According to the CLSI 24-A3 guidelines, the current recommendations are to measure the QC material a minimum of 20 times on 20 separate days. In practice, the ideal 20 measurements performed on 20 different days may not be possible and all laboratories face situations or scenarios that could hinder fulfilling this requirement. A possible approach includes four measurements per day for 5 consecutive days (yielding 20 points) and establishment of preliminary control values until sufficient internal data is available.
- From those 20 data points obtain initial mean and standard deviation.
- Compare this data with Bio-Rad product insert ranges and Unity peer data if available.
- Keep in mind your initial mean and standard deviation may need to be reestablished when moving to a new lot of reagent or calibrator.