Lot-to-lot Reagent Variation in Immunoassay: Retrospective Analysis of Daily Quality Control Results

Kim, Hyun Soo; Kang, Hee Jung; Whang, Dong Hee; Lee, Seong Gyu; Park, Min Jeong; Park, Ji Young; Cho, Hyoun Chan; Lee, Kyu Man

Abstract

BACKGROUND
Lot-to-lot reagent reproducibility is an important issue in immunoassays. However, there have been no universal criteria for acceptable lot-to-lot reproducibility. We sought to evaluate the inter-lot reagent difference by analyzing the results of various quality control materials during a certain period of time.
METHODS
The results of control materials using different reagent lots and same control lots for immunoassays of HBsAg, anti-HBs, alpha-fetoprotein (AFP), ferritin, and CA 19-9 were analyzed. The average value, standard deviation, and coefficient of variation obtained from each reagent lot were calculated and differences in mean control values between two different reagent lots were assessed. We also analyzed the difference between the last control result using one reagent and the first control result using a new reagent.
RESULTS
There was no significant difference in control values among reagent lots during this study period in all immunoassays of HBsAg, anti-HBs, AFP, ferritin, and CA 19-9. Some of the reagents showed statistical differences in QC values, but the difference was not considered clinically different. Also, at the time of reagent lot change, there was no significant difference in reagent parallel tests.
CONCLUSIONS
Lot-to-lot reagent variation was not significant in immunoassays evaluated in this study. However, this study has been performed during relatively short period by one to three reagent lot changes, parallel testing should be continuously checked at reagent lot changes in each laboratory for continuous quality assurance. These results can be used as basic data for setting the criteria of acceptance on inter-lot difference in reagent parallel tests.