Measurement traceability and US IVD manufacturers: the impact of metrology

Armbruster, Dave

doi:10.1007/s00769-009-0535-6

Cited by 9 publications

(5 citation statements)

References 5 publications

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“…The bias shown in our results between FreeStyle Libre and HemoCue is likely because of the use of noncommutable reference materials and calibrators in a multistep traceability chain in the case of FreeStyle Libre. 17–20 This negative bias could possibly be adjusted with adjusted algorithms.…”

Section: Discussionmentioning

confidence: 99%

A Clinical Trial of the Accuracy and Treatment Experience of the Flash Glucose Monitor FreeStyle Libre in Adults with Type 1 Diabetes

Ólafsdóttir

Attvall

Sandgren

et al. 2017

Diabetes Technology & Therapeutics

156

132

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Background: In Sweden, FreeStyle Libre a flash glucose monitoring system came onto the market in 2014 as a complement to self-monitoring of blood glucose. The aim of this study was to evaluate the accuracy and treatment experience of the FreeStyle Libre system.Methods: Fifty-eight adults with type 1 diabetes used FreeStyle Libre for 10–14 days and measured capillary blood glucose levels with the HemoCue blood glucose measurement system at least six times a day simultaneously.Results: For the entire study period, the mean absolute relative difference (MARD) was 13.2% (95% confidence interval [CI] 12.0%–14.4%). MARD was 13.6% (95% CI 12.1%–15.4%) during week 1 and 12.7% (95% CI 11.5%–13.9%) during week 2. The mean absolute difference (MAD) for the whole study period was 19.8 mg/dL (1.1 mmol/L) (95% CI 17.8–21.8 mg/dL), including 20.5 mg/dL (1.14 mmol/L) during week 1 and 19.0 mg/dL (1.05 mmol/L) during week 2. The overall correlation coefficient was 0.96. For glucose values <72, 72–180, and >180 mg/dL (<4, 4–10, and >10 mmol/L), the MARD was 20.3% (95% CI 17.7%–23.1%), 14.7% (95% CI 13.4%–16%), and 9.6% (95% CI 8.5%–10.8%), respectively, and respective MAD values were 12.3, 17.8, and 23.6 mg/dL (0.69, 0.99, and 1.31 mmol/L). Using the 10-item visual analog scale, patients rated their experience with FreeStyle Libre as generally positive, with mean values ranging from 8.22 to 9.8.Conclusions: FreeStyle Libre had a similar overall MARD as continuous blood glucose monitoring systems in earlier studies when studied in similar at-home conditions. The overall patient satisfaction was high.

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Section: Discussionmentioning

confidence: 99%

A Clinical Trial of the Accuracy and Treatment Experience of the Flash Glucose Monitor FreeStyle Libre in Adults with Type 1 Diabetes

Ólafsdóttir

Attvall

Sandgren

et al. 2017

Diabetes Technology & Therapeutics

156

132

View full text Add to dashboard Cite

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“…Some years ago, Thienpont et al (37) already pointed out that the absence of clearly defi ned tolerable deviations derived from clinical needs " might results in a large gray zone with respect to the extent of traceability expected from diagnostic manufacturers, partially or totally invalidating its theoretical advantages " . Today, there is a substantial agreement that the uncertainty of measurement that fi ts for purpose must be defi ned across the entire traceability chain, starting with the provider of reference materials, extending through the diagnostic manufacturers and their processes for assignment of calibrator values, and ultimately to the fi nal result reported to clinicians by end users (i.e., the clinical laboratories) (38,39) . This approach should be applied to every analyte measured in the clinical laboratory in order to establish if the current status of the uncertainty budget of its measurement associated with the proposed metrological traceability chain is suitable for clinical application of the test (40) .…”

Section: Need To Defi Ne the Clinically Acceptable Limits For Validatmentioning

confidence: 99%

Implementation of standardization in clinical practice: not always an easy task

Panteghini

2012

Clinical Chemistry and Laboratory Medicine (CCLM)

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As soon as a new reference measurement system is adopted, clinical validation of correctly calibrated commercial methods should take place. Tracing back the calibration of routine assays to a reference system can actually modify the relation of analyte results to existing reference intervals and decision limits and this may invalidate some of the clinical decision-making criteria currently used. To maintain the accumulated clinical experience, the quantitative relationship to the previous calibration system should be established and, if necessary, the clinical decision-making criteria should be adjusted accordingly. The implementation of standardization should take place in a concerted action of laboratorians, manufacturers, external quality assessment scheme organizers and clinicians. Dedicated meetings with manufacturers should be organized to discuss the process of assay recalibration and studies should be performed to obtain convincing evidence that the standardization works, improving result comparability. Another important issue relates to the surveillance of the performance of standardized assays through the organization of appropriate analytical internal and external quality controls. Last but not least, uncertainty of measurement that fi ts for this purpose must be defi ned across the entire traceability chain, starting with the available reference materials, extending through the manufacturers and their processes for assignment of calibrator values and ultimately to the fi nal result reported to clinicians by laboratories.

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“…Standardised and harmonised clinical laboratory test results [24][25][26] improve the quality of healthcare by ensuring reliable screening, diagnosis and supporting appropriate treatments. They also reduce the risk of diagnostic and treatment errors that may be caused by unnecessary variation in test results.…”

Section: Standardisation and Harmonisation In Clinical Chemistrymentioning

confidence: 99%

Full method validation in clinical chemistry

Theodorsson

Magnusson

2017

Accred Qual Assur

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Clinical chemistry is subject to the same principles and standards used in all branches of metrology in chemistry for validation of measurement methods. The use of measuring systems in clinical chemistry is, however, of exceptionally high volume, diverse and involves many laboratories and systems. Samples for measuring the same measurand from a certain patient are likely to encounter several measuring systems over time in the process of diagnosis and treatment of his/her diseases. Several challenges regarding method validation across several laboratories are therefore evident, but rarely addressed in current standards and accreditation practices. The purpose of this is paper to address some of these challenges, making a case that appropriate conventional method validation performed by the manufacturers fulfils only a part of the investigation needed to show that they are fit for purpose in different healthcare circumstances. Method validation across several laboratories using verified commercially available measuring systems can only be performed by the laboratories-users themselves in their own circumstances, and need to be emphasised more by the laboratories themselves and accreditation authorities alike.

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Measurement traceability and US IVD manufacturers: the impact of metrology

Cited by 9 publications

References 5 publications

A Clinical Trial of the Accuracy and Treatment Experience of the Flash Glucose Monitor FreeStyle Libre in Adults with Type 1 Diabetes

A Clinical Trial of the Accuracy and Treatment Experience of the Flash Glucose Monitor FreeStyle Libre in Adults with Type 1 Diabetes

Implementation of standardization in clinical practice: not always an easy task

Full method validation in clinical chemistry

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