burden of atrial fibrillation (AF) and its complications in China, there is no literature on AF among Chinese living in Europe. The present study was performed to investigate the prevalence of and risk factors for AF in Chinese first generation migrants settled in Europe.

METHODS

A cross-sectional survey was performed in 2014 on Chinese first generation migrants aged 16 to 59years settled in Prato (Italy) adopting principles of community based participatory research. All participants underwent recording of 30s of a single-channel ECG and associations of AF with socio-demographic, anthropometric, clinical factors, and sleep history were examined using logistic regression.

RESULTS

Of the 1608 participants, 12 had AF (0.75%; 95% CI 0.33 to 1.17) - four men and eight women. All subjects with AF had a CHA2DS2VASc index≥1. Although no participant with AF had contraindications to oral anticoagulation, none was treated with oral anticoagulants. At multivariable adjusted logistic regression AF was associated with hypertension with an OR of 4.40 (95% CI 1.09-17.81; p=0.038).

CONCLUSIONS

Chinese are one of the fastest growing migrant populations in Europe and their health has become a key issue to host nations. The issue of AF is to be considered in future prevention programs for elusive ethnic minorities and adequately powered trials specifically designed to investigate AF prevalence and to test prevention approaches are now needed.

Accuracy and precision assessment of a new blood glucose monitoring system

BACKGROUND

Blood glucose self-monitoring by individuals with diabetes is essential in controlling blood glucose levels. The International Organization for Standardization (ISO) introduced new standards for blood glucose monitoring systems (BGMS) in 2013 (ISO 15197: 2013). The CONTOUR PLUS® (CONTOUR PLUS) BGMS has been demonstrated to meet the 2013 ISO standards; however, no Chinese data on CONTOUR PLUS accuracy and precision have been published.

METHODS

This study evaluated the accuracy and precision of CONTOUR PLUS BGMS in quantitative glucose testing of capillary and venous whole blood samples obtained from 363 patients at three different hospitals.

RESULTS

Results of fingertip and venous blood glucose measurements by the CONTOUR PLUS system were compared with laboratory reference values to determine accuracy. Accuracy was 98.1% (96.06%-99.22%) for fingertip blood tests and 98.1% (96.02%-99.21%) for venous blood tests. Precision was evaluated across a wide range of blood glucose values (5.1-17.2 mmol/L), testing three blood samples repeatedly 15 times with the CONTOUR PLUS blood glucose meter using test strips from three lots. All within-lot results met ISO criteria (i.e., SD<0.42 mmol/L for blood glucose concentration <5.55 mmol/L; CV<7.5% for blood glucose concentration ≥5.55 mmol/L). Between-lot variations were 1.5% for low blood glucose concentration, 2.4% for normal and 3.4% for high.

CONCLUSIONS

Accuracy of both fingertip and venous blood glucose measurements by the CONTOUR PLUS system was >95%, confirming that the system meets ISO 15197: 2013 requirements.

Performance Comparison of CGM Systems: MARD Values Are Not Always a Reliable Indicator of CGM System Accuracy

BACKGROUND

The ongoing progress of continuous glucose monitoring (CGM) systems results in an increasing interest in comparing their performance, in particular in terms of accuracy, that is, matching CGM readings with reference values measured at the same time. Most often accuracy is evaluated by the mean absolute relative difference (MARD). It is frequently overseen that MARD does not only reflect accuracy, but also the study protocol and evaluation procedure, making a cross-study comparison problematic.

METHODS

We evaluate the effect of several factors on the MARD statistical properties: number of paired reference and CGM values, distribution of the paired values, accuracy of the reference measurement device itself and the time delay between data pairs. All analysis is done using clinical data from 12 patients wearing 6 sensors each.

RESULTS

We have found that a few paired points can have a potentially high impact on MARD. Leaving out those points for evaluation thus reduces the MARD. Similarly, accuracy of the reference measurements greatly affects the MARD as numerical and graphical data show. Results also show that a log-normal distribution of the paired references provides a significantly different MARD than, for example, a uniform distribution.

CONCLUSIONS

MARD is a reasonable parameter to characterize the performance of CGM systems when keeping its limitations in mind. To support clinicians and patients in selecting which CGM system to use in a clinical setting, care should be taken to make MARD more comparable by employing a standardized evaluation procedure.