Reducing the effects of control materials based on interchangeability of estimates of day‐to‐day imprecision between commercial control materials and serum samples

BACKGROUND: Reduce the effects in the storage‐and‐thawing process of commercial control materials based on their interchangeability evaluation. METHODS: Seven assays—anti‐streptolysin O, complement 3, carcinoembryonic antigen, urea, ferritin, total bilirubin, and glucose—were selected. Commercial control materials and serum samples with similar concentrations were chosen as samples. The experiment was carried out in three stages. In the first stage, the assays with statistical differences in imprecision were screened. In the second stage, two specimens were sealed with parafilm and frozen at −80°C and thawed in the water bath, and the imprecision differences were compared again. Finally, the effective means to reduce the effects were included in the standard operating procedure to repeat confirmation. RESULTS: In the first stage, there was only a statistical difference (p < 0.05) in the imprecision of glucose and total bilirubin between two specimens, and the imprecision of control materials was higher than the serum samples. In the second stage, glucose imprecision was not statistically different (p > 0.05) and lower than in the first stage. In the third stage, the methods from the second stage were confirmed to be effective at reducing control material effects. CONCLUSION: Finding variation factors and confirming and standardizing the measures will help lessen commercial control material effects.