Lab Med Online.  2017 Oct;7(4):182-188. 10.3343/lmo.2017.7.4.182.

Evaluation of Cobas b 101 HbA1c Analyzer Performance for Point-of-Care Testing

Affiliations
  • 1Department of Laboratory Medicine, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul, Korea. mjkkmd@gmail.com

Abstract

BACKGROUND
The use of point-of-care (POC) devices for evaluating HbA1c is increasing; accordingly, comparisons between these devices and central laboratory methods are important. In the present study, we evaluated the analytical performance of the cobas b 101 analyzer for POC HbA1c testing.
METHODS
The analytical quality of the cobas b 101 system was assessed based on repeatability, within-laboratory precision, linearity, and lot-to-lot reproducibility. Two specimen types, i.e., EDTA whole blood and capillary blood, were examined using the cobas b 101 system and the Variant II Turbo instrument.
RESULTS
The coefficient of variation for within laboratory precision was 5.22% for a normal HbA1c level and 2.56% for a higher HbA1c level. The method showed good linearity, with a coefficient of correlation of 0.990. In a comparison of two different HbA1c disk lots, a strong correlation (r=0.986) and a mean %difference of −2.9% were observed. The cobas b 101 results using EDTA whole blood were strongly correlated with the Variant II Turbo results (r=0.958), with a mean %difference of 0.8%; the cobas b 101 results using capillary blood were strongly correlated with the Variant II Turbo results, using EDTA whole blood (r=0.976), with a mean %difference of 2.0%. A comparison between HbA1c levels in EDTA whole blood and capillary blood obtained using the cobas b 101 showed a strong correlation (r=0.985) and a mean %difference of 1.3%.
CONCLUSIONS
The cobas b 101 analyzer is convenient for the measurement of HbA1c levels for diabetes management.

Keyword

HbA1c; Point-of-care testing; Diabetes

MeSH Terms

Capillaries
Edetic Acid
Methods
Point-of-Care Systems*
Point-of-Care Testing*
Edetic Acid

Figure

  • Fig. 1 Lot-to-lot reproducibility of the cobas b 101 HbA1c test. (A) Regression analysis of the cobas b 101 using EDTA venous blood from two different lots. The linear curve and 95% confidence interval [CI] are represented as red and blue lines, respectively. (B) Bland-Altman difference plot summarizing lot-to-lot comparisons.

  • Fig. 2 Comparison of the cobas b 101 with the Variant II Turbo. (A) Regression of the cobas b 101 results using EDTA blood against the Variant II Turbo results using EDTA blood. The linear curve and 95% confidence interval [CI] are represented as red and blue lines, respectively. (B) Bland-Altman difference plot summarizing the comparison between the cobas b 101 results using EDTA blood and Variant II Turbo results using EDTA blood. (C) Regression of the cobas b 101 results using capillary blood against the Variant II Turbo results using EDTA blood. The linear curve and 95% confidence interval [CI] are represented as red and blue lines, respectively. (D) Bland-Altman difference plot summarizing the comparison between the cobas b 101 results using capillary blood and Variant II Turbo results using EDTA blood.

  • Fig. 3 Regression analysis of the cobas b 101 using two types of samples, EDTA venous whole blood and capillary blood. (A) Regression analysis of the cobas b 101 using two types of samples, EDTA venous blood and capillary blood. The linear curve and 95% confidence interval [CI] are represented as red and blue lines, respectively. (B) Bland-Altman difference plot summarizing the comparison between the venous whole blood and capillary blood samples tested using the cobas b 101.


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