INTRODUCTION: The prevalence of diabetes mellitus is increasing in all over the world. HbA1c is one of the diagnostic test for diabetes mellitus. But once HbA1c analysis measured, is that result accurate and absolute? Uncertainty of measurement is a quality parameter of measurement results, which is used to represent a dispersing level of test results. The aim of this study is to estimate the uncertainty of measurement for HbA1c and retrospectively re-evaluate the patient results, with respect to the estimation of measurement uncertainty and suggest a solution for the results that were close to cut-off levels.
METHODS: The results of 10212 patients who were analyzed HbA1c test in our laboratory in 2016 were retrospectively reviewed. The HbA1c levels were measured by a high performance liquid chromatography method. The uncertainty of measurement on serum HbA1c level was estimated according to Eurachem/CITAC Guide CG. The HbA1c analysis results were re-evaluated by estimation of measurement uncertainty.
RESULTS: Measurement uncertainty (95 % confidence interval) for HbA1c is estimated to ± 4.6 %. When measurement uncertainty is taken into account, the 6.5% value is acceptable to be reported between 6.2% -6.8%. It was observed that the results of 1555 patients were affected by uncertainty values.
DISCUSSION AND CONCLUSION: Medical laboratories must produce the necessary data and analytical results in order to achieve the correct interpretation and use of the results. A test result is not enough powerful without an assessment of its reliability. The interpretation of values which are close to cut-off levels may change, when evaluated with uncertainty of measurement. Therefore, reporting HbA1c analysis results with estimation of measurement uncertainty is important to show measurements that contained within the true limits and the level of confidence.