Application of statistical methods to monitor quality control results of ELISA screening tests

The reliability of quality control results of ELISA screening tests are one of the major issues in validation process especially in transfusion transmitted infectious disease by HBV, HCV, HIV and HTLV. Basic statistics such as mean, standard deviation, coefficient of variation and bias are used to monitor quality control results to identify random and systematic errors. Increased random error causes increased variation about the mean and a higher standard deviation or CV% which allows us to compare precision in ELISA methods. Systematic error is identified by bias or a shift in the mean value and shows a change in accuracy. Total error includes random and systematic errors can be minimized as follow: - Handle reagents, calibrators and controls with extreme care - Review reagent preparation instructions - Check expiration dates on reagents/calibrators - Check reconstitution date of reagents and calibrators - Use volumetric pipette to measure control and reagent diluent)change pipette frequently(- Make fresh reagent frequently, pour fresh reagent each day, and store unused portions properly - Bring reagents to room temperature prior to use and return to the refrigerator immediately after use - Calibrate tests more frequently - Perform cleaning procedures more frequently - Clean internal reservoir frequently