INTRODUCTION: In the context of the accreditation of medical laboratories according to the ISO 15189: 2012 standard, the optimisation of an internal quality control (IQC) schedule is an important element of analytical quality. The study focuses on an essential test for the follow-up of diabetic patients: Haemoglobin A1c (HbA1c).
METHODS: The analysis was performed on three TERA® Capillarys (Sebia®) analyzers. Data were collected for 1 month calculating imprecision and analytical bias. A total error allowable (TEa) of 6% was used to calculate the Sigma metrics. A statistical quality control (SQC) procedure based on the Sigma metrics of the analytical procedure, the selected rules and numbers of control measurements were applied to determine the optimised run size and to guarantee the required quality of patient care.
RESULTS: With a mean of 5-Sigma. “Normalised Chart” showed a good/excellent performance for the HbA1c method. The SQC run size nomogram indicated a desirable event size of around 53 samples/capillary (for n=1 and 13s) and 170 samples/capillary (for n=2 and 13s).
DISCUSSION AND CONCLUSION: Our study demonstrated the usefulness of the sigma metric SQC run size nomogram to determine the control strategy for HBA1c and contributes to the quality of results rendered to patients.