Analytical performance of the Axis-Shield Afinion for hemoglobin A1c measurement: impact of lot number.

BACKGROUND

As the implementation of POC analyzers in clinical department is growing and HbA1c has been included in diagnostics, it appears mandatory to evaluate the accuracy of the POC method to be used. The aim of our study is to evaluate the analytical performance and usefulness of the Afinion analyzer, and the impact of HbF, hemoglobin variants, and changes of reagent lots.

METHODS

The Afinion analyzer (Axis-Shield, Oslo, Norway) is based on affinity separation methodology. Analytical performances including imprecision studies and correlation with currently used HPLC were performed on Biochemistry laboratory. We evaluated the effects of presence of variants on the results of HbA1c. Two reagent lots were evaluated on samples without variant as well as on samples with in the presence of hemoglobin variants HbA/S. The practicability of the system was also tested installing the instrument on pediatric consultation.

RESULTS

Imprecision studies of Afinion were acceptable. Linear regression analysis indicated good correlation between HbA1c values with Afinion (r > 0.97) in comparison with HPLC method. Overall, the Afinion overestimated the HbA1 compared to the MenariniHA8140. These differences were confirmed when the estimated average glucose was calculated. In addition, the variance of cartridge lots requires its use with caution and the problem of lot number instability must be resolved, requiring an adjustment of the calibration by the manufacturer.

CONCLUSIONS

The Afinion analyzer met the acceptance criteria of analytical performance, requires minimal operator interaction and presents good correlation with the laboratory method. Beyond the analytical performance, the different regression lines for different lots is a matter of concern. The reproductibility of the production of the different reagent lots for POC devices appears inadequate for its use in a clinical department.