Accuracy Assessment of Two Novel Systems for Self-Monitoring of Blood Glucose Following ISO 15197:2013

For the assessment of self-monitoring of blood glucose (SMBG) systems’ accuracy, the standard ISO (International Organization for Standardization) 15197 is widely accepted and applicable for manufacturers to obtain the CE (Conformité Européene) mark for their system in the European Union. In 2013, a revision of the ISO 15197 ¹ standard was published in which accuracy criteria are more stringent than in the 2003 version: ² At least 95% of a system’s measurement results shall fall within ±15 mg/dl of the comparison measurement results at blood glucose (BG) concentrations <100 mg/dl and within ±15% at BG concentrations ≥100 mg/dl. In addition, at least 99% of individual measurement results shall fall within consensus error grid zones A and B and system accuracy shall be evaluated with 3 test strip lots of a system.

In this study, we assessed system accuracy of 2 enhanced systems (Accu-Chek Aviva, Accu-Chek Performa) with 3 test strip lots each following ISO 15197:2013.

The study was performed in compliance with the German Medical Devices Act at the Institut für Diabetes-Technologie Forschungs- und Entwicklungsgesellschaft mbH an der Universität Ulm, Ulm, Germany. The study protocol was approved by the Ethics Committee and the Federal Institute for Drugs and Medical Devices.

Meters and test strips were procured by the manufacturer (Roche Diagnostics GmbH, Mannheim, Germany) since both systems are not yet available in Germany.

For each system, measurements were performed on capillary blood samples from fingertips from 100 different subjects following testing procedures described in the standard ISO 15197. Comparison measurements were performed with a hexokinase laboratory method (laboratory glucose analyzer cobas® 6000 c501, Roche Diagnostics GmbH). This hexokinase method is traceable to NIST (National Institute of Standards and Technology) standard reference material.

Both systems fulfilled accuracy criteria of ISO 15197:2013 with 99.5% to 100% of results within the required limits (Figure 1).

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Figure 1.

Difference plots of the 2 novel self-monitoring of blood glucose systems applying criteria of ISO 15197:2013: ±15 mg/dL / ±15% for glucose concentrations <100 mg/dL / ≥100 mg/dL. For each of the 3 evaluated test strip lots, absolute differences between the system’s measurement results and the mean comparison measurement results (200 data, duplicate measurements on a sample with each test strip lot) are displayed.

For BG concentrations <100 mg/dl, Accu-Chek Aviva showed with the tested lots 100% of results within ±15 mg/dl, 97% to 100% within ±10 mg/dl and 84% to 88% within ±5 mg/dl. For BG concentrations ≥100 mg/dl, the system showed 99% to 100% of results within ±15 %, 98% to 99% within ±10% and 70% to 74% within ±5%. Accu-Chek Performa showed with the tested lots 100% of results within ±15 mg/dl, 98% to 100% within ±10 mg/dl and 87% to 97% within ±5 mg/dl for BG concentrations <100 mg/dl. For BG concentrations ≥100 mg/dl, the system showed 100% of results within ±15 %, 96% to 99% of results within ±10% and 71% to 77% of results within ±5%.

Both systems showed 100% of results within zone A of the consensus error grid. The relative bias according to Bland and Altman ³ ranged from 0.4% to 1.4% for the Accu-Chek Aviva and from –0.5% to 0.7% for the Accu-Chek Performa.

The obtained performance data of the 2 enhanced systems are comparable with data reported for the predecessor systems.^{4 -6} Both systems achieved high accuracy when criteria of the recently published standard ISO 15197:2013 were applied. In addition, only small biases were found when compared with the laboratory method with only minor variations between the 3 evaluated test strip lots.