Commutability of external quality assessment materials for point‐of‐care glucose testing using the Clinical and Laboratory Standards Institute and International Federation of Clinical Chemistry approaches

Abstract Background: Determination of blood glucose concentration is one of the most important measurements in clinical chemistry worldwide. Analyzers in central laboratories (CL) and point-of-care tests (POCT) are both frequently used. In Germany, regular participation in external quality assessment (EQA) schemes is mandatory for laboratories performing glucose testing. Methods: Glucose testing data from the two German EQAs “Reference Institute for Bioanalytics” (RfB) and “INSTAND – Gesellschaft zur Förderung der Qualitätssicherung in medizinischen Laboratorien” (Instand) were analyzed from 2012 to 2016. Multivariable odds ratios (OR) for the probability to reach a “good” result were calculated. Imprecision and bias were determined and clinical risk of measurement errors estimated. Results: The device employed was the most important variable required for a “good” performance in all EQAs. Additional participation in an EQA for CL automated analyzers improved performance in POCT EQAs. The reciprocal effect was less pronounced. New participants performed worse than experienced participants especially in CL EQAs. Imprecision was generally smaller for CL, but some POCT devices reached a comparable performance. Large lot-to-lot differences occurred in over 10% of analyzed cases. We propose the “bias budget” as a new metric to express the maximum allowable bias that still carries acceptable medical risk. Bias budgets were smallest and clinical risks of errors greatest in the low range of measurement 60–115 mg/dL (3.3–6.4 mmol/L) for most devices. Conclusions: EQAs help to maintain high analytical performances. They generate important data that serve as the foundation for learning and improvement in the laboratory healthcare system.

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Combi scheme: new combined internal/external quality-assessment scheme in The Netherlands

Clinical Chemistry ◽

10.1093/clinchem/37.7.1196 ◽

1991 ◽

Vol 37 (7) ◽

pp. 1196-1204 ◽

Cited By ~ 14

Author(s):

Herman Steigstra ◽

Rob T Jansen ◽

Henk Baadenhuijsen

Keyword(s):

The Netherlands ◽

Quality Assessment ◽

Internal Control ◽

External Quality Assessment ◽

Clinical Chemistry ◽

Laboratory Data ◽

Data Communication ◽

Professional Organization ◽

Internal Quality ◽

External Quality

Abstract The Dutch Foundation for Quality Assessment in Clinical Chemistry (SKZL) is the professional organization that conducts external quality-assessment schemes in The Netherlands. However, such schemes in fact assess the performance of the internal quality-control systems of the participating laboratories. In this paper we describe a new concept, relating the data for internal control materials with those for external samples and thereby leading to a combined external/internal scheme (Combi). The statistical principles underlying the Combi scheme are discussed and examples of the graphical presentation of the results are shown. Because the laboratory data are transmitted over the public telephone system to the computers of the SKZL, we also describe the principles of the data communication. At two-month intervals a statistical presentation is sent to all participants. The central database is updated daily with the received results, making possible an on-line consultation regarding the statistics of the accumulated findings of the control materials in use.

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Accuracy of HbA1c as Monitored by External Quality Assessment and Compared With Patient Mean Values

Journal of Diabetes Science and Technology ◽

10.1177/1932296818785622 ◽

2018 ◽

Vol 12 (4) ◽

pp. 771-779 ◽

Cited By ~ 6

Author(s):

Gunnar Nordin

Keyword(s):

Quality Assessment ◽

External Quality Assessment ◽

Point Of Care ◽

Small Variation ◽

Specific Method ◽

External Quality ◽

Swedish Population ◽

Mean Values ◽

Hba1c Test ◽

Performance Specifications

Background: The accuracy and trueness of results from a laboratory test, such as the HbA1c test, should not be taken for granted but must be checked continuously. A tool for this is the participation in external quality assessment (EQA) for all laboratories performing the HbA1c-test. An additional possibility to detect changes in trueness is to monitor variations in patient cohort mean or median values that is not explained by changes in treatment or selection of patients. Methods: Results reported to an EQA scheme for HbA1c during 20 years have been extracted from Equalis database. The results are compared to current analytical performance specifications (APS) and to the mean HbA1c levels for the Swedish population of persons with type 2 diabetes. Results: The accuracy of the HbA1c test has improved during the period. The hospital lab methods used in Sweden now fulfil APS agreed by professional organizations in Sweden. The accuracy for point-of-care tests (POCT) methods vary over time and fulfil APS for some periods. The bias found for some of the methods might explain changes seen in patient mean values for HbA1c in Sweden during the period 2007-2017. Conclusions: The global standardization of HbA1c has resulted in an improved comparability for HbA1c-results worldwide. But even small variation in trueness for the methods in use might have important impact on mean HbA1c values for cohorts of patients. When a systematic error is observed for a specific method it is therefore essential that manufacturers correct the method without delay.

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