Application of Sigma Metrics for Assessing Analytical Performance of Drug Assay in Patient Care.

BACKGROUND: Clinical laboratories are indispensable in-patient care, particularly for conditions like epilepsy, where precise monitoring is vital. Phenytoin and valproate are commonly used antiepileptics. Sigma metrics may be utilized to monitor overall performance of diagnostic laboratories, ensuring accurate and reliable results. In this regard, our study aimed to evaluate the performance of Indiko Drug analyzer by using Sigma metrics based on different total allowable error (TEa) sources and to determine the consequences of these variations in Sigma metric evaluation.

METHODS: TEas of 25% and 15% requirements were selected from different industry standards to calculate Sigma metrics of drugs phenytoin and valproate. Coefficient of variation (CV) and bias records were taken from internal quality control (IQC) and external quality assessment scheme (EQAS), respectively.

RESULTS: According to TEa based on different international bodies` database specifications of Sigma calculation, TEa 25% showed an average Sigma of both drugs greater than 6 (world class), compared to greater than 3 (marginally acceptable) for TEa 15%.

CONCLUSIONS: The study emphasizes the importance of thorough analysis and documentation in handling analytes with poor Sigma scores to mitigate laboratory errors and ensure reliability. It recommends root cause analysis and corrective action plans to achieve world-class Sigma goals. However, challenges remain in selecting the appropriate method for calculating Sigma metrics and TEa before harmonizing Sigma metrics across laboratories to minimize confusion.